Methyl Salicylate Increases Attraction and Function of Beneficial Arthropods in Cranberries.

Jordano Salamanca,Vera Kyryczenko-Roth,Cesar Rodriguez-Saona,Brígida Souza

doi:10.3390/insects10120423

Abstract

Methyl salicylate (MeSA) is an herbivore-induced plant volatile (HIPV) known to attract the natural enemies of herbivores in agro-ecosystems; however, whether this attraction leads to an increase in natural enemy functioning, i.e., predation, remains largely unknown. Here, we monitored for 2 years (2011–2012) the response of herbivores and natural enemies to MeSA lures (PredaLure) by using sticky and pitfall traps in cranberry bogs. In addition, European corn borer, Ostrinia nubilalis, egg masses were used to determine whether natural enemy attraction to MeSA leads to higher predation. In both years, MeSA increased adult hoverfly captures on sticky traps and augmented predation of O. nubilalis eggs. However, MeSA also attracted more phytophagous thrips and, in 2012, more plant bugs (Miridae) to sticky traps. Furthermore, we used surveillance cameras to record the identity of natural enemies attracted to MeSA and measure their predation rate. Video recordings showed that MeSA lures increase visitation by adult lady beetles, adult hoverflies, and predatory mites to sentinel eggs, and predation of these eggs doubled compared to no-lure controls. Our data indicate that MeSA lures increase predator attraction, resulting in increased predation; thus, we provide evidence that attraction to HIPVs can increase natural enemy functioning in an agro-ecosystem.

Highlights

Biological control services provided by natural enemies of herbivores constitute an integral part of integrated pest management (IPM) programs in agricultural crops [1,2,3,4]; these services can be negatively impacted by certain anthropogenic activities [5]
methyl salicylate (MeSA) had no effect on the predatory arthropod community captured in pitfall traps in both years (Table 1) or on adult scarab (Scarabaeidae) and soldier (Cantharidae) beetles captured in pitfall traps in 2011 and 2012, respectively (p > 0.05 for both)
From the field trapping and video recording experiments, we demonstrated that MeSA attracts natural enemies of herbivores—including adult hoverflies, adult lady beetles, and predatory mites—in the natural enemies of herbivores—including adult hoverflies, adult lady beetles, and predatory cranberries and that this attraction led to higher predation of sentinel eggs

Summary

Introduction

Biological control services provided by natural enemies of herbivores constitute an integral part of integrated pest management (IPM) programs in agricultural crops [1,2,3,4]; these services can be negatively impacted by certain anthropogenic activities [5]. Humans have often domesticated crops for traits associated with high productivity as opposed to defenses against herbivory. Crop domestication can inadvertently reduce the emissions of herbivore-induced plant volatiles (HIPVs), as has been observed in cranberry, Vaccinium macrocarpon Ait. Elevated HIPV production and emission are often triggered by herbivore feeding and oviposition [14,15]. These HIPVs are considered a form of indirect defense in plants because they serve as important foraging cues for natural enemies of herbivores—such as insect predators—during prey location [16,17,18,19,20,21] and could, enhance natural enemy ecosystem function (i.e., predation)

Methods

Results

Discussion

Conclusion