Current Issue
2025 Vol.16 NO.3
2025,
16(3):
327-333.
doi: 10.15886/j.cnki.rdswxb.20240190
Abstract
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Abstract:
To clarify the occurrence and damage of leafminers on vegetables in Ningxia, China, and the species composition of their parasitoid wasps, sampling surveys on leafminers and their parasitoids on vegetables in Ningxia were conducted. The species were identified by morphological methods. From 2016 to 2019, there were five common species of leafminers observed in Ningxia, including Liriomyza sativae, Liriomyza huidobrensis, Phytomyza horticola, Liriomyza bryoniae and Liriomyza chinensis. Among these leafminers, L. huidobrensis was the highest in occurrence and number of host plants, particularly preferring Cucurbitaceae plants. L. bryoniae was only found on Brassica campestris and Lycopersicon esculentum, with low damage. The parasitoid wasp species attacking leafminers were found to have 27 species from 17 genera of 4 families. The dominant parasitoid species, based on population and parasitism rates, were Neochrysocharis formosa (1 129 individuals, 41.81% of the total) and Diglyphus isaea (458 individuals, 16.96% of the total). Leafminers in Ningxia have caused varying degrees of damage to crops, especially Fabaceae crops. It is crucial to strengthen field monitoring, early warning systems, and implement green control measures. Additionally, the region has abundant parasitoid wasp resources, and further efforts should be made to protect these natural enemies. Special attention should be given to exploring the potential biological control capabilities of dominant parasitoids such as N. formosa and D.isaea, in order to achieve sustainable and environmentally friendly pest management.
To clarify the occurrence and damage of leafminers on vegetables in Ningxia, China, and the species composition of their parasitoid wasps, sampling surveys on leafminers and their parasitoids on vegetables in Ningxia were conducted. The species were identified by morphological methods. From 2016 to 2019, there were five common species of leafminers observed in Ningxia, including Liriomyza sativae, Liriomyza huidobrensis, Phytomyza horticola, Liriomyza bryoniae and Liriomyza chinensis. Among these leafminers, L. huidobrensis was the highest in occurrence and number of host plants, particularly preferring Cucurbitaceae plants. L. bryoniae was only found on Brassica campestris and Lycopersicon esculentum, with low damage. The parasitoid wasp species attacking leafminers were found to have 27 species from 17 genera of 4 families. The dominant parasitoid species, based on population and parasitism rates, were Neochrysocharis formosa (1 129 individuals, 41.81% of the total) and Diglyphus isaea (458 individuals, 16.96% of the total). Leafminers in Ningxia have caused varying degrees of damage to crops, especially Fabaceae crops. It is crucial to strengthen field monitoring, early warning systems, and implement green control measures. Additionally, the region has abundant parasitoid wasp resources, and further efforts should be made to protect these natural enemies. Special attention should be given to exploring the potential biological control capabilities of dominant parasitoids such as N. formosa and D.isaea, in order to achieve sustainable and environmentally friendly pest management.
2025,
16(3):
334-341.
doi: 10.15886/j.cnki.rdswxb.20230142
Abstract:
Metcalfa pruinosa (Say, 1830) is an invasive pest of the genus Solenopsis that originated in North America, spread rapidly after being accidentally introduced into Europe in the late 1970s, and has been found to invade East Asia in recent years. M. pruinosa is a highly polyphagous insect with low host specificity that colonizes a variety of trees, shrubs, fruit trees and crops in agricultural, forest and urban areas. Although not reported in China, the pest has the potential risk of invasion. A qualitative assessment and a semi-quantitative analysis of this pest were carried out by using the pest risk analysis program and multi-index comprehensive evaluation method according to the international and national standards of pest risk analysis. The semi-quantitative analysis showed that the comprehensive risk R value of this pest was 2.41. It is a highly dangerous pest in China, and it is a potential threat to important fruit trees such as citrus, plum and apple as well as soybean crops in China. It is hence suggested that quarantine departments strengthen the regulation and supervision of the products from the quarantined area, perform early monitoring and warning, and formulate effective quarantine and control methods for this pest in China.
Metcalfa pruinosa (Say, 1830) is an invasive pest of the genus Solenopsis that originated in North America, spread rapidly after being accidentally introduced into Europe in the late 1970s, and has been found to invade East Asia in recent years. M. pruinosa is a highly polyphagous insect with low host specificity that colonizes a variety of trees, shrubs, fruit trees and crops in agricultural, forest and urban areas. Although not reported in China, the pest has the potential risk of invasion. A qualitative assessment and a semi-quantitative analysis of this pest were carried out by using the pest risk analysis program and multi-index comprehensive evaluation method according to the international and national standards of pest risk analysis. The semi-quantitative analysis showed that the comprehensive risk R value of this pest was 2.41. It is a highly dangerous pest in China, and it is a potential threat to important fruit trees such as citrus, plum and apple as well as soybean crops in China. It is hence suggested that quarantine departments strengthen the regulation and supervision of the products from the quarantined area, perform early monitoring and warning, and formulate effective quarantine and control methods for this pest in China.
2025,
16(3):
342-347.
doi: 10.15886/j.cnki.rdswxb.20240152
Abstract:
The fitness cost of resistance to dimefluthrin in Aedes albopictus was analyzed by population life table comparison method using the resistant line (RR) of Ae. albopictus for experiment with the susceptible line SS as control. The results showed that the net reproduction rate (R0), mean generation time (T), intrinsic rate of increase (rm), finite rate of increase (λ), and population doubling time (D) were 41.13, 11.77 d, 0.32 d−1, 1.38 d−1, and 2.17 d, respectively, for the susceptible line population, and. 26.48, 14.27 d, 0.23 d−1, 1.26 d−1, and 3.01 d, respectively, for the resistant line. The resistant line of Ae. albopictus was longer in population doubling time than the susceptible line, indicating that its reproductive rate has slowed down. The pupation rate and emergence rate of the susceptible and resistant lines were all 100%, indicating there was no significant difference between them. The average development time from first instar larvae to pupae was (9.66±0.17)d for the susceptible line and (11.31±0.17)d for the resistant line; the average emergence time of pupae for both of the lines was (2.15±0.04) and (2.90±0.03)d, respectively; the average survival time of female mosquitoes was (30.03±1.60) and (21.83±1.12)d, respectively, for both of the lines, and there were all significant differences. The development time of larval and pupal stages and the life span of adult mosquitoes were prolonged, indicating that there is a certain fitness cost of resistance to dimefluthrin in Ae. albopictus.
