Location: Fruit and Vegetable Insect Research
Title: Absence of photoperiod effects on mating and ovarian maturation by three haplotypes of potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae) Authors
Submitted to: Journal of British Columbia Entomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 17, 2014
Publication Date: N/A
Interpretive Summary: The potato psyllid is the insect vector of zebra chip, a devastating disease of potato in the United States. Researchers at USDA-ARS Wapato in Washington, in collaboration with scientists from the Potato Commissions of Washington, Idaho, and Oregon assessed the role of daylength in the winter survival and subsequent spread of three genetic variants of this insect pest collected in Texas, California, and Washington. It was discovered that short days had no effects on reproductive development and that these insects are able to survive the winter in several life stages, resulting in local populations during the spring. Information from this research will help growers in the Pacific Northwest prevent damage to potato due to zebra chip by effectively targeting local populations of potato psyllid for control.
Technical Abstract: We examined the effects of photoperiod on reproductive diapause of three haplotypes of potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae), collected from three geographic locations: south Texas (Central haplotype), California (Western haplotype), and Washington State (Northwestern haplotype). Psyllids were reared from egg hatch to adult eclosion under short- and long-day conditions, to determine whether short-days led to a lack of mating, delays in ovarian development, and accumulation of fat by female psyllids. Our expectation was that a reproductive response to short-days, if present, would be more likely to be exhibited by psyllids of the northern-latitude haplotype (Northwestern) than psyllids of the other two haplotypes. We also examined whether this species exhibited a photoperiod-controlled polymorphism in body size, as observed in other psyllid species, by comparing six body and wing measures of psyllids reared under short- and long-day conditions. Virtually 100% of females of each haplotype exhibited both egg maturation and mating at both long- and short-day conditions, providing no evidence that this species exhibits a photoperiod-induced reproductive diapause. Fat was present in most psyllids, although with higher probability of presence in short-day females than long-day females. Photoperiod had no effect on body size. We found differences among haplotypes in body size, with psyllids from Washington State (Northwestern haplotype) having larger wings and longer tibia than psyllids of the two southern populations. Our photoperiod results, combined with overwintering observations for this and other Triozidae, prompted us to hypothesize that potato psyllid – at least in the Pacific Northwest growing region – overwinters in a temperature-controlled quiescence rather than in a true diapause.