Relative developmental and reproductive fitness associated with pyrethroid resistance in the major southern African malaria vector, Anopheles funestus

• Published in: Bulletin of entomological research Vol. 97; no. 6; pp. 599 - 605
• Main Authors: Okoye, P.N., Brooke, B.D., Hunt, R.H., Coetzee, M.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.12.2007
• Subjects: Africa, Southern; animal fertility; Animals; Anopheles - growth & development; Anopheles - physiology; Anopheles funestus; Biological and medical sciences; developmental stages; egg hatchability; fecundity; Feeding Behavior - physiology; Female; Fertilization - physiology; fitness; fitness costs; Fundamental and applied biological sciences. Psychology; insect development; insect reproduction; insect vectors; insecticide resistance; Insecticide Resistance - physiology; insecticide resistance management; Insecticides; life tables; longevity; malaria; Malaria - transmission; Male; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; mortality; Oviparity - physiology; Pyrethrins; pyrethroid insecticides; pyrethroids; resistance costs; southern Africa; Vectors. Intermediate hosts; Southern Africa; Mozambique; Africa; Africa, Southern; southern Africa; pyrethroids; Anopheles funestus; insecticide resistance management; insecticide resistance; fitness; Protozoal disease; Malaria; Insecta; Parasite; Pyrethroids; Parasitosis; Infection; Reproduction; Arthropoda; Culicidae; Development; Ectoparasite; Pesticide resistance; Invertebrata; Vector; Diptera; Fitness
• ISSN: 0007-4853; 1475-2670
• DOI: 10.1017/S0007485307005317

The effect of pyrethroid resistance on the fitness of a laboratory strain of Anopheles funestus originating from southern Mozambique was evaluated by comparing the developmental and reproductive characteristics of a pyrethroid resistant strain with an insecticide susceptible strain. Fitness was evaluated in terms of fecundity, fertility, egg production, developmental time and life stage progression and survival. Of the eggs laid by females of the resistant strain, 81.5% hatched while only 66.9% were recorded in the susceptible strain. The time from egg hatch to adult emergence was longer for the resistant strain (15.9 days) than the susceptible strain (15.2 days). A significantly higher proportion of eggs from the resistant strain (61.6%) survived to adulthood compared with those of the susceptible strain (49%). Fecundity and larval and pupal survival did not differ significantly between strains. Of spermathecae dissected from females of the resistant strain, 56.8% were fertilized compared to 52.6% from the susceptible strain. The proportion of females that successfully produced eggs was 43.3% and 23.3% for the resistant and susceptible strains respectively. Complete failure of larval hatch was recorded in 28.6% of susceptible strain families compared to 7.7% of resistant families. Our results show that pyrethroid resistance in southern African An. funestus does not incur any loss of fitness under laboratory conditions. These results suggest that the removal of pyrethroid insecticide selection pressure may not lead to a regression of resistance alleles in pyrethroid resistant An. funestus populations in southern Africa.