The fitness cost of resistance to dimefluthrin in Aedes albopictus was analyzed by population life table comparison method using the resistant line (RR) of Ae. albopictus for experiment with the susceptible line SS as control. The results showed that the net reproduction rate (R0), mean generation time (T), intrinsic rate of increase (rm), finite rate of increase (λ), and population doubling time (D) were 41.13, 11.77 d, 0.32 d−1, 1.38 d−1, and 2.17 d, respectively, for the susceptible line population, and. 26.48, 14.27 d, 0.23 d−1, 1.26 d−1, and 3.01 d, respectively, for the resistant line. The resistant line of Ae. albopictus was longer in population doubling time than the susceptible line, indicating that its reproductive rate has slowed down. The pupation rate and emergence rate of the susceptible and resistant lines were all 100%, indicating there was no significant difference between them. The average development time from first instar larvae to pupae was (9.66±0.17)d for the susceptible line and (11.31±0.17)d for the resistant line; the average emergence time of pupae for both of the lines was (2.15±0.04) and (2.90±0.03)d, respectively; the average survival time of female mosquitoes was (30.03±1.60) and (21.83±1.12)d, respectively, for both of the lines, and there were all significant differences. The development time of larval and pupal stages and the life span of adult mosquitoes were prolonged, indicating that there is a certain fitness cost of resistance to dimefluthrin in Ae. albopictus.
2025,
16(3):
348-356.
doi: 10.15886/j.cnki.rdswxb.20240153
Abstract:
As two tick-borne pathogens that are widely prevalent in tropical and subtropical regions, Anaplasma platys (A. platys) and Anaplasma phagocytophilum (A. phagocytophilum) are of great zoonotic and public health significance. To date, seroepidemiological investigations and analysis of associated risk factors for A. phagocytophilum and A. platys in companion dogs in Hainan are not documented. In this study, 184 companion dogs in the Haikou area of Hainan Province were tested for antibodies to Anaplasma spp. by using a standard commercialized kit, and the associated risk factors were analyzed with 128 clinical questionnaires. The results showed that the seroprevalence of antibodies of companion dogs to A. phagocytophilum/A. platys in Haikou area was 7.1%. Modeling calculations revealed a significant correlation between tick bites and seropositive antibodies to Anaplasma spp. among all investigated risk factors, further clarifying the important role of ticks as a vector. This study lays the foundation for the Anaplasma spp. epidemiologic study of companion dogs in Hainan province, and provides an important scientific basis for the prevention and control of anaplasmosis.
As two tick-borne pathogens that are widely prevalent in tropical and subtropical regions, Anaplasma platys (A. platys) and Anaplasma phagocytophilum (A. phagocytophilum) are of great zoonotic and public health significance. To date, seroepidemiological investigations and analysis of associated risk factors for A. phagocytophilum and A. platys in companion dogs in Hainan are not documented. In this study, 184 companion dogs in the Haikou area of Hainan Province were tested for antibodies to Anaplasma spp. by using a standard commercialized kit, and the associated risk factors were analyzed with 128 clinical questionnaires. The results showed that the seroprevalence of antibodies of companion dogs to A. phagocytophilum/A. platys in Haikou area was 7.1%. Modeling calculations revealed a significant correlation between tick bites and seropositive antibodies to Anaplasma spp. among all investigated risk factors, further clarifying the important role of ticks as a vector. This study lays the foundation for the Anaplasma spp. epidemiologic study of companion dogs in Hainan province, and provides an important scientific basis for the prevention and control of anaplasmosis.
2025,
16(3):
357-362.
doi: 10.15886/j.cnki.rdswxb.20240111
Abstract:
Hainan rice, as an important part of Hainan agriculture, possesses unique development advantages with its superior tropical natural conditions and abundant light and temperature resources. By analyzing the current status of the Hainan rice industry in terms of planting area, production, rice varieties and branding. The analysis showed that there are major problems in rice production in Hainan, such as high cost, low yield and no premium. In order to solve these problems and promote the green and efficient development of Hainan's rice industry, proposed relevant countermeasures and suggestions, including promoting intelligent mechanised planting to reduce costs, relying on scientific and technological innovations to improve rice yield, implementing green production modes to improve the quality and efficiency of rice, as well as strengthening brand building and market promotion. The comprehensive application of these countermeasures aims to improve the market competitiveness of Hainan rice, achieve a win-win situation in terms of ecological and economic benefits, and promote the sustainable development of rice industry in Hainan.
Hainan rice, as an important part of Hainan agriculture, possesses unique development advantages with its superior tropical natural conditions and abundant light and temperature resources. By analyzing the current status of the Hainan rice industry in terms of planting area, production, rice varieties and branding. The analysis showed that there are major problems in rice production in Hainan, such as high cost, low yield and no premium. In order to solve these problems and promote the green and efficient development of Hainan's rice industry, proposed relevant countermeasures and suggestions, including promoting intelligent mechanised planting to reduce costs, relying on scientific and technological innovations to improve rice yield, implementing green production modes to improve the quality and efficiency of rice, as well as strengthening brand building and market promotion. The comprehensive application of these countermeasures aims to improve the market competitiveness of Hainan rice, achieve a win-win situation in terms of ecological and economic benefits, and promote the sustainable development of rice industry in Hainan.
2025,
16(3):
363-369.
doi: 10.15886/j.cnki.rdswxb.20240145
Abstract:
Auxin is widely present in plants and plays an important role in mediating plant development and disease resistance. The Aux/IAA family are widely involved in the early response of auxin and regulate the entire process of auxin signal transduction. In order to study the characteristics of Aux/IAA and their roles in reponse to stresses, this study cloned and identified the MeIAA19 from cassava, which encodes 244 aa with a typical PB1 conserved domain of Aux/IAA proteins. Additionally, MeIAA19 protein, expressed and purified from DE3 strains, could significantly induced ROS burst and MePR1 and MePR2 expression. Moreover, the expression level of MeIAA19 significantly increased with time under Xam infection. These results will provide a certain theoretical basis for exploring the function and mechanism of action of the MeIAA19 in cassava.
Auxin is widely present in plants and plays an important role in mediating plant development and disease resistance. The Aux/IAA family are widely involved in the early response of auxin and regulate the entire process of auxin signal transduction. In order to study the characteristics of Aux/IAA and their roles in reponse to stresses, this study cloned and identified the MeIAA19 from cassava, which encodes 244 aa with a typical PB1 conserved domain of Aux/IAA proteins. Additionally, MeIAA19 protein, expressed and purified from DE3 strains, could significantly induced ROS burst and MePR1 and MePR2 expression. Moreover, the expression level of MeIAA19 significantly increased with time under Xam infection. These results will provide a certain theoretical basis for exploring the function and mechanism of action of the MeIAA19 in cassava.
