Larval parasitism of the silver spotted skipper, Epargyreus clarus (Cramer) (Lepidoptera: Hesperiidae) in the Washington D.C. area

Authors: LILL, J. T. - George Washington University; WEISS, MARTHA - Georgetown University; BLOCK, CEDAR - George Washington University; Kula, Robert

Submitted to: Proceedings of the Entomological Society of Washington
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2020
Publication Date: 1/29/2021
Citation: Lill, J., Weiss, M.R., Block, C., Kula, R.R. 2021. Larval parasitism of the silver spotted skipper, Epargyreus clarus (Cramer) (Lepidoptera: Hesperiidae) in the Washington D.C. area. Proceedings of the Entomological Society of Washington. https://doi.org/10.4289/0013-8797.123.1.120.
DOI: https://doi.org/10.4289/0013-8797.123.1.120

Interpretive Summary: Parasitic insects attack herbivorous insects that cause billions of dollars of damage to forests annually. The parasitic wasps and flies treated in this paper attack caterpillars that feed on native and exotic plants in North American eastern deciduous forest. Increased knowledge of these parasitoids can help determine their impact as natural enemies of these caterpillars. This research uncovered parasitoids associated with a frequently encountered forest caterpillar; species interactions were discerned at four trophic levels: plant-herbivore-primary/secondary parasitoid. The seasonal rate of parasitism over a four-year period was reported, as were new trophic associations for four parasitoid wasp species. This paper will be useful to scientists conducting research on forest caterpillars, as well as personnel responsible for controlling and regulating pest and potential pest caterpillars.

Technical Abstract: Over a 4-year time span (2013–2016), we collected and reared several thousand larvae of the common skipper butterfly, Epargyreus clarus (Cramer), from six different commonly used host plants growing at sites in and around the Washington, DC metropolitan area. Of these, more than 1,500 survived to pupation or parasitoid emergence, with annual frequencies of parasitism ranging from 1.7–7.6%. More parasitoids tended to emerge from E. clarus larvae collected later in the season, and parasitism varied significantly among host plants. In total we reared six morphologically distinct species of primary parasitoids (all koin obiont endoparasitoids) from E. clarus larvae; these included four species of Braconidae and a single species each of Ichneumonidae and Tachinidae. The braconid Pneumagathis spiracularis (Muesebeck) is reported as a parasitoid of E. clarus for the first time along with the first host plant associations for P. spiracularis. New host plant associations are reported for the ichneumonid Casinaria lamina (Viereck) parasitic on E. clarus. We also report the trigonalid Orthogonalys pulchella (Cresson) as a parasitoid of P. spiracularis along with new host plant associations; P. spiracularis is the first reported host other than a species of Tachinidae and the second record of a trigonalid parasitic on a species of Braconidae. Images of adult parasitoids are provided, and relevant natural history data are presented based on our careful rearing protocol.