Does the choice of a suitable sorghum hybrid help control the maize weevil in the tropic region?


Abstract: Sorghum is the fifth most important cereal grown in Brazil, with a total production of 2,177 thousand tons, in the 2018/19 crop. Widely used in animal feed, sorghum is stored for a few months and damaged, especially by maize weevil, Sitophilus zeamais. The lack of data about the susceptibility of modern hybrids of sorghum to maize weevil may underestimate the potential loss, especially in the tropics.Therefore, the objective of this study was to identify sources of resistance to S. zeamais in sorghum hybrids during storage. The experiments were carried out using glass jars (1.7 l), with about 1.5 kg of 35 sorghum hybrids grains, characterized by water content and specific mass. The jars were infested with 70 adult insects and stored under ambient conditions (January-April). After 100 days of storage, number of live insects, water content and specific mass were assessed. Weight loss was estimated by data on specific mass corrected by water content. The experimental design was completely randomized with three replicates for each hybrid and the data underwent analysis of variance followed by the Waller-Duncan test (p < 0.05), in addition to correlation and cluster analysis.There was a significant difference in the number of adult S. zeamais among the hybrids (F34,96 = 1.63, P < 0.0482), with hybrids CMSXS3002, 50A50, CMSXS3000 and 1527039, with a smaller number of live insects after storage. The hybrids with the highest number of live insects were AGN1806, XB6018, BRG37115 and BRS373. Significant and positive correlation was found between weight loss and number of live insects. Some sorghum hybrids demonstrate tolerance to the development of S. zeamais; however, in the more susceptible ones, losses can occur over 11.6% in the period of 100 days of storage.

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