ARS | Publication request: Comparison of reproductive and flight capacity of beet webworm, Loxostege sticticalis (Lepidoptera: Pyralidae), developing from diapause and non-diapause larvae

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 13, 2012
Publication Date: N/A

Interpretive Summary: The beet webworm is a serious agricultural pest of several crops and pasture in Asia. It overwinters as a full grown caterpillar in southern regions in a state of diapause (hibernation) and escapes summer heat by migrating north. Many crop pests in North America use the same strategy, and their place and time of arrival in the north are difficult to predict. We found that the moths are more likely to make long-distance flights after overwintering than after developing directly to adulthood like they do in the summer generations. Individuals in hibernation use up some of their stored energy, but this reduces their lifetime egg laying potential only if adults are not able to feed on nectar to supplement their energy reserves. This information will be used by university and government scientists in China, the U.S., and elsewhere around the globe to better understand the relationship between hibernation, reproductive potential, and migration by these and related migratory pests. The more we learn about such pests and their biology, the better we can warn farmers of infestations and protect the crops they attack.

Technical Abstract: The beet webworm, Loxostege sticticalis L (Lepidoptera: Pyralidae), employs both diapause and migration as life history strategies. To determine the role diapause plays in the population dynamics of L. sticticalis, the reproductive and flight potentials of adults originating from diapause and non-diapause larvae were investigated under controlled laboratory conditions. Pre-oviposition period, lifetime fecundity, and daily egg production of females originating from diapause larvae were not significantly different from those originating from non-diapause larvae, showing that diapause has no significant effect on reproductive capacity when adults are provided with an adequate carbohydrate source. However, females that developed from diapause larvae lived significantly longer than those from non-diapause larvae. Flight capacity, including flight duration, distance and velocity of 3-day-old adults were all significantly greater in adults originating from diapause larvae than those from non-diapause larvae. The percentage of females originating from non-diapause larvae whose longest flight duration was greater than 3 h and whose total flight distance was greater than 16 km in adults were 40% and 27.5%, while those from diapause larvae were 73.3% and 51.1%, respectively. Together, these results suggest that long-distance flight potential of L. sticticalis is greater after larval diapause than after direct development to adulthood.