Open-access First report of earwig Doru luteipes (Dermaptera: Forficulidae) preying on corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae) nymphs

Earwigs are an important group of predators of various pests, including lepidopteran eggs (Pacheco et al., 2021), caterpillars (Ahissou et al., 2021), aphids (Alins et al., 2023), and thrips (Silva et al., 2022). In corn cultivation, they are the main predators of the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) because of their ability to feed on eggs (Pacheco et al., 2021) and early instar larvae (Ahissou et al., 2021).

Besides S. frugiperda, a primary concern in corn cultivation is the presence of the maize leafhopper Dalbulus maidis (Hemiptera: Cicadellidae). This insect serves as a vector for pathogens, including viruses (maize rayado fino virus) and mollicutes (maize bushy stunt phytoplasma and corn stunt spiroplasma) (Sabato, 2017; Oliveira and Frizzas, 2022), which can severely impact productivity by up to 100%. While there are known natural enemies in the field, such as parasitoids (Querino et al., 2017) and naturally occurring entomopathogenic fungi (Souza et al., 2021), there is limited information available regarding predators targeting corn leafhoppers. The present study aims to document D. luteipes as a potential predator of maize leafhoppers and assess its predation capabilities.

The study was carried out in a controlled laboratory setting. Adult earwigs were collected in February, from a commercial corn field (50 days after planting) on February, 8th 2024 in Ponta Grossa, Paranawhere no insecticides were applied. Earwigs were manually collected from the whorl regions of the plants. Maize leafhopper nymphs were collected from the same field using an insect aspirator tube between the third and fifth instars. In the laboratory (at room temperature), the insects were housed in Petri dishes (10 replicates) containing filter paper to maintain humidity (Figure 1A). Additionally, a portion of maize leaves measuring 10 × 10 cm was included in each Petri dishes as a natural substrate for the insects (Figure 1A). One adult female earwig was placed in each Petri dish to monitor the feeding activity of the earwigs. Subsequently, 10 corn leafhopper nymphs (4th instar) were deposited in each Petri dish. Monitoring occurred at 12-hour intervals. Subsequently, the nymphs were quantified again to estimate the feeding capacity of the earwigs and to confirm the corn leafhoppers predation.

Figure 1
Methodology to evaluated earwig preying. Earwig and maize leafhopper nymphs to assessment predation on Petri dish (A). Earwig preying maize leaf hopper nymph (B).

Overall, each earwig adult consumed approximately 4.6 individuals within 12 hours. This study provides the initial evidence of earwigs preying on D. maidis nymphs (Figure 1B). In field observations, nymphs were primarily found in the whorl region of maize or on expanded leaves (personal observation). Therefore, crop management activities should be cautiously adopted to preserve natural enemies.

The observed predation potential emphasizes the importance of careful consideration in pest management strategies, such as using selective pesticides to protect earwigs. These pesticides aid in conserving natural enemies, enhancing the effectiveness of biological control agents in pest suppression (Moreira et al., 2022). Finally, this study demonstrated that adult D. luteipes have the predation capacity on D. maidis nymphs. Further research is required to elucidate the biological aspects of D. luteipes feeding on leafhopper nymphs.

Acknowledgements

We thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). We also thank Fundação Araucária.

References

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Publication Dates

  • Publication in this collection
    21 Oct 2024
  • Date of issue
    2024

History

  • Received
    27 Apr 2024
  • Accepted
    13 Aug 2024
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