Fungivory: a new and complex ecological function of Doru luteipes (Scudder) (Dermaptera: Forficulidae).

D D Da Silva,R V Costa,R C Pacheco,L V Cota,S M Mendes,J E F Figueiredo,R C Marucci,D F Parreira

doi:10.1590/1519-6984.238763

Abstract

We report the discovery that the earwig predator Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) feed on Puccinia polysora Underw uredospore, the causal agent of Southern Rust of Corn (SRC), which is a primary disease affecting the maize crop in Brazil. We performed experiments in laboratory and greenhouse to test the effect of D. luteipes (1st/2nd and 3rd/4th instars, and adults) fungivory on the P. polysora uredospore concentration. All trials showed a significant reduction of the initial concentration of uredospore. There was a reduction in uredospore concentration with increase in number of D. luteipes feeding on them. We also tested the uredospore consumption by quantifying its percentage in the feces of D. luteipes. Nymphs of the 2nd, 4th instar and adults fed 88%, 85%, and 83.8% of the uredospore, respectively. For nymphs of the 3rd instar, the percentage of uredospore consumption (75.6%) was statistically significant compared with the other groups. In greenhouse experiment, at twenty-eight days after plant inoculation with 9.9 x 104 uredospores, the percentage of uredospore consumption was 81.7%. Our results confirmed the fungivory of D. luteipes on P. polysora uredospore. This is the first report of D. luteipes fungivory, which may play an important role in the biological control of P. polysora in corn.

Highlights

The earwig Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) is the most common insect predator found in cornfields in Brazil (Cruz, 1995; Cruz and Oliveira, 1997)
In the experiments in the laboratory to test the D. luteipes feeding on P. polysora uredospores, the lower concentration of uredospores (3.81 x 10-4 uredospores/mL) was observed in the treatment with D. luteipes, which differed statistically (Fc: 6.636; GL: 19; P-value: 0.027 CV%: 11.56) from the controls (5.32 x 10-4 uredospores/mL) (Figure 2A)
In the greenhouse experiment to evaluate the effect of the feeding period of D. luteipes over the concentration of P. polysora uredospores, there was a significant interaction between the evaluation periods and treatments on the uredospore concentration (Fc: 3.73; GL: 36; P-value: 0.034; CV%: 39.82) (Table 1)

Summary

Introduction

The earwig Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) is the most common insect predator found in cornfields in Brazil (Cruz, 1995; Cruz and Oliveira, 1997). Doru luteipes is insect is a voracious predator and can eat up to 21 first instar larvae of Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) per. The ability to feed on corn pollen enables D. luteipes to survive under the low availability of prey. This situation strongly evidences the relationship between this predatory species and the maize plants (Marucci et al, 2019)

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Results

Conclusion