2025,
16(3):
370-378.
doi: 10.15886/j.cnki.rdswxb.20240146
Abstract:
In order to investigate the protein function of MeDAWDLE, Cassava SC 124 was used as a variety of cassava to isolate and identify its MeDAWDLE through PCR amplification. The evolutionary tree revealed that MeDAWDLE shares high homology with the DAWDLE protein in apples at a homology rate of 76.3%. Analysis of the physicochemical properties of MeDAWDLE sequence revealed that the molecular weight of MeDAWDLE is 52 kDa and that the theoretical isoelectric point of MeDAWDLE is 5.04. Expression analysis showed that MeDAWDLE is distributed in different tissues and organs of cassava, and the transcript of MeDAWDLE is upregulated under stress conditions. To explore the protein function of MeDAWDLE, the expression vector was constructed and the protein was induced. Further protein function analysis revealed that MeDAWDLE can significantly increase the reactive oxygen species (ROS) levels and the disease resistance of cassava. All these results indicated that MeDAWDLEmight play an important role in cassava stress response.
In order to investigate the protein function of MeDAWDLE, Cassava SC 124 was used as a variety of cassava to isolate and identify its MeDAWDLE through PCR amplification. The evolutionary tree revealed that MeDAWDLE shares high homology with the DAWDLE protein in apples at a homology rate of 76.3%. Analysis of the physicochemical properties of MeDAWDLE sequence revealed that the molecular weight of MeDAWDLE is 52 kDa and that the theoretical isoelectric point of MeDAWDLE is 5.04. Expression analysis showed that MeDAWDLE is distributed in different tissues and organs of cassava, and the transcript of MeDAWDLE is upregulated under stress conditions. To explore the protein function of MeDAWDLE, the expression vector was constructed and the protein was induced. Further protein function analysis revealed that MeDAWDLE can significantly increase the reactive oxygen species (ROS) levels and the disease resistance of cassava. All these results indicated that MeDAWDLEmight play an important role in cassava stress response.
2025,
16(3):
379-388.
doi: 10.15886/j.cnki.rdswxb.20240057
Abstract:
In order to clarify the effect of biochar application on maize (Zea mays) in the tropics, two types of biochar, peanut hull biochar and rice hull biochar, were applied to the maize field at the rates of 10, 20, 40, and 60 t·hm−2), with no biochar as the control (CK), to observe their effects on the growth, development, nutrient accumulation and yield of the maize, and the soil properties in the maize field three years after biochar application. The results showed that the plant height and leaf SPAD values of maize were not significantly different among treatments throughout the reproductive period, while at the silking stage, the leaf SPAD values of maize in the 40 t·hm−2 treatment were significantly higher than those in the 60 t·hm−2 treatment. In addition, with the increase of biochar application rate, the soil pH and the contents of organic carbon, ammonium nitrogen, soil available phosphorus and soil available potassium in the 0～40 cm soil layer at the maturity stage of maize increased gradually. Except for the 40 t·hm−2 treatment, the 60 t·hm−2 treatment significantly increased the soil pH, and the contents of organic carbon, ammonium nitrogen, soil available phosphorus and soil available potassium as against the other treatments. At the same time, there was no significant difference in the contents of soil ammonium nitrogen and soil available phosphorus between the 40 t·hm−2 treatment and CK. The 40 t·hm−2 treatment had the highest accumulation in maize dry matter, nitrogen, phosphorus and potassium, and was highest in number of grains in ears and yield, which were significantly higher than those of the CK treatment. However, there was no significant difference in utilization efficiency of nitrogen, phosphorus and potassium between the 40 t·hm−2 treatment and CK. Correlation analysis found that yield was significantly positively correlated with soil pH, dry matter accumulation, plant N, P and K accumulation and number of grains in ears. Taken together, the 40 t·hm−2 biochar treatment could improve the soil and the growth and nutrient utilization and yield of maize, which could be optimal in the tropics, and rice hull biochar was superior to peanut hull biochar.
In order to clarify the effect of biochar application on maize (Zea mays) in the tropics, two types of biochar, peanut hull biochar and rice hull biochar, were applied to the maize field at the rates of 10, 20, 40, and 60 t·hm−2), with no biochar as the control (CK), to observe their effects on the growth, development, nutrient accumulation and yield of the maize, and the soil properties in the maize field three years after biochar application. The results showed that the plant height and leaf SPAD values of maize were not significantly different among treatments throughout the reproductive period, while at the silking stage, the leaf SPAD values of maize in the 40 t·hm−2 treatment were significantly higher than those in the 60 t·hm−2 treatment. In addition, with the increase of biochar application rate, the soil pH and the contents of organic carbon, ammonium nitrogen, soil available phosphorus and soil available potassium in the 0～40 cm soil layer at the maturity stage of maize increased gradually. Except for the 40 t·hm−2 treatment, the 60 t·hm−2 treatment significantly increased the soil pH, and the contents of organic carbon, ammonium nitrogen, soil available phosphorus and soil available potassium as against the other treatments. At the same time, there was no significant difference in the contents of soil ammonium nitrogen and soil available phosphorus between the 40 t·hm−2 treatment and CK. The 40 t·hm−2 treatment had the highest accumulation in maize dry matter, nitrogen, phosphorus and potassium, and was highest in number of grains in ears and yield, which were significantly higher than those of the CK treatment. However, there was no significant difference in utilization efficiency of nitrogen, phosphorus and potassium between the 40 t·hm−2 treatment and CK. Correlation analysis found that yield was significantly positively correlated with soil pH, dry matter accumulation, plant N, P and K accumulation and number of grains in ears. Taken together, the 40 t·hm−2 biochar treatment could improve the soil and the growth and nutrient utilization and yield of maize, which could be optimal in the tropics, and rice hull biochar was superior to peanut hull biochar.
2025,
16(3):
389-399.
doi: 10.15886/j.cnki.rdswxb.20230143
Abstract:
The rubber tree (Hevea brasiliensis) is an important economic crop in tropical areas of China, and its related industries play an important role in the local agricultural economy. The powdery mildew fungus Erysiphe quercicola is the most severe disease infecting H. brasiliensis. The effector proteins secreted by phytopahogenic microbes play important roles in the pathogenesis, but how effector proteins promote the infection by E. quercicola is less documented, which has limited disease resistance breeding programme and disease control strategies. The E. quercicola has 24 highly conserved candidate effector proteins, which has homologous in many other powdery mildews. It is possible that these proteins are required for the pathogenicity of powdery mildew. In order to find the important virulence factor among the 24 CSEPs, two conserved effector proteins were selected for functional analysis and found that only the effector CSEP00565 suppressed hypersensitive responses induced by Phytophthora infestans INF1 when these effectors were expressed in Nicotiana benthamiana. The effector CSEP00565 suppressed callose deposition induced by fungal chitin and bacteria flg22 when this effector was expressed in Arabidopsis thaliana, further supporting that CSEP00565 has a function to inhibit plant immunity. When CSEP00565 was further silenced by using spray-induced gene, the pathogenicity of the fungus significantly decreased. And the expression level of CSEP00565 was up-regulated at the haustorium formation stage (24 h) after inoculation with E. quercicola. Further research has discovered that the signal peptide of CSEP00565 possesses the activity of direct protein secretion. All these results indicate that CSEP00565 is a key virulence factor in promoting the infection by E. quercicola, which is conducive to understanding of the molecular mechanisms underlying H. brasiliensis-E. quercicola interaction.
