Several parameters on the oviposition site preference of Aedes albopictus were studied, including color, container type, salinity, and water type. Dark-colored glass jars, especially black, blue, and red ones were preferred over light-colored jars. The black-colored ovitrap with a paper strip performed better than other types of containers. Seasoned tap water had the highest egg count when compared with a saline water series. In addition, water that had previously been used for the culture of Ae. albopictus was the most preferred for oviposition. The significance of this study in conjunction with the present Aedes mosquito surveillance and monitoring program is discussed.
During a mosquito survey in Ulu Gombak, Selangor, Peninsular Malaysia, October 2-16, 2003, we observed a peculiar oviposition habit of Armigeres flavus. This strange behavior is described and illustrated with photographs; although it is well known, no detailed description has been made previously.
A prospective field study was carried out to investigate any preferential differences of gravid female Aedes mosquitoes in ovipositing their eggs in man-made containers placed in different environmental conditions. The findings of this study show that gravid female Aedes mosquitoes preferred to breed in containers found in the outdoor garden than those placed on the patio and or inside the house. The findings also show that if the breeding habitats in the garden were removed, they would favorably use the breeding habitats found on the patio or inside the house as alternatives. An incidental interesting finding in this study shows that ultra-low volume fogging of insecticides using the vehicle-mounted equipment carried out outside the house may promote the gravid female Aedes mosquitoes to enter the house to breed.
Buruli ulcer (BU) is a globally recognized, yet largely neglected tropical disease whose etiologic agent is Mycobacterium ulcerans. Although the exact mode of transmission is unclear, epidemiological evidence links BU incidence with slow-moving or stagnant, aquatic habitats, and laboratory-based experiments have shown disease manifestation in animals with dermal punctures. Therefore, hypotheses for transmission include contact with slowmoving aquatic habitats and associated biting aquatic insects, such as mosquitoes. Recent research demonstrated the toxin produced by M. ulcerans, mycolactone, is an attractant for adult mosquitoes seeking a blood-meal as well as oviposition sites. In the study presented here, we examined the impact of mycolactone at different concentrations on immature lifehistory traits of Aedes aegypti, which commonly occurs in the same environment as M. ulcerans. We determined percent egg hatch was not significantly different across treatments. However, concentration impacted the survivorship of larval mosquitoes to the adult stage (p < 0.001). Resulting adults also showed a slight preference, but not significant (p > 0.05), for oviposition in habitats contaminated with mycolactone suggesting a legacy effect.
Aedes albopictus poses a public health risk in tropical countries and temperate countries in recent decades due to its capability to transmit various human arboviruses including dengue, yellow fever, and chikungunya. Vector control is the key for preventing transmission of these pathogenic viruses. Improving the effectiveness of currently utilized collection methods, such as ovitraps, is important for best species abundance monitoring, assessment of the threat of arbovirus transmission, and optimizing control activities. Therefore, this study aimed to assess the potential use of lactic acid bacteria (LAB) waste as an infusion-baited ovitrap for Aedes collection. The performance of overnight tap water, grass hay infusion and LAB waste infusion were compared for their ability in attracting gravid female Ae. albopictus. In this study, the LAB waste infusion was substantially more alluring to Ae. albopictus mosquitoes than the two controls grass hay infusion and tap water.
An exophilic population of the vector mosquito Anopheles balabacensis Baisas was investigated in two mark-recapture studies (16.ix-13.x.1986 and 6-26.i.1987) at an inland, foothill village in Sabah, Malaysia. Wild female mosquitoes were intercepted as they came to feed on man or buffalo, given a bloodmeal, marked with fluorescent dust and released. The recapture rate was about 12%. A new method of analysis is proposed which uses cross-correlation and a time series model. The estimated survival per oviposition cycle was 0.48-0.54 and the oviposition cycle interval 2-3 days.
To understand the effects of fish predator’s kairomones on Aedes mosquitoes’
oviposition, we established an experiment using gravid Aedes females. Kairomones
concentrations were established using Hampala macrolepidota. One individual fish was
placed inside containers with varying water levels (1 L, 5 L, and 10 L of water). The fish
were kept in the containers for 24 hours and were removed immediately at the start of
each trial in order to have the kairomones remnants. Twenty gravid adult females of
Aedes aegypti and Aedes albopictus were allowed to lay eggs on oviposition site with
various treatments: (1) control without any kairomones; (2) kairomone remnant in 1 L of
water; (3) kairomone remnant in 5 L of water; and (4) kairomone remnant in 10 L of water.
