Relação entre densidade larval e ciclo de vida, tamanho e fecundidade de Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) em laboratório

Abstract

-We focused on the evaluation of the infl uence that the larval density have on the life cycle, size and fecundity of Aedes aegypti (L.). The bioassays were conducted at 26 ± 2ºC and at 12h light. Five larval densities (200, 500, 750, 1000 and 1250 larvae/l) and two feeding systems (one with a fi xed amount of 100 mg of food, and other with an amount of food proportional to the number of larvae/ tray) were tested. Egg and larval development time and survivorship, sex ratio, longevity, fecundity and the size of adults were evaluated on a daily basis. The life cycle of A. aegypti was signifi cantly affected by the density when offered 100 mg of food per tray. The period of larval development increased from 8.3 to 37.9 days whereas female fecundity and wing length decreased from 105.7 to 41.8 eggs/ female and from 4.6 mm to 3.6 mm, respectively, by changing from a density of 200 to 1250 larvae/l. Signifi cant differences of these variables were not detected when offering 1.9 mg of food per larvae, except for the size of the adults. Females emerged from rearing densities of 1250 larvae/l grew larger, with an average wing length of 5.2 mm.

The influence of larval density on triacylglycerol content in Aedes aegypti (Linnaeus) (Diptera: Culicidae)

“…Population density is a stress factor that influences the development of insects, and it affects individuals in different aspects, such as reproductive success, size, and formation of reserves (Baldal et al, 2005; Baleba et al, 2019; Gilles et al, 2011). Studies evaluating only larval density increase, without a corresponding increase in the availability of food resources, have found nutritional impairment, interfering in the uptake and incorporation of nutrients, as well as cannibalism, starvation death, and smaller adult size (Beserra et al, 2009; Briegel, 1990; Price et al, 2015). Our study evaluated the stress caused by high‐larval density on total TAG reserves in immature mosquitoes, pupae and adult female fat bodies, maintaining the same nutritional ratio per larva in rearing conditions, thus excluding from this context the competition for food resources.…”

“…D. melanogaster larvae subjected to high rearing densities were more resistant to starvation, with slower development and higher amount of lipid reserves, in addition to greater efficiency in egg‐laying, resulting from this environmental context (Borash & Ho, 2001). Beserra et al (2009) showed that in A. aegypti , when only the larval density was varied (no change in food/larva ratio), there were no effects on the duration of larval development, survival rate, and larval mortality. In the case of adults, these same authors did not observe changes in longevity and fertility.…”

Differential Hatching, Development, Oviposition, and Longevity Patterns among Colombian Aedes aegypti Populations

“…Fecundity was estimated based on the average number of eggs laid per female [ 21 , 40 ]. The sex ratio was determined by dividing the number of adult females by the number of adult males [ 42 ].…”

“…aegypti populations from different regions may present diverse growth and reproduction patterns [ 38 ]. In pathogen vectors, there are biological patterns inherent to each population, such as development, survival, mortality, longevity, and fertility, influenced by intrinsic and extrinsic factors specific to the region of origin [ 38 , 39 , 40 , 41 , 42 ]. Examples of intrinsic population factors are genetics [ 43 , 44 , 45 ], larval density [ 46 , 47 ] and microbiota composition [ 48 , 49 , 50 , 51 ], while extrinsic factors include temperature [ 47 , 52 , 53 , 54 ], water pH [ 55 , 56 ], presence of insecticides [ 57 , 58 , 59 , 60 ], and availability of food and biological resources [ 46 , 47 , 61 , 62 ].…”