RESUMO
@#Malaria, a mosquito-borne disease, is caused by protozoa of the genus Plasmodium and constitutes a serious public health problem. Because current insecticides used to control malaria face resistance due to continuous use, new alternatives are prompted. Considering this context, and the insecticidal potential of vertebrate venoms/secretions, crude and methanolic extracts from two frog species were tested as larvicides against Anopheles darlingi. Skin secretions of Rhinella marina and Rhaebo guttatus were obtained by manual stimulation. Then, methanol was added to obtain steroidal fractions from both venoms. Mosquitos were captured in suburban areas of Porto Velho and An. darlingi females were later fed with blood and stimulated to oviposit. The larvae were fed with fish food until the 3rd and 4th instars. For the larvicidal assays, crude secretions and methanolic fractions of both frog species were evaluated, and larvae mortality was recorded after 48 hours. Crude extracts and steroidal fractions from both species had larvicidal effects, with an LC50 of 127.5 and 133 ppm for the crude extract and steroidal fraction of R. marina, and an LC50 of 37.5 and 35.8 ppm for the crude extract and steroidal secretion of R. guttatus, respectively. The present work reports for the first time the larvicidal effects of the skin secretions from bufonid species occurring in the western Amazon region. Further studies should be carried out to investigate the purified components responsible for the observed activity.
RESUMO
Anopheles darlingi is the main vector of the disease in the Amazon, and several studies on its ecology and behavior have been conducted. Although the basic nutritional requirements of insects are well known, quantitative needs with respect to food components and their balance vary among insect species; therefore, such information is needed in order to improve insect rearing for mass production. The present work evaluated the effect of different animal diets on larval biology and the utilization of different sugar sources in An. darlingi adults. First instar larvae obtained from wild-captured mosquitoes were reared in plastic trays containing 1 L of water and fed daily according to their larval instar stage with different commercial diets for fish, reptiles, and dogs, as well as a manipulated diet including Macapo. Larval mortality was recorded daily, and development time was calculated as the time required for 50% of the larvae to reach the last larval instar. Pupae and adults produced from larvae fed with different animal diets were also counted daily. Adults were fed with 10% sugar solutions of honey, sucrose, and sugar cane molasses, and longevity was recorded. Larval mortality was reduced for larvae feeding on fish food (higher protein content) compared to those fed with dog food (lower protein content) in later instars; the first and third instars presented a higher mortality than other instars, regardless of the food provided. Larval development time was reduced in larvae fed with fish food compared with dog food. The average daily production of pupae and adults were significantly higher in the treatment using fish food than in all other diet treatments. In general, adults from larvae fed on fish food and those that ingested honey as an adult sugar source lived longer than those reared on other treatments. Fish food, i.e., Tetramin Tropical Flakes, for larvae and honey, as a carbohydrate source for adults, seem to better support the rearing of Anopheles darlingi under our experimental conditions.
RESUMO
@#Anopheles darlingi is the main vector of the disease in the Amazon, and several studies on its ecology and behavior have been conducted. Although the basic nutritional requirements of insects are well known, quantitative needs with respect to food components and their balance vary among insect species; therefore, such information is needed in order to improve insect rearing for mass production. The present work evaluated the effect of different animal diets on larval biology and the utilization of different sugar sources in An. darlingi adults. First instar larvae obtained from wild-captured mosquitoes were reared in plastic trays containing 1 L of water and fed daily according to their larval instar stage with different commercial diets for fish, reptiles, and dogs, as well as a manipulated diet including Macapo. Larval mortality was recorded daily, and development time was calculated as the time required for 50% of the larvae to reach the last larval instar. Pupae and adults produced from larvae fed with different animal diets were also counted daily. Adults were fed with 10% sugar solutions of honey, sucrose, and sugar cane molasses, and longevity was recorded. Larval mortality was reduced for larvae feeding on fish food (higher protein content) compared to those fed with dog food (lower protein content) in later instars; the first and third instars presented a higher mortality than other instars, regardless of the food provided. Larval development time was reduced in larvae fed with fish food compared with dog food. The average daily production of pupae and adults were significantly higher in the treatment using fish food than in all other diet treatments. In general, adults from larvae fed on fish food and those that ingested honey as an adult sugar source lived longer than those reared on other treatments. Fish food, i.e., Tetramin Tropical Flakes, for larvae and honey, as a carbohydrate source for adults, seem to better support the rearing of Anopheles darlingi under our experimental conditions.