The rubber tree (Hevea brasiliensis) is an important economic crop in tropical areas of China, and its related industries play an important role in the local agricultural economy. The powdery mildew fungus Erysiphe quercicola is the most severe disease infecting H. brasiliensis. The effector proteins secreted by phytopahogenic microbes play important roles in the pathogenesis, but how effector proteins promote the infection by E. quercicola is less documented, which has limited disease resistance breeding programme and disease control strategies. The E. quercicola has 24 highly conserved candidate effector proteins, which has homologous in many other powdery mildews. It is possible that these proteins are required for the pathogenicity of powdery mildew. In order to find the important virulence factor among the 24 CSEPs, two conserved effector proteins were selected for functional analysis and found that only the effector CSEP00565 suppressed hypersensitive responses induced by Phytophthora infestans INF1 when these effectors were expressed in Nicotiana benthamiana. The effector CSEP00565 suppressed callose deposition induced by fungal chitin and bacteria flg22 when this effector was expressed in Arabidopsis thaliana, further supporting that CSEP00565 has a function to inhibit plant immunity. When CSEP00565 was further silenced by using spray-induced gene, the pathogenicity of the fungus significantly decreased. And the expression level of CSEP00565 was up-regulated at the haustorium formation stage (24 h) after inoculation with E. quercicola. Further research has discovered that the signal peptide of CSEP00565 possesses the activity of direct protein secretion. All these results indicate that CSEP00565 is a key virulence factor in promoting the infection by E. quercicola, which is conducive to understanding of the molecular mechanisms underlying H. brasiliensis-E. quercicola interaction.
2025,
16(3):
400-405.
doi: 10.15886/j.cnki.rdswxb.20240108
Abstract:
The occurrence of fresh corn pests is serious in Hainan, which seriously threatens the safety of fresh corn production. In order to develop a technical model suitable for the green production of corn in Hainan, a survey was made of the occurrence of the main harmful populations and natural enemies of corn pests from 2019−2023, and the prevention and control experiments and demonstrations were also completed. The results showed that Spodoptera frugiperda infested corn during the whole growth period of corn and accounted for more than 40% of the pest population, which results in an infestation percentage of 25% to 43%. As a secondary pest, Ostrinia furnacalis accounted for more than 25% of the pest population, and the percentage of infestation caused thereby was 5% to 17%. With the invasion of S. frugiperda, the application frequency of chemical pesticides in a single corn growth period increased significantly in 2020, from 4.27～5.47 times in 2019 to 7.73～8.77 times in 2020, which may have a potential negative impact on the environment. Natural enemy insects play an important role in the biological control of corn pests, among which parasitic natural enemies are dominant and account for 75.89% of the population. The parasitism rates of Trichogramma sp. and Telenomus remus were 23.22% and 7.91%, respectively. In 2023, by applying the combined control strategy of natural enemy insects and pathogenic microorganisms, the control effect of S. frugiperda and O. furnacalis reached 81.41% and 78.77%, respectively, which were equivalent to the chemical control effect. The combined control mode of parasitic wasps and Metarhizium sp. has a significant effect on pest control, reduces the use of chemical pesticides, is safe for corn production, and can be applied to the pest control of fresh corn in Hainan.
The occurrence of fresh corn pests is serious in Hainan, which seriously threatens the safety of fresh corn production. In order to develop a technical model suitable for the green production of corn in Hainan, a survey was made of the occurrence of the main harmful populations and natural enemies of corn pests from 2019−2023, and the prevention and control experiments and demonstrations were also completed. The results showed that Spodoptera frugiperda infested corn during the whole growth period of corn and accounted for more than 40% of the pest population, which results in an infestation percentage of 25% to 43%. As a secondary pest, Ostrinia furnacalis accounted for more than 25% of the pest population, and the percentage of infestation caused thereby was 5% to 17%. With the invasion of S. frugiperda, the application frequency of chemical pesticides in a single corn growth period increased significantly in 2020, from 4.27～5.47 times in 2019 to 7.73～8.77 times in 2020, which may have a potential negative impact on the environment. Natural enemy insects play an important role in the biological control of corn pests, among which parasitic natural enemies are dominant and account for 75.89% of the population. The parasitism rates of Trichogramma sp. and Telenomus remus were 23.22% and 7.91%, respectively. In 2023, by applying the combined control strategy of natural enemy insects and pathogenic microorganisms, the control effect of S. frugiperda and O. furnacalis reached 81.41% and 78.77%, respectively, which were equivalent to the chemical control effect. The combined control mode of parasitic wasps and Metarhizium sp. has a significant effect on pest control, reduces the use of chemical pesticides, is safe for corn production, and can be applied to the pest control of fresh corn in Hainan.
2025,
16(3):
406-414.
doi: 10.15886/j.cnki.rdswxb.20240079
Abstract:
To investigate if the proline aminopeptidases (PIPases) regulate the virulence of Xanthomonas campestris pv. campestris (Xcc), we first analyzed the putative PIPases in Xcc by bioinformatics; then expressed and purified these proteins, and detected their PIPase activities in vitro; finally studied the roles of these genes in Xcc virulence by analyzing the infective ability, growth rates, motility, and extracellular enzyme activities of the mutants and the coressponding complementary strains of these mutatns. The results indicate that Xcc encodes two PIPases, PipA and PipB. Mutation of either gene led to a decrease in Xcc virulence. Overexpression of pipA or pipB resulted in enhanced motility. In addition, pipA overexpression increased the activities of the extracellular proteases in Xcc, but pipB did not have this activity. Therefore, PipA and PipB may affect Xcc virulence by regulating its motility, and PipA may also regulate extracellular protease activity to affect Xcc infection.
