Parasitization of lepidopterans as affected by nematicide-insecticide use in soybean.
1990
McCutcheon G.S. | Turnipseed S.G. | Sullivan M.J.
Larvae of green cloverworm, Plathypena scabra (F.), soybean looper, Pseudoplusia doplusia includens (Walker), and corn earworm, Heliothis zea (Boddie), were sampled in soybean plots (maturity groups V and VII) treated with high rates of aldicarb, carbofuran, and fenamiphos for nematode control and with acephate for thrips control. Larval collections from both maturity groups indicated that the most abundant parasitoid of lepidopterous larvae in soybean treated with nematicide and insecticide was Cotesia marginiventris (Cresson), which was responsible for >90% of the parasitism in 1984 and 1985. Thirty-three percent of small Plathypena scabra were parasitized in 1984; 23% were parasitized in 1985. None of the treatments appeared to affect the occurrence of parasitism in Plathypena scabra larvae adversely. Soybean treated with aldicarb hosted significantly more Plathypena scabra and parasitoids than untreated plots. Soybean (maturity group V) hosted significantly higher H. zea populations in soybean treated with carbofuran (1984) or aldicarb (1985) than in untreated control plots. Heliothis nuclear polyhedrosis virus and the parasitoids Microplitis croceipes (Cresson) and Cotesia marginiventris were important in regulating H. zea populations.
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