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Egg-laying decisions by female insects should balance aspects related to immature survival and foraging profitability of emerging larvae. Using field-captured individuals, we characterized the egg distribution of Istocheta aldrichi (Diptera: Tachinidae) on the body of its adult host, the Japanese beetle Popillia japonica (Coleoptera: Scarabaeidae). We determined whether the pattern varies as a function of host sex and the number of eggs laid on a given host. Out of the 5667 eggs observed, 95.9% were located on the host pronotum. Furthermore, eggs on the pronotum were mostly positioned in the center of this sclerite and oriented perpendicular to the host body axis. The proportion of eggs placed on other parts of the host body increased with the number of eggs per host (superparasitism). Successful development of I. aldrichi into pupae was maximum for eggs laid on the host pronotum than for eggs laid on other parts of the host. Oviposition decisions in I. aldrichi are likely shaped by trade-offs between vulnerability to grooming by the host and foraging profitability of neonate larvae (i.e., their capacity to penetrate the host cuticle), but also by the mating and defensive behaviors of the Japanese beetle. [ABSTRACT FROM AUTHOR]

The Adzuki bean beetle (ABB), Callosobruchus chinensis infests and produces several successive generations in stored lentil (Lens culinaris); although all grains are not equally damaged by the insect. Thus, to answer the question why some of the grains are left undamaged, this study was conducted with the objective of determining if the observed difference either as damaged or undamaged in a stored grain is due to the difference in level of resistance to ABB. To achieve this objective a standard choice and no-choice tests were conducted using four lentil genotypes and 0 to 24 h old ABB. The two genotypes were derived from damaged lentil grains by ABB. Lentil genotypes and genotype by age interaction did not affect the number of eggs laid per female per day; the proportion of grains with eggs or holes; eggs per grain, holes per grain and mean developmental time. On the other hand, ABB age significantly affected all the parameters considered. The number of eggs laid per female per day increased from age two to age three and declined thereafter. All parameters but mean developmental time followed a similar patter as the number of eggs per female per day. On the contrary, mean developmental time increased continuously as the age of the ABB increased. This study confirmed that grains left undamaged in bulk stored grain are not resistant to Adzuki bean beetle. [ABSTRACT FROM AUTHOR]

Indianmeal moth, Plodia interpunctella (Hübner), is one of the most important pests in retail stores and processed food facilities, but little is known about its ovipositional response to varying sizes and qualities of food sources. In this study, we monitored oviposition for 48 hours divided into 16 consecutive 3-h intervals, and found that, on average, P. interpunctella females laid eggs 6.4 times. We found a positive correlation between number of oviposition events and total oviposition. We conducted laboratory experiments to examine the distribution of eggs laid by P. interpunctella females in dishes that varied in size and number. Experiments were conducted with "improved" food (cracked or walnut oil-treated wheat kernels) and "control" food (plain untreated wheat kernels). In trials with dishes of two different sizes, P. interpunctella females seemed to distribute eggs according to the surface area of dishes regardless of the food. In trials with improved food, total oviposition was positively associated with the number of dishes, whereas the number of control dishes had no apparent effect on total oviposition. In trials with one improved food dish and one to eight control food dishes, P. interpunctella females consistently preferred oil-treated wheat kernels, whereas they showed no preference for cracked wheat kernels. Using an index of randomness (Dp), we demonstrated that the distribution of eggs was significantly different from a Poisson distribution, thus indicating that it was nonrandom, regardless of the number of dishes. Using an index of aggregation (Im2), we showed that for all the foods, the distribution of eggs became increasingly aggregated with higher numbers of dishes and that this trend was most pronounced in trials with improved foods. [ABSTRACT FROM AUTHOR]