Parasitoid Wasp Community Dynamics in Vineyards Following Insecticide Application

Bracha Schindler,Efrat Gavish-Regev,Tamar Keasar

doi:10.3389/fenvs.2021.785669

Abstract

In order to integrate parasitoid wasps in agroecosystems as biological control agents, we need to understand how insecticides affect the parasitoids in the crops and their surroundings. We investigated the non-target effect of Indoxacarb, an insecticide commonly used against European grapevine moth, on parasitoid wasp communities in vineyards. We focused on characterizing: 1. The dynamics of common wasp species, and 2. Wasp abundance and species richness in the vineyard center, edge, and nearby natural area. Seven vineyards, with neighboring natural areas, were sampled before, and up to 2 weeks after, Indoxacarb applications over 2 years. We expected initial negative effects of spraying in the vineyard with some effect of Indoxacarb drift into the natural habitat, followed by wasp recovery, first in natural areas, then at the vineyard edge and finally in the center. Sticky traps were hung at the vineyard edge and center to evaluate migration into and out of the vineyard. Vacuum sampling was used to obtain parasitoid total abundance and species richness, and the abundances of four common species (43% of the wasps collected). From the vacuum samples we found that total wasp abundance and richness declined after spraying in the vineyards’ margins and center but rose over time in the natural area. Vineyard wasp abundance was restored to pre-spraying levels within 2 weeks. Among the abundant species, Trichogramma sp. and Telenomus sp., which parasitize lepidopteran hosts, declined after spraying, and Trichogramma sp. recovered more quickly than Telenomus sp. Two other abundant species, Lymaenon litoralis and Oligosita sp., did not decline after spraying. In the sticky traps, wasp abundance increased at the vineyard edge but not center after spraying, suggesting that there was migration of wasps at the vineyard edge, into or out of the crop. The results indicate an effect of Indoxacarb on the parasitoid wasp community, particularly on parasitoids of lepidopterans, the target group of Indoxacarb. The results also indicate a potential for recovery of the parasitoid community through migration from neighboring natural vegetation.

Highlights

Conservation of biological control agents, such as parasitoid wasps, in agricultural areas can aid in integrated pest management schemes
Parasitoid richness and abundance were highest in natural habitat, higher in the herbaceous vegetation than in the vines, and higher in the vineyard margins than at their center (Figure 2), i.e., vineyard habitats that were close or similar in vegetation to the natural areas were richer in parasitoids
The dominant species in the natural and vineyard habitat, as well as overall parasitoid abundance and species richness appeared to recover within 2 weeks

Summary

Introduction

Conservation of biological control agents, such as parasitoid wasps, in agricultural areas can aid in integrated pest management schemes. An additional study in various field crops found negative effects of the insecticides DemetonS-methyl, an organothiophosphate, and Cypermethrin, a pyrethroid, on abundance of aphid parasitizing wasps, and less so of the insecticide Pirimicarb, a carbamate (Smart et al, 1989). While these examples suggest some potential harmful side effects of pesticides to parasitoid assemblages, communities-level field studies remain few and scattered. How parasitoid communities recover after spraying remains poorly explored

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