Improvements in the in vitro rearing of the tachinid parasitoid Exorista larvarum (L.)

Tachinid parasitoids are less studied than parasitic hymenopterans. Yet, they play a major role in regulating herbivore insect populations and their importance is increasingly recognized. The tachinid larval parasitoid Exorista larvarum (L.), an antagonist of lepidopterous defoliators, is suitable to be cultured both in vivo and in vitro, and yields of fecund adults approaching those usually obtained in host larvae have been achieved on artificial media. A recent study aimed at investigating the effect of supplementing haemolymph of the black soldier fly (BSF) or the Chinese oak silkworm (COS) to an insect material-free artificial medium. The supplementation (20% w/w) was based on the assumption that insect additives, though derived from nonpermissive hosts, may optimize the media. The results suggested that BSF haemolymph positively influenced the in vitro development of E. larvarum and the quality of the in vitro-reared females. Conversely, COS haemolymph was less adequate. Another study assessed the effects of storage at suboptimal temperatures (20°C for 5 days or until pupation, or 15° for 5 days or until egg hatching) on the in vitro development of E. larvarum. For the experiments, parasitoid eggs were removed from host larvae and placed on media. In all the situations tested, the in vitro development of E. larvarum was delayed and the parasitoid eventually reached the adult stage, although some negative effects on the quality of the adult flies were observed.