LAUSR

Melanaphis sacchari is a pest recently introduced in Mexico and can cause up to 100% of losses to the sorghum crop (Sorghum vulgare). The integrated management strategy of this aphid includes the use of natural enemies, for this reason, in order to contribute to solve the problems caused by this insect, the objective was to evaluate the effect of the release of Chrysoperla externa on the population of M. sacchari in the cultivation of sorghum under natural environments of cultivation and greenhouse. The hypothesis is that the population density of M. sacchari and the number of infested sorghum plants is lower when C. externa is released. The release of C. externa was evaluated in sorghum cultivation under natural conditions (field) and semi-controlled conditions (greenhouse). The initial field density was 20 and final density was 153.29 ± 44.52 and 568.26 ± 151.87 aphids per plant in the treatment with C. externa and in the treatment without release. The difference between the treatments was significant (p£0.012 and p=0.023). The average number of infested plants in the field was less than the control 8.71 ± 2.28 and 19.35 ± 4.65. Greenhouse population density started with 15 aphids per plant and increased exponentially to 10 716 ± 3961, 16 136 ± 1092, 11 819 ± 496, and 20 612 ± 520 in the treatments with C. externa and 2 290 680 ± 1693, and 3 632 040 ± 3179 in the treatments without C. externa. The number of infested plants was lower in the treatments with C. externa (139, 221, 128 and 156) than in the treatments without C. externa (3240 both treatments). There was a significant difference between the population densities (p£0.001) and between the number of infested plants (p=0.0001). Therefore, C. externa controls M. sacchari only when combined with crop management. These results provide information for the integrated management of this pest and establish the problem of its control due to its great reproductive capacity.