Agriculture & Food, Volume 9, 2021

Abstract: The elm leaf beetle, Xanthogaleruca luteola, defoliates severely Ulmus spp. (Ulmaceae) in many countries, including central and southern Chile, and can even kill young trees. It still has no effective control treatment. Herein, the insecticide capacity of the aqueous extract from green fruits of Melia azedarach (Meliaceae), a tree for ornamental use, was evaluated at three concentrations on X. luteola adults on elm tree in Santiago, Chile. Five 50 cm branches selected at random were sprayed per extract, infested with 15 newly emerged adults, and enclosed with cloth. Mortality obtained with 0.0 (control), 1.8, 3.6, and 7.1% w/v concentrations and three replicates were evaluated periodically from day 3 through 15 after spray. Statistics were analysed through ANOVA and significance differences between treatments and times after spray were estimated with the Tukey test. The LC50 was calculated using the Probit method and adjusted for Chi-square. All concentrations had insecticide effect compared to the control. The maximum mean mortality (90%, at 7.1% w/v) was reached at 9 d. The lowest LC50 was 10.94% w/v on day 6. Beetles’ mortality shown a positive linear response, increasing with extract concentration. Also, the phenology of M. azedarach was observed during a year in Santiago, for further use in pest control studies. We suggest the green fruits should be harvested the first half of December. These results could be applied for the integrated management of X. luteola on infested elms.