Eficácia de inseticidas contra Aleurodicus cocois Curtis, 1846 (Hemiptera: Sternorryncha: Aleyrodidae) e seletividade a Amblyseius largoensis Muma, 1955 (Mesostigmata: Phytoseiidae)

Abstract

Cashew cultivation, an important sector of Brazilian agriculture, faces phytosanitary challenges that compromise productivity and fruit quality, largely due to the limited availability of registered pesticides and the lack of crop-specific management strategies. Therefore, the development and evaluation of effective alternatives for pest control are essential. Among the main threats is the cashew whitefly, Aleurodicus cocois Curtis, 1846 (Hemiptera: Sternorrhyncha: Aleyrodidae), a sap-sucking insect that colonizes the aerial parts of plants, reduces the photosynthetic area, causes loss of branch vigor and premature leaf drop, ultimately decreasing yield. Among the natural enemies associated with cashew, the predatory mite Amblyseius largoensis Muma, 1955 (Mesostigmata: Phytoseiidae) plays a relevant role in regulating pest populations, contributing to integrated pest management. This study evaluated the efficacy of six neurotoxic insecticides (Abamectin, Acephate, Flupiradifurone, Imidacloprid, Acetamiprid, and Tiametoxam) against A. cocois, considering exposure time, susceptibility by instar, and the determination of lethal concentrations (LC50 and LC90) for the insecticides that showed higher mortality in the initial evaluations. Subsequently, the selectivity of LC90 to the predator A. largoensis was assessed through analyses of survival, prey consumption, oviposition, egg viability, and food conversion efficiency under topical and residual exposure. Bioassays with A. cocois revealed differences among treatments, in which Acephate, Flupiradifurone, and Tiametoxam caused mortality above 80%, whereas Imidacloprid, Acetamiprid, and Abamectin resulted in mortality equal to or lower than 63.5% within the first 24 hours. After 48 hours, all treatments showed increased lethality, and after 72 hours, mortality reached total or near-total levels. Susceptibility was high and uniform across most instars, except for the fourth instar treated with Abamectin, which showed lower mortality and greater variability in response. Concentration-response curves indicated high toxicity of Tiametoxam, Acephate, and Flupiradifurone. Regarding LC90 selectivity to A. largoensis, Acephate was highly toxic under both exposure routes, compromising predator persistence in the agroecosystem. Tiametoxam, although not causing high mortality, altered biological parameters, reducing oviposition, prey consumption, and egg viability. In contrast, Flupiradifurone showed high selectivity, not affecting survival, reproduction, or food conversion efficiency, with reduced egg viability only under residual exposure. These findings indicate compatibility of Flupiradifurone and partial compatibility of Tiametoxam with A. largoensis, demonstrating their potential for use in integrated pest management programs in cashew cultivation.