Exotic ladybirds for biological control of herbivorous insects – a review

Gabriele Rondoni,Tania Zaviezo,Jana Collatz,António Onofre Soares,Audrey A Grez,Julie‐Éléonore Maisonhaute,Eric Conti,Isabel Borges,Alejandro C Costamagna,Matthew J.W Cock,Eric Lucas,Andy G Howe,Edward W Evans,François Dumont

doi:10.1111/eea.12963

Abstract

AbstractSince the late 19th century, exotic ladybirds (Coleoptera: Coccinellidae) have been used extensively for suppressing herbivorous insects of economic importance. In recent decades, the introduction of non‐native biological control (BC) agents has been greatly limited due to the awareness of the potential non‐target effects of introductions. Nonetheless, recent episodes of biological invasions of economically important pests have raised the need to carefully consider whether the expected benefits of pest control go beyond the possible environmental risks of introduction. To better understand the factors that contributed to successful BC programs, here we review the literature behind classical and augmentative BC using exotic ladybirds. Additionally, by means of case studies, we discuss the BC efficacy of selected exotic species, e.g., Coccinella septempunctata L., Harmonia axyridis (Pallas), and Hippodamia variegata (Goeze), and their position within the communities of predators in the introduced areas of USA, Canada, and Chile. In Europe, much of the research on exotic ladybirds has been conducted on the undesired impact of H. axyridis. Therefore, we summarize the risk assessment data for this species and review the field research investigating the ecological impact on European aphidophagous predators. According to the BIOCAT database of classical BC programs, 212 ladybird species belonging to 68 genera have been released in about 130 years of BC activity, with 14.6% of introductions having resulted in partial, substantial, or complete control of the target pest. However, because post‐release evaluation of establishment and BC success has not always been conducted, this rate could underestimate the successful cases. Among other factors, ladybird establishment and pest suppression mostly depend on (1) intrinsic factors, i.e., high voracity, synchronized predator‐prey life cycle, and high dispersal ability, and (2) extrinsic factors, i.e., adaptability to the new environment and landscape composition. This review contributes to improved understanding of ladybirds as exotic BC agents.

Highlights

The use of exotic – i.e., non-native – natural enemies of insect herbivores has been widely adopted in biological control (BC) (Van Driesche et al, 2008), to deal with the accidental introduction of plant pests into a new geographical area (Mason et al, 2008; Heimpel & Mills, 2017; Kenis et al, 2017b)
Using DNA gutcontent analysis, this study revealed a low intraguild predation (IGP) rate on A. bipunctata (2.8% of sampled H. axyridis) across countries, 9.6% tested positive for A. decempunctata, whereas 2.8% of larvae screened positive for Episyrphus balteatus (De Geer) (Diptera: Syrphidae) DNA; no Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) DNA was detected
In 130 years of classical BC programs, ladybirds have been extensively released for controlling herbivorous pests

Summary

Introduction

The use of exotic – i.e., non-native – natural enemies of insect herbivores has been widely adopted in biological control (BC) (Van Driesche et al, 2008), to deal with the accidental introduction of plant pests into a new geographical area (classical BC) (Mason et al, 2008; Heimpel & Mills, 2017; Kenis et al, 2017b). In spite of the positive impact of H. axyridis on aphid control (Koch & Costamagna, 2017), the commercialization of the ladybird by biocontrol suppliers has been interrupted due to the awareness of potential non-target effects on native predators (reviewed by Roy et al, 2016).

Results

Conclusion