Bracon wasps for ecological pest control-a laboratory experiment
Jessica Lettmann1, Karsten Mody1,2, Tore-Aliocha Kursch-Metz3
1Ecological Networks, Technische Universität Darmstadt, Darmstadt, Germany.
Peerj
|June 14, 2021
Summary
Biological control using parasitoid wasps like Bracon brevicornis and Bracon hebetor offers an eco-friendly pest control alternative. Optimal rearing temperatures and host availability ensure high reproductive success and effective pest management.
Area of Science:
- Entomology
- Biological Control
- Pest Management
Background:
- Synthetic pesticides pose environmental risks; biological control using natural enemies is a sustainable alternative.
- Parasitoid wasps, specifically Bracon brevicornis and Bracon hebetor (Hymenoptera: Braconidae), are cosmopolitan species that parasitize lepidopteran pests such as Ephestia kuehniella.
- Understanding the reproductive success and efficacy of these wasps under varying conditions is crucial for optimizing their use in pest control.
Purpose of the Study:
- To compare the reproductive success of Bracon brevicornis and Bracon hebetor on Ephestia kuehniella.
- To investigate the influence of temperature and host larva availability on wasp reproduction and efficacy.
- To determine optimal conditions for rearing these parasitoid wasps for biological control applications.
Main Methods:
- Laboratory experiment comparing reproductive success of B. brevicornis and B. hebetor on E. kuehniella.
- Varying temperatures (12°C to 36°C) and host densities (single vs. multiple host larvae per parasitoid).
- Assessing offspring number, sex ratio, and parasitoid efficacy (host paralysis and parasitism rates).
Main Results:
- Optimal rearing temperatures for both Bracon species were between 20-27°C, yielding the highest offspring numbers and a female-biased sex ratio.
- Increased host availability (more larvae) resulted in higher total offspring but lower average offspring per host.
- Bracon brevicornis demonstrated higher efficacy (>80%) across all tested conditions, while Bracon hebetor's efficacy varied with temperature and host density.
Conclusions:
- Both Bracon brevicornis and Bracon hebetor can be effectively used for biological pest control, with optimal rearing between 20-27°C.
- Temperature significantly impacts offspring production, but host paralysis occurs even at suboptimal temperatures (12°C and 36°C).
- Practitioners can utilize either species across a range of temperatures and host densities to achieve high pest control efficacy, with B. brevicornis showing slightly more consistent performance.
