Oviposition responses of soybean looper (Lepidoptera: Noctuidae) to varieties and growth stages of soybean.
Four varieties of soyabean belonging to different maturity groups (G) were each planted on 4 dates in Mississippi to measure relative oviposition preference of Pseudoplusia includens [Chrysodeixis includens]. The varieties were 'Avery' (G IV), 'Hutcheson' (G V), 'Sharkey' (G VI) and 'Braxton' (G VII). Plant growth stages evaluated in 1991 were 2 late vegetative stages (ranging from V8 to V12, depending on variety), and 2 reproductive stages including full bloom (R2) and early pod (R3). In 1992, growth stages included 1 late vegetative stage (ranging from V7 to V12, depending on variety), and R2, R3 and R4 (full pod) stages. In both years, the most mature growth stages for the soyabean varieties tested were preferred for oviposition. Moths laid significantly more eggs in the middle to upper plant canopy than in the lower canopy, and the bottom (abaxial) surface of the leaf was preferred over the top (adaxial) leaf surface, stems, blooms or pods. Knowledge of potential infestation levels of P. includens on soyabean varieties at different growth stages assists in selection of planting dates and varieties and enhances sampling efficiency and insecticide control technology.