An optimized method for mass rearing the tiger-fly, Coenosia attenuata (Diptera: Muscidae)

Joana Martins,Elisabete Figueiredo,Ana C Ramos,Célia Mateus

doi:10.14411/eje.2015.059

Abstract

The tiger-fly Coenosia attenuata Stein (Diptera: Muscidae) is a predator that is currently thought to be a useful biological control agent in greenhouses, especially in the Mediterranean region. Here, we present a method for rearing this predator in the labora- tory by feeding it on fungus gnats (fed on Pleurotus ostreatus fungus) and drosophilids (Diptera). Over the past two years, this method has been continuously used to successfully produce predators for bioecological studies in the laboratory. Rearing cages with one, five or 10 male-female pairs, either of laboratory or field origin, were compared using females that were either unmated and recently emerged, or mated and about 20 days old (post-emergence). We evaluated the following parameters: number of rearing cages in which adults emerged, number and sex ratio of emerged adults, period from the introduction of parental pairs into cages and the emergence of the first offspring adults, and the period over which emergence occurred in the cages. Based on our results and in order to minimize the space needed for the colony, cages should be stocked with ca. 10 parental pairs, either of field or laboratory origin, with at least some mated females about 20 days post emergence. We also found that the predator's rearing substrate in the cages is improved if coconut fibre is mixed with the soil. These findings will improve the efficiency of C. attenuata rearing, an important step if it is to be used as a biological control agent.

Highlights

Greenhouse crops in the Mediterranean region are affected by several pests
Kühne et al (1994) describe a “three-step rearing method” that involves rearing species of Bradysia Winnertz, 1867 (Diptera: Sciaridae) on a substrate of wood-fibre mixed with species of Fusarium Link, 1809 (Ascomycota: Hypocreales: Nectriaceae), which serves as an oviposition substrate for C. attenuata
Significant differences were detected in terms of the origin of the parental pairs: emergence occurred in 57.9% of cages initiated with field collected individuals but only 9.5% of cages initiated with laboratory reared individuals

Summary

Introduction

The tiger-fly, Coenosia attenuata Stein, 1903 (Diptera: Muscidae), is a useful biological control agent of many of these pests, as both the larvae and adults are predators (Moreschi & Colombo, 1999; Sensenbach, 2004). It is one of the only known species to feed on adult fungus gnats, shore flies, whiteflies and leafminers (Kühne, 1998, 2000). C. attenuata possesses other traits that favour its use as a biological control agent in greenhouses, such as a tolerance of high temperatures (Gilioli et al, 2005) and the fact that it kills more prey than it can consume (Martinez & Cocquempot, 2000). Coenosia attenuata is distributed worldwide (Hennig, 1964; Pohl et al, 2011) and was first detected in Portugal in 2001, in the Oeste region (Prieto et al, 2005; Martins et al, 2012)

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