Life cycle and mode of infection of Leptolegnia chapmanii (Oomycetes) parasitizing Aedes aegypti

The life cycle and mode of infection of mosquito larvae by Leptolegnia chapmanii (Oomycetes: Saprolegniales) were determined. The life cycle is typical of saprolegniaceous fungi, as the species is dimorphic producing diplanetic biflagellate zoospores. Sexual reproduction is by means of gametangial contact and results in the production of a characteristic papillate oogonium containing a subcentric or eccentric oospore. L. chapmanii is capable of infecting Aedes aegypti larvae both by germination of encysted secondary zoospores on the exterior cuticle and by germination of ingested zoospore cysts in the larval midgut. Once the fungus is established in the host, the disease, a coelomomycosis, is fatal. The encystment pattern of secondary zoospores on the larval cuticle appcars preferential. Scanning electron microscopy indicates that mechanical pressure is not the sole force utilized by the fungus for cuticle penetration.     

Production of Oogonia and Oospores of <Emphasis Type="Italic">Leptolegnia chapmanii</Emphasis> Seymour (Straminipila: Peronosporomycetes) in <Emphasis Type="Italic">Aedes aegypti</Emphasis> (L.) Larvae at Different Temperatures

The aquatic oomycete fungus Leptolegnia chapmanii Seymour is pathogenic to mosquito larvae, but it has been little studied since it was first isolated. Although studies have been performed on different biological isolates of L. chapmanii around the world, they were made on zoospores and a very little or even nothing is known about the sexual stage (oogonia and oospores), which allows L. chapmanii to remain in the environment when conditions are not favorable. The main objective of this study was to determine the relationship between temperature and time of onset of L. chapmanii oogonia and oospores in Ae. aegypti larvae. Leptolegnia chapmanii-infected IV instar Ae. aegypti larvae were incubated at different temperatures between 5 and 45°C and photoperiod-controlled for 90 days. The number of oogonia and oospores was examined daily for each tested temperature. As was expected, low temperatures extended the times of oogonia formation, as much as seven times. Likewise, temperatures significantly affect the number of oogonia produced.     

Impact of short-term temperature challenges on the larvicidal activities of the entomopathogenic watermold Leptolegnia chapmanii against Aedes aegypti, and development on infected dead larvae

The oomycete Leptolegnia chapmanii is among the most promising entomopathogens for biological control of Aedes aegypti. This mosquito vector breeds in small water collections, where this aquatic watermold pathogen can face short-term scenarios of challenging high or low temperatures during changing ambient conditions, but it is yet not well understood how extreme temperatures might affect the virulence and recycling capacities of this pathogen. We tested the effect of short-term exposure of encysted L. chapmanii zoospores (cysts) on A. aegypti larvae killed after infection by this pathogen to stressful low or high temperatures on virulence and production of cysts and oogonia, respectively. Cysts were exposed to temperature regimes between ?12 °C and 40 °C for 4, 6 or 8 h, and then their infectivity was tested against third instar larvae (L3) at 25 °C; in addition, production of cysts and oogonia on L3 killed by infection exposed to the same temperature regimes as well as their larvicidal activity were monitored. Virulence of cysts to larvae and the degree of zoosporogenesis on dead larvae under laboratory conditions were highest at 25 °C but were hampered or even blocked after 4 up to 8 h exposure of cysts or dead larvae at both the highest (35 °C and 40 °C) and the lowest (?12 °C) temperatures followed by subsequent incubation at 25 °C. The virulence of cysts was less affected by accelerated than by slow thawing from the frozen state. The production of oogonia on dead larvae was stimulated by short-term exposure to freezing temperatures (?12 °C and 0 °C) or cool temperatures (5 °C and 10 °C) but was not detected at higher temperatures (25 °C–40 °C). These findings emphasize the susceptibility of L. chapmanii to short-term temperature stresses and underscore its interest as an agent for biocontrol of mosquitoes in the tropics and subtropics, especially A. aegypti, that breed preferentially in small volumes of water that are generally protected from direct sunlight.     

