An innovative strategy for control of fungus gnats using entomopathogenic nematodes alone or in combination with waterlogging.

Chaoying Chen,Shuyuan Zheng,Mingyang Ma,Qifeng Song,Jingjing Li,Xinghui Gu,David Shapiro-Ilan,Weibin Ruan,Haikun Ma

doi:10.21307/jofnem-2020-057

Abstract

Chive gnat (Bradysia odoriphaga) is a soil-borne pest of Chinese chives, which causes millions of dollars in yield losses per year. Traditional methods, such as chemical pesticides leave detrimental chemical residues on plants, which potentially threaten human health. To find a sustainable method of reducing the chive gnat, the authors evaluated the effects of waterlogging and the addition of entomopathogenic nematode (EPN) on reducing chive gnat in Chinese chives via three pot experiments and one field demonstration. Results indicated that increasing the duration of waterlogging markedly increases chive gnat mortality. The presence of EPN also caused chive gnat mortality to increase with exposure time. Most importantly, the combination of waterlogging and EPN had synergistic effects on chive gnat mortality; the combination led to higher mortality than using waterlogging and EPN alone. The study demonstrated that a combination of two environmental friendly methods of fungus gnat control could lead to synergistic effects, which may provide novel approaches to economic and environmentally sustainable pest management measures.

Highlights

Fungus gnats (Bradysia spp., Sciaridae) are small, dark-colored flies whose larval stages feed on organic matter and fungi
The following entomopathogenic nematode (EPN) were used in this study: four exotic strains, Steinernema feltiae (SN strain, France), S. carpocapsae (All strain, Georgia, USA), Heterorhabditis bacteriophora (HB1 strain, Australia), H. indica, as well
Waterlogging the chive for 4 hr doubled B. odoriphaga mortality compared with waterlogging for 2 hr (Fig. 1)

Summary

Introduction

Fungus gnats (Bradysia spp., Sciaridae) are small, dark-colored flies whose larval stages feed on organic matter and fungi. They are opportunistic herbivores on plant roots and underground stem tissues, causing significant yield losses in crops (Arimoto et al, 2018; Katumanyane et al, 2018a, b; Gou et al, 2019). The chive gnat, Bradysia odoriphaga Yang and Zhang, feeds on more than 30 species plants of at least seven families (Zhang et al, 2016). An innovative strategy for control of fungus gnats using entomopathogenic nematodes alone or in combination: Chen et al. EPNs have been intensively studied and considered to be potential alternative control agents for Bradysia spp. on a large scale (San-Blas et al, 2017; Katumanyane et al, 2018b)

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Conclusion