Harmful occurrence of Rosy rustic moth (Hydraecia micacea) (Noctuidae: Lepidoptera) on hop in the Czech Republic

Abstract

The Rosy rustic moth (<I>Hydraecia micacea</I>) has been a pest of hop in Czech hop regions for a long time. It causes most severe damages in hop gardens infested by quackgrass (<I>Elytrigia repens</I>) on waterlogged<B> </B>areas. Larvae emerge from the second half of April to the middle of May. The sum of effective temperatures (SET) necessary for hatching larvae has been determined to be 78.6C over a 4-year average. Young larvae first feed on leaves of quackgrass, and later move to hop plants where they feed inside the shoots and rootstocks. Occurrence and damage are<B> </B>most frequent at the edges of hop gardens and in places with anchorages between two hop gardens. The ichneumonid wasp <I>Ichneumon sarcitorius</I> and the fly <I>Lidella thompsoni</I> are the most common parasitoids of this pest. Numbers of males caught in pheromone traps were very low. More males were trapped near hop gardens typical for repeated harmful occurrence of the rosy rustic moth. Females trapped in a light trap from the second half of August to the last decade of September had already full-developed eggs in their ovaries.