Analysis of molecular markers for metamorphic competency and their response to starvation or feeding in the mosquito, Aedes aegypti (Diptera: Culicidae)

The nutritional condition of fourth instar larvae of the yellow fever mosquito, Aedes aegypti, governs female longevity and egg production, both are key determinants of pathogen transmission. As well, nutrition provisions larval growth and development and attains its greatest pace in the last larval instar in preparation for metamorphosis to an adult. These developmental processes are regulated by a complex endocrine interplay of juvenile hormone, neuropeptides, and ecdysteroids that is nutrition sensitive. We previously determined that feeding for only 24 h post-ecdysis was sufficient for fourth instar Ae. aegypti larvae to reach critical weight and accumulate sufficient nutritional stores to commit to metamorphosis. To understand the genetic basis of metamorphic commitment in Ae. aegypti, we profiled the expression of 16 genes known to be involved in the endocrine and nutritional regulation of insect metamorphosis in two ways. The first set is a developmental profile from the beginning of the fourth instar to early pupae, and the second set is for fourth instars starved or fed for up to 36 h. By comparing the two sets, we found that seven of the genes (AaegCYP302, AaegJHE43357, AaegBrCZ4, AaegCPF1-2, AaegCPR-7, AaegPpl, and AaegSlif) were expressed during metamorphic commitment in fourth instars and in fed but not starved larvae. Based on these results, the seven genes alone or in combination may serve as molecular indicators of nutritional and metamorphic status of fourth instar Ae. aegypti larvae and possibly other mosquito species in field and laboratory studies to gauge sub-lethal effects of novel and traditional cultural or chemical controls.     

Nationwide Investigation of the Pyrethroid Susceptibility of Mosquito Larvae Collected from Used Tires in Vietnam

Pyrethroid resistance is envisioned to be a major problem for the vector control program since, at present, there are no suitable chemical substitutes for pyrethroids. Cross-resistance to knockdown agents, which are mainly used in mosquito coils and related products as spatial repellents, is the most serious concern. Since cross-resistance is a global phenomenon, we have started to monitor the distribution of mosquito resistance to pyrethroids. The first pilot study was carried out in Vietnam. We periodically drove along the national road from the north end to the Mekong Delta in Vietnam and collected mosquito larvae from used tires. Simplified susceptibility tests were performed using the fourth instar larvae of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus. Compared with the other species, Ae. aegypti demonstrated the most prominent reduction in susceptibility. For Ae. aegypti, significant increases in the susceptibility indices with a decrease in the latitude of collection points were observed, indicating that the susceptibility of Ae. aegypti against d-allethrin was lower in the southern part, including mountainous areas, as compared to that in the northern part of Vietnam. There was a significant correlation between the susceptibility indices in Ae. aegypti and the sum of annual pyrethroid use for malaria control (1998–2002). This might explain that the use of pyrethroids as residual treatment inside houses and pyrethroid-impregnated bed nets for malaria control is attributable to low pyrethroid susceptibility in Ae. aegypti. Such insecticide treatment appeared to have been intensively administered in the interior and along the periphery of human habitation areas where, incidentally, the breeding and resting sites of Ae. aegypti are located. This might account for the strong selection pressure toward Ae. aegypti and not Ae. albopictus.     

Thermal response and reversibility of prolonged larval diapause in the chestnut weevil, Curculio sikkimensis

Curculio sikkimensis undergoes prolonged larval diapause that is terminated by chilling and warming cycles. To examine the effects of warming temperatures and their duration on diapause termination, we exposed diapause larvae that had not been reactivated after chilling at 5 °C to 20 or 25 °C and chilled them again before incubation at 20 °C. With increasing warming duration at 20 °C, diapause termination after chilling increased and shorter chilling durations became effective. In contrast, few or no larvae warmed at 25 °C terminated diapause after chilling, irrespective of the warming duration. To investigate the effect of warming temperature on diapause intensity, larvae with diapause weakened by initial incubation at 20 °C after the first chilling were subsequently incubated at 15, 20, or 25 °C, then chilled at 5 °C before incubation at 20 °C. Diapause termination increased significantly after the larvae were treated at 15 or 20 °C but decreased significantly after they were treated at 25 °C. The intensification of prolonged diapause at 25 °C was reversed when the larvae were transferred to 20 °C. Diapause intensity in C. sikkimensis therefore decreases at 20 °C, increases at 25 °C, and can be reversed by alternately exposing diapause larvae to 20 and 25 °C. In C. sikkimensis, prolonged diapause does not always proceed in one direction, and its intensity fluctuates in response to ambient temperature conditions.     

