Location: Southern Insect Management ResearchTitle: Spinosad and mixtures of an entomopathogenic fungus and pyrethrins for control of Sitona lineatus (Coleoptera: Curculionidae) in field peas
|SHRESTHA, GOVINDA - Oregon State University|
|METTUPALLI, SINDHURA - Montana State University|
|SHARMA, ANAMIKA - Montana State University|
|GADI, RAMADEVI - Montana State University|
|MILLER, DEBRA - Montana State University|
|Reddy, Gadi V.P.|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2019
Publication Date: 1/6/2020
Citation: Shrestha, G., Mettupalli, S., Sharma, A., Gadi, R., Miller, D.A., Reddy, G.V. 2020. Spinosad and mixtures of an entomopathogenic fungus and pyrethrins for control of Sitona lineatus (Coleoptera: Curculionidae) in field peas. Journal of Economic Entomology. 113:669-678. https://doi.org/10.1093/jee/toz348.
Interpretive Summary: The pea leaf weevil is an important pest of field peas and faba beans in the world. Based on the laboratory tests conducted, spinosad and the combination of B. bassiana and Pyrethrins caused the greatest mortality to adults of pea leaf weevil and reduced damage to plants. On the other hand, B. bassiana GHA caused significant adult mortality only under laboratory conditions and not on pea plants in cage studies. Field studies are necessary to further test the efficacy of Spinosad and B. bassiana + Pyrethrins against larval stages of pea leaf weevil, nodulation, as well as their ability to improve seed yield. In addition, cost/benefit analysis has to determine if application of these two bio-pesticides are economical and sustainable for Montana field pea producers. Overall, Spinosad could be an option for managing pea leaf weevil population, especially for organic field pea producers, and could be easily incorporated into an integrated pest management program.
Technical Abstract: The pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae), is an important pest of field peas and faba beans in most temperate regions of the world. As no information is currently available on efficacy of bio-pesticides for S. lineatus control, laboratory bioassays were performed to evaluate the impact of several bio-pesticides (Spinosad, Beauveria bassiana GHA, Pyrethrins, B. bassiana + Pyrethrins, and B. bassiana + Azadirachtin) against adults of this pest. The concentrations used in this bioassay were 0.1, 0.5, 1.0 and 2.0 times the lowest labeled rate of each product. Results were further verified in cage experiments by assessing bio-pesticide effects on adult mortality and feeding damage in pea plants. The impact of bio-pesticides on mortality of larvae of two beneficial species (Chrysoperla carnea and Adalia bipunctata) was also tested in laboratory conditions. We found spinosad to be the most promising candidate, causing 100% adult mortality, especially at high and medium concentrations. Beauveria bassiana GHA and its combination with pyrethrins caused 60-62% adult mortality, but only at the highest concentration. In contrast, B. bassiana + azadirachtin and pyrethrins treatments caused only minimal adult mortality at all concentrations. In cage experiments, spinosad and B. bassiana + pyrethrins had significant effects on adult mortality and provided foliage protection from adult feeding. Conversely, the fungus treatment alone showed inconsistent performance. B. bassiana and spinosad were generally harmless to C. carnea and A. bipunctata larvae, but B. bassiana + pyrethrins wastoxic towards both beneficial species. These results could help to improve integrate pest management programs intended to control S. lineatus.