Inhibitory effects of permethrin on flight responses, host‐searching, and foraging behaviour of Cotesia vestalis (Hymenoptera: Braconidae), a larval parasitoid of Plutella xylostella (Lepidoptera: Plutellidae)

Abstract

Although it is well known that the application of broad‐spectrum synthetic insecticides reduces the effectiveness of natural enemies, the details of the actual mechanisms, including the lethal and sublethal effects of this reduction, are not fully understood. The inhibitory effects of a pyrethroid insecticide (permethrin), Adion 20% EC on the flight responses, host‐searching behaviour and foraging behaviour of Cotesia vestalis (Hymenoptera: Braconidae), a larval parasitoid of the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), were investigated under laboratory conditions. In choice trials, the wasps showed significant preference for P. xylostella‐infested Komatsuna plants over insecticide‐treated plants, suggesting an inhibitory effect of the insecticide on the flight response of C. vestalis. When offered a pair of plants, the wasps showed a significant preference for P. xylostella‐infested plants compared to uninfested plants. However, significantly more wasps were attracted to infested permethrin‐treated plants than to uninfested plants, suggesting that the wasps are attracted to the volatile infochemicals from the infested plants, even if treated with permethrin. The searching time was significantly shorter and the mortality of C. vestalis adults on the insecticide‐treated plants significantly higher than in the control plants treated with distilled water. These results suggest that the application of the insecticide had an inhibitory effect on the wasps’‐searching behaviour and consequently reduced the effectiveness of C. vestalis as a biological control agent against P. xylostella. In addition, the strength of the inhibitory effect of permethrin on the attraction of the wasps to the plants is critical to the survival of C. vestalis. Our results suggest that the attraction of the wasps to the permethrin‐treated infested plants increases the risk of their exposure to this insecticide.

Effects of insecticides on the foraging behaviour and survival of Cotesia vestalis, a larval parasitoid of the diamondback moth, Plutella xylostella

“…2001, 2004). In previous reports, application of permethrin to P. xylostella ‐infested Komatsuna plants, Brassica rapa , has adversely affected the foraging behaviour and the subsequent survival of female parasitoids (Kawazu et al. 2010).…”

“…2007; Choh et al. 2008; Kawazu et al. 2010), as well as those produced by herbivores themselves, such as sex pheromone (Mitchell and Mau 1971; Noldus 1989; Leal et al.…”

“…After landing on the infested plants, parasitoids can find hosts by using the volatile and/or contact infochemicals that are produced by the infested plants, hosts, and host products (Shiojiri et al. 2000b; Kawazu et al. 2010).…”

Pengaruh insektisida deltametrin terhadap perilaku orientasi parasitoid Anagrus nilaparvatae (Pang et Wang) (Hymenoptera: Mymaridae)

“…Kawazu et al (2010) menunjukkan fenomena yang sama pada Cotesia vestalis (Haliday) yang terhambat perilaku pencarian makan akibat aplikasi permetrin pada tanaman. Selain itu, perubahan fisiologi dan biokimia tanaman setelah aplikasi insektisida pada tanaman padi (Wu et al 2001;Qiu et al;Ratna 2011) diduga memberikan kontribusi pada penghambatan perilaku parasitoid dalam menemukan inangnya.…”

Sublethal Effects of Pyrethroids on Insect Parasitoids: What We Need to Further Know

“…Desneux et al (2006ab) also confirmed that the orientation behaviour A. ervi and D. rapae toward aphidinfested plants is not altered after parasitoid exposure to deltamethrin, suggesting that the greater vigour in the surviving insects may explain this lack of effect; similar results were observed by Desneux et al (2004a) when analysing A. ervi responses to the odour from aphid-infested plants after parasitoid exposure to increasing doses of lambda-cyhalothrin residues. In very recent study, Kawazu et al (2010) demonstrated that permethrin had an inhibitory effect on Cotesia vestalis (Hymenoptera: Braconidae) flight response, given that wasps showed significant preference for host-infested plants over insecticide-treated plants. Moreover, searching time was significantly shorter and the mortality of C. vestalis adults on the insecticide-treated plants significantly higher than in the control plants (treated with distilled water).…”