The experiment was carried out in the conventional and organic experimental fields of the Institute of Agriculture – Karnobat, in the period 2019 – 2022. The aim of the experiment was to study the influence of weed infestation and cropping system of pea (Pisum sativum (Linn.)) on the beneficial and harmful entomofauna. Six and seven species of insects from seven families and three orders were found to damage pea in organic and conventional farming, respectively. Their density was higher in conventional farming. The most economically important and the most widespread pest in both types of cropping was the aphid Acyrthosiphon pisum (Harris, 1776). Of the beneficial insects, thirteen species were found in pea in organic and eleven in conventional farming, from eight families and five orders. Greater species diversity and higher numbers were observed in organically grown pea during all four years of the study. The absence of herbicide treatment in organic farming and the presence of more blooming vegetation stimulate the multiplication of beneficial entomofauna, regulating the population density of the aphids in pea. The correlations between the blooming vegetation and the beneficial entomofauna and between the beneficial and harmful entomofauna have been demonstrated.
Keywords: pea, beneficial and harmful entomofauna, weeds, organic and conventional farming