Effects of temperature, pH and salinity on the infection of Leptolegnia chapmanii Seymour (Peronosporomycetes) in mosquito larvae

The effects of temperature, pH, and NaCl concentrations on the infectivity of zoospores of Leptolegnia chapmanii (Argentine isolate) were determined for Aedes aegypti and Culex pipiens under laboratory conditions. Zoospores of L. chapmanii were infectious at temperatures between 10 and 35 degrees C but not at 5 or 40 degrees C. At the permissive temperatures, mortality rates in young instars were much higher than in older instars and larvae of Ae. aegypti were more susceptible to L. chapmanii than larvae of Cx. pipiens. At 25 degrees C, Ae. aegypti larvae challenged with L. chapmanii zoospores resulted in 100% infection at pH levels ranging from 4 to 10. Larvae of Cx. pipiens exposed to similar pH and zoospore concentrations resulted in increasing mortality rates from 62% to 99% at pH 4 to 7, respectively, and then decreased to 71% at pH 10. Aedes aegypti larvae exposed to L. chapmanii zoospores in NaCl concentrations ranging from 0 to 7 parts per thousand (ppt) at 25 degrees C resulted in 100% mortality while mortality rates for Cx. pipiens decreases from 96% in distilled water to 31.5% in water with 6 ppt NaCl. Control Cx. pipiens larvae died when exposed at a NaCl concentration of 7 ppt. Vegetative growth of L. chapmanii was negatively affected by NaCl concentrations. These results have demonstrated that the Argentinean isolate of L. chapmanii tolerated a wide range of temperatures, pH, and salinity, suggesting that it has the potential to adapt to a wide variety of mosquito habitats.     

Development of the mosquito pathogen Leptolegnia chapmanii (Straminipila: Peronosporomycetes) on an inexpensive culture medium based on sunflower seed

An inexpensive culture medium based on sunflower seed extract (SSE) for production of Leptolegnia chapmanii was developed. Vegetative growth on solid and liquid SSE was compared with two culture media used routinely (peptone, yeast and glucose (PYG) and Emerson YPss). Results indicate that the oomycete is able to grow on SSE medium, producing more zoospores at a faster rate as well as inducing higher mortality rates in Aedes aegypti larvae.     

Factors affecting horizontal transmission of the microsporidium Amblyospora albifasciati to its intermediate copepod host Mesocyclops annulatus

Factors that directly impact horizontal transmission of the microsporidium Amblyospora albifasciati to its intermediate copepod host, Mesocyclops annulatus were examined in laboratory bioassays. Results were evaluated in relation to life history strategies that facilitate persistence of the parasite in natural populations of its definitive mosquito host, Ochlerotatusalbifasciatus. A moderately high quantity of meiospores from mosquito larvae was required to infect adult female copepods; the IC50 was estimated at 3.6 × 10⁴ meiospores/ml. Meiospore infectivity following storage at 25 °C was detected up to 30 days, while meiospores stored at 4 °C remained infectious to copepods for 17 months with virtually no decline in infectivity. Uninfected female M. annulatus are long-lived; no appreciable mortality was observed in field-collected individuals for 26 days, with a few individuals surviving up to 70 days. The pathological impact of A. albifasciati infection on M. annulatus resulted in a 30% reduction in survivorship after 7 days followed by gradual progressive mortality with no infected individuals surviving more than 40 days. This moderate level of pathogenicity allows for a steady continual release of spores into the environment where they may be ingested by mosquito larvae. Infected female copepods survived in sediment under conditions of desiccation up to 30 days, thus demonstrating their capacity to function as a link for maintaining A. albifasciati between mosquito generations following periods of desiccation. The susceptibility of late stage copepodid M. annulatus to meiospores of A. albifasciati and subsequent transstadial transmission of infection to adult females was established.     

Individual and combined effects of Bacillus thuringiensis var. israelensis, temephos and Leptolegniachapmanii on the larval mortality of Aedes aegypti

Larvicidal effects of interaction between Bacillus thuringiensis var. israelensis (Bti), temephos and Leptolegnia chapmanii zoospores on larvae of Aedes aegypti were determined under laboratory and seminatural conditions. In laboratory bioassays, two concentrations of Bti (0.012, 0.027 ppm), two of temephos (0.00035, 0.001 ppm), and a single concentration of L. chapmanii zoospores (6.1 × 10⁴ zoospores ml⁻¹) were evaluated. Trials under field-like conditions were performed in a single container and then placed either in the shade or in direct exposure to sunlight. We evaluated concentrations of Bti and temephos at 3-fold those normally used in laboratory tests: 0.09 and 0.003 ppm, respectively, plus 1.8 × 10⁵ zoospores ml⁻¹ of L. chapmanii. The combined effect of sublethal concentrations of Bti, temephos, and L. chapmanii zoospores thus indicated that this fungus is not inhibited by the larvicides and also demonstrated the synergistic effect of the action of L. chapmanii when used together with Bti and temephos.     

