33 research outputs found

    Timing of oviposition by western flower thrips (Thysanoptera: Thripidae) in apple fruit

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    Adult western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), were most abundant on flower clusters of apple, Malus × domestica Borkhausen, from king bloom to full bloom. Low numbers of thrips remained on the clusters after petal fall as fruit enlarged. Thrips larvae peaked in numbers after densities of adults had peaked, usually by petal fall. Two staining procedures were developed for detecting thrips eggs in the surface of fruit ovary tissues (the edible portion of fruit), and in other blossom tissues (stamen, style, calyx, stem and leaves). Eggs were abundant in the latter tissues throughout the bloom and post—bloom periods; the calyx appeared to be highly preferred. Few eggs were detected in fruit ovary tissues during bloom. Egg numbers in ovary tissues began to increase about 8-13 d after full bloom, when fruit had grown beyond 5 mm diameter. The most effective timing of pesticides corroborated the oviposition data. Formetanate hydrochloride or spinosad caused the greatest reduction in oviposition injury (pansy spot) when applied from full bloom to about 5 mm fruit diameter

    Absence of photoperiod effects on mating and ovarian maturation by three haplotypes of potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae)

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    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 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. Phortoperiod 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 tibiae than psyllids of the two southern populations. Our photoperiod results, combined with overwintering observations for this species and for 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
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