Stylet penetration behaviors of cotton aphids Aphis gossypii Glover on a transgenic cotton line ＂GK-12＂ expressing Bt toxic protein of Cry 1A （Bt cotton） and a non- Bt conventional cotton line ＂Simian-3＂ （CK co...Stylet penetration behaviors of cotton aphids Aphis gossypii Glover on a transgenic cotton line ＂GK-12＂ expressing Bt toxic protein of Cry 1A （Bt cotton） and a non- Bt conventional cotton line ＂Simian-3＂ （CK cotton） were recorded with the direct current electrical penetration graph （DC-EPG） technique. Cotton aphids reared on Bt cotton （abbreviated as Bt-aphids） and its parental non-Bt control line （CK-aphids） for more than 20 generations each, were used for recordings on two cotton lines. Among 47 selected parameters reflecting the activities of aphid stylets within plant tissues, there were eight parameters of CK-aphids showing significant differences between the performances of CK- aphids on Bt cotton and CK cotton, while for Bt-aphids, all the parameters were statistically equal between the performances on the two cotton lines. All parameters with significant differences indicated that CK-aphids could penetrate into Bt cotton more easily, but the phloem saps of Bt cotton were not as good as those of regular cotton for CK-aphids. Based on the present results, we concluded that there were some factors in Bt cotton affecting penetration behaviors of CK-aphids, but it just took several generations for CK-aphids to completely adapt Bt cotton, and Bt-aphids could feed on two cotton lines without difficulty.展开更多
Three commercial neem [Azadirachta indica A. Juss (Meliaceae)]-basedinsecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder, were evaluatedfor oviposition deterrence, antifeedant effect on la...Three commercial neem [Azadirachta indica A. Juss (Meliaceae)]-basedinsecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder, were evaluatedfor oviposition deterrence, antifeedant effect on larvae, and toxicity to eggs and larvae of thebeet armyworm, Spodoptera exigua (Huebner) (Lepidoptera: Noctuidae), on cotton leaves in thelaboratory. Oviposition deterrence in no-choice, and two- and five-choice assays, was observed forthe neem-based insecticide treatments when compared with a non-treated control. Neem-basedinsecticides also deterred feeding by beet armyworm larvae. Direct contact with neem-basedinsecticides decreased the survival of beet army-worm eggs. Survival of beet armyworm larvae fed for7 days on leaves treated with neem-based insecticides was reduced to 27, 33, 60, and 61% for neemleaf powder, Ecozin, Agroneem, and Neemix, respectively. Possibilities for adoption of neem-basedinsecticides in commercial cotton for beet armyworm control are discussed.展开更多
基金Acknowledgments We thank W. F. Tjallingii, Wageningen University, the Netherlands, for the scientific and technical support on DC-EPG applications, and E. A. Backus, USDA Agricultural Research Service, Crop Diseases, Pests ＆ Genetics Unit, USA, for help and comments on statistical data analysis. This work was supported jointly by National Key Basic Research Program of China （No. G2000046803）, National Natural Science Foundation of China （No. 39970153） and Jiangsu Science Foundation （BK2006501）.
文摘Stylet penetration behaviors of cotton aphids Aphis gossypii Glover on a transgenic cotton line ＂GK-12＂ expressing Bt toxic protein of Cry 1A （Bt cotton） and a non- Bt conventional cotton line ＂Simian-3＂ （CK cotton） were recorded with the direct current electrical penetration graph （DC-EPG） technique. Cotton aphids reared on Bt cotton （abbreviated as Bt-aphids） and its parental non-Bt control line （CK-aphids） for more than 20 generations each, were used for recordings on two cotton lines. Among 47 selected parameters reflecting the activities of aphid stylets within plant tissues, there were eight parameters of CK-aphids showing significant differences between the performances of CK- aphids on Bt cotton and CK cotton, while for Bt-aphids, all the parameters were statistically equal between the performances on the two cotton lines. All parameters with significant differences indicated that CK-aphids could penetrate into Bt cotton more easily, but the phloem saps of Bt cotton were not as good as those of regular cotton for CK-aphids. Based on the present results, we concluded that there were some factors in Bt cotton affecting penetration behaviors of CK-aphids, but it just took several generations for CK-aphids to completely adapt Bt cotton, and Bt-aphids could feed on two cotton lines without difficulty.
文摘Three commercial neem [Azadirachta indica A. Juss (Meliaceae)]-basedinsecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder, were evaluatedfor oviposition deterrence, antifeedant effect on larvae, and toxicity to eggs and larvae of thebeet armyworm, Spodoptera exigua (Huebner) (Lepidoptera: Noctuidae), on cotton leaves in thelaboratory. Oviposition deterrence in no-choice, and two- and five-choice assays, was observed forthe neem-based insecticide treatments when compared with a non-treated control. Neem-basedinsecticides also deterred feeding by beet armyworm larvae. Direct contact with neem-basedinsecticides decreased the survival of beet army-worm eggs. Survival of beet armyworm larvae fed for7 days on leaves treated with neem-based insecticides was reduced to 27, 33, 60, and 61% for neemleaf powder, Ecozin, Agroneem, and Neemix, respectively. Possibilities for adoption of neem-basedinsecticides in commercial cotton for beet armyworm control are discussed.
