Contributions to the biology of the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), and its larval parasitoid Diadegma insulare (Hymenoptera: Ichneumonidae)

• Author / Creator

  Munir, Sadia

• The diamondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a destructive, and widely distributed species occurring universally wherever Brassicaceae are grown. Plutella xylostella was first reported in western Canada in 1885 and now causes extensive crop yield losses, depending on the year, throughout the Canadian prairies. Biological control through its major larval endoparasitoid, Diadegma insulare (Hymenoptera: Ichneumonidae), has been an important management strategy in North America. In western Canada, the parasitoid is responsible for a greater degree of parasitism than other native parasitoid species, providing an opportunity for integration of biological control with other management strategies of Plutella xylostella. My investigation focused on an in-depth understanding of the parasitoid’s ecology, bitrophic and tritrophic interactions among the host plant species, P. xylostella, and D. insulare. My studies on oviposition preferences and developmental performance of P. xylostella and D. insulare on host plants with water deficit stress indicated that although P. xylostella females preferred to deposit eggs on vigorous plants, not those under water stress, their preimaginal development on non-stressed plants was similar to that on stressed plants. However, water stress had a strong effect on developmental parameters of D. insulare. My studies on the development of D. insulare at various constant temperature regimes indicated that most of the fitness parameters and the rate of parasitism by D. insulare increased with a decrease in temperature. Investigations on selective floral plant species and their impact on the life-history traits of P. xylostella and D. insulare showed that none of the floral plant species were favored by the pest or parasitoid. However, floral species had a contrasting effect on various life-history traits of a pest-parasitoid system.A four-year field survey of P. xylostella and its associated parasitoid fauna in southern Alberta, Canada, indicated the dominance of larval parasitoids, particularly D. insulare, in most years.

• Subjects / Keywords

  • Biology, Diamondback moth, Diadegma insulare

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-fkjv-bv60

• License

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