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Updated: Jul 19, 2026

Monitoring Colony-level Effects of Sublethal Pesticide Exposure on Honey Bees
Published on: November 15, 2017
Sub-lethal effects of deltamethrin on walking behaviour and response to host kairomone of the egg parasitoid
Gianandrea Salerno1, Stefano Colazza, Eric Conti
1Department of Arboriculture and Plant Protection-Entomology, University of Perugia, Borgo XX Giugno, Perugia 06121, Italy. salerno@unipg.it
Abstract:
The lethal doses of the pyrethroid deltamethrin were estimated for the egg parasitoid Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae), and the sub-lethal effects of an LD25 on female walking behaviour were evaluated. Linear speed of treated parasitoids was reduced compared with that of untreated ones for a period of up to 24 h. The sub-lethal effects of deltamethrin on parasitoid response to patches contaminated by a contact kairomone from its host, Nezara viridula L (Heteroptera: Pentatomidae), was also evaluated. Both treated and untreated parasitoids responded to host-contaminated patches by increasing residence time and decreasing linear speed. However, treated females showed a significantly lower residence time compared with untreated females. Both treated and untreated females showed a similar decrease over time in the proportion of time spent in the host-contaminated patch. Hence, we hypothesise that the sub-lethal effect of deltamethrin on host foraging may decrease T basalis efficacy in controlling N viridula.

