Toxicity of Insecticides and Miticides to Natural Enemies in Australian Grains: A Review.

Kathy Overton,Paul A Umina,Ary A Hoffmann,Olivia L Reynolds

doi:10.3390/insects12020187

Abstract

Simple SummaryControlling invertebrate pests in crop fields using chemicals has been the main management strategy within the Australian grains industry for decades. However, chemical use can have unintended effects on natural enemies, which can play a key role in suppressing and controlling pest outbreaks within crops. We undertook a literature review of studies that have conducted chemical toxicity testing against arthropod natural enemies relevant to the Australian grains industry to examine trends and highlight research gaps and priorities. Most toxicity trials have been conducted in the laboratory, with few at larger, and hence, industry-relevant scales. Researchers have used a variety of methods when conducting toxicity testing, making it difficult to compare within and across different species of natural enemies. Furthermore, we found many gaps in testing, leading to unknown toxicity effects for several key natural enemies, some of which are economically important predators and parasitoids. Through our review, we make several key recommendations for future areas of research that could arm farmers and their advisors with the knowledge they need to make informed decisions when it comes to controlling crop pests.Continued prophylactic chemical control to reduce pest populations in Australian grain farming systems has limited the effectiveness of biological control via natural enemies in crops within an integrated pest management (IPM) framework. While a variety of data is available to infer potential non-target effects of chemicals on arthropod natural enemies, much of it may be irrelevant or difficult to access. Here, we synthesise the literature relevant to Australian grain crops and highlight current knowledge gaps for potential future investment. A range of testing methodologies have been utilised, often deviating from standardised International Organization for Biological Control (IOBC) protocols. Consistent with findings from over 30 years ago, research has continued to occur predominantly at laboratory scales and on natural enemy families that are easily reared or commercially available. There is a paucity of data for many generalist predators, in particular for spiders, hoverflies, and rove and carabid beetles. Furthermore, very few studies have tested the effects of seed treatments on natural enemies, presenting a significant gap given the widespread global use of neonicotinoid seed treatments. There is a need to validate results obtained under laboratory conditions at industry-relevant scales and also prioritise testing on several key natural enemy species we have identified, which should assist with the adoption of IPM practices and decrease the reliance on broad-spectrum chemicals.

Highlights

Large-scale agricultural enterprises, in western agriculture, rely predominantly upon prophylactic chemical control and host plant resistance/tolerance to reduce invertebrate pest populations [1,2]
Of the 2786 unique entries conducted across relevant Modes of Action (MoA) and natural enemy families relevant to Australian grain crops, we found the majority of entries were focused on older chemistries; most entries tested the toxicity of synthetic pyrethroids (Group 3A; 25.97%), organophosphates (Group 1B; 19.73%), and carbamates (Group 1A; 13.61%) (Figure 1)
At a higher taxonomic level (i.e., Order), we found that trends observed at the family level were upheld (Figure 4), with most entries investigating the toxicity of broad-spectrum MoAs (Groups 1A, 1B, and 3A at 13.61%, 19.73%, and 25.97%, respectively; Figure 4), we found that considerable research was conducted on avermectins (Group 6; 8.99%) and Bacillus thuringiensis (Bt) (Group 11A; 5.09%) (Figure 4)

Summary

Introduction

Large-scale agricultural enterprises, in western agriculture, rely predominantly upon prophylactic chemical control and host plant resistance/tolerance to reduce invertebrate pest populations [1,2]. This has resulted in an over-reliance on chemicals and the emergence and spread of pesticide resistance in a wide range of pest species across an array of agroecosystems [3,4]. With a diminishing number of effective chemical control options, the Australian grains industry is left with limited cost-effective crop protection strategies for pest management [3]

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