LRES M.S. Thesis Defense
- Monday, December 11, 2017 at 9:15am
- Animal Biosciences Building, 134 - view map
Investigating the Potential of Sugar Resources to Enhance Effectiveness of Wheat Stem Sawfly Parasitoids
The wheat stem sawfly, Cephus cinctus Norton, is the most destructive insect pest of wheat in the Northern Great Plains of North America. Biological control is an important tool for integrated pest management of this pest; therefore the main objective of this research was to evaluate how to enhance reproductive capacity of Bracon cephi and B. lissogaster, the two most important biological control agents of C. cinctus. First, we investigated the role of diapause and the effects of sugar feeding on reproduction of females. For that, we provided sucrose solution to postdiapause and non-diapause adult females, and we quantified and compared their longevity, egg load and egg volume. Our results showed no differences between postdiapause and non-diapause individuals of B. cephi and B. lissogaster. In contrast, sugar feeding, increased longevity and egg load of both parasitoid species. The egg load of B. cephi was surprisingly low compared to B. lissogaster. However, only B. cephi increased egg volume when sugar was provided. This study highlighted the differences in life-history between both parasitoid species, and showed the great potential of sugar resources in enhancing their reproductive capacity. Subsequently, we investigated the effect of flower nectar on the same, above mentioned, reproductive traits of parasitoids. We chose buckwheat (Fagopyrum esculentum), lacy phacelia (Phacelia tanacetifolia), deerhorn clarkia (Clarkia pulchella), canola (Brassica napus), and safflower (Carthamus tinctorius) based on their occurrence as native, use in pollinator enhancement and occurrence in rotational or cover crop plantings in Montana. We found that only B. cephi females were able to benefit from these flowering plants. The longevity and egg volume of females increased with buckwheat, and egg volume increased with both buckwheat and the native species, deerhorn clarkia. The strong effect of buckwheat on reproduction of B. cephi females suggests that flowers with similar nectar quality might have similar profound impacts. This information will be of great importance for selection of suitable flower species to enhance reproductive capacity of parasitoids through habitat management. Collectively, this research showed that there is great potential to enhance effectiveness of parasitoids with sugar supplementation. This information will be of great importance for improving endemic biological control of C. cinctus.
- Department of Land Resources and Environmental Sciences