Persistence and pathogenicity of a native isolate of Leptolegnia chapmanii against Aedes aegypti larvae in different anthropic environments

The oomycete Leptolegnia chapmanii has been identified as a potential control agent of the primary vector of dengue, Aedes aegypti. In our assays, the persistence and pathogenicity of a native isolate of L. chapmanii decreased over time regardless of location. However, the mortality of Ae. aegypti larvae was significantly lower (p < 0.05) in containers located outside without sun protection (89% at first week and 9% at sixth week) compared with the containers located indoors (97% at first week and 42% at sixth week) and outside with shade (89% at first week and 29% at sixth week) possibly because of exposure to sun radiation.     

Selective and frequency dependent predation of aquatic mosquito predator Diplonychus indicus Venkatesan & Rao (Hemiptera: Belostomatidae) on immature stages of three mosquito species

Frequency dependent mosquito larval size (II and IV instars) and species selection by the water bug Diplonychus indicus against three mosquito species Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi was studied in the laboratory. The different frequencies used for each species selection were 20:30:50, 30:50:20, 50:20:30, 25:35:40, 35:40:25 and 40:25:35 of fourth instars of the respective three prey species. All nymphal water bugs (I–V instars) selected IV instar mosquito larvae and the mean proportion of late (larger) larvae eaten by the predator instars was significantly higher than the mean proportion of early (smaller) larvae eaten (F= 2.28; P < 0.001). In all six ratios used to determine the frequency dependent mosquito species selection, all the stages of the water bug selected Ae. aegypti over the other two species (F= 452.43; P < 0.001). The mean number of mosquito larvae eaten increased as its density increased based on various ratios of larvae offered. The study indicated that the predatory efficiency of D. indicus was high when Ae. aegypti was offered as prey, suggesting the utility of this mosquito predator in the control of dengue vectors.     

Heat tolerance, behavioural temperature selection and temperature-dependent respiration in larval Octopus huttoni

This study reports temperature effects on paralarvae from a benthic octopus species, Octopus huttoni, found throughout New Zealand and temperate Australia. We quantified the thermal tolerance, thermal preference and temperature-dependent respiration rates in 1-5 days old paralarvae. Thermal stress (1 °C increase h⁻¹) and thermal selection (∼10-24 °C vertical gradient) experiments were conducted with paralarvae reared for 4 days at 16 °C. In addition, measurement of oxygen consumption at 10, 15, 20 and 25 °C was made for paralarvae aged 1, 4 and 5 days using microrespirometry. Onset of spasms, rigour (CT_max) and mortality (upper lethal limit) occurred for 50% of experimental animals at, respectively, 26.0±0.2 °C, 27.8±0.2 °C and 31.4±0.1 °C. The upper, 23.1±0.2 °C, and lower, 15.0±1.7 °C, temperatures actively avoided by paralarvae correspond with the temperature range over which normal behaviours were observed in the thermal stress experiments. Over the temperature range of 10 °C-25 °C, respiration rates, standardized for an individual larva, increased with age, from 54.0 to 165.2 nmol larvae⁻¹ h⁻¹ in one-day old larvae to 40.1-99.4 nmol h⁻¹ at five days. Older larvae showed a lesser response to increased temperature: the effect of increasing temperature from 20 to 25 °C (Q₁₀) on 5 days old larvae (Q₁₀=1.35) was lower when compared with the 1 day old larvae (Q₁₀=1.68). The lower Q₁₀ in older larvae may reflect age-related changes in metabolic processes or a greater scope of older larvae to respond to thermal stress such as by reducing activity. Collectively, our data indicate that temperatures >25 °C may be a critical temperature. Further studies on the population-level variation in thermal tolerance in this species are warranted to predict how continued increases in ocean temperature will limit O. huttoni at early larval stages across the range of this species.     

