# Comparative Assessment of the Potential of Xylocoris flavipes (Hemiptera: Anthocoridae) and Two Cheyletus spp. (Trombidiformes: Cheyletidae) for Managing Liposcelis decolor (Psocodea: Liposcelididae)

## TL;DR

This study compares three predators for controlling Liposcelis decolor psocids, finding Xylocoris flavipes most effective across various conditions.

## Contribution

The study provides new insights into the effectiveness of Xylocoris flavipes and two Cheyletus species for biological control of psocids under different environmental conditions.

## Key findings

- Xylocoris flavipes suppressed Liposcelis decolor populations by over 97% across all tested conditions.
- Cheyletus species required higher humidity (above 63%) to survive and reproduce.
- Xylocoris flavipes tolerated a wider range of humidity and reproduced best at warmer temperatures.

## Abstract

Managing psocids with conventional insecticides is difficult due to tolerance and resistance. This study evaluated three predator species—two predatory mites, Cheyletus eruditus and Cheyletus malaccensis, and the warehouse pirate bug, Xylocoris flavipes—to determine their potential for managing Liposcelis decolor, a psocid species with high tolerance to phosphine. The comparison used data from two separate laboratory studies conducted under similar temperature and humidity conditions but with different predator-to-prey ratios. All three predators effectively reduced L. decolor populations, with X. flavipes achieving the highest prey suppression—above 97% across all environmental conditions tested. Xylocoris flavipes also tolerated a wider range of relative humidity levels, whereas C. eruditus and C. malaccensis required relative humidity above 63% to survive and reproduce. Temperature influenced predator progeny production differently. Cheyletus eruditus and C. malaccensis produced more offspring at cooler temperatures (20–24 °C), whereas X. flavipes reproduced best at warmer temperatures (28–32 °C) with lower predator–prey ratios. These studies provide baseline information on how environmental conditions influence predator performance, with X. flavipes demonstrating broader environmental tolerance suitable for diverse storage conditions. Suppression caused by the predators demonstrate their potential as a biological control agent to manage psocids.

Psocids are difficult to manage using insecticides, hence the need for alternatives including biological control. Evaluation of data from two separate studies was conducted. One study investigated the potential of Cheyletus eruditus (Shrank) (Trombidiformes: Cheyletidae) and Cheyletus malaccensis Oudemans to manage Liposcelis decolor (Pearman) (Psocodea: Liposcelididae), whereas the other investigated the potential of Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae) to do the same. Temperature and relative humidity conditions were similar in both studies. However, the five predator–prey (P-P) ratios for the mites (0:20, 1:20, 2:20, 4:20 and 10:20) were different from those of X. flavipes (0:240, 1:240, 2:240, 3:240 and 5:240). The three predators demonstrated significant prey suppression; however, the level of control by X. flavipes was higher compared to the mites. At optimal prey conditions of 32 °C and 75% RH, all predators maintained high suppression. Temperature significantly influenced progeny production, with high reproduction observed at 20 and 24 °C for the Cheyletus spp. and at 28 and 32 °C for X. flavipes. Relative humidity of 63% was detrimental to Cheyletus spp. progeny production. While the results from this evaluation for the purpose of comparison should be interpreted cautiously, the different performances of the predators provide valuable insights for biological control of stored-product psocids.