# Infection, Choice Behavior, and Cross-Infectivity of the Sculpted Damsel Bug, Nabis roseipennis, Offered the Tarnished Plant Bug, Lygus lineolaris, Infected with Entomopathogenic Nematodes

## TL;DR

This study shows that certain nematodes can effectively kill a major crop pest without harming a beneficial insect predator, supporting sustainable pest control methods.

## Contribution

The research identifies specific nematode strains that are highly effective against the tarnished plant bug while being safe for the sculpted damsel bug.

## Key findings

- Nematode strains HbHP88, HbVS, Sc17c+e, and SfSN caused high mortality in the tarnished plant bug.
- Predators avoided infected prey and did not become infected after consuming it.
- The nematodes had minimal impact on the beneficial sculpted damsel bug.

## Abstract

The tarnished plant bug is a major pest of row crops in the southern United States, causing significant economic losses in cotton and other commodities. This study evaluated the ability of entomopathogenic nematodes to control this pest while assessing the safety of these nematodes for a beneficial insect predator commonly found in crop fields. The objectives were to determine whether nematodes could infect and kill the tarnished plant bug, whether infection alters predator feeding behavior, and whether predators could become infected after consuming infected prey. Laboratory and greenhouse experiments showed that several nematode strains caused high mortality in the pest but had minimal effects on the beneficial predator. Predators consistently avoided infected prey, and even when feeding did occur, no transmission of infection to the predator was observed. These findings demonstrate that selected nematode strains are effective against a key agricultural pest while posing little risk to natural enemies. This research supports integrating nematode-based biological control into crop protection programs and highlights their potential to reduce reliance on chemical insecticides, benefiting both environmental health and sustainable agriculture.

The tarnished plant bug, Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae), is an economically important pest of row crops worldwide. Ten isolates of entomopathogenic nematodes (EPNs) (Rhabditida: Steinernematidae and Heterorhabditidae) were evaluated against the third instar nymphal stage of the tarnished plant bug and its generalist predator, the sculpted damsel bug, Nabis roseipennis Reuter (Hemiptera: Nabidae), one of the most abundant and commonly encountered damsel bugs in cotton and soybean agroecoscapes across the Southeastern United States. The objectives of these experiments were to assess the infectivity of entomopathogenic nematodes (EPN) by direct topical exposure against the sculpted damsel bug and tarnished plant bug, whether the predator prey choice is affected by EPN infection, and if feeding on EPN-infected tarnished plant bug (TPB) prey items could result in cross-infection of the predator. Mortality rates at a concentration of 200 infective juveniles (IJs)/mL significantly differed among isolates and insect species, ranging from 30% to 93% for tarnished plant bugs and from 6% to 38% for sculpted damsels, respectively. The third instars of L. lineolaris were more susceptible to the ten nematode isolates than N. roseipennis. Higher pathogenicity on the tarnished plant bug and a low mortality potential make strains HbHP88, HbVS, Sc17c+e, and SfSN the most promising candidates for the biological control of L. lineolaris under lab and greenhouse conditions while preserving beneficial predators of the Southeastern United States.