-The objective of this work was to evaluate the natural resistance of soybean cultivars to Chrysodeixis includens. For this, four commercial soybean cultivars recommended for the Southern region of Brazil were used: BR 36, NA 5909 RG, BMX Turbo RR, and Benso 1RR. In the laboratory, larvae were subjected to the antixenosis feeding assay, in which they were free or not to choose among old leaves, new leaves, and pods. Neonate larvae were subjected to two antibiosis tests: in the first one, they were fed with leaves from the middle third of the plants of the four cultivars; and, in the second one, with leaves or pods of the NA 5909 RG cultivar. Chrysodeixis includens larvae prefer leaves over pods and old leaves over new ones. The Benso 1RR cultivar extends the development cycle of C. includens, but only BMX Turbo RR will reduce the population growth of larvae in the next generations.Index terms: integrated pest management, IPM, lepidopteran pests, plant resistance, Plusiinae. Resistência natural de cultivares de soja à lagarta-falsa-medideiraChrysodeixis includens (Lepidoptera: Noctuidae) Termos para indexação: manejo integrado de pragas, MIP, lepidópteros-praga, resistência de plantas, Plusiinae.

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Control of Anastrepha fraterculus (Diptera: Tephritidae) is usually accomplished with synthetic insecticides, which can be a problem considering exportation of fruits. This study aimed to evaluate mortality and offspring effects on A. fraterculus using peach, strawberry guava and apple fruits treated with andiroba (Carapa guianensis) oil. Higher mortality rate was observed when compared to control on strawberry guava and apple fruits treated with andiroba oil (18.4 % and 35.0 % points more than the control). The mean number of pupae observed in the offspring was inferior to the control on strawberry guava and apple fruits treated with andiroba oil (100 % control) and, on peach fruits (68.3 % fewer pupae). Andiroba oil shows promising results as an alternative product to control A. fraterculus. Studies are still needed especially considering the effectiveness of andiroba oil under field conditions.

The looper caterpillar Chrysodeixis includens (Walker) is considered the main defoliating pest in soybean crops, which contributes to yield losses. Delaying its resistance to insecticides is a major challenge in its management. This study aimed to characterize the susceptibility of C. includens to flubendiamide, cyantraniliprole, spinetoram and methomyl, as well as to establish a diagnostic concentration for monitoring resistance. The insecticide was applied to the surface of the artificial diet. For the dose-response curve, concentrations that resulted in 5 to 99 % mortality were used to estimate the lethal concentrations (LC50 and LC99) and resistance ratios (RR50 and RR99). The diagnostic concentrations were based on concentrations that provided 90 to 99 % mortality in the susceptible reference population. For flubendiamide and methomyl, the decrease in the susceptibility resulted in estimated RR50 of 6.2 to 24.2 and 4.4 to 19.6 times, respectively. For cyantraniliprole and spinetoram, there was little difference in susceptibility among the populations, with RR99 lower than 6.1 times. Differences in the susceptibility of C. includens were evident from concentrations of 0.5053, 5.053, 0.1579 and 28.42 μg cm-2, respectively for flubendiamide, cyantraniliprole, spinetoram and methomyl.

Anastrepha fraterculus is the main horticultural pest for food crops in southern Brazil. This study aimed to identify the damage caused by this species, evaluate its development, and correlate its infestation rate with physical and chemical characteristics of Packhams and Williams pear fruit cultivars at five different stages of development. In the field, cages were installed on branches of the pear plants in which two couples of A. fraterculus were released for a period of 48 hours. The damage resulting from oviposition was evaluated at fifteen-day intervals from the day the insects were released until harvest. The evaluation of damage consisted of visual observation of decayed and deformed fruits and the presence of larvae. In the laboratory, two couples were individualized with one fruit in a 750 mL pot for 48 hours. The evaluations consisted of counting the number of living third-instar larvae, pupae and adults. The physical and chemical analyses consisted of the determination of fruit peel and pulp texture, color, soluble solid content and transversal diameter. The incidence of the fruit fly on Packhams and Williams fruits occurred when fruits measured 54.9 and 52.8 mm respectively. The development of A. fraterculus in pear fruits of both cultivars is related mainly to fruit peel and pulp hardness.