# An Evaluation of Spodoptera littoralis and Spodoptera exigua as Natural Prey for the Generalist Predator Chrysoperla carnea

## TL;DR

This study explores how well lacewing larvae, a common predator, can feed on the eggs and larvae of two moth species, helping improve their use in pest control.

## Contribution

The study evaluates the suitability of Spodoptera eggs and larvae as prey for Chrysoperla carnea, revealing predator preferences and impacts on development and reproduction.

## Key findings

- Chrysoperla carnea larvae adapted to preying on Spodoptera littoralis eggs but avoided its second-instar larvae.
- Feeding on Spodoptera exigua larvae negatively affected predator development and fecundity.
- Spodoptera littoralis eggs provided better nutritional value for the predator compared to other diets.

## Abstract

The role of generalist predators in the biological control of crop pests is increasingly recognized due to their resilience and adaptability. Understanding their feeding habits is crucial for their conservation in agroecosystems and for assessing their impact on various pests. Chrysoperla carnea, a significant biological control agent, is known for its voracious predation. Despite extensive knowledge about its predation on aphids, there is limited research on its interactions with other natural prey. This study focuses on evaluating the eggs and early larvae of the beet armyworm (Spodoptera exigua) and the cotton leafworm (Spodoptera littoralis) as potential natural prey for C. carnea. Interaction and fasting enhanced prey encounters among lacewing larvae. Mobile larvae in the dual combination of preys reduced no-choice instances. When two chrysopid larvae were present, they did not attack each other, indicating increased chances of predator–prey encounters. Chrysoperla carnea larvae adapted to preying on S. littoralis eggs, but discriminated against its second-instar larvae. Spodoptera littoralis eggs showed optimal nutritional quality. Diets based on live S. exigua larvae negatively impacted predator development and fecundity, while moth eggs improved adult reserves. These findings contribute to the optimization of lacewing use in pest control programs.

Chrysoperla carnea (Stephens) is a common generalist predator in agroecosystems, frequently used for the control of soft-bodied pests in augmentative releases. Better knowledge of its interactions with secondary natural prey is necessary to optimize field biocontrol performance. This work evaluates the eggs and early larvae of Spodoptera exigua (Hübner) and Spodoptera littoralis (Boisduval) as natural prey for the third larval instar of C. carnea, and the predator preferences for different prey stages under varying conditions, assessing the impact on its life cycle and reproduction, in comparison with commercial diets based on Ephestia kuehniella Zeller eggs. Prey choice results were uniform for each dual prey combination irrespective of previous predator conditions (larvae number or fasting). Chrysoperla carnea did not show preference for Ephestia or Spodoptera eggs, but preferred eggs prior to larvae of the natural prey. Diets based on the frozen eggs of natural and factitious prey species showed similar effects on the development and reproduction of predator, but when C. carnea fed on S. exigua larvae, several negative effects were assessed, such as longer preimaginal development, lower adult emergence, and a reduced fecundity. These results are helpful for improving the use of lacewings as biocontrol agents in pest control programs.