Abstract
Exogenous vertebrate-derived factors circulating in the blood have the capacity to modulate the biology of haematophagous insects. These include insulin, insulin growth factor 1 (IGF) and transforming growth factor β1 (TGFβ). The effects of the consumption of these three proteins were examined on laboratory strains of Anopheles arabiensis. SENN, an insecticide susceptible strain and SENN DDT, a resistant strain selected from SENN, were fed with host factor-supplemented sucrose. Adult longevity was measured and insecticide resistance phenotype over time was assessed by WHO bioassay. Detoxification and oxidative stress defence enzyme activity was assessed calorimetrically. Insulin supplementation augmented insecticide resistance in young adult mosquitoes. This effect was due to the hormonal nature of the protein, as heat-denatured insulin did not elicit the same response. In contrast, IGF and TGFβ consumption generally reduced the expression of insecticide resistance. Insulin ingestion significantly reduced longevity in the insecticide susceptible strain. IGF elicited the same response in the susceptible strain, while TGF consumption had no effect on either strain. Consumption of all factors significantly decreased Glutathione S-transferase activity and increased cytochrome P450 and superoxide dismutase activity. This suggests that the altered detoxification phenotype is mediated primarily by cytochrome P450 activity, which would result in an increase in oxidative stress. The increased superoxide dismutase activity suggests that this enzyme class alleviates the oxidative stress as opposed to glutathione-based redox systems. Oxidative stress responses play a crucial role in insecticide resistance and longevity. These data show that ingested hormonal factors can affect mosquito longevity and insecticide susceptibility, both of which are important characteristics in terms of malaria transmission and control.
Highlights
Haematophagy by mosquitoes that is necessary for embryonic development and enables disease transmission can affect the life history parameters of adult females
Laboratory studies have demonstrated that high levels of insulin supplementation increase parasite load [4] and decrease the lifespan of the malaria vector Anopheles stephensi [9]
This study aimed to examine the effects of insulin, insulin growth factor 1 (IGF) and transforming growth factor (TGF) consumption on the longevity and expression of insecticide resistance in two laboratory strains of An. arabiensis which differ in resistance phenotype
Summary
Haematophagy by mosquitoes that is necessary for embryonic development and enables disease transmission can affect the life history parameters of adult females. For anthropogenic mosquitoes, circulating blood-borne components ingested by the human host, such as antibiotics, have life history consequences for adult female mosquitoes [2]. One of the most important blood-borne factors ingested by mosquitoes is insulin. Exogenous host-derived insulin can exert numerous effects on the mosquito. These include stimulation of ecdysteroid production [3] and the immunological response to Plasmodium infection [4, 5]. This is due to the capacity of insulin to activate invertebrate receptors of insulin-like proteins (ILPs). The consumption of substantial amounts of exogenous insulin is not advantageous to female mosquitoes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
