Host instar influence on offspring sex ratio and female preference of Neodryinus typhlocybae (Ashmead) (Hymenoptera, Dryinidae) parasitoid of Metcalfa pruinosa (Say) (Homoptera, Flatidae)

Publication date: Available online 17 May 2018Source: Biological ControlAuthor(s): Riccardo Favaro, Jacob Roved, Vincenzo Girolami, Isabel Martinez-Sañudo, Luca MazzonAbstractThe parasitoid wasp Neodryinus typhlocybae (Ashmead) was introduced to Europe for the biological control of nearctic planthopper Metcalfa pruinosa (Say), which causes severe damage to both crops and ornamental species in the absence of specialized natural enemies. We performed a series of experiments to evaluate the host instar preference and the effects on parasitoid offspring sex.Results showed that parasitism occurs mostly on 3rd, 4th and 5th host instars. Male parasitoid offspring were reared exclusively from 3rd instars. Both male and female offspring originated from the 4th instar, but the sex ratio remained male-biased. A greater proportion of female offspring originated from the 5th instar. Virgin mothers produced exclusively male progeny.When female wasps were exposed to an equal proportion of 3rd, 4th and 5th host instars, parasitism occurred predominantly on the 5th instar, while the least parasitized was the 3rd instar. The age of female wasps did not influence the preference for host instars or the offspring sex ratio. However, females previous experienced with small host instars resulted in a greater production of female offspring on the 5th instar, compared to females which had never encountered small instars.We discuss the relevance of these findings, which could provide new insights for...

Source: Biological Control - July 5, 2018 Category: Biology Source Type: research