Abstract
Abstract: 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.
Highlights
The soybean [Glycine max (L.) Merrill] crop has a prominent position in the Brazilian economy, with an annual output exceeding 95 million tons
Three experiments with four commercial soybean cultivars recommended for the Southern region of Brazil were conducted in a climate chamber, in a laboratory, at 25±2°C, 60±10% relative humidity, and 14-hour photophase, consisting of one feeding antixenosis assay and two antibiosis assays
The antixenosis assay showed that C. includens larvae differed regarding consumption of soybean leaves and pods, when compared by linear contrast, in the free-choice test (F = 104.19; df = 11, 168; p=0.0001) and in the no-choice test (F = 664.70; df = 11, 348; p=0.0001)
Summary
The soybean [Glycine max (L.) Merrill] crop has a prominent position in the Brazilian economy, with an annual output exceeding 95 million tons. Compared with other countries, Brazil is positioned as the second largest producer of soybean, accounting for approximately 30% of global production (Campos, 2010; Usda, 2016). In Argentina, Brazil, Chile, and Uruguay, 69 species of the order Lepidoptera have been associated with the soybean crop (Formentini et al, 2015). Some species, including those of the genera Spodoptera, Helicoverpa, and Heliothis, can damage the pods by feeding on them (Santos et al, 2010; Hoffmann-Campo et al, 2012; Formentini et al, 2015); these injuries to the pods reduce soybean grain yield and quality (Rogers & Brier, 2010; Shankar et al, 2014)
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