Preliminary investigation on identification of seed alfalfa pests and life history studies of dominant destructive species in Hamadan.
A study on seed lucerne pests and their life cycle was carried out in 1996-99 in Hamadan, Iran. The most important and destructive species were Lygus rugulipennis, L. pratensis, L. gemellatus, L. punctatus, Adelphocoris lineolatus, Apion aestivum [A. trifolii] and Bruchophagus roddi. The population densities of the tarnished plant bugs, including L. pratensis and L. rugulipennis, and lucerne tarnished bug, Adelphocoris lineolatus, were high. Their feeding on flowering stage caused flower shattering to an extent that only the axes of flowers were left. All the Lygus species overwintered as adult under the tree bark, dead plants or in marginal weeds of lucerne fields, whereas Adelphocoris lineolatus overwintered in lucerne stems as eggs. In early spring, with temperature increasing up to 9.5°C, the overwintering Lygus species appeared, and upon slight feeding and copulation laid eggs in stems of host plants, whereas Adelphocoris lineolatus appeared at 20°C. These species were abundant at flowering stage of lucerne plants at the second cut and thus caused the highest damage in this stage.