Efeito dos insecticidas botânicos no controlo da lagarta do funil do milho (Spodoptera frugiperda) na cultura do milho

Abstract

The corn caterpillar (MFL) is an invasive and polyphagous pest, originating from the American continent, where it has more than 350 hosts in addition to corn, its main host. It was detected in Africa in 2016 and in particular in Mozambique in 2017. Chemical insecticides have been used more to control this pest, causing serious environmental problems. Many alternative methods have been recommended and studied, including botanical pesticides. The present work aimed to evaluate the effect of botanical insecticides on the control of the corn caterpillar (Spodoptera frugiperda). The experiment was installed in the FAEF experimental field from January to June 2023, using the causalized complete block design (DBCC), with 4 treatments and 4 replications; 1 - Control, 2 - Azadirachta indica leaves, 3 - Biol (mixture of Aloe vera leaves, Calatropis procera, Tefrosia purpurea and Canavalia ensiformis seeds, chilli (Cyperus giganteus) and tobacco (Nicotina tabacum) and 4 - Calatropis leaves procera. Regarding the level of infestation, the control treatment recorded a higher level of infestation (86.7%) compared to other treatments such as Calatropis procera (77.9%), Biol (72.9%) and Azadirachta indica (71.2%), however all treatments differed, statistically among themselves. Regarding the level of damage, the control treatment had an average scale of 5 (moderate damage, on the damage scale) meaning that the plants had holes in the leaves and a completely destroyed funnel. The treatments Azadirachta indica, Biol and Calatropis procera registered scale 3 (low damage) meaning that the plants presented small circular lesions and some elongated lesions on the funnel leaves. All treatments differed statistically from each other in terms of level of damage. The control treatment had, statistically, lower yield than the corn grain in relation to treatments with botanical pesticides. However, the botanical treatments did not differ statistically in terms of grain yield. As for the estimate of yield losses if botanical insecticides had not been applied, the Azadirachta indica treatment had a yield loss of around (19.4%), Biol (22.32%) and Calatropis procera (17%). The application of treatments proved to be beneficial in controlling FAW, as the B/C Ratio is greater than 1. Greater net returns were found in the use of Biol as it has a greater benefit/cost ratio(TRADUÇÃO NOSSA).