Laboratory susceptibility tests of Aedes aegypti and Culex quinquefasciatus larvae to the entomopathogenic nematode Heterorhabditis bacteriophora

Abstract

Introducción. Aedes aegypti es el vector de los virus del dengue, la fiebre amarilla, el Zika y el chikungunya, y Culex quinquefasciatus, de los virus de la encefalitis de Saint Louis y de la del Oeste del Nilo.Objetivo. Evaluar la capacidad infecciosa de Heterorhabditis bacteriophora N4 en larvas de C. quinquefasciatus y A. aegypti en el laboratorio.Materiales y métodos. Treinta larvas de segundo estadio de cada especie de mosquito se expusieron a diferentes dosis (0:1, 1:1, 5:1, 15:1, 100:1, 500:1, 750:1 y 1.500:1) de ejemplares juveniles infectivos del nematodo. Se hicieron cuatro réplicas por dosis.Resultados. El parasitismo varió entre 2,5 y 80 % en C. quinquefasciatus y entre 4,2 y 92,5 % en A. aegypti, con diferencias significativas entre las dosis (p<0,0001). Las DL50 fueron de 160,8 ejemplares juveniles infectivos por larva de C. quinquefasciatus y 113,6 por larva de A. aegypti; 4 a 6 % de los ejemplares juveniles infectivos llegaron a la fase adulta en C. quinquefasciatus, y 12 a 61 % en A. aegypti. Nuevos ejemplares juveniles infectivos aparecieron a partir de la dosis de 100:1. En A. aegypti aparecieron solo con dosis superiores a esta y, en C. quinquefasciatus, con una dosis de 1500:1. Se observó melanización de los ejemplares juveniles infectivos en las dos especies de mosquitos.Conclusión. Se estableció la sensibilidad de estas especies de mosquitos al parasitismo producido por un aislamiento autóctono de H. bacteriophora en condiciones de laboratorio y su potencial efecto como agente de control biológico.

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

“…Edmunds et al (2017) indicated that, in the aquatic environment, EPNs could survive long enough to parasitize and to kill Chironomus plumosus larvae [42]. Steinernematids invade through natural openings and then puncture the gut wall to enter the body cavity in caterpillars and mosquitoes [43,[54][55][56]. We also found similar results in Ae.…”

“…albopictus 3rd and 4th instar larvae, but not the 1st and 2nd instar larvae and pupae. This difference might be due to two reasons: (1) the nematodes are difficult to penetrate directly through the cuticle or per os in the 1st and 2nd instar larvae with a tiny body size [36,37,43,47,53]. (2) The pupal stage does not have natural openings for nematode entry.…”

“…In aquatic habitat, IJs of terrestrial nematodes sink to the bottom of the containers where mosquito larvae frequently feed on the organic detritus and may swim actively in search of hosts resulting in successful infection of mosquitoes [40,42]. EPNs can infect a wide range of susceptible mosquito species [36,37,[39][40][41]43]. Therefore, we investigated the mosquitocidal effects of S. abbasi, which is an indigenous nematode isolated from Taiwan by Liao et al (2001) [44], against Ae.…”

Virulence of Entomopathogenic Nematodes and their Symbiotic Bacteria against Insect Pests, with Special Reference to Agrotis ipsilon (Lepidoptera: Noctuidae): A Comprehensive Review.

“…Also, Ben Husin and Porta (2021) discussed some factors affecting the survival and efficacy of EPNs against the tomato leafminerTuta absoluta (Lepidoptera: Gelechiidae), such as the EPN species; RH, temperature range, time required by EPNs to enter a tomato leaf and number of applications in whole leaf bioassays. Therefore, it is important to study the environmental conditions of the areas where EPN exists to ensure its success as a biological control agent (Ulvedal et al, 2017;Toksoz and Saruhan, 2018).…”

“…The lower susceptibility of earlier instar larvae may be due to their small mouthparts or feeding behavior that excludes large particles (Bedding et al, 1983). The IJs are difficult to penetrate directly through the cuticle or pores in the 1 st and 2 nd instar larvae with very small body sizes (Molta and Hominick, 1989;Ulvedal et al, 2017). For some detail, large-sized hosts could more readily ingest IJs without damaging them, while smallsized early instar larvae rarely ingest IJs, more often crushing them with their mandibular teeth because of their smaller oral aperture.…”