To investigate if the proline aminopeptidases (PIPases) regulate the virulence of Xanthomonas campestris pv. campestris (Xcc), we first analyzed the putative PIPases in Xcc by bioinformatics; then expressed and purified these proteins, and detected their PIPase activities in vitro; finally studied the roles of these genes in Xcc virulence by analyzing the infective ability, growth rates, motility, and extracellular enzyme activities of the mutants and the coressponding complementary strains of these mutatns. The results indicate that Xcc encodes two PIPases, PipA and PipB. Mutation of either gene led to a decrease in Xcc virulence. Overexpression of pipA or pipB resulted in enhanced motility. In addition, pipA overexpression increased the activities of the extracellular proteases in Xcc, but pipB did not have this activity. Therefore, PipA and PipB may affect Xcc virulence by regulating its motility, and PipA may also regulate extracellular protease activity to affect Xcc infection.
2025,
16(3):
415-422.
doi: 10.15886/j.cnki.rdswxb.20240022
Abstract:
Cotton verticillium wilt is a destructive disease that seriously affects the cotton industry. Verticillium dahliae is the main causing agent of cotton verticillium wilt in Chin. It is difficult to effectively controll this disease through conventional methods, and it hence is of great significance to establish a rapid and efficient detection method for early monitoring, diagnosis, and controlling of this disease. A highly conserved DNA sequence among strains of V. dahliae and a high divergence among different species were discovered by using NCBI BLAST. Based on this DNA segment, six pairs of PCR primers were designed and one set of primers that are highly specific and sensitive were eventually selected for detecting V. dahliae through nested PCR. And the optimal amplification conditions for these primers were determined. A set of nested PCR primers were identified, namely V.d-2 and V.d-5. The amplification conditions are as follows: 95 ℃ for 5 minutes, 95 ℃ for 30 seconds, 58 ℃ for 30 seconds, 72 ℃ for 1 minute, performed 35 cycles. The resulting bands are of sizes 512 bp and 375 bp, respectively. Resulting nested PCR can be used to detect the lowest amount of pathogenic DNA at 1×10−6 ng·μL−1, which is 3 orders of magnitude higher in sensitivity compared to the conventional PCR. The primer specifity was verified by using 15 species of pathogens such as Verticillium longisporum, etc. The lowest number of 10 spores each conton seed bearing pathogen of V. dahliae can be detected by using this method.
Cotton verticillium wilt is a destructive disease that seriously affects the cotton industry. Verticillium dahliae is the main causing agent of cotton verticillium wilt in Chin. It is difficult to effectively controll this disease through conventional methods, and it hence is of great significance to establish a rapid and efficient detection method for early monitoring, diagnosis, and controlling of this disease. A highly conserved DNA sequence among strains of V. dahliae and a high divergence among different species were discovered by using NCBI BLAST. Based on this DNA segment, six pairs of PCR primers were designed and one set of primers that are highly specific and sensitive were eventually selected for detecting V. dahliae through nested PCR. And the optimal amplification conditions for these primers were determined. A set of nested PCR primers were identified, namely V.d-2 and V.d-5. The amplification conditions are as follows: 95 ℃ for 5 minutes, 95 ℃ for 30 seconds, 58 ℃ for 30 seconds, 72 ℃ for 1 minute, performed 35 cycles. The resulting bands are of sizes 512 bp and 375 bp, respectively. Resulting nested PCR can be used to detect the lowest amount of pathogenic DNA at 1×10−6 ng·μL−1, which is 3 orders of magnitude higher in sensitivity compared to the conventional PCR. The primer specifity was verified by using 15 species of pathogens such as Verticillium longisporum, etc. The lowest number of 10 spores each conton seed bearing pathogen of V. dahliae can be detected by using this method.
2025,
16(3):
423-429.
doi: 10.15886/j.cnki.rdswxb.20240137
Abstract:
Pine wilt disease, caused by Bursaphelenchus xylophilus, has done significant damage to pine forests. The trunk injection method is a new way to prevent and control B. xylophilus. It is urgent to develop new prevention and control agents that can slow down B. xylophilus's resistance to existing insecticides. Plant-derived natural active substances are a promising option as they have a strong toxic effect on B. xylophilus. This study selected five common plants (Mikania micrantha, Lantana camara, Camellia oleifera, Melia azedarach, and Polygonum hydropiper) in the Guangxi Zhuang Autonomous Region to obtain their water extracts. The study investigated the toxic effects of these extracts on B. xylophilus using an immersion method and analyzed their impact on B. xylophilus 's activity and reproductive capabilities. The results showed that the water extracts from all five plants had some toxic effect on B. xylophilus. Specifically, Lantana camara achieved a corrected mortality rate of 95.05% after 72 hours of treatment at a concentration of 40 g·L−1. Lantana camara exhibited the strongest inhibition of B. xylophilus's activity, while Melia azedarach showed the strongest inhibition of B. xylophilus 's reproductive capability. Research results indicate that Lantana camara and Melia azedarach can be used to serve as potential materials for developing green control agents against B. xylophilus.
Pine wilt disease, caused by Bursaphelenchus xylophilus, has done significant damage to pine forests. The trunk injection method is a new way to prevent and control B. xylophilus. It is urgent to develop new prevention and control agents that can slow down B. xylophilus's resistance to existing insecticides. Plant-derived natural active substances are a promising option as they have a strong toxic effect on B. xylophilus. This study selected five common plants (Mikania micrantha, Lantana camara, Camellia oleifera, Melia azedarach, and Polygonum hydropiper) in the Guangxi Zhuang Autonomous Region to obtain their water extracts. The study investigated the toxic effects of these extracts on B. xylophilus using an immersion method and analyzed their impact on B. xylophilus 's activity and reproductive capabilities. The results showed that the water extracts from all five plants had some toxic effect on B. xylophilus. Specifically, Lantana camara achieved a corrected mortality rate of 95.05% after 72 hours of treatment at a concentration of 40 g·L−1. Lantana camara exhibited the strongest inhibition of B. xylophilus's activity, while Melia azedarach showed the strongest inhibition of B. xylophilus 's reproductive capability. Research results indicate that Lantana camara and Melia azedarach can be used to serve as potential materials for developing green control agents against B. xylophilus.
