Culex molestus is an obligatory autogenous mosquito that is closely associated with subterranean habitats in urban areas. The objective of our study was to investigate the influence of larval and adult nutrition on the role of males in determining the expression of autogeny in Cx. molestus. Mosquitoes raised at low and high larval diets had sex ratio, wing length, mating rates, autogenous egg raft size, and hatching rates recorded. There was a higher ratio of males to females when raised at a low larval diet. Mean wing lengths of both males and females were significantly greater when raised at the high larval diet regime. Regardless of larval or adult diet, males mated with only a single female. Mosquitoes raised at the higher larval diet regimes developed significantly more autogenous eggs. However, the egg raft size was reduced when adult females were denied access to sugar. The results of this study indicate that the performance of males in the reproductive process is influenced by both larval diet and adult sugar feeding.
The fundamental approach to the biological control of Aedes albopictus requires the mass rearing of mosquitoes and the release of highly competitive adults in the field. As the fitness of adults is highly dependent on the development of immatures, we aimed to identify the minimum feeding regime required to produce viable and competitive adults by evaluating three response parameters: development duration, immature mortality, and adult wing length. Our study suggests at least 0.60 mg/larva/day of larval diet composed of dog food, dried beef liver, yeast, and milk powder in a weight ratio of 2:1:1:1 is required to maximize adult fitness. With standardized protocols in mass rearing, intensive studies can be readily conducted on mosquito colonies to facilitate comparisons across laboratories. This study also evaluated the differences in response of laboratory and field strains under different feeding regimes. We found that strain alone did not exert substantial effects on all response parameters. However, the field strain exhibited significantly lower immature mortality than the laboratory strain under the minimum feeding regime. Females and males of the laboratory strain had longer wing lengths under nutritional constraint due to the higher mortality that resulted in reduced interactions with the remaining larvae. Meanwhile, the field strain exhibited heterogeneous duration of immature development compared with the laboratory strain. The disparities demonstrated by the two strains in this study suggest the effect of inbreeding surfaced after a long term of laboratory colonization. Despite the trade-offs resulting from laboratory colonization, the competitiveness of the laboratory strain of Ae. albopictus is comparable to the field strain, provided the larvae are fed optimally.
Due to conservation and rehabilitation efforts, mangrove forests represent some of the largest environmental niches in Malaysia. However, there is little information on the potential risks posed by mosquitoes that are directly and indirectly associated with mangrove forests. To study the potential health risk to humans active within and in close vicinity of mangrove forests, this research focused on the day biting habits of mosquitoes in mangrove forests of Kedah, Malaysia. The bare leg catch (BLC) method was used to collect adult mosquitoes during a 12-h period from 7:30 a.m. to 7:30 p.m. in both disturbed and less disturbed areas of mangroves. In total, 795 adult mosquitoes from 5 genera and 8 species were collected, and over 65% of the total mosquitoes were collected from the less disturbed area. The predominant species from the less disturbed area was Verrallina butleri; in the disturbed area the dominant species was Culex sitiens. The peak biting hour differed for each species, with Aedes albopictus and Cx. sitiens recorded as having a bimodal biting activity peak during dawn and dusk. For Ve. butleri an erratic pattern of biting activity was recorded in the less disturbed area but it peaked during the early daytime for both collection points. Overall, the distinct pattern of day biting habits of mosquitoes within mangroves peaked during dawn and dusk for the less disturbed area but was irregular for the disturbed area throughout the day. The presence of vectors of pathogens such as Ae. albopictus for both areas raises the need for authorities to consider management of mosquitoes in mangrove forests.
The nutritional requirements of mosquitoes include both sugar (generally derived from the nectar of flowers) and blood (humans or animals). Mosquitoes express different degrees of preferences towards hosts depending on behavioral, ecological, and physiological factors. These preferences have implications for mosquito-borne disease risk. The present study is directed to reveal the effect of the human blood groups on the fecundity and fertility of the malaria vector Anopheles stephensi. In laboratory tests, mosquitoes were fed on ABO blood groups via artificial membrane feeders, and the level of attraction against different blood groups was tested by the electroantennogram and wind tunnel bioassay under control conditions. Results indicate that the female mosquitoes had a strong preference towards the blood group B, while in the case of females fed on O blood group had the highest digestibility rate. Overall, the human blood type had a significant impact on the fecundity and fertility of female An. stephensi. The highest numbers of eggs are laid, in the case of blood group B, (mean (± SD)) 216.3 (8.81) followed by the AB, 104.06 (7.67), and O, 98.01 (7.04). In the case of blood group B, females attain the highest fertility of about 92.1 (9.98). This study provides novel insight into the ABO blood type host choice of the mosquitoes that are still partially unknown and suggests encouraging personal protection for relevant individuals within communities at risk, which is a useful tool for preventing malaria where the An. stephensi is present as a dominant vector.
The effective control of Aedes mosquitoes using traditional control agents is increasingly challenging due to the presence of insecticide resistance in many populations of key mosquito vectors. An alternative strategy to insecticides is the use of toxic sugar baits, however it is limited due to short-term efficacy. Alginate-Gelatin hydrogel beads (AGHBs) may be an effective alternative by providing longer periods of mosquito attraction and control, especially of key vectors of dengue viruses such as Aedes aegypti and Aedes albopictus. Sodium alginate (ALG) and gelatin (GLN) are natural polymers, which can be a potential candidate to develop the AGHBs baits due to their biodegradability and environmental safety. Here we provide an assessment of the preparation of AGHBs optimized by varying the concentrations of ALG, GLN, and its cross-linking time (TIME). Fourier transform infrared spectroscopy (FTIR) analysis results in the determination of liquid bait loaded in the AGHBs. The evaluation of AGHBs' effectiveness as the potential baiting tool based on the mortality rate of mosquitoes after the bait consumption. The 100 % percent mortality of Aedes mosquitoes was obtained within 72 h of bait consumption. The field evaluation also justifies the applicability of AGHBs for outdoor applications. We conclude that the AGHBs are applicable as a baiting tool in carrying liquid bait in achieving mosquito mortality.