In vitro production of zoospores by the mosquito pathogen Lagenidium giganteum (Oomycetes: Lagenidiales) on solid media

Reliable, large-scale production of Lagenidium giganteum zoospores was obtained on solid media. The fungus was grown for 7 days in a liquid medium of wheat germ, hemp seed, yeast extract, and glucose, then placed onto hemp-seed agar. Zoosporogenesis was induced on agar by immersing the fungal cultures into water. Zoospore production began 10 hr postimmersion, peaked at 18 hr, and ceased by 36 hr. A single, 10-cm Petri dish of fungus on hemp-seed agar produced 1.7?3.8 × 10⁷ zoospores during the 26 hr of zoosporogenesis. Optimal zoospore production occurred with 4- to 7-day-old cultures; cultures older than 10 days produced few zoospores. The temperature range for zoosporogenesis was 15–35°C. The extent of zoosporogenesis was directly related to the volume of water used to induce zoospore formation and inversely proportional to agar thickness. Bioassay of zoospores against second instar Culex quinquefasciatus larvae yielded an LD₅₀ of 400 zoospores/ml.     

Solute effects on Lagenidium giganteum: zoospore motility and bioassay reproducibility

The zoospores of Lagenidium giganteum rapidly lose motility when dispersed in deionized water. Several organic solutes were tested for the ability to prolong zoospore activity. Peptone at 0.2 and 0.05 g/liter was more effective than methionine and glucose, individually or in combination. The use of 0.2 g/liter of peptone as a medium for bioassays of L. giganteum against 3-day-old Aedes aegypti reduced the mean LD₅₀ to 12.9 zoospores/ml as compared to 133 with field water and 124 with deionized water. The use of peptone also dramatically improved the reproducibility of the assays and the goodness of fit of the resultant probit regression lines. The mean χ² values were 7.4 for 0.2 g/liter of peptone, 26.8 for field water, and 47.8 for deionized water. It is suggested that the erratic results obtained from use of deionized water are due to variation in the osmotic stress to which the zoospores were exposed, depending on the amount of debris that is introduced into the assays along with the mosquito larvae.     

Effect of Aedes aegypti (Diptera:Culicidae) Age on Sex Ratios in Romanomermis culicivorax (Nematoda:Mermithidae)

First, second, third, early and late fourth-instar larvae, and pupae of Aedes aegypti were infected with Romanomerrais culicivorax and reared at 20, 25, and 30 C. An increase in the ratio of male to female nematodes was observed with increase in host age at the time of infection at each temperature. The number of pupal and late fourth-instar infections was low, but R. culicivorax continued to develop in adult A. aegypti. Since male nematodes were recovered from both male and female hosts infected as late fourth instars or pupae, the sex of the host did not influence the sex of the nematode.     

Diapause pupal color diphenism induced by temperature and humidity conditions in Byasa alcinous (Lepidoptera: Papilionidae)

We investigated whether diapause pupae of Byasa alcinous exhibit pupal color diphenism (or polyphenism) similar to the diapause pupal color polyphenism shown by Papilio xuthus. All diapause pupae of B. alcinous observed in the field during winter showed pupal coloration of a dark-brown type. When larvae were reared and allowed to reach pupation under short-day conditions at 18 °C under a 60 ± 5% relative humidity, diapause pupae exhibited pupal color types of brown (33%), light-brown (25%), yellowish-brown (21%), diapause light-yellow (14%) and diapause yellow (7%). When mature larvae reared at 18 °C were transferred and allowed to reach pupation at 10 °C and 25 °C under a 60 ± 5% relative humidity after a gut purge, the developmental ratio of brown and light-brown, yellowish-brown, and diapause light-yellow and diapause yellow types was 91.2, 8.8 and 0.0% at 10 °C, and 12.2, 48.8 and 39.0% at 25 °C, respectively. On the other hand, when mature larvae reared at 18 °C were transferred and allowed to reach pupation at 10 °C, 18 °C and 25 °C under an over 90% relative humidity after a gut purge, the developmental ratio of brown and light-brown, yellowish-brown, and diapause light-yellow and diapause yellow types was 79.8, 16.9 and 3.3% at 10 °C, 14.5, 26.9 and 58.6% at 18 °C, and 8.3, 21.2 and 70.5% at 25 °C, respectively. These results indicate that diapause pupae of brown types are induced by lower temperature and humidity conditions, whereas yellow types are induced by higher temperature and humidity conditions. The findings of this study show that diapause pupae of B. alcinous exhibit pupal color diphenism comprising brown and diapause yellow types, and suggest that temperature and humidity experienced after a gut purge are the main factors that affect the diapause pupal coloration of B. alcinous as environmental cues.     

