Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of veget...Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of vegetable crops by directly feeding on phloem sap thereby inducing physiological disorders, and also serve as a vector to gemini viruses. Invariably the destructive feeding of B. tabaci affects the productivity and aesthetic values of vegetables and other horticultural crops and hence is considered a serious economic pest. A bioassay experiment was carried out by rearing B. tabaci populations on four vegetable crops under controlled laboratory conditions to determine its life table and demographic parameters. Results showed that the intrinsic rate of growth which measures the population size and growth pattern was highest for populations reared on tomato crops with the following values: rm 0.145 female female−1 day−1, the gross reproduction rate (Ro), and finite growth rate λ were highest for population reared on tomato, correspondingly the development period from egg-adult emergence was shortest with a value of 26 d. Conversely, the computed demographical parameters rm, λ and Ro for the population reared on sweet pepper were 0.106 female female−1 day−1 respectively, with a corresponding development period egg-adult emergence as 36d. The computed biological parameters for okra and garden egg varied with intermediary values between tomato and pepper host materials. The survivorship rates were quite significant for the smaller instars (Instars 1-III) with over 80% surviving to pre-pupa and pupa stage for the populations reared for all the test materials. High mortality was noticed for the pre-pupa and pupa stages as their survival rates were significantly low compared to the high survival rates of the smaller instars. Less than 50% of pupae failed to emerge to adults except for populations reared on tomato test materials where 52% emerged to adults. The study indicated tomato as the most suitable host among the four vegetable crops. Although life table and demographic parameters are invaluable information for forecasting pest populations and help in designing pest management efforts, further investigations such as the economic threshold and economic injury levels of B. tabaci population are requisite decision tools for sound pest management decisions of B. tabaci on these vegetable crops. The information obtained from this investigation would be quite relevant for extension service and pest management practitioners where mixed vegetable farming is a common practice.展开更多
The tobacco whitefly,Bemisia tabaci,is a notorious pest affecting various crops globally,and it exhibits high levels of resistance to various insecticides.Afidopyropen is a recently commercialized pyropene insecticide...The tobacco whitefly,Bemisia tabaci,is a notorious pest affecting various crops globally,and it exhibits high levels of resistance to various insecticides.Afidopyropen is a recently commercialized pyropene insecticide for B.tabaci control with high selectivity and a novel mode of action.We previously identified a high level of afidopyropen resistance in a field-collected population after selection in the lab,and named it the HD-Afi strain.In the present study,minimal cross-resistance in the HD-Afi strain was found between afidopyropen and other common chemical agents.However,the P450 enzyme activity in HD-Afi was 2.18 times the level in susceptible strain HD-S.Expression analysis revealed that two of 12 candidate P450 genes,namely CYP6DW3 and CYP4C64,were significantly up-regulated in HD-Afi.Silencing CYP6DW3 and CYP4C64 by RNA interference(RNAi)substantially increased the susceptibility of whitefly adults,confirming their involvement in afidopyropen resistance.Homology modeling and molecular docking analyses demonstrated stable binding of afidopyropen to CYP6DW3 and CYP4C64,with binding free energies of–6.87 and–6.11 kcal mol^(-1),respectively.The findings of this study suggest that the induction of CYP6DW3 and CYP4C64 facilitates afidopyropen detoxification,contributing to the development of resistance in B.tabaci.展开更多
The whitefly Bemisia tabaci are considered as a taxonomically complex that contained some destructive pests.Two of the most prevalent cryptic species are B.tabaci Middle East-Asia Minor 1（MEAM1）and Mediterranean（ME...The whitefly Bemisia tabaci are considered as a taxonomically complex that contained some destructive pests.Two of the most prevalent cryptic species are B.tabaci Middle East-Asia Minor 1（MEAM1）and Mediterranean（MED）.In an extensive field survey of the B.tabaci complex present throughout part of China from 2004 to 2007,we obtained 93 samples of B.tabaci from 22 provinces.We determined that these Chinese haplotypes included 2 invasive species（MEAM1 and MED）,and 4 indigenous cryptic species（Asia II 1,Asia II 3,China 3 and Asia II 7）by sequencing mitochondrial cytochrome oxidose one gene（mtCOI）.The diversity and genetic differentiation of a subset of 19 populations of B.tabaci were studied using cDNA amplified fragment length polymorphism（AFLP）.Prior to 2007,MEAM1 was a dominant species in many provinces in China.By 2007,MED was dominant in 11 provinces.Both invasive and indigenous species were simultaneously found in some regions.Indigenous species of B.tabaci were found in six provinces in southern China.MED and MEAM1 have broad ranges of host plants,and indigenous species appeared to have much narrower host ranges.All Asia II 3 samples were found on cotton except one on aubergine.China 3 has more host plants than Asia II 3.Twelve samples of China 3 were collected from sweet potato,Japanese hop,squash and cotton.A total of 677 reproducible bands amplified with 5 AFLP primer combinations were obtained.The highest proportion of polymorphic bands was 98.7% and the lowest was 91.9%.Unweighted pair-group method analysis indicated that the clustering was independent of the different species.MED showed the lowest degree of similarity than the other species.The data indicate that both MEAM1and MED were rapidly established in China.展开更多
