# Storage of Euschistus heros (Fabricius, 1794) Eggs for Biological Control with Telenomus podisi Ashmead, 1851 in Open Fields in Brazil

## TL;DR

This study finds that Euschistus heros eggs can be stored at ultra-low temperatures or in liquid nitrogen without harming the parasitoid Telenomus podisi, which is important for biological control programs.

## Contribution

The study identifies optimal storage conditions for E. heros eggs to maintain parasitoid quality for biological control.

## Key findings

- Eggs stored in ULT freezers or liquid nitrogen had the highest parasitism rates by T. podisi.
- Conventional freezers reduced parasitoid viability and parasitism success.
- Storage at low temperatures enables off-season production of parasitoids.

## Abstract

A successful augmentative biological control program requires continuous and large-scale production of high-quality natural enemies, which depends on the development of appropriate storage techniques for these organisms and their hosts. In this study, we stored Euschistus heros (Fabricius, 1978) eggs at low temperatures, to determine the most viable storage condition and the duration for which these eggs can be stored without reducing acceptance by the parasitoid Telenomus podisi Ashmead, 1893, as well as the quality of its progeny (individuals to be released in the field). Egg storage was evaluated under three conditions: a conventional freezer (–15°C), an ultra-low temperature (ULT) freezer (–80°C), and liquid nitrogen (–196°C) for a period of 12 months. Parasitism of eggs stored under these three conditions was assessed at different intervals. The parasitoid parental (F0) generation was evaluated for parasitism, egg-to-adult development time, emergence, and sex ratio. In the progeny (F1), parasitism, emergence, and longevity in newly laid E. heros eggs were assessed. The ULT freezer and liquid-nitrogen storage conditions resulted in the highest parasitism rates of T. podisi in both the parental generation and its progeny. Storage in a conventional freezer was less suitable for parasitism and the viability of T. podisi. The results confirm that E. heros eggs can be stored in a ULT freezer or liquid nitrogen while maintaining their quality, thereby enabling production and storage during the off-season.