Ovipositional preferences and larval performances of two populations of Indianmeal moth, Plodia interpunctella

Oviposition decisions by female insects can determine the survival and fitness of their offspring. In this study, we assessed the larval performance and adult oviposition preferences of two populations of the Indianmeal moth, Plodia interpunctella (Hubner) (Lepidoptera: Pyralidae), one a long-term laboratory colony and another recently collected from the field. Development assays on a variety of foods were conducted on individual larvae in small shell vials, and data were collected for survival (percent), development time (days), and adult weight (mg). Larvae from both populations did not survive on ground walnut, pecan, coriander, and fennel. There were significant differences in larval survival on laboratory diet, chick pea, and soybean between the two populations. Development times were the longest on prunes and barley. Mean adult weights were the highest on chick pea, laboratory diet, and soybean for the laboratory moths whereas soybean and chick pea were very suitable for the field moths. Overall, field moths weighed significantly less than the laboratory moths. Adult ovipositional preferences were assessed in no-choice and four-choice oviposition bioassays in plastic boxes containing diets differing in quality. In a no-choice situation, the numbers of eggs laid by laboratory moths on soybean, apricots, and wheat were not significantly different. Field moths laid significantly greater numbers of eggs on soybean, and those numbers were similar to those laid on barley. In four-choice bioassays, laboratory moths oviposited in diets previously determined to be unsuitable for their progeny survival. Field moths were more selective and laid significantly greater numbers of eggs on soybean than in dishes containing barley, coriander, or an empty dish. Our studies clearly showed that laboratory colonization of Plodia interpunctella for long periods can alter the behavioral patterns of immatures and adults.