Photoperiodic reaction in the beet webworm Loxostege sticticalis L. (Pyraloidea, Crambidae) from eastern and western parts of its Eurasian range

Stable and variable life‐history responses to temperature and photoperiod in the beet webworm, Loxostege sticticalis

“…Under short‐day conditions, in contrast, the vast majority of larvae enter diapause and yet a small amount of active individuals is also present. The current experimental design does not allow for precise estimation of diapause incidence which requires the dissection of the cocoons, and that is done in a separate study (Akhanaev et al., ). Furthermore, it has been found surprisingly difficult to distinguish between diapausing and non‐diapausing pre‐pupae as there is no obvious gap in emergence times between active and diapausing individuals (this is summarized and commented on in Appendix S1).…”

“…It was introduced into North America and has now dispersed across the Nearctic zone. Adults can travel over hundreds of kilometers, and there are periodic outbreaks of the pest that cause enormous agricultural losses (Akhanaev et al., ). The beet webworm populations vary in their voltinism both temporally and spatially, with generations overlapping to a great extent.…”

“…Despite the beet webworm's large distribution range, there is no substantial latitudinal variation of the critical day length for the induction of pre‐pupal winter diapause. The photoperiodic induction of diapause in this species has been studied many times and from many localities (Figure ), and the critical value has been invariably about 14 h, only slightly affected by temperature (Goryshin et al., ; Saulich et al., ; Huang et al., ; Akhanaev et al., ). However, European steppes differ considerably from mountain steppes and semi‐deserts of Buryatia and Mongolia.…”