Relationships of the gall midge, Asphondylia miki Wachtl (Diptera, Cecidomyiidae), with the host plant, alfalfa (Medicago sativa) and ectoparasites of its larvae and pupae (Hymenoptera, Eulophidae) in the forest-steppe of the middle volga region

Abstract

The studies were carried out in crops of alfalfa ( Medicago sativa ssp. × varia ) in 2018-2022 in the forest-steppe of Samara Province. Asphondylia miki galls were taken into account in alfalfa crops from the beginning of their formation to the end of the growing season on sites from 0.1 to 1 m2 in 10-fold repetition. Statistical processing of the obtained data was carried out by methods of variance analysis. At spring sowing of alfalfa, as well as in its perennial crops, gall midge A. miki develops in two, and during summer sowing in the rst year of the culture’s life in one generation per year, pupae overwinter in galls, the imago of the wintering generation occurs in April. The greatest damage to alfalfa by the larvae of A. miki (40-68% of generative shoots) and the number of its galls (500-830 copies/m2) were observed in the rst year of the culture’s life when it was sown in summer, with the coincidence of the greatest ight of imago with the budding of the culture, which led to signi cant losses in the yield of alfalfa seeds (13-81%). In summer alfalfa crops of the rst year of development without the use of chemical plant protection agents, parasitic hymenopterans contribute to the death of larvae and pupae of A. miki in on average 60% of its galls. Among them, a gregarious ectoparasite Sigmophora brevicornis (Eulophidae) mainly preying on A. miki larvae accounted for about 77% of the individuals of the identi ed parasites. In the S. brevicornis population, males and females had similar body coloration and belonged to three phenotypes: the lightest brownish yellow, yellowish brown, and dark coloration, which accounted for 53, 28 and 19% of parasite individuals, respectively.