Effect of temperature,hydrogen ion concentration and osmotic potential on zoospore production by threePythium species isolated from pond water

Pythium fluminum produced zoospores most abundantly at 15°C, whereas the optima forPythium group F andP. marsipium were 20 and 25°C, respectively. Increasing the incubation temperature above the optimum resulted in the decrease of the duration of zoospore production. InPythium group F the ability to produce zoospores was not lost even after incubation at 40°C for 24 h. On the other hand,P. marsipium andP. fluminum lost the ability under these conditions. Zoospore production was inhibited at pH 4.5 and 10.5 in all the species tested.Pythium fluminum andP. marsipium were found to have two pH optima for zoospore production (7.5 and 9.5 for the former and 5.5 and 8.5 for the latter). The optimum pH for zoospore production byPythium group F was 6.5–7.5. Moderate osmotic potentials (–0.27–0.47 MPa) appeared to favor zoospore production by the pythia tested. The effect of temperature, pH and osmotic potential on zoospore production was discussed in relation to pollution of pond water.     

Microbial synthesis of spherical nanosilver and nanogold for mosquito control

Biosynthesis of metal nanoparticles using microorganisms is an important area of research in nanobiotechnology, which is an emerging eco-friendly science of well-defined sizes, shapes and controlled monodispersity. The present study proposed a green process for the extracellular production of silver (Ag) and gold (Au) nanoparticles (NPs) using the soil fungi Chrysosporium keratinophilum and Verticillium lecanii. The synthesized NPs were formed fairly uniform with spherical shape determined by Transmission Electron Microscope (TEM) and confirmed by Scanning Electron Microscope (SEM). Elemental analysis on single particle was carried by EDX analysis. The results were further supported by UV-vis spectrophotometry. In addition, we have also investigated the effect of synthesized AgNPs and AuNPs against the larvae and pupae of Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti. The efficacy test was performed at different concentrations for periods of different lengths by the probit analysis. The larvae and pupae of Cx. quinquefasciatus, An. stephensi and Ae. aegypti were found highly susceptible to the synthesized AgNPs than the AuNPs. The larvae of Cx. quinquefasciatus and Ae. aegypti were found to be more susceptible to the AgNPs and AuNPs synthesized using the C. keratinophilum and V. lecanii compared with the larvae of An. stephensi. The pupae of Ae. aegypti have shown higher mortality against the synthesized AgNPs than the pupa of Cx. quinquefasciatus, while no adverse effects could be observed in the pupa of An. stephensi. By this approach, it is suggested that this rapid synthesis of nanoparticles would be useful for developing a biological process for mosquito control.     

Larval sites of the mosquito Aedes aegypti formosus in forest and domestic habitats in Africa and the potential association with oviposition evolution

Adaptations to anthropogenic domestic habitats contribute to the success of the mosquito Aedes aegypti as a major global vector of several arboviral diseases. The species inhabited African forests before expanding into domestic habitats and spreading to other continents. Despite a well‐studied evolutionary history, how this species initially moved into human settlements in Africa remains unclear. During this initial habitat transition, African Ae. aegypti switched their larval sites from natural water containers like tree holes to artificial containers like clay pots. Little is known about how these natural versus artificial containers differ in their characteristics. Filling this knowledge gap could provide valuable information for studying the evolution of Ae. aegypti associated with larval habitat changes. As an initial effort, in this study, we characterized the microenvironments of Ae. aegypti larval sites in forest and domestic habitats in two African localities: La Lopé, Gabon, and Rabai, Kenya. Specifically, we measured the physical characteristics, microbial density, bacterial composition, and volatile chemical profiles of multiple larval sites. In both localities, comparisons between natural containers in the forests and artificial containers in the villages revealed significantly different microenvironments. We next examined whether the between‐habitat differences in larval site microenvironments lead to differences in oviposition, a key behavior affecting larval distribution. Forest Ae. aegypti readily accepted the artificial containers we placed in the forests. Laboratory choice experiments also did not find distinct oviposition preferences between forest and village Ae. aegypti colonies. These results suggested that African Ae. aegypti are likely generalists in their larval site choices. This flexibility to accept various containers with a wide range of physical, microbial, and chemical conditions might allow Ae. aegypti to use human‐stored water as fallback larval sites during dry seasons, which is hypothesized to have initiated the domestic evolution of Ae. aegypti.