The biology, ecology, and harmfulness of the flea-beetle Chaetocnema aridula Gill (Coleoptera, Chrysomelidae) in the forest-steppe of the middle Volga Area

Abstract

In the forest-steppe of Samara Province, Chaetocnema aridula Gill. dominates among all the species of Chaetocnema Steph. found in cereal crops. The species develops mainly on winter wheat, and, to a lesser extent, on spring wheat and barley. In autumn, adult beetles aggregate on millet for pre-hibernation feeding. The highest population density of Ch. aridula was observed in the humid and warm 1997 and the lowest one, in the extremely dry 1998. In late April-the first third of May, adults begin oviposition after wintering. Larvae appear in winter and spring wheat in mid-May and in late May-early June, respectively. Larvae pupate in winter wheat, beginning from mid-June; in spring crops, pupation begins in mid-June. Adults of a new generation emerge between the middle of June and the middle of July. In spring crops, development of Ch. aridula finishes 2–3 weeks later than in winter crops. Larvae penetrate shoots in the upper soil level in the tillering zone. 50–80% of wheat and barley plants are damaged by larvae. In damaged plants, the number of shoots increases by 1.2–5.8 times, and the number of productive shoots decreases to 17–68%. In plants damaged by flea-beetles, harvest losses constitute 62–90% and 5–20% in winter and spring wheat crops, respectively, and the total harvest loss constitutes 0.3–3.9 and 1–15%, respectively.