Low-temperature storage of Exorista larvarum puparia as a tool for assisting parasitoid production

Tachinid parasitoids deserve to be better exploited as natural enemies of insect pests. The development of efficient mass-rearing techniques for these entomophagous insects may encourage their use in biological control programs. Exorista larvarum (L.) (Diptera: Tachinidae) is a Palearctic species, which has been introduced in northern America for the control of the gypsy moth, Lymantria dispar (L.). The potential use of this polyphagous parasitoid of Lepidoptera against other forest and agricultural pests encourages research aimed at the improvement of techniques for its rearing, including protocols for storage at low temperature. This technology allows a certain degree of control over the speed of development of the stored insects and assists mass-rearing facilities that have to match production with demand, especially during field outbreaks of pests. With the aim of developing storage protocols for E. larvarum, we investigated the effects of storage for 1–4 weeks of 1-day-old puparia at 15 °C. Lower temperatures (5 and 10 °C) and longer storage periods were excluded following the outcome of preliminary experiments. Parasitoid emergence and quality control parameters of the female flies obtained from the stored puparia were evaluated. In addition, female lipid body reserves were measured. The temperature of 15 °C proved to be suitable for all the durations tested, although some detrimental effects were observed following storage (e.g., lower longevity and fecundity). Our findings may prove useful to increase the flexibility of E. larvarum colony management.