Effects of fungal infection on feeding and survival of Anopheles gambiae (Diptera: Culicidae) on plant sugars

• Published in: Parasites & vectors 2015-01, Vol.8 (1), p.35-35, Article 35
• Main Authors: Ondiaka, Sopher N, Masinde, Elizabeth W, Koenraadt, Constantianus JM, Takken, Willem, Mukabana, Wolfgang R
• Format: Article
• Language: English
• Subjects: adults; Analysis; Animals; Anopheles; Anopheles - microbiology; Anopheles - physiology; Anopheles gambiae; Anopheles gambiae s.s; Anthracenes; Asteraceae - chemistry; beauveria-bassiana; Carbohydrates; Castor oil; culex-quinquefasciatus; Culicidae; desert locust; Dextrose; digestion; Diptera; Distribution; entomopathogenic fungi; entomopathogenic fungus; Feeding Behavior - physiology; Female; females; food-consumption; Fungi; Glucose; Health aspects; Host plants; Infection; Insect Vectors; Malaria; Malaria - prevention & control; malaria transmission; Malaria vector; Male; males; Metarhizium - pathogenicity; Metarhizium anisopliae; Methods; Mosquito Control - methods; Parthenium hysterophorus; Ricinus - chemistry; Ricinus communis; schistocerca-gregaria; Sugar; Sugar feeding; Survival Analysis; vector control; vectorial capacity; weeds; western kenya
• ISSN: 1756-3305; 1756-3305
• DOI: 10.1186/s13071-015-0654-3

BACKGROUND: The entomopathogenic fungus Metarhizium anisopliae shows great promise for the control of adult malaria vectors. A promising strategy for infection of mosquitoes is supplying the fungus at plant feeding sites. METHODS: We evaluated the survival of fungus-exposed Anopheles gambiae mosquitoes (males and females) fed on 6% glucose and on sugars of Ricinus communis (Castor oil plant) and Parthenium hysterophorus (Santa Maria feverfew weed). Further, we determined the feeding propensity, quantity of sugar ingested and its digestion rate in the mosquitoes when fed on R. communis for 12 hours, one and three days post-exposure to fungus. The anthrone test was employed to detect the presence of sugar in each mosquito from which the quantity consumed and the digestion rates were estimated. RESULTS: Fungus-exposed mosquitoes lived for significantly shorter periods than uninfected mosquitoes when both were fed on 6% glucose (7 versus 37 days), R. communis (7 versus 18 days) and P. hysterophorus (5 versus 7 days). Significantly fewer male and female mosquitoes, one and three days post-exposure to fungus, fed on R. communis compared to uninfected controls. Although the quantity of sugar ingested was similar between the treatment groups, fewer fungus-exposed than control mosquitoes ingested small, medium and large meals. Digestion rate was significantly slower in females one day after exposure to M. anisopliae compared to controls but remained the same in males. No change in digestion rate between treatments was observed three days after exposure. CONCLUSIONS: These results demonstrate that (a) entomopathogenic fungi strongly impact survival and sugar-feeding propensity of both sexes of the malaria vector An. gambiae but do not affect their potential to feed and digest meals, and (b) that plant sugar sources can be targeted as fungal delivery substrates. In addition, targeting males for population reduction using entomopathogenic fungi opens up a new strategy for mosquito vector control.