Insecticide Activity of Weeds to Pests of Stored Product and Crops

Farmers from family farming faces serious problems of pest attack, both in their production on the field and in storage. The weed species with insecticidal action were identified through toxicity tests to insects. The species of plants tested were Ageratumm conyzoides, Euphorbia heterophylla, Sida rhombifolia and Sida spinosa and the insects were Leucoptera coffeella, Macrosiphum rosae, Atta sexdens rubropilosa, Solenopsis invicta and Sitophilus zeamais. The aim of this study was to identify weeds with insecticide activity against agricultural pests, extract the active compounds of weeds and perform bioassays with hexane and ethanol extracts of weeds on agricultural pests and stored grain. The plant material was subjected to extraction with ethanol and hexane. The mortality bioassays were conducted in a completely randomized design with four replications in triple factorial design (4 x 5 x 2). The data of mortality were subjected to analysis of variance and the differences among means were compared by Tukey's test (p < 0.05). We detected significant differences between the mortality rates for the different species of plants, insect species and between the types of solvents and also in the interactions between insect species x types of solvents, plant species x types of solvents, plant species x insect species and between plant species x species of insects and types of solvents. In general, the hexane extracts of the plant species A. conyzoides and S. rhombifolia were the most toxic. The most susceptible insects species were L. coffeella, S. invicta and M. rosae.