Date of Award

1987

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Entomology

Abstract

Laboratory observations on the mating behavior of soybean loopers, Pseudoplusia includens (Walker), indicated a calling pattern that was highly variable both within individual females over time and among individuals. However, some trends were apparent. The onset of calling showed temporal advancement over the first three nights of calling after adult emergence; the duration of calling showed a temporal advancement during the first six nights, while the termination of calling receded over the same period then reversed its trend. The majority of females initiated calling three nights following emergence while maximum percent calling was observed around five hours after the onset of scotophase. Spermatophore counts were highly correlated to the number of observed matings. Pairing relationships were less conclusive, although almost half of the multiple mating pairs exhibited mate fidelity. Influence of tethered flight and carbohydrate deprivation on soybean looper, whole body lipics, oviposition rate and survivorship was examined using a factorial experimental design. Food had a greater effect than flight on all three variables, although flight did decrease fecundity. Individuals that were subjected to only one stress, either two hours of daily flight or water as their only food source, were significantly different from both the no-stress group (nonflown and fed) and those that were both starved and flown. The general trend apparent for all parameters was nonflown-fed $>$ flown-fed $\cong$ nonflown-starved $>$ flown-starved, except for stored lipids which showed no statistical difference between flown-starved and nonflown-starved moths. Average longevity ranged from nine days for nonflown-fed moths to six days for flown-starved moths. These data demonstrated that the availability of a nectar source may be an important factor in the success of long distance soybean looper dispersal and subsequent reproduction. Comparison of daily and seasonal values of total body lipid, proportionate allocation of egg types, and age at first mating were examined in adult soybean loopers. Laboratory females possessed more whole body lipids than laboratory males. Laboratory individuals had a greater percentage of whole body lipids and number of chorionated eggs when compared to field collected individuals. Late season females delayed chorionated egg production and had higher non-egg lipids than summer females. Both sexes contained a greater percentage of whole body lipids late in the fall when compared to early season moths. There was no shift in time of mating or number of matings between seasons. Thus, soybean loopers appear to exhibit a number of the characteristics associated with Johnson's oogenesis-flight syndrome proposed for migratory insects.

Pages

91

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