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Psyche
Volume 2018, Article ID 8078049, 13 pages
https://doi.org/10.1155/2018/8078049
Research Article

Population Dynamics of Native Parasitoids Associated with the Asian Chestnut Gall Wasp (Dryocosmus kuriphilus) in Italy

1Department of Agrifood Production and Environmental Sciences, University of Florence, Via Maragliano 77, 50144 Florence, Italy
2Plant Health and Molecular Biology Laboratory, National Food Chain Safety Office, Directorate of Plant Protection, Soil Conservation and Agri-Environment, Budaörsi Str. 141-145, Budapest 1118, Hungary

Correspondence should be addressed to Tiziana Panzavolta; ti.ifinu@atlovaznapt

Received 30 November 2017; Revised 18 January 2018; Accepted 8 February 2018; Published 13 March 2018

Academic Editor: Juan Corley

Copyright © 2018 Tiziana Panzavolta et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Native parasitoids may play an important role in biological control. They may either support or hinder the effectiveness of introduced nonnative parasitoids released for pest control purposes. Results of a three-year survey (2011–2013) of the Asian chestnut gall wasp (ACGW) Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) populations and on parasitism rates by native indigenous parasitoids (a complex of chalcidoid hymenopterans) in Italian chestnut forests are given. Changes in D. kuriphilus gall size and phenology were observed through the three years of study. A total of 13 species of native parasitoids were recorded, accounting for fluctuating parasitism rates. This variability in parasitism rates over the three years was mainly due to the effect of Torymus flavipes (Walker) (Hymenoptera: Torymidae), which in 2011 accounted for 75% of all parasitoid specimens yet decreased drastically in the following years. This strong fluctuation may be related to climatic conditions. Besides, our data verified that parasitoids do not choose host galls based on their size, though when they do parasitize smaller ones, they exploit them better. Consequently, ACGWs have higher chances of surviving parasitism if they are inside larger galls.