The Invasion and Encapsulation of the Entomopathogenic Nematode, Steinernema abbasi, in Aedes albopictus (Diptera: Culicidae) Larvae

Abstract

The Asian tiger mosquito, Aedes albopictus, is of crucial concern to the public and veterinary health because of its vector role in transmission of several mosquito-borne diseases. Over the past decades, entomopathogenic nematodes (EPNs) have been used to control important agricultural insect pests and are considered to be effective against mosquitoes as well. The objectives of this study were to investigate the mosquitocidal effects of Steinernema abbasi to Ae. albopictus and the encapsulation processes of invading nematodes in the mosquito host. In this study, we found that S. abbasi was pathogenic to 3rd and 4th instar larvae of Ae. albopictus by entering the hemocoel of the 3rd and 4th instar larvae mainly through mouth and gastric caecum or by penetrating pupae through the intersegmental membrane or trumpet. The mosquito larvae infected with a single nematode caused a high mortality. Although EPNs in the hemocoel of mosquitoes were melanized and encapsulated, most Ae. albopictus larvae failed to survive after infection with S. abbasi. Overall, we demonstrated that S. abbasi is pathogenic to Ae. albopictus larvae, suggesting that this S. abbasi isolate has potential as a biocontrol agent for managing this vector mosquito.

Survival and efficacy of entomopathogenic nematodes on exposed surfaces

“…This ability of desiccated IJs to rehydrate inside the insect gut and resume infectivity was also reported by Wojicik and Georgis 55 . Recent research on Diptera has also indicated the ability of IJs to infect larvae by passage to the haemolymph from the gut through the peritrophic membrane 56 . This would indicate that motility of rehydrated IJs inside the insect gut is critical for successful infection.…”

The parasitic impact of Romanomermis iyengari Welch (Nematoda: Mermithidae) on the survival and biology of the common mosquito, Culex pipiens L. (Diptera: Culicidae)

“…The immune system of mosquito larvae is a potential physiological mechanism to combat pathogens that invade their haemocoele (Hillyer 2010). After invasion of their haemocoele, mosquito larvae have a diverse array of cellular and humoral immune responses (Shamseldean et al 2006;Liu et al 2020). It is reasonable to suggest that the fourth instar of Cx.…”

The cecropin-prophenoloxidase regulatory mechanism is a cross-species physiological function in mosquitoes

“…The source and maintenance of the mosquitoes has been described previously ( Liu et al., 2020 ). Ae.…”