Life stage and population density of Plutella xylostella affect the predation behavior of Euborellia annulipes

The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is the main pest of brassica crops worldwide. The ringlegged earwig, Euborellia annulipes (Lucas) (Dermaptera: Anisolabididae), has been reported as a potential predator of lepidopteran larvae, including this pest, and may therefore be used for biological control. Knowledge about predator–prey interactions is important to establish pest management strategies. Therefore, the objective of this work was to evaluate the influence of the developmental stage (larva and pupa) and density of P. xylostella on the preference and functional response of E. annulipes adult females. We used choice and no‐choice tests to evaluate the foraging behavior and preference of E. annulipes on DBM life stages and varied prey density to assess the type of functional response of the ringlegged earwig. Larvae were preferred over pupae, and the predator’s functional response was type II for both prey stages. Our results report the potential of E. annulipes as a biocontrol agent of P. xylostella. Understanding their interactions may help in decision‐making and optimization of integrated management strategies.     

Last-male paternity of Euborellia plebeja, an earwig with elongated genitalia and sperm-removal behavior

Both sexes of the earwig Euborellia plebeja (Dermaptera: Anisolabididae) mate frequently. The elongated intromittent organs of males are as long as their bodies. Previous studies have revealed that this organ is used to remove rival sperm from the female sperm-storage organ (spermatheca), the length of which is twice that of the female body. The fitness benefit of sperm removal was quantified using two mating experiments with paternity analysis. As expected, given that the sperm-removal organ is shorter than the sperm-storage organ, males gained only about 20% of paternity per single mating with sperm-saturated females. The significance of frequent repeated matings with the same female by males is discussed.     

Earwig preying on ambrosia beetle: Evaluating predatory process and prey preference

Earwigs (Dermaptera), such as Forficula auricularia L., are important euryphagous predators for a wide variety of prey and can markedly influence the populations of orchard pests. Most previous studies on earwig feeding behaviour have not used adult beetles of the prey species; few researchers have focused on prey preference in earwigs. Some fragments of beetle exoskeleton and an earwig adult, Anisolabella marginalis (Dohrn), were found in the same cage, where adults of ambrosia beetle, Euwallacea interjectus (Blandford), were emerging from the logs of a fig tree infected with Ceratocystis canker (fig wilt disease). Thus, A. marginalis was suspected of being a predator of E. interjectus. To shed light on this issue, in the laboratory, we set up a test arena and observed and recorded behavioural interactions between A. marginalis and E. interjectus. E. interjectus was collected from the logs of fig trees and reared on an artificial diet, along with six different ambrosia beetle species, which were collected from a trap (baited with ethanol) and a fallen maple tree. A series of laboratory experiments demonstrated that A. marginalis is actually a predator of E. interjectus and other species of ambrosia beetle, indicating its a potential for use in effective pest control in the field. The predators frequently consume and tend to select their prey depending on prey size, rather than sex and beetle species. Furthermore, earwigs have alternative predatory strategies for dealing with seven different species, although they use their forceps to cut the body of most tested beetles.