Oviposition, host plant choice and survival of a grass feeding butterfly, the woodland brown (Lopinga achine) (Nymphalidae: Satyrinae)

Abstract

Abstract. Oviposition, host plant choice and survival on different plants of a grass-feeding butterfly, Lopinga achine, were studied in the field and in the laboratory. Grass-feeding butterflies are generally thought to be non- specific in their host plant choice. This seems not to be true for L. achine. Females were selective in their host plant choice and preferred to oviposit near Carex montana, although they do not attach their eggs to any plant. Carex montana was also generally preferred by the larvae in laboratory experiments among the plants available in the field. However, the larvae preferred three species that they seldom encounter in the field (Agrostis capillaris, Phleum pratense and Poa pratensis) before C. montana when they were offered these four species. Most of the larvae found in the field (>80%), were found on C. montana. The larvae survived significantly better on C. montana than on six other species in rearing experiments. The results indicate that host plant choice occurs in two steps in L. achine: 1) the females choose a patch to drop the egg to the ground, usually in the vicinity of a C. montana plant 2) the newly hatched larva moves to the host plant. The apparent dependence of the Swedish mainland L. achine population on a single host plant has important conservation implications.