Parasitism by tachinid parasitoids (Diptera: Tachinidae) in connection with their survival strategy

Abstract

Parasitism by tachinid parasitoid(s) was investigated for 7 species of lepidopteran host larvae collected in Ibaraki Prefecture, Japan in 1997 and 1998. A total of 188 tachinid larvae emerged from 157 out of 1,051 field-collected hosts. Compsilura concinnata (Meigen), Exorista japonica (Townsend), Pales pavida (Meigen), Senometopia excisa (Fallén), Zenillia libatrix (Panzer), Blepharipa sp. and Exorista spp. were identified. New hosts of E. japonica, P. pavida and Z. libatrix were recorded. Emergence of more than 1 conspecific larva from a single host individual was observed in hosts parasitized by E. japonica, P. pavida, S. excisa or Blepharipa sp. Three different types of species combinations in multiparasitism were also observed: (1) E. japonica and P. pavida; (2) E. japonica and Tachinidae sp.; and (3) Blepharipa sp. and Tachinidae spp. These results suggest that E. japonica, P. pavida, S. excisa and Blepharipa sp. larvae potentially have a high "tolerance" for the presence of other tachinid larvae. Probably, this enables these tachinid larvae to coexist tolerantly with conspecific and/or heterospecific tachinid larvae and, therefore, benefits their survival when there are not sufficient hosts available.