Effects of parasitization by Thripinema nicklewoodi, a potential biological control agent, on the feeding behavior and impatiens necrotic spot virus (INSV) transmission of western flower thrips, Frankliniella occidentalis, were studied in laboratory. The area of feeding damage on bean leaf disk was compared between normal and parasitized thrips. There was no statistical difference in total leaf damage made by 1st and 2nd instar larvae between the normal and parasitized thrips. However, leaf damage from parasitized adult female thrips was significantly less than that from normal adult female thrips. This negative effect was also found for honey feeding and pollen feeding. These results support a previous report that the nematode parasitization does not have negative effect on the survivorship of immature thrips but on that of adults. The effect of parasitization on INSV transmission was investigated by comparing rates of INSV infection (using ELISA) for adult thrips fed on impatiens leaves with INSV symptoms and previously exposed to the nematode as immature stages versus controls never exposed to nematode. There was a significant reduction in the number of thrips infected with INSV among nematode-parasitized thrips. A negative effect of nematode presence on virus growth or survivorship in the thrips host is proposed from the results of additional experiments.These studies provide information useful for the application of this nematode in thrips control as well as understanding the relationship between the host and parasite.
Species 1: Thysanoptera Thripidae Frankliniella occidentalis (western flower thrips)
Species 2: Tylenchida Allantonematidae Thripinema nicklewoodi
Keywords: Feeding Behavior, INSV Transmission
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