Reproductive decisions are sensitive to cues of life expectancy: the case of a moth

Life history theory predicts that reproductive effort should increase as life expectancy decreases. Empirical evidence in support of this hypothesis is still fragmentary. We measured the effects of different potential indexes of mortality risk on oviposition in a geometrid moth Scotopteryx chenopodiata L. We conducted two experiments: in one we manipulated mortality risk by clipping wings or depriving the moths of food; in the other we studied the effect of incidental injuries, and varied host quality and food availability. Physical injuries led to a higher oviposition rate and shorter latency (i.e. a shorter discrimination period before oviposition) on both a high-ranked and a low-ranked host. High mortality risk was associated with a shorter latency to oviposit on the low-ranked, but not on the high-ranked host. These effects remained significant when we controlled for the influences of estimated adult age and eggload. Insects deprived of food as adults increased oviposition activity in the first experiment but not in the second. Our results suggest that certain cues of an adverse environment, as well as the individualʹs terminal condition, can increase reproductive effort and reduce host selectivity in insects.