There are significant differences between the numbers of eggs laid by both Aedes species
for each different treatment (F = 9.131, df = 16, p
This study was conducted to evaluate the effectiveness of a floor gully come with grating to prevent the oviposition of Aedes aegypti in the floor trap. In order to conduct the test, two containers were placed into a mosquito cage (30 cm × 30 cm × 30 cm). Both containers were filled with declorinated seasoned tap water and covered with floor gully c/w grating and normal floor gully, respectively. A total of 50 gravid Ae. aegypti females were then released into the cage and left for a week. All the eggs obtained from the test were allowed to remain inside the containers for the eggs to hatch. The number of hatched larvae was counted and recorded. Five replicates were conducted concurrently. There was a significant difference of Ae. aegypti larvae obtained between container with floor gully c/w grating and normal floor gully (p < 0.05). A total of 96.41% reduction of Ae. aegypti larvae was obtained in the container with floor gully c/w grating compared with the normal floor gully, indicating that the floor gully c/w grating used in this study was able to prevent oviposition of Ae. aegypti in holding water.
For successful parasitism, parasitoid females must oviposit and the progeny must develop in individual hosts. Here, we investigated the determinants of host acceptance for oviposition and host suitability for larval development of Drosophila parasitoids from Bogor and Kota Kinabalu (≍1,800 km northeast of Bogor), Indonesia, in tropical Asia. Asobara pleuralis (Ashmead) from both localities oviposited frequently (>60%) in all of the drosophilid species tested, except the strain from Kota Kinabalu oviposited rarely (10%) in Drosophila eugracilis Bock & Wheeler. Leptopilina victoriae Nordlander from both localities only oviposited frequently (>77%) in species from the Drosophila melanogaster species group except D. eugracilis (<3.7%), whereas Leptopilina pacifica Novković & Kimura from Bogor oviposited frequently (>85%) only in species from the Drosophila immigrans species group. Thus, host acceptance appeared to be affected by host taxonomy, at least in Leptopilina species. Host suitability varied considerably, even among closely related drosophilid species, which suggests that the host suitability is at least in part independent of host taxonomy and that it has been determined via parasitoid-host coevolutionary interactions (i.e., arms race). Host acceptance did not always coincide with host suitability, i.e., parasitoids sometimes oviposited in unsuitable host species. Geographic origin strongly affected the host acceptance and suitability in the A. pleuralis-D. eugracilis parasitoid-host pair, whereas it only weakly affected the acceptability and suitability in other parasitoid-host combinations.
The likelihood of dipteran maggots colonizing a corpse due to nocturnal oviposition can be used to challenge the postmortem interval (PMI) estimated assuming diurnal oviposition. Earlier experiments tested nocturnal oviposition behavior by exposing fresh baits once during a single night. In this pilot study, oviposition behavior was studied using beef baits, which, simulating the decay of the body seen in case situations, decomposed inside cages designed to open and close at scheduled intervals during consecutive night or twilight periods. Freshly hatched maggots from diurnally oviposited eggs emerged in control baits on the third day, while a limited number of maggots attributable to nocturnal or twilight oviposition were observed in experimental baits only on the fifth or sixth day, indicating a categorical delay. These results suggest that such delayed and limited nocturnal oviposition is not forensically significant since the larger maggots deriving from diurnal oviposition would be the ones considered when estimating PMI.
Reciprocal and homologous mating experiments between Malaysian Aedes aegypti and Aedes albopictus mosquitoes were conducted in the laboratory. Two methods were employed, namely an artificial mating technique and a natural cage mating technique. The study demonstrated there exists a strong reproductive isolation between Ae. aegypti and Ae. albopictus. Insemination occurred in cross-mating experiments between Ae. aegypti females and Ae. albopictus males and also between Ae. albopictus females and Ae. aegypti males. Cross mating between Ae. aegypti females and Ae. albopictus males produced more eggs than that between Ae. albopictus females and Ae. aegypti males with both artificial mating and natural cage mating techniques. The matings did not result in the production of viable eggs by the females. No embryonation of these eggs was observed when the eggs were bleached. With homologous mating Aedes aegypti produced significantly greater numbers of eggs compared to Aedes albopictus mosquitoes, and all the eggs hatched successfully.
