The entomopathogenic fungus Beauveria bassiana reduces instantaneous blood feeding in wild multi-insecticide-resistant Culex quinquefasciatus mosquitoes in Benin, West Africa

Abstract

BackgroundMosquito-borne diseases are still a major health risk in many developing countries, and the emergence of multi-insecticide-resistant mosquitoes is threatening the future of vector control. Therefore, new tools that can manage resistant mosquitoes are required. Laboratory studies show that entomopathogenic fungi can kill insecticide-resistant malaria vectors but this needs to be verified in the field.MethodsThe present study investigated whether these fungi will be effective at infecting, killing and/or modifying the behaviour of wild multi-insecticide-resistant West African mosquitoes. The entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were separately applied to white polyester window netting and used in combination with either a permethrin-treated or untreated bednet in an experimental hut trial. Untreated nets were used because we wanted to test the effect of fungus alone and in combination with an insecticide to examine any potential additive or synergistic effects.ResultsIn total, 1125 female mosquitoes were collected during the hut trial, mainly Culex quinquefasciatus Say. Unfortunately, not enough wild Anopheles gambiae Giles were collected to allow the effect the fungi may have on this malaria vector to be analysed. None of the treatment combinations caused significantly increased mortality of Cx. quinquefasciatus when compared to the control hut. The only significant behaviour modification found was a reduction in blood feeding by Cx. quinquefasciatus, caused by the permethrin and B. bassiana treatments, although no additive effect was seen in the B. bassiana and permethrin combination treatment. Beauveria bassiana did not repel blood foraging mosquitoes either in the laboratory or field.ConclusionsThis is the first time that an entomopathogenic fungus has been shown to reduce blood feeding of wild mosquitoes. This behaviour modification indicates that B. bassiana could potentially be a new mosquito control tool effective at reducing disease transmission, although further field work in areas with filariasis transmission should be carried out to verify this. In addition, work targeting malaria vector mosquitoes should be carried out to see if these mosquitoes manifest the same behaviour modification after infection with B. bassiana conidia.

Effects of Beauveria bassiana on Survival, Blood-Feeding Success, and Fecundity of Aedes aegypti in Laboratory and Semi-Field Conditions

“…quinquefasciatus in Benin. 19 Fungus-exposed mosquitoes in the laboratory laid fewer eggs over a lifetime than control mosquitoes, most likely caused by reduced lifespan. A similar effect was found in An.…”

“…If one considers the extensive work reported on entomopathogenic fungi for mosquito control, only four studies, two in Tanzania 15,17 (Anopheles spp. ), one in Benin 19 (Culex quinquefasciatus), and one in Brazil 9 (Ae. aegypti), have been in field conditions.…”

“…These experiments exposed mosquitoes to entomopathogenic fungi either on black cotton cloth 9,15,17 or polyester netting. 19 Mosquitoes were then held to observe mortality either in a large cage 9 or in smaller cups 15,19 or plastic tubes. 17 Such small holding containers may introduce artifacts that affect survival or behavior, for example by presenting a shorter distance required to fly to a food source (e.g., sugar/water solution in a small cage), and limit the ability of an insect to thermoregulate in response to environmental cues.…”

Isolation and efficacy of entomopathogenic fungus (Metarhizium anisopliae) for the control of Aedes albopictus Skuse larvae: suspected dengue vector in Pakistan

“…insecticide resistance, environmental pollution, toxic hazards to human and other non-target organisms [8] . To mitigate these problems, a major emphasis has recently been taken by using entomopathogenic fungus as larvicides which can provide an alternate to synthetic chemical insecticides [9] . In general, mosquitoes show susceptibility towards entomopathogenic fungi and its derived products.…”

Biological Activity of Insecticidal Toxins: Structural Basis, Site-Directed Mutagenesis and Perspectives

“…Fungus is an entomopathogenic option. Beauveria bassiana has a long history in relation to the control of lepidopteran, coleopteran and dipteran species (Howard et al, 2010;Qin et al, 2010;Cruz et al, 2006;Shah & Pell, 2003). Metarhizium anisopliae has been used against ticks and insects, this fungus has a wide set of virulent factors, such as lipolytic enzymes, proteases, chitinases and toxins (destruxins) (Schrank & Vainstein, 2010;Pava-Ripoll et al, 2008 (Roh et al, 2010;Whetstone & Hammock, 2007).…”