文摘Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of vegetable crops by directly feeding on phloem sap thereby inducing physiological disorders, and also serve as a vector to gemini viruses. Invariably the destructive feeding of B. tabaci affects the productivity and aesthetic values of vegetables and other horticultural crops and hence is considered a serious economic pest. A bioassay experiment was carried out by rearing B. tabaci populations on four vegetable crops under controlled laboratory conditions to determine its life table and demographic parameters. Results showed that the intrinsic rate of growth which measures the population size and growth pattern was highest for populations reared on tomato crops with the following values: rm 0.145 female female−1 day−1, the gross reproduction rate (Ro), and finite growth rate λ were highest for population reared on tomato, correspondingly the development period from egg-adult emergence was shortest with a value of 26 d. Conversely, the computed demographical parameters rm, λ and Ro for the population reared on sweet pepper were 0.106 female female−1 day−1 respectively, with a corresponding development period egg-adult emergence as 36d. The computed biological parameters for okra and garden egg varied with intermediary values between tomato and pepper host materials. The survivorship rates were quite significant for the smaller instars (Instars 1-III) with over 80% surviving to pre-pupa and pupa stage for the populations reared for all the test materials. High mortality was noticed for the pre-pupa and pupa stages as their survival rates were significantly low compared to the high survival rates of the smaller instars. Less than 50% of pupae failed to emerge to adults except for populations reared on tomato test materials where 52% emerged to adults. The study indicated tomato as the most suitable host among the four vegetable crops. Although life table and demographic parameters are invaluable information for forecasting pest populations and help in designing pest management efforts, further investigations such as the economic threshold and economic injury levels of B. tabaci population are requisite decision tools for sound pest management decisions of B. tabaci on these vegetable crops. The information obtained from this investigation would be quite relevant for extension service and pest management practitioners where mixed vegetable farming is a common practice.
基金partly supported by research grants from the Outstanding Youth Foundation of the Beijing Academy of Agriculture and Forestry Sciences,China(YXQN202301)the National Natural Science Foundation of China(32272522)the Beijing Natural Science Foundation,China(6232005)。
文摘The tobacco whitefly,Bemisia tabaci,is a notorious pest affecting various crops globally,and it exhibits high levels of resistance to various insecticides.Afidopyropen is a recently commercialized pyropene insecticide for B.tabaci control with high selectivity and a novel mode of action.We previously identified a high level of afidopyropen resistance in a field-collected population after selection in the lab,and named it the HD-Afi strain.In the present study,minimal cross-resistance in the HD-Afi strain was found between afidopyropen and other common chemical agents.However,the P450 enzyme activity in HD-Afi was 2.18 times the level in susceptible strain HD-S.Expression analysis revealed that two of 12 candidate P450 genes,namely CYP6DW3 and CYP4C64,were significantly up-regulated in HD-Afi.Silencing CYP6DW3 and CYP4C64 by RNA interference(RNAi)substantially increased the susceptibility of whitefly adults,confirming their involvement in afidopyropen resistance.Homology modeling and molecular docking analyses demonstrated stable binding of afidopyropen to CYP6DW3 and CYP4C64,with binding free energies of–6.87 and–6.11 kcal mol^(-1),respectively.The findings of this study suggest that the induction of CYP6DW3 and CYP4C64 facilitates afidopyropen detoxification,contributing to the development of resistance in B.tabaci.
基金funded by the National Basic Research and Development Program ofChina(2009CB119200)the National Natural Science Foundation of China(31071683)the Earmarked Fund forModern Agro-Industry Technology Research System,China(CARS-27)
文摘The whitefly Bemisia tabaci are considered as a taxonomically complex that contained some destructive pests.Two of the most prevalent cryptic species are B.tabaci Middle East-Asia Minor 1（MEAM1）and Mediterranean（MED）.In an extensive field survey of the B.tabaci complex present throughout part of China from 2004 to 2007,we obtained 93 samples of B.tabaci from 22 provinces.We determined that these Chinese haplotypes included 2 invasive species（MEAM1 and MED）,and 4 indigenous cryptic species（Asia II 1,Asia II 3,China 3 and Asia II 7）by sequencing mitochondrial cytochrome oxidose one gene（mtCOI）.The diversity and genetic differentiation of a subset of 19 populations of B.tabaci were studied using cDNA amplified fragment length polymorphism（AFLP）.Prior to 2007,MEAM1 was a dominant species in many provinces in China.By 2007,MED was dominant in 11 provinces.Both invasive and indigenous species were simultaneously found in some regions.Indigenous species of B.tabaci were found in six provinces in southern China.MED and MEAM1 have broad ranges of host plants,and indigenous species appeared to have much narrower host ranges.All Asia II 3 samples were found on cotton except one on aubergine.China 3 has more host plants than Asia II 3.Twelve samples of China 3 were collected from sweet potato,Japanese hop,squash and cotton.A total of 677 reproducible bands amplified with 5 AFLP primer combinations were obtained.The highest proportion of polymorphic bands was 98.7% and the lowest was 91.9%.Unweighted pair-group method analysis indicated that the clustering was independent of the different species.MED showed the lowest degree of similarity than the other species.The data indicate that both MEAM1and MED were rapidly established in China.
