RESUMO
Tetranychus urticae is the main pest of strawberry crops and can cause up to 80% of productivity losses under high infestations. Aiming to search T. urticae management alternatives compatible with eco-friendly or organic-based food production systems, this study evaluated the lethal and sublethal toxicities of formulated derivatives from Annonaceae (rich in acetogenins) against this pest species. In addition, it also evaluated the selectivity of the most promising formulation to the predatory mites Neoseiulus californicus and Phytoseiulus macropilis, which are largely applied in biological control in Brazil. Among the derivatives tested, the emulsion from the ethanolic seed extract of Annona mucosa-ESEAm (major component: acetogenin bis-tetrahydrofuran rolliniastatin-1) caused pronounced mortality of T. urticae after 120 h of exposure (LC50 = 465.5 mg L-1), in a comparable or superior manner to an abamectin-based synthetic acaricide used as positive control (LC50 = 1243.4 mg L-1). Moreover, ESEAm exposure resulted in a significant decrease in the number of eggs laid by females and caused the most pronounced ovicidal action for T. urticae, with only 5% embryonic viability. However, ESEAm also showed high toxicity to the predatory mites tested, causing 100% mortality for both species after 120 h exposure, similar to abamectin. The interaction between these bioacaricides and biological control agents should be tested under field conditions to further assess the potential ecological selectivity of these derivatives.
Assuntos
Acetogeninas , Ácaros , Controle Biológico de Vetores , Tetranychidae , Acetogeninas/toxicidade , Animais , Brasil , Feminino , Comportamento PredatórioRESUMO
Schizotetranychus oryzae Rossi de Simons (Acari: Tetranychidae) is considered one of the most important phytophagous mite in rice cultivation in the Americas South, Central, and North. This study aimed to examine some biological aspects of S. oryzae developing on leaves of three different cultivars of rice [Oryza sativa (L.)-Poaceae] produced in the state of Rio Grande do Sul, Brasil. The plants were kept in a room at 25 ± 1°C, with natural light (photophase of approximately 14 h) and 70 ± 5% relative humidity. During the immature stages, observations were carried out daily at 7 am, 1 pm, and 7 pm. The results showed that the mean duration of the egg-adult period in days were similar between cultivars evaluated (Irga 424, 11.27 ± 0.13; Taim, 11.21 ± 0.14 and Sinuelo, 11.13 ± 0.15). Egg-adult viability on Irga 424, Sinuelo, and Taim was 61.9, 85.71, and 90.48%, respectively, being lowest on Irga 424 (χ2 = 28.62, p < 0.0001). The duration of the immature stages was not affected by cultivar, but on Irga 424, egg-adult viability and female longevity were lower. The results of this study can help select O. sativa cultivar resistant to S. oryzae. However, historically, the IRGA 424 has lower populations of S. oryzae in field conditions.