2025,
16(3):
430-441.
doi: 10.15886/j.cnki.rdswxb.20240180
Abstract:
A faunal analysis was made of Heteroptera insects in the main peak region of Jianfengling, Mountans, Hainan Island to elucidate species composition and distribution patterns of Heteroptera insects in this region. This is of great significance for the biodiversity conservation of Jianfengling Mountains. The faunal characteristics of the Heteroptera insects in the main peak area of Jianfengling Mountains, Hainan Island was analyzed through line transect survey, species identification, data collation and analysis. The analysis results show that a total of 100 species of Heteroptera insects were recorded in the main peak area of Jianfengling Mountains, Hainan Island, belonging to 85 genera and 15 families. Among the families identified the Reduviidae and Pentatomidae are dominant. The Reduviidae has the higher number of species, with a total of 34 species, accounting for 34% of the total species; followed by the Pentatomidae, with a total of 25 species, accounting for 25% of the total species. Overall, there is no obvious dominant genus in this region. In terms of the composition of genera, monotypic genera contain the highest number of species, with a total of 74 species, accounting for 74% of the total species; oligotypic genera contain 26 species, accounting for 26% of the total species. The genus with the largest number of species is Physopelta, with a total of 5 species recorded, accounting for 5% of the total species. The Heteroptera insects in the main peak area of Jianfengling Mountains on Hainan Island are mainly composed of Oriental and Palearctic realms in the Zoological fauna of the world at the genus level, with the Oriental realm accounting for the highest proportion, followed by the Palearctic realm. In the zoogeographic fauna of China, the components at genus levels are mainly composed of those in South China region, Southwest District region and Central China region, exhibiting the distribution characteristics of multiple regions. Among them, the components from the South China region account for the highest proportion, followed by those from the Southwest District region and Central China region. Overall, the diversity of insect species in the Jianfengling Mountains area of Hainan Island is relatively complex. All these results provide basic information for the comprehensive investigation and research of insects in the Jianfengling Mountains area of Hainan Island, and at the same time also offer scientific reference for the prevention and control of Heteroptera pests and the protection and utilization of predatory Heteroptera insects.
A faunal analysis was made of Heteroptera insects in the main peak region of Jianfengling, Mountans, Hainan Island to elucidate species composition and distribution patterns of Heteroptera insects in this region. This is of great significance for the biodiversity conservation of Jianfengling Mountains. The faunal characteristics of the Heteroptera insects in the main peak area of Jianfengling Mountains, Hainan Island was analyzed through line transect survey, species identification, data collation and analysis. The analysis results show that a total of 100 species of Heteroptera insects were recorded in the main peak area of Jianfengling Mountains, Hainan Island, belonging to 85 genera and 15 families. Among the families identified the Reduviidae and Pentatomidae are dominant. The Reduviidae has the higher number of species, with a total of 34 species, accounting for 34% of the total species; followed by the Pentatomidae, with a total of 25 species, accounting for 25% of the total species. Overall, there is no obvious dominant genus in this region. In terms of the composition of genera, monotypic genera contain the highest number of species, with a total of 74 species, accounting for 74% of the total species; oligotypic genera contain 26 species, accounting for 26% of the total species. The genus with the largest number of species is Physopelta, with a total of 5 species recorded, accounting for 5% of the total species. The Heteroptera insects in the main peak area of Jianfengling Mountains on Hainan Island are mainly composed of Oriental and Palearctic realms in the Zoological fauna of the world at the genus level, with the Oriental realm accounting for the highest proportion, followed by the Palearctic realm. In the zoogeographic fauna of China, the components at genus levels are mainly composed of those in South China region, Southwest District region and Central China region, exhibiting the distribution characteristics of multiple regions. Among them, the components from the South China region account for the highest proportion, followed by those from the Southwest District region and Central China region. Overall, the diversity of insect species in the Jianfengling Mountains area of Hainan Island is relatively complex. All these results provide basic information for the comprehensive investigation and research of insects in the Jianfengling Mountains area of Hainan Island, and at the same time also offer scientific reference for the prevention and control of Heteroptera pests and the protection and utilization of predatory Heteroptera insects.
2025,
16(3):
442-450.
doi: 10.15886/j.cnki.rdswxb.20240067
Abstract:
The MYB transcription factor family plays an important role in plant response to environmental stress. Capsicum annuum is the most widely cultivated species in the genus Capsicum. The transcriptome data obtained by our group were analyzed, based on which MYB44 transcription factor was selected for bioinformatics analysis of the cis-acting elements of the promoter, protein structure, evolutionary relationship. A preliminary experimental research was then conducted on subcellular localization and low temperature response. The open reading frame (ORF) of CaMYB44 gene is 981 bp in length, encoding an unstable hydrophilic protein with an amino acid of 326 aa. It is predicted that CaMYB44 protein has no signal peptide and transmembrane domain, is a non-secretory protein, and belongs to R2R3 MYB. Phylogenetic tree analysis showed that it had high homology with SmMYB73, NtMYB44-like, StMYB44-like and SlMYB44, followed by AtMYB70 and OsMYB77. Cis-acting element analysis showed that the promoter region contained a low temperature response element and multiple abscisic acid and light response elements. Subcellular localization results showed that CaMYB44 was localized in the nucleus. The RT-qPCR showed that the expression of CaMYB44 was down-regulated after 24 h of low temperature stress at 4 ℃, which was similar to the expression trend of other negative regulatory factors under low temperature stress. This paper provides basic data for further analysis of low temperature tolerance transcription factors in C. annuum.
The MYB transcription factor family plays an important role in plant response to environmental stress. Capsicum annuum is the most widely cultivated species in the genus Capsicum. The transcriptome data obtained by our group were analyzed, based on which MYB44 transcription factor was selected for bioinformatics analysis of the cis-acting elements of the promoter, protein structure, evolutionary relationship. A preliminary experimental research was then conducted on subcellular localization and low temperature response. The open reading frame (ORF) of CaMYB44 gene is 981 bp in length, encoding an unstable hydrophilic protein with an amino acid of 326 aa. It is predicted that CaMYB44 protein has no signal peptide and transmembrane domain, is a non-secretory protein, and belongs to R2R3 MYB. Phylogenetic tree analysis showed that it had high homology with SmMYB73, NtMYB44-like, StMYB44-like and SlMYB44, followed by AtMYB70 and OsMYB77. Cis-acting element analysis showed that the promoter region contained a low temperature response element and multiple abscisic acid and light response elements. Subcellular localization results showed that CaMYB44 was localized in the nucleus. The RT-qPCR showed that the expression of CaMYB44 was down-regulated after 24 h of low temperature stress at 4 ℃, which was similar to the expression trend of other negative regulatory factors under low temperature stress. This paper provides basic data for further analysis of low temperature tolerance transcription factors in C. annuum.
