Effects of selected insecticides on Cotesia plutellae, endoparasitoid of Plutella xylostella |
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Authors: | M Haseeb T-X Liu WA Jones |
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Institution: | (1) Vegetable IPM Laboratory, Texas Agricultural Experiment Station, Texas A&M University, 2415 East Highway 83, Weslaco, TX, 78596-8399, USA;;(2) USDA, ARS, Kika de la Garza Subtropical Agricultural Research Center, Beneficial Insect Research Unit, 2413 E. Highway 83, Weslaco, TX 78596, USA;(3) Present address: Center for Biological Control, Florida A&M University, Tallahassee, FL 32307-4100, USA |
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Abstract: | Effects of field dosages ofselected insecticides to Cotesiaplutellae (Kurdjumov) (Hymenoptera: Braconidae), a larval endoparasitoidof Plutella xylostella L. (Lepidoptera: Plutellidae), wereinvestigated under laboratory conditions.Emergence of adult C. plutellae frominsecticide-treated pupae was not significantlydifferent from the control treatment. Contacttoxicity to C. plutellae adults variedgreatly among the insecticides in a paperresidue contact bioassay. Threeazadirachtin-based insecticides, Agroneem(4.8 mg a.i.liter–1), Neemix (20 mga.i.liter–1) and Ecozin (20 mgai.liter–1) caused 11.1, 16.7 and 5.6%adult mortality, respectively. Of fourcommercial Bacillus thuringiensis (Bt)insecticides examined (all at 1.2 mga.i.liter–1), Crymax and Xentari had noeffect on adult parasitoids, whereas Mattchcaused 5.6% mortality, and Dipel caused 11.1%mortality. Indoxacarb (53 mg a.i.liter–1), -cyhalothrin (28 mg a.i.liter–1) andspinosad (53 mg a.i.liter–1) caused 100,88.5 and 50% adult mortalities, respectively.Low adult mortality (0–5.6%) was recorded fromingestion of azadirachtin-based, Btinsecticides and indoxacarb, compared with100% adult mortality in treatments of spinosador -cyhalothrin. Compared with the watercontrol, ingestion of azadirachtin-basedinsecticides significantly reduced parasitismby 50–57%, and Bt insecticides by 8–25%.However, ingestion of these insecticides didnot affect longevity of male and femaleparasitoid adults with one exception; femalelongevity was significantly reduced in theindoxacarb treatment. Insecticide residuescaused considerable mortality of C.plutellae adults, 39 and 44% mortality causedby 10 d old indoxacarb and -cyhalothrin,respectively, and 24 and 0% mortality causedby 7 and 10 d old residues of spinosad,respectively. |
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Keywords: | Cotesia plutellae diamondback moth insecticides IPM non-target effects parasitoid Plutella xylostella |
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