Lethal and sublethal effects of pesticides used in Brazilian citrus groves on Panonychus citri (Acari: Tetranychidae)

Abstract

Pesticides have been blamed as the principal factor responsible for biological disequilibrium favoring the population increase of Panonychus citri (McGregor) in Brazilian citrus groves. In order to generate subsidies for the integrated management of this pest, we evaluated the lethal and sublethal effects of pesticides used in citrus on P. citri. We tested 18 pesticides by evaluating mortality of adult female, egg viability and adult avoidance. For imidacloprid, pyriproxyfen, dimethoate, deltamethrin, lambda-cyhalothrin and lime sulfur, the principal insecticides used in Brazilian orchards, the oviposition behavior and the incidence of adult females on discontinuous pesticide residues were evaluated. The pesticides which caused adult P. citri mortality were: abamectin (94%), dimethoate (86%), lime sulfur (69%), fenpropathrin (44%), diafenthiuron (25%) and lambda-cyhalothrin (23%). The pesticides affecting egg viability were: fenpropathrin (53%), dimethoate (30%) and lime sulfur (22%). Fenpropathrin, lambda-cyhalothrin and lime sulfur caused repellent effects of 55, 45 and 22%, respectively. P. citri preferred areas untreated with deltamethrin, lambda-cyhalothrin and lime sulfur for oviposition and permanence, but the species could not distinguish areas treated with imidacloprid, pyriproxyfen and dimethoate. The insecticides abamectin, dimethoate and diafenthiuron affected survival and did not cause changes in P. citri behavior. These pesticides should be used mainly in periods P. citri occurs. On the other hand, fenpropathrin, lambda-cyhalothrin, lime sulfur and deltamethrin affect dispersal behavior, oviposition and P. citri incidence and their use should be avoided.

Behavioral response ofPanonychus citri(McGregor) (Acari: Tetranychidae) to synthetic chemicals and oils

“…Maximum dispersal from treated to un-treated or half-treated surfaces depended on the concentration of chemicals Iftner & Hall (1983). The dispersal towards half-treated adaxial surfaces was significantly different from vegetable oil application than others at LC 30, as observed by Alves, Casarin & Omoto (2018).…”

“…The culture was reared in the growth chamber with a 16:8h (Light:Dark) photoperiod and 26 ± 1 °C temperature. One to three-day-old adult females ( He et al, 2011 ; Alves, Casarin & Omoto, 2018 ) were used for said experimentation reared in the laboratory for several generations (more than 50 generations). The 1–3-day-old adult females were used due to fully developed adultery and ready for egg-laying after 4–5 days.…”

“…Since, the impact of agrochemicals on target pest or insect can be assessed through the application rate (lethal and sublethal), application timing, and mode of action. The use of the sublethal effect of chemicals is considered a more accurate approach to measure toxicity, which changes individuals behavioral responses that survive from toxic exposure ( Desneux, Decourtye & Delpuech, 2007 ; Biondi et al, 2013 ; Turchen et al, 2016 ; Alves, Casarin & Omoto, 2018 ).…”

Peer Review #1 of "Behavioral response of Panonychus citri (McGregor) (Acari: Tetranychidae) to synthetic chemicals and oils (v0.1)"

“…The culture was reared in the growth chamber with a 16:8h (Light: Dark) photoperiod and 26±1 ºC temperature. One to three-day-old adult females (He et al, 2011;Alves et al, 2018) were used for said experimentation reared in the laboratory for several generations (more than 50 generations). The one to three-day-old adult females were used due to fully developed adultery and ready for egg-laying after 4 to 5 days.…”

“…Since, the impact of agrochemicals on target pest or insect can be assessed through the application rate (lethal and sublethal), application timing, and mode of action. The use of the sublethal effect of chemicals is considered a more accurate approach to measure toxicity, which changes individuals behavioral responses that survive from toxic exposure (Desneux et al, 2007;Biondi et al, 2013;Turchen et al, 2016;Alves et al, 2018). Dispersal behaviors define as any movement from one place to another for the survival of any organism due to environmental stress or non-viable to live (e.g., lack of food or surrounding climatic constraints) (Clobert et al, 2001;Ims & Hjermann, 2001).…”