A study was made of the oviposit behavior of gravid female Aedes mosquitos in man-made habitats under field conditions. The study showed that the gravid female Aedes mosquitos preferred containers with relatively easy access but not too open to external environmental influence. The dark surface of the containers served as the initial and long-range attractant to the breeding sites. Volatile chemicals generated by the decaying vegetation in the container may serve as a close-range attractant. Finally, the water quality and the quantity of 'food' derived from decaying vegetative matter in the water determined the amount of eggs deposited in each container. The study confirmed previous findings that each gravid female Aedes mosquito had the tendency to lay her eggs in more than one container. However, the results of the study suggests that under favorable conditions, each gravid female Aedes mosquito could be encouraged to lay all her eggs in a single breeding site.
Moisture plays a major role in the dynamics of mosquito populations, especially those breeding in container habitats. Despite this importance, the role of moisture conditions as they affect oviposition and egg development in Aedes vectors remains largely unexplored. We investigated the effect of exposing gravid female Aedes albopictus mosquitoes and their eggs to different moisture levels (MLs) for various periods on oviposition and hatching. Overall, high-moisture substrates (HMSs; 66% and 72%) provided better environments for egg laying. The timing of initial egg laying was far longer at the lowest substrate moisture level (LSML, 25% and 41.2%) than at HMSs. The numbers of eggs laid were much lower in the drier environments. At LSMLs, gravid females retained increasing numbers of mature eggs until death, and egg retention decreased gradually with increasing ML. The HMSs also provided better environments for larval eclosion. The numbers of eggs hatched were lower at the LSML than the HSML environment. No egg hatching occurred after 1 h exposure to moisture. However, egg hatching occurred by installment, with spontaneous hatching (SH) increasing gradually with increasing ML. High-moisture conditions combined with long exposure (30 h and 48 h) favored SH. These results suggest that Ae. albopictus females can respond to better moisture conditions for increased success of embryonation and larval eclosion. This information may be useful in the colonization of floodwater Aedes species.
A forensic entomological study conducted in an oil palm plantation in Tanjung Sepat, Selangor, Malaysia on 3 August 2007 revealed that a housefly, Musca domestica Linnaeus oviposited its eggs on a freshly dead pig. This finding indicated that housefly might play an important role in forensic investigation in determining post-mortem interval (PMI), although it was not yet found in human corpses or any animal carrion. This preliminary paper presented a first record of Musca domestica eggs found on animal carcass in the country.
Fifty children aged 6 to 13 years and infected with Ascaris lumbricoides were selected for the study. The number of eggs laid daily by a female Ascaris increased with increase in its length, weight and diameter. Female worms became mature and started laying eggs when they reached a length of 118 mm. Adult female worms measuring 3.7 mm or more in diameter were found to be mature. The minimum weight of a worm producing eggs was 1.1 g. On average the number of eggs produced by the female decreased with increase in the worm load.
Simulium (Simulium) umphangense, a new human-biting species of black fly, is described based on females captured while attacking humans in western and central Thailand. The female of this new species is similar to those of S. (S.) indicum Becher, S. (S.) nigrogilvum Summers, and S. (S.) vanellum Huang et al. in the Simulium griseifrons species-group of the subgenus Simulium Latreille in having the frons densely covered with golden-yellow short hairs, a character rarely found in the subgenus Simulium. This new species is readily distinguished from the three related species by having a darkened fore tibia, a bare subcosta (or rarely with a few hairs), and an ovipositor valve not protruded posteriorly. Additional diagnostic characters of this new species are noted. This is the seventh human-biting species of black fly in Thailand.
