This article combines both a review of the literature and original data from our research. The comparative efficacy of Bacillus thuringiensis （Berliner） traits Bollgard, Bollgard II, WideStrike, and non-Bt expressin...This article combines both a review of the literature and original data from our research. The comparative efficacy of Bacillus thuringiensis （Berliner） traits Bollgard, Bollgard II, WideStrike, and non-Bt expressing cotton, Gossypium hirsutum L., for control of the noctuid complex of bollworm, Helicoverpa zea （Boddie）; fall armyworm, Spodopterafrugiperda （J.E. Smith）; beet armyworm, Spodoptera exigua （Htibner）; and cabbage looper, Trichoplusia ni （Hiibner）, were evaluated in the Lower Rio Grande Valley of Texas during 2005-2009. Noctuid larval survival and damage to leaves on non-Bt cotton were 3.6-fold greater than on Bollgard II or WideStrike cotton and 1.5-fold greater than on cotton varieties with the Bollgard trait. Transgenic cotton has reduced the need for conventional insecticides with benefits to human health and the environment. The revenue differences between Bt and conventional cotton for last four years in LRGV of Texas was 214.35/ha and profit about 94.95/ha. We also analyzed cotton noctuid losses between Bt and conventionally grown cotton in the USA summary of all states and Texas summary of all regions.展开更多
Mated 3-day-old female boll weevils, Anthonomus grandis grandis Boheman, reared from field-infested cotton （Gossypium hirsutum L.） squares were topically treated with an estimated LD50 of malathion （2μg） to asses...Mated 3-day-old female boll weevils, Anthonomus grandis grandis Boheman, reared from field-infested cotton （Gossypium hirsutum L.） squares were topically treated with an estimated LD50 of malathion （2μg） to assess its effects on fecundity, oviposition, and body fat condition. Two different food sources, cotton squares and artificial diet, were assessed in malathion-treated and nontreated （control） weevils. The LD50 caused ≈ 50% mortality in the square-fed malathion treatment, but the artificial diet-fed malathion-treated weevils were less susceptible. LD50 survivors fed on the squares produced ≥ 9 times more chorionated eggs in the ovaries and oviposited ≥ 19-fold more than survivors fed artificial diet, regardless of the malathion treatment. Boll weevils that survived a 2μg LD50 malathion and also fed squares were ≈4.5-fold leaner than diet-fed weevils. Our findings demonstrate that non-resistant boll weevils surviving a sublethal dose of malathion will reproduce without any delay or significant loss in fecundity, and the food source for which boll weevils are maintained when conducting these assays will directly affect the results. The significance of these findings and how they are related to the final stages of eradicating the boll weevil from the US are discussed.展开更多
文摘This article combines both a review of the literature and original data from our research. The comparative efficacy of Bacillus thuringiensis （Berliner） traits Bollgard, Bollgard II, WideStrike, and non-Bt expressing cotton, Gossypium hirsutum L., for control of the noctuid complex of bollworm, Helicoverpa zea （Boddie）; fall armyworm, Spodopterafrugiperda （J.E. Smith）; beet armyworm, Spodoptera exigua （Htibner）; and cabbage looper, Trichoplusia ni （Hiibner）, were evaluated in the Lower Rio Grande Valley of Texas during 2005-2009. Noctuid larval survival and damage to leaves on non-Bt cotton were 3.6-fold greater than on Bollgard II or WideStrike cotton and 1.5-fold greater than on cotton varieties with the Bollgard trait. Transgenic cotton has reduced the need for conventional insecticides with benefits to human health and the environment. The revenue differences between Bt and conventional cotton for last four years in LRGV of Texas was 214.35/ha and profit about 94.95/ha. We also analyzed cotton noctuid losses between Bt and conventionally grown cotton in the USA summary of all states and Texas summary of all regions.
文摘Mated 3-day-old female boll weevils, Anthonomus grandis grandis Boheman, reared from field-infested cotton （Gossypium hirsutum L.） squares were topically treated with an estimated LD50 of malathion （2μg） to assess its effects on fecundity, oviposition, and body fat condition. Two different food sources, cotton squares and artificial diet, were assessed in malathion-treated and nontreated （control） weevils. The LD50 caused ≈ 50% mortality in the square-fed malathion treatment, but the artificial diet-fed malathion-treated weevils were less susceptible. LD50 survivors fed on the squares produced ≥ 9 times more chorionated eggs in the ovaries and oviposited ≥ 19-fold more than survivors fed artificial diet, regardless of the malathion treatment. Boll weevils that survived a 2μg LD50 malathion and also fed squares were ≈4.5-fold leaner than diet-fed weevils. Our findings demonstrate that non-resistant boll weevils surviving a sublethal dose of malathion will reproduce without any delay or significant loss in fecundity, and the food source for which boll weevils are maintained when conducting these assays will directly affect the results. The significance of these findings and how they are related to the final stages of eradicating the boll weevil from the US are discussed.