2025,
16(3):
451-460.
doi: 10.15886/j.cnki.rdswxb.20230135
Abstract:
Through field preliminary screening and re-screening experiments, pitaya was treated by spraying after pollination with nine plant growth regulators, including chlorpropham (CPPU), trans-abscisic acid (S-ABA), 6-benzylaminopurine (6-BA), ethephon (ETH), gibberellic acid (GA3), brassinolide (BR), diethyl aminoethyl hexanoate (DA-6), compound sodium nitrophenolate (CSN), and 1-naphthaleneacetic acid (NAA), to observe the effect of the growth regulators on scales green-retaining and fruit weight improvement of pitaya. The results indicate that appropriate plant growth regulators can promote scales green-retaining and fruit weight improvement in pitaya fruits. Treatments with CPPU diluted at 50 times, 200 times, and 100 times on the 13th and 23rd days after pollination were best in retention of green scales, and their green scale ratios were 74.84%, 74.26%, and 72.41%, respectively, with an increase ratio of 0.55, 0.53, and 0.5 times compared to the control group. The most effective treatments for promoting fruit weight were those of spraying GA3 at a dilution of 500 times on the 13th day after pollination, and spraying GA3 at dilutions of 500 times and 2000 times on the 13th and 23rd days after pollination, and their fruit weights were 411.32 g, 498.32 g, and 484.17 g, respectively, with an increase in weight ratio of 0.39, 0.32, and 0.31 times compared to the control group. The labor cost was considered in actual production in this experiment, and pitaya was thus sprayed with the plant growth regulators for only one round. The results showed that the treatment with GA3 diluted 500-folds on the 13th day after pollination was the best among the treatments in green retention of scales and fruit weight gain. Under this treatment the proportion of green parts of scales was 70.2%, showing a significant increase of 15.8% compared to the control group, and the average fruit weight was 411.3 g, significantly higher by 116.2 g compared to the control group, meeting the requirements for field production.
Through field preliminary screening and re-screening experiments, pitaya was treated by spraying after pollination with nine plant growth regulators, including chlorpropham (CPPU), trans-abscisic acid (S-ABA), 6-benzylaminopurine (6-BA), ethephon (ETH), gibberellic acid (GA3), brassinolide (BR), diethyl aminoethyl hexanoate (DA-6), compound sodium nitrophenolate (CSN), and 1-naphthaleneacetic acid (NAA), to observe the effect of the growth regulators on scales green-retaining and fruit weight improvement of pitaya. The results indicate that appropriate plant growth regulators can promote scales green-retaining and fruit weight improvement in pitaya fruits. Treatments with CPPU diluted at 50 times, 200 times, and 100 times on the 13th and 23rd days after pollination were best in retention of green scales, and their green scale ratios were 74.84%, 74.26%, and 72.41%, respectively, with an increase ratio of 0.55, 0.53, and 0.5 times compared to the control group. The most effective treatments for promoting fruit weight were those of spraying GA3 at a dilution of 500 times on the 13th day after pollination, and spraying GA3 at dilutions of 500 times and 2000 times on the 13th and 23rd days after pollination, and their fruit weights were 411.32 g, 498.32 g, and 484.17 g, respectively, with an increase in weight ratio of 0.39, 0.32, and 0.31 times compared to the control group. The labor cost was considered in actual production in this experiment, and pitaya was thus sprayed with the plant growth regulators for only one round. The results showed that the treatment with GA3 diluted 500-folds on the 13th day after pollination was the best among the treatments in green retention of scales and fruit weight gain. Under this treatment the proportion of green parts of scales was 70.2%, showing a significant increase of 15.8% compared to the control group, and the average fruit weight was 411.3 g, significantly higher by 116.2 g compared to the control group, meeting the requirements for field production.
2025,
16(3):
461-468.
doi: 10.15886/j.cnki.rdswxb.20240114
Abstract:
An attempt was made to analyze the physiological changes and transcriptome expression differences in Nypa fruticans seedlings under low light levels (CK:100% of natural light intensity; Z1: 30% of natural light intensity; Z2: 20% of natural light intensity) through shading experiments to reveal the physiological responses and differential changes in the transcriptome of N. fruticans seedlings under low light levels, providing a scientific basis for the breeding of N. fruticans. The results indicated that at 40 days under low light conditions, the superoxide dismutase (SOD) activity in N. fruticans seedlings was 57.1% higher in Z1 and 62.1% higher in Z2 as compared to CK. Similarly, peroxidase (POD) activity was 41.2% higher in Z1 and 35.7% higher in Z2 compared to CK. Malondialdehyde (MDA) content was 42.6% lower in Z1 and 32.9% lower in Z2 compared to CK. However, chlorophyll (Chl) content was decreased by 61.1% in Z1 and 70.3% in Z2 compared to CK. Soluble protein (SP) content remained stable with no significant differences observed. The root-shoot ratio was 57.6% lower in Z1 and 48.1% lower in Z2 compared to CK. Under low light levels, N. fruticans seedlings were adapted to reduced light intensity within approximately 10 days by enhancing antioxidant enzyme activities, increasing leaf area, and promoting lateral root growth. Even in lower light availability, seedlings were further adapted to the environment by improving light absorption efficiency and regulating hormone levels.
An attempt was made to analyze the physiological changes and transcriptome expression differences in Nypa fruticans seedlings under low light levels (CK:100% of natural light intensity; Z1: 30% of natural light intensity; Z2: 20% of natural light intensity) through shading experiments to reveal the physiological responses and differential changes in the transcriptome of N. fruticans seedlings under low light levels, providing a scientific basis for the breeding of N. fruticans. The results indicated that at 40 days under low light conditions, the superoxide dismutase (SOD) activity in N. fruticans seedlings was 57.1% higher in Z1 and 62.1% higher in Z2 as compared to CK. Similarly, peroxidase (POD) activity was 41.2% higher in Z1 and 35.7% higher in Z2 compared to CK. Malondialdehyde (MDA) content was 42.6% lower in Z1 and 32.9% lower in Z2 compared to CK. However, chlorophyll (Chl) content was decreased by 61.1% in Z1 and 70.3% in Z2 compared to CK. Soluble protein (SP) content remained stable with no significant differences observed. The root-shoot ratio was 57.6% lower in Z1 and 48.1% lower in Z2 compared to CK. Under low light levels, N. fruticans seedlings were adapted to reduced light intensity within approximately 10 days by enhancing antioxidant enzyme activities, increasing leaf area, and promoting lateral root growth. Even in lower light availability, seedlings were further adapted to the environment by improving light absorption efficiency and regulating hormone levels.
