Responses of Liriomyza trifolii (Diptera: Agromyzidae) to chemical and biorational insecticides
Keywords:
leafminer, mine, pesticide, spray dateAbstract
One of the most troublesome pests of snap beans is the American serpentine leafminer, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae). Growers commonly use abamectin, spinosad, and cyromazine to manage L. trifolii populations; however, the biological insecticide azadirachtin and the fungus Isaria fumosorosea Wize offer promising alternatives. We tested the effectiveness of these five insecticides for controlling L. trifolii under field conditions in southern Florida. Abamectin and spinosad were generally the most effective for reducing L. trifolii mines, larvae, and/or pupae. Cyromazine and azadirachtin were less effective than abamectin or spinosad, although better than I. fumosorosea or the untreated control. Isaria fumosorosea was the least promising treatment; however, it still performed better than the control in reducing L. trifolii mines, larvae, and/or pupae. As pesticide effectiveness increased, differences in numbers of mines, larvae, and pupae appeared to be reduced among the 5 dates that pesticides were sprayed. Overall, mines appeared to be more effectively controlled 1 to 2 d after treatment than after 7 d, whereas larvae and pupae were controlled equally throughout the period. The pesticides employed can be classified into 3 general groups based on modes of action: abamectin and spinosad (disrupters of insect neural and muscular systems), cyromazine and azadirachtin (disrupters of molting), and I. fumosorosea (invades the insect, produces a toxin, and halts feeding). Pesticides with at least two modes of action were each able to provide effective control. Alternating pesticides may therefore control L. trifolii while limiting the development of resistance in L. trifolii populations.
Resumen
Un de los peores plagas de habichuelas es el minador serpentino Americano, Liriomyza trifolii Burgess (Diptera: Agromyzidae). Frecuentemente, los productores utilizan abamectina, spinosad, y ciromazina para el control de L. trifolii. Sin embargo, azadiractina, una insecticida biológica, y el hongo, Isaria fumosorosea (Wize) AHS Br. Y G. Sm., pueden ofrecer alternativas eficaces. Pusimos a la prueba el rendimiento de todas estas insecticidas para el control de L. trifolii en el campo en el sur de Florida. Abamectina y spinosad fueron generalmente los más eficaces para la reducción de las minas, larvas, y/o pupas. Ciromazina y azadiractina aparecieron menos eficaz que abamectina o spinosad, pero más eficaz que I. fumosorosea o el control no tratado. Isaria fumosorosea fue el tratamiento menos eficaz, aunque más eficaz del control para la reducción de las minas, larvas, y/o pupas. Como la eficacia de pesticidas aumentó, las diferencias en los números de las minas, larvas, y pupas disminuyieron entre los 5 aerosoles. En general, las minas aparecieron controlado más eficaz a 1–2 d después de la rociada que después de 7 d, pero las larvas y pupas fueron controlados por igual en todo el período. Sobre la base de modos de acción, los plaguicidas se clasificaron en tres grupos generales: abamectina y spinosad (disruptores de sistemas neurales y musculares en insectos), ciromazina y azadiractina (interrumpen la muda), y I. fumosorosea (invade el insecto y detiene la alimentación). Cada de las pesticidas con modos de acción diferentes fué capaz de proporcionar un control eficaz. Alternando el uso de ellos puede controlar L. trifolii mientras illimitando el desarrollo de resistencia causada por el uso continuo de las pesticidas con un modo de acción único.
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