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The lesser mealworm, Alphitobius diaperinus (Panzer, 1797) (Coleoptera: Tenebrionidae), is considered the primary insect pest in broiler farms in Brazil. In this study, we characterized the susceptibility of A. diaperinus populations from broiler farms of southern Brazil to cypermethrin and chlorpyrifos. Larvae and adults of A. diaperinus were exposed to these technical insecticides diluted in acetone in residual bioassays. A geographic variation in the susceptibility of larvae and adults of A. diaperinus to both insecticides was detected. The larval LC50 for cypermethrin ranged from 0.43 to 7.33 µg a.i./cm2. Two populations from Santa Catarina state presented higher resistance ratios of 13.6- and 17-fold. When adults were exposed to cypermethrin, the LC50 ranged from 0.46 to 4.93 µg a.i./cm2, with population SC-3 from Santa Catarina having lower susceptibility (resistance ratio of 10.7-fold). When exposed to chlorpyrifos, A. diaperinus larvae present LC50 values ranging from 0.21 to 4.30 µg a.i./cm2. Larvae from Paraná and Santa Catarina (SC-1 population) presented the highest resistance ratios, ranging from 10- to 20-fold. In adults, the LC50 of chlorpyrifos ranged from 0.17 to 5.30 µg a.i./cm2, showing a maximum resistance ratio of 31-fold in a population from Paraná state. Based on LC99 values, candidate diagnostic concentrations of 15 and 12 µg a.i./cm2 of cypermethrin and chlorpyrifos, respectively, were also estimated for the resistance monitoring of A. diaperinus in Brazil. The implications of these results in Insect Resistance Management are discussed.

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Climatic variables affect soybean yield components. Understanding how they are interrelated is essential for planning and boosting crop productivity. The aim of this study was to evaluate whether the photothermal quotient can be used to predict the productivity and 1000-grain weight of soybean. Five experiments were carried out at the Federal University of Santa Maria in growing seasons of 2013/14 to 2017/18 using the main cultivars (154) sown in the state of Rio Grande do Sul (RS), Brazil. The experiments were organized in a randomized block design with four replicates, evaluating grain productivity and 1000-grain weight. The results showed that years with the highest grain productivity and 1000-grain weight were associated with regular rainfall and high photothermal quotients (approximately 2.3 MJ m-2). There was a positive and significant correlation between grain productivity and the average number of days without rainfall (r = 0.98). In addition, there was a negative correlation with air temperature (r = -0.8). Air temperature and days without rain are decisive factors for yield and grain weight. The photothermal quotient can be used as a basis for predicting soybean grain productivity.