2025,
16(3):
469-474.
doi: 10.15886/j.cnki.rdswxb.20240034
Abstract:
In order to explore the population status and dynamic changes of Camellia sinensis var. assamica in Hainan Tropical Rainforest National Park, and to provide a scientific theoretical basis for the protection of the subsequent populations, this study used quadrat survey methods to investigate the Camellia sinensis var. assamica populations in different regions of the national park. The results are as follows: (1) The Camellia sinensis var. assamica population in Hainan Tropical Rainforest National Park has a high number of seedlings, the main body of which are small-diameter individuals, and fewer individuals of large and old trees, which is a growing population. (2) The survival curve of the Camellia sinensis var. assamica population is close to the Deevey-I type, with a high survival rate of seedlings and a high mortality rate of medium-sized trees in the second stage. (3) Different protection measures should be taken in different regions: Yinggeling and Bawang Mountain regions have abundant Camellia sinensis var. assamica seedlings and stable population development, so the focus should be on the protection of large and old trees; Limu Mountain region lacks large-diameter Camellia sinensis var. assamica individuals, so the focus should be on the protection of medium-sized individuals, so as to enable them to smoothly transition to the large-diameter stage; Diaoluo Mountain region is hindered in the regeneration of the Camellia sinensis var. assamica populations, so the nurturing of small-sized Camellia sinensis var. assamica individuals should be carried out, so as to make the transition to adult trees and realize the population regeneration smoothly. The local residents' awareness of Camellia sinensis var. assamica resources protection is relatively weak, so we should actively carry out science popularization activities related to the protection of Camellia sinensis var. assamica resources to enhance the protection awareness of the local residents.
In order to explore the population status and dynamic changes of Camellia sinensis var. assamica in Hainan Tropical Rainforest National Park, and to provide a scientific theoretical basis for the protection of the subsequent populations, this study used quadrat survey methods to investigate the Camellia sinensis var. assamica populations in different regions of the national park. The results are as follows: (1) The Camellia sinensis var. assamica population in Hainan Tropical Rainforest National Park has a high number of seedlings, the main body of which are small-diameter individuals, and fewer individuals of large and old trees, which is a growing population. (2) The survival curve of the Camellia sinensis var. assamica population is close to the Deevey-I type, with a high survival rate of seedlings and a high mortality rate of medium-sized trees in the second stage. (3) Different protection measures should be taken in different regions: Yinggeling and Bawang Mountain regions have abundant Camellia sinensis var. assamica seedlings and stable population development, so the focus should be on the protection of large and old trees; Limu Mountain region lacks large-diameter Camellia sinensis var. assamica individuals, so the focus should be on the protection of medium-sized individuals, so as to enable them to smoothly transition to the large-diameter stage; Diaoluo Mountain region is hindered in the regeneration of the Camellia sinensis var. assamica populations, so the nurturing of small-sized Camellia sinensis var. assamica individuals should be carried out, so as to make the transition to adult trees and realize the population regeneration smoothly. The local residents' awareness of Camellia sinensis var. assamica resources protection is relatively weak, so we should actively carry out science popularization activities related to the protection of Camellia sinensis var. assamica resources to enhance the protection awareness of the local residents.
2025,
16(3):
475-486.
doi: 10.15886/j.cnki.rdswxb.20240073
Abstract:
Exploring the spatial ecological niche delineation between co-distributed proximate species is crucial to understand their coexistence in the community. A survey of two species of pheasants, Red Junglefowl (Gallus gallus jabouillei) and Chinese Francolin (Francolinus pintadeanus), were made at 105 and 79 distribution sites in Datian National Nature Reserve, Hainan, from March 2023 to January 2024, respectively, using the line transect method and satellite tracking technology. A maximum entropy model was used to predict the suitable habitats for these two species of pheasants by combining 12 environmental variables, and analyze their overlap. The results showed that there are differences in the distribution patterns of suitable habitats for the two species of pheasants. The suitable habitat for the Red Junglefowl was located in the north-western and central parts of the reserve, which are dominated by deciduous broad-leaved and scrub forests, while the suitable habitat of the Chinese Francolin was located in the northern part of the reserve, and was mainly in the grass area. The potential suitable habitats of the two species of pheasants were 633.18 hm2 and 337.31 hm2, accounting for 48.61% and 25.89% of the area of the reserve, respectively. The ecological overlap indices of the Red Junglefowl and the Chinese Francolin were low, with D and I values being 0.421 and 0.711, respectively, and the overlapping area of suitable habitat was 41.31 hm2, which accounted for 17.64% and 17.22% of the area of the suitable habitats for the Red Junglefowl and the Chinese Francolin, respectively. There were similarities and differences in the selection of environmental factors by the two species. Differences lie in the fact that the variables with the greatest influence on the habitat distribution of the two species of pheasants were the distance from the ranger path and the normalized difference vegetation index (NDVI), which are mainly manifested in the fact that the Red Junglefowl preferred deciduous broad-leaved forests and scrubs near the ranger paths, whereas the Chinese Francolin was more influenced by the NDVI; similarities lie in the fact that the variable with the second highest influence on the habitat distribution of the two species of pheasants was the distance from the water source, which was manifested in the fact that the Red Junglefowl and the Chinese Francolin preferred to distribute within 400 m and 500～1000 m from water sources, respectively. This survey reveals a spatial sympatric niche relationship between the Red Junglefowl and the Chinese Francolin, and helps to further understand the interspecific competition and coexistence mechanisms of tropical pheasants.
Exploring the spatial ecological niche delineation between co-distributed proximate species is crucial to understand their coexistence in the community. A survey of two species of pheasants, Red Junglefowl (Gallus gallus jabouillei) and Chinese Francolin (Francolinus pintadeanus), were made at 105 and 79 distribution sites in Datian National Nature Reserve, Hainan, from March 2023 to January 2024, respectively, using the line transect method and satellite tracking technology. A maximum entropy model was used to predict the suitable habitats for these two species of pheasants by combining 12 environmental variables, and analyze their overlap. The results showed that there are differences in the distribution patterns of suitable habitats for the two species of pheasants. The suitable habitat for the Red Junglefowl was located in the north-western and central parts of the reserve, which are dominated by deciduous broad-leaved and scrub forests, while the suitable habitat of the Chinese Francolin was located in the northern part of the reserve, and was mainly in the grass area. The potential suitable habitats of the two species of pheasants were 633.18 hm2 and 337.31 hm2, accounting for 48.61% and 25.89% of the area of the reserve, respectively. The ecological overlap indices of the Red Junglefowl and the Chinese Francolin were low, with D and I values being 0.421 and 0.711, respectively, and the overlapping area of suitable habitat was 41.31 hm2, which accounted for 17.64% and 17.22% of the area of the suitable habitats for the Red Junglefowl and the Chinese Francolin, respectively. There were similarities and differences in the selection of environmental factors by the two species. Differences lie in the fact that the variables with the greatest influence on the habitat distribution of the two species of pheasants were the distance from the ranger path and the normalized difference vegetation index (NDVI), which are mainly manifested in the fact that the Red Junglefowl preferred deciduous broad-leaved forests and scrubs near the ranger paths, whereas the Chinese Francolin was more influenced by the NDVI; similarities lie in the fact that the variable with the second highest influence on the habitat distribution of the two species of pheasants was the distance from the water source, which was manifested in the fact that the Red Junglefowl and the Chinese Francolin preferred to distribute within 400 m and 500～
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