RESUMO
The aphid, Schizaphis graminum Rondani (Hemiptera: Aphididae), is one of the most destructive pests of wheat. It is responsible for significant economic losses in the agricultural sector, with an estimated 45% of wheat fields affected. Plant-based insecticides have seen a rapid increase in popularity in recent years due to their efficacy, cost-effectiveness, biodegradability, and lower toxicity compared to synthetic pesticides. The study aimed to evaluate the toxic potential of S. longipedunculata extracts against S. graminum and investigate the insect's feeding behavior on wheat. Initially macerated in methanol, the different extracts of S. longipedunculata organs were fractionated using n-hexane, chloroform, ethyl acetate, and butanol. The feeding behavior was analyzed by comparing the waveforms generated by the EPG with the control. After 72 h of treatment, the ethyl acetate fraction extracted from root had the highest toxicity against aphids, with mean 26 mortality of S. graminum at LC50 of 330 ppm; 25 mortality S. graminum at LC50 of 400 ppm for leaves; and mean 24.5 mortality S. graminum at LC50 of 540 ppm in stem bark. EPG analysis indicated that the extract fractions enhanced plant tissue resistance by significantly preventing aphid access to the phloem. The toxic effect of the botanical extracts significantly enhanced the chemical composition of the leaf medium, resulting in a drastic reduction in the number of tissue attacks by S. graminum. In summary, besides their toxicity to S. graminum, extracts of S. longipedunculata reinforce the plant's defense mechanisms, significantly reducing the S. graminum population. They also reinforce wheat's defense mechanisms. S. longipedunculata can, therefore, be used as a promising agent in the biological control of S. graminum.