Ecology of a hymenopteran parasitoid, Cotesia vanessae (Braconidae)
Citation
Hervet, V.A.D., R.A. Laird and K.D. Floate. 2016. Ecology of a hymenopteran parasitoid, Cotesia vanessae (Braconidae). XXV International Congress of Entomology. Orlando, FL, September 25-30. doi: 10.1603/ICE.2016.113328 [oral presentation]
Résumé en langage clair
Introduction: Cotesia vanessae is a Eurasian parasitoid recently reported from North America. It is a gregarious endoparasitoid whose hosts are primarily caterpillars from the Noctuidae family. Only parthenogenetic females have been collected in North America, but male/female populations are known in Europe. We investigated the potential of C. vanessaeto control North American noctuid crop pest caterpillars, as well as aspects of interspecific and intraspecific competition between developing parasitoid larvae and their caterpillar hosts.
Mathods: A no-choice test was conducted in the laboratory. Individual C. vanessae were exposed to caterpillars until one stinging event was witnessed. About 30 caterpillars of each species tested were parasitized this way. Parasitized caterpillars were then reared individually at 20° C until parasitoid emergence, undetermined cause of caterpillar death, or until successful pupation. Parasitism success, parasitoid development time, offspring numbers per host and parasitoid mass were recorded to assess the fitness of the parasitoid on the different host species.
Results/Conclusion: Out of 46 potential hosts tested (30 pests, 16 non-pests), 34 of them (24 pests, 10 non-pests) supported the development of the parasitoid. The highest parasitoid fitness was observed on caterpillars from the subfamily Plusiinae (“semi-looper” caterpillars). Scramble and contest competition was observed in developing parasitoid larvae. An unusual case of lose-lose relationship between the parasitoid and some caterpillar species was observed where both parasitoids and their hosts died before completing their development.
Résumé
Introduction: Cotesia vanessae is a Eurasian parasitoid recently reported from North America. It is a gregarious endoparasitoid whose hosts are primarily caterpillars from the Noctuidae family. Only parthenogenetic females have been collected in North America, but male/female populations are known in Europe. We investigated the potential of C. vanessaeto control North American noctuid crop pest caterpillars, as well as aspects of interspecific and intraspecific competition between developing parasitoid larvae and their caterpillar hosts.
Mathods: A no-choice test was conducted in the laboratory. Individual C. vanessae were exposed to caterpillars until one stinging event was witnessed. About 30 caterpillars of each species tested were parasitized this way. Parasitized caterpillars were then reared individually at 20° C until parasitoid emergence, undetermined cause of caterpillar death, or until successful pupation. Parasitism success, parasitoid development time, offspring numbers per host and parasitoid mass were recorded to assess the fitness of the parasitoid on the different host species.
Results/Conclusion: Out of 46 potential hosts tested (30 pests, 16 non-pests), 34 of them (24 pests, 10 non-pests) supported the development of the parasitoid. The highest parasitoid fitness was observed on caterpillars from the subfamily Plusiinae (“semi-looper” caterpillars). Scramble and contest competition was observed in developing parasitoid larvae. An unusual case of lose-lose relationship between the parasitoid and some caterpillar species was observed where both parasitoids and their hosts died before completing their development.