Introduction: Entomological surveillance is crucial to determine the abundance of dengue vector and to evaluate breeding areas of Aedes aegypti and Aedes albopictus. The objective of this study is to determine the distribution and breeding preference for both Ae. aegypti and Ae. albopictus in dengue endemic areas. Materials and Methods: Ovitraps surveillance was conducted in two dengue endemic areas; AU2, Keramat and Seksyen 7, Shah Alam, Selangor. A minimum number of 100 ovitraps were deployed for 5 days in the study sites. Samples collected were brought back to the lab and all larvae recovered were identified to species level. Results: The ovitap index (OI) in both localities exceeded the transmission threshold of 10% with the OI recorded ranged from 42.3-79.8% in AU2, Keramat and 16.7-42.9% in Seksyen 7, Shah Alam. Ae. albopictus was the dominant species in AU2 Keramat with the highest ratio Ae. aegypti to Ae. albopictus recorded was 1.00:22.79. Nonetheless, in Seksyen 7, Shah Alam the difference in Ae. aegypti to Ae. albopictus ratio is not really prominent with 1.00:3.61 for ovitraps deployed outdoor and 3.40:1.00 for ovitraps set indoor. It was determined that single infestation of either Ae. aegypti or Ae. albopictus is more frequent for ovitraps deployed indoor and/or outdoor, respectively. It was also determined that mixed infestations were found in this study indicating that both species can oviposit in the same container. Conclusion: This study indicates that OI is still above transmission threshold in both study sites. While Ae. aegypti and Ae. albopictus remain as a dominant indoor and outdoor breeder, respectively, mixed breeding of Aedes species in a same container was also observed.
Black soldier fly (Hermetia illucens (Linnaeus, 1758)) larvae inhibit oviposition of house fly (Musca domestica Linnaeus, 1758) by releasing a semiochemical, although in some situations, inhibition is only partial. We hypothesized that there is a certain period in the life cycle of black soldier fly when it can cause antibiosis of the house fly. Choice and non-choice tests were used to separately examine the effectiveness of each developmental stage of black soldier fly (egg, larval (phase I, II, and III), prepupal and pupal stages) and crude extract of larvae on house fly oviposition. Tests using each developmental stage were compared with controls lacking black soldier fly. The effects of black soldier fly on the number of newly hatched house fly larvae were evaluated and there was a significant difference between the test and control in the number of eggs laid by house fly for all phases of the black soldier fly larval stage. Strong inhibition was found in some black soldier fly larval phases. Significant differences in the numbers of house fly eggs oviposited in food containers treated with crude extract were found when compared with a control, confirming that chemicals from black soldier fly larvae resulted in inhibition of oviposition of house fly. The results from experiment also indicated that chemicals from black soldier larvae influenced the number of house fly larvae newly hatched from eggs.
Larvae of Aedes albopictus Skuse typically inhabit natural and artificial containers. Since these larval habitats are replenished by rainfall, Ae. albopictus may experience increased loss of immature stages in areas with high levels of rainfall. In this study, we investigated the effects of rainfall and container water level on population density, and oviposition activity of Ae. albopictus. In field and laboratory experiments, we found that rainfall resulted in the flushing of breeding habitats. Excess rain negatively impacted larval and pupal retention, especially in small habitats. When filled with water to overflowing, container habitats were significantly repellent to ovipositing females. Taken together, these data suggest that rainfall triggers population loss of Ae. albopictus and related species through a direct detrimental effect (flushing out) and an indirect effect (ovipositional repellency).
Nepenthes pitcher plants are colonized by a variety of specialized arthropods. As Aedes mosquitoes are container breeders, Nepenthes pitchers are a potential candidate oviposition site for vector species, such as Aedes aegypti (L.) and Aedes albopictus (Skuse). However, Aedes spp. are not commonly encountered in Nepenthes pitchers, and the environment inside the pitchers of some species is lethal to them. One exception is Nepenthes ampullaria Jack, whose pitchers are known to be colonized by Ae. albopictus on very rare occasions. Given that Ae. albopictus larvae can survive in N. ampullaria pitcher fluids, we sought to determine why pitcher colonization is rare, testing the hypothesis that gravid Aedes mosquitoes are deterred from ovipositing into container habitats that have similar characteristics to N. ampullaria pitchers. Using plastic ovitraps of different sizes, colors, and with different types of fluids (based on the characteristics of N. ampullaria pitchers), we compared oviposition rates by Aedes mosquitoes in urban and rural areas within the geographical range of N. ampullaria near Kuala Lumpur, Malaysia. Ovitraps that were black and large (>250-ml capacity) accumulated significantly more eggs than ovitraps that were smaller, or green in color. In terms of size and color, small, green ovitraps are analogous to N. ampullaria pitchers, indicating that these pitchers are not particularly attractive to gravid Ae. albopictus. Although Aedes spp. are capable of colonizing N. ampullaria pitchers, the pitchers are relatively unattractive to gravid females and do not represent a significant habitat for larvae of dengue vectors at present.