Toxicidade de acaricidas a Steneotarsonemus concavuscutum Lofego & Gondim Jr. (Acari: Tarsonemidae) e sua resposta comportamental

Abstract

Steneotarsonemus concavuscutum Lofego & Gondim Jr. cause chlorotic spots, necrosis, distortion, resinosis and abortion in coconut fruit. However, these damages have been usually attributed to Aceria guerreronis Keifer. The control of mites in coconut fruit is done, normally, through the spraying of acaricides registered to control of A. guerreronis. The aim of this study was to evaluate the toxicity of acaricides registered in Brazil to control of A. guerreronis against S. concavuscutum. Additionally, the behavior walking of the tarsonemid exposed to acaricides it was analyzed as well as its effects these acaricides on fruits colonization and oviposition. Toxicity was estimated by Probit analysis, based on adult mortality in arenas sprayed under Potter tower. The mites behavior exposed to acaricides was studied in arenas traded with and without chance of choice through a tracking system (ViewPoint Life Sciences Montreal, Canadá). The LC50's for abamectin and fenpyroximate was 1.1mg/L and 2757 mg/L, respectively. Azadirachtin, spirodiclofen and hexythiazox caused mortality of up to 25%. The total walked distance and walking velocity of mite greatest when S. concavuscutum was exposed to azadirachtin and smallest when exposed to abamectin, not differed from other treatments. All acaricides caused irritability to S. concavuscutum. However repellence was only observed in 5% of the population tested for abamectin and azadirachtin. The exposure to abamectin reduced the number of mites that reached the perianth and remained alive, differing from other treatments. However there was no difference in the number of eggs found in this region. No acaricide showed ovicidal effect or sterilizing on females. Among the acaricides recommended for control of A. guerreronis, only abamectin and fenpyroximate were able to control S. concavuscutum.