Resistance of the stable fly, Stomoxys calcitrans (Diptera: Muscidae), to cypermethrin in outbreak areas in Midwestern Brazil.

Antonio Thadeu Medeiros De Barros,Paulo Henrique Duarte Cançado,Luísa Nogueira Domingues,Vinícius Duarte Rodrigues

doi:10.1590/s1984-29612019089

Abstract

Population explosions of the stable fly (Stomoxys calcitrans) have become a serious concern for livestock producers near sugarcane mills in some regions of Brazil due to the insect's massive reproduction on sugarcane byproducts and waste. Despite the limited efficiency of insecticides for controlling stable fly outbreaks, producers still rely on chemical control to mitigate the alarming infestations in affected areas. This study evaluated the susceptibility of S. calcitrans populations to cypermethrin in the state of Mato Grosso do Sul, Brazil. Stable flies were tested from three field populations and two colonies, established from flies previously collected at sugarcane mills. Wild flies were collected with Nzi traps in areas of sugarcane plantations. Both wild and colonized flies were exposed to eleven concentrations of cypermethrin in impregnated filter paper bioassays. All the populations proved to be resistant to cypermethrin, with resistance factors among field populations ranging from 6.8 to 38.6. The intensive use of insecticides has led to the development of pyrethroid resistance in stable fly populations in the proximities of sugarcane mills in the state of Mato Grosso do Sul.

Highlights

Over the last decade, outbreaks of the stable fly (Stomoxys calcitrans) resulting from its large-scale proliferation in organic wastes and byproducts from ethanol production at sugarcane mills (CORRÊA et al, 2013) have become an unprecedented problem, causing significant socioeconomic impacts in several municipalities of southeastern and Midwestern Brazil (DOMINGHETTI et al, 2015)
This study evaluated the susceptibility of S. calcitrans populations to cypermethrin in the state of Mato Grosso do Sul, Brazil
The excessive use of pesticides to control cattle ectoparasites is very common in Brazil, leading to the widespread dissemination of resistance in arthropods such as the southern cattle tick (Rhipicephalus microplus) (KLAFKE et al, 2017) and the horn fly (BARROS et al, 2012)

Summary

Introduction

Outbreaks of the stable fly (Stomoxys calcitrans) resulting from its large-scale proliferation in organic wastes and byproducts from ethanol production at sugarcane mills (CORRÊA et al, 2013) have become an unprecedented problem, causing significant socioeconomic impacts in several municipalities of southeastern and Midwestern Brazil (DOMINGHETTI et al, 2015). In addition to the economic losses resulting from such outbreaks, this pest has resulted in yearly losses of up to US$ 335 million in Brazilian livestock (GRISI et al, 2014). Commercial insecticide products have been widely employed to reduce the alarming infestations in cattle herds close to sugarcane mills, even though no method of controlling stable flies in cattle raised in extensive livestock farming systems has proved to be effective (BROCE, 2006). The purpose of this study was to evaluate the susceptibility of colonized and wild S. calcitrans populations from outbreak areas in the state of Mato Grosso do Sul, Brazil, to the pyrethroid cypermethrin

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