Abstract
BACKGROUNDSlugs and snails constitute major crop pests. Withdrawal of metaldehyde has prompted a search for more environmentally friendly yet fast acting molluscicides. This study investigated the response of representative molluscs to conidia and volatile organic compounds (VOCs) of the insect pathogenic fungus Metarhizium brunneum Petch.RESULTSConidia of M. brunneum had antifeedant/repellent properties with repellency being dependent upon the fungal strain and conidia concentration. Three commonly produced fungal VOCs, 1‐octene, 3‐octanone and 1‐octen‐3‐ol, were repellent at low doses (1–5 μL) but could kill slugs and snails on contact or fumigation. At the highest dose tested (10 μL), 100% mortality was achieved for Cornu aspersum Muller (garden snail) and Derocerus reticulatum Muller (grey field slug) within 1 h post‐treatment with the first deaths being recorded in <11 min. Aqueous formulations (20% v/v) of the most potent VOCs, 3‐octanone and 1‐octen‐3‐ol, could be sprayed onto plants to kill or drive the pest of the crop with no phytotoxic effects.CONCLUSIONThe sensitivity of terrestrial molluscs to 3‐octanone and 1‐octen‐3‐ol and the ephemeral nature of these compounds makes these excellent candidates for development as mollusc repellents or molluscicides. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Highlights
Snails and slugs are serious pests of agricultural and horticultural crops
This paper reports that these compounds are highly repellent or toxic to slugs and snails
3.1 Antifeedant properties of M. bruneum conidia In no choice assays, Cornu aspersum consumption of lettuce leaves treated with conidia of M. brunneum was dependent upon the fungal dose and strain (Fig. 2(a))
Summary
Snails and slugs are serious pests of agricultural and horticultural crops. They cause feeding damage to both aerial and subterranean parts of the plant, including leaves, shoots, roots, tubers, corms, bulbs, flowers and seed. Slug and snail population densities have increased over the years due to changes in crop management such as minimum tillage, direct drilling, and over-wintering arable crops.[2,3] Their pest status is set to increase further due to legislative changes to pesticide usage and climate change with weather patterns favoring their population growth.[3,4] The problem is often exacerbated by the accidental introduction of highly damaging invasive mollusc species such as the golden apple snails (Pomacea canaliculate Lamarck, Pomacea maculata Perry), which have devastated rice crops in Asia and pose a serious threat to food security in the region.[5,6,7]. This study investigated the response of representative molluscs to conidia and volatile organic compounds (VOCs) of the insect pathogenic fungus Metarhizium brunneum Petch
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