BEHAVIORAL STUDIES ON FOOD PREFERENCE AND HOST-PLANT SELECTION OF BLACK CUTWORM AGROTIS IPSILON HUFNAGAL (NOCTUIDAE, LEPIDOPTERA)
Abstract
Behavioral studies were conducted to investigate food induction effects on black cutworm larval feeding preferences and adult oviposition preferences; aversion-learning behavior; and effects of test-plants on the biology of the insect. Plants tested were curled dock, Rumex crispus; lambsquarter, Chenopodium album; corn, Zea mays; and soybeans, Glycine max. Larval feeding preference was determined in multi-choice tests. Larvae were tested in the 6th instar. The order of preference for larvae reared on artificial diet and plants was curled dock over lambsquarter over corn =/or over soybeans. The only induction established was for lambsquarter-reared larvae. Similar feeding preferences existed in larvae exposed to inducing source in the early and late instar; by brief exposure of 48 hours; and through one-larval molt. However, absence of induction was noticed for lambsquarter in these experiments. Exposing larvae to artificial diet before and after feeding on the inducing plant did not alter the preference. Results on adult oviposition preferences indicate that curled dock remained the preferred host with or without previous exposure, followed by soybeans and corn. Lambsquarter did not elicit significant oviposition response in multi- and no-choice tests. No direct relationship was established between larval food and adult oviposition preference. Adult longevity, fecundity and egg fertility were highest on artificial diet and curled dock followed by corn, soybeans and lambsquarter. Investigations on aversion-learning show that illness can be induced in larvae by feeding on plants treated with Ambush('R), Lorsban('R) and Sevin('R). After recovery, larvae tested in two-choice tests, did not avoid plants that induced illness. The pattern of plant preference was consistent with earlier tests even though feeding on the treated preferred-plant caused sickness. However, reduced feeding consumption was observed in Ambush('R) treatment. Experiments were also conducted to evaluate effects of test diets on duration, survival and growth rate of larvae; duration, survival and weight of pupae; adult sex-ratio and on overall life span. Life span was longest on crops plants, intermediate on artificial diet and shortest on weeds.
Degree
Ph.D.
Subject Area
Entomology
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