Polarotaxis and scototaxis in the supratidal amphipod Platorchestia platensis

Talitrid amphipods use many cues for orientation during forays between temporary burrows and feeding areas, and for locating beaches when submerged, with visual cues being particularly important. Little evidence exists for polarized light among these visual cues despite extensive orientation by celestial and underwater polarized light in other crustaceans and in insects. We used electroretinography to assess spectral sensitivity in the eye of the beach flea Platorchestia platensis, and behavioral studies to test whether linearly polarized light serves as an orientation cue. Two spectral classes were present in the P. platensis eye with maxima at 431 and 520 nm. Non-uniform orientation of amphipods in the laboratory arena required either light/dark or polarized cues. Scototactic movements depended on arena conditions (day/night, wet/dry), while orientation under linearly polarized light was wavelength-dependent and parallel to the e-vector. Subsequent tests presented conflicting and additive scototactic and polarotactic cues to differentiate among these responses. In dry conditions, orientation parallel to the polarization e-vector overcame a dominant negative scototaxis, confirming that polarotaxis and scototaxis are separate orientation responses in this species. These behavioral results demonstrate talitrid amphipods can perceive and orient to linearly polarized light, and may use it to orient toward preferred zones on beaches.     

Learning and memory in the mosquito Aedes aegypti shown by conditioning against oviposition deterrence

Oviposition site choice by female mosquitoes, Aedes aegypti (L) (Diptera: Culicidae), was affected by rearing them in water treated with 0.016% of the repellent Mozaway trade mark containing citronella and neem. Given a choice between a bowl of repellent-treated and a bowl of untreated water, Ae. aegypti reared in untreated water strongly preferred to oviposit on the clean water (93-98%) instead of repellent-treated water. This demonstrates effective deterrence of oviposition by dilute Mozaway trade mark. Those reared in repellent-treated water were less deterred: 38-46% of their eggs were laid on the repellent-treated water and 54-62% on the clean water. Evidently the female mosquitoes reared in repellent-treated water were conditioned against oviposition site deterrence, as shown when choice tests were conducted 6 days post-emergence from the treated water. This demonstrates learning and memory in the mosquito Ae. aegypti, with implications for dengue vector surveillance and control.     

Larval development of Aedes aegypti and Aedes albopictus in peri-urban brackish water and its implications for transmission of arboviral diseases

Aedes aegypti (Linnaeus) and Aedes albopictus Skuse mosquitoes transmit serious human arboviral diseases including yellow fever, dengue and chikungunya in many tropical and sub-tropical countries. Females of the two species have adapted to undergo preimaginal development in natural or artificial collections of freshwater near human habitations and feed on human blood. While there is an effective vaccine against yellow fever, the control of dengue and chikungunya is mainly dependent on reducing freshwater preimaginal development habitats of the two vectors. We show here that Ae. aegypti and Ae. albopictus lay eggs and their larvae survive to emerge as adults in brackish water (water with <0.5 ppt or parts per thousand, 0.5-30 ppt and >30 ppt salt are termed fresh, brackish and saline respectively). Brackish water with salinity of 2 to 15 ppt in discarded plastic and glass containers, abandoned fishing boats and unused wells in coastal peri-urban environment were found to contain Ae. aegypti and Ae. albopictus larvae. Relatively high incidence of dengue in Jaffna city, Sri Lanka was observed in the vicinity of brackish water habitats containing Ae. aegypti larvae. These observations raise the possibility that brackish water-adapted Ae. aegypti and Ae. albopictus may play a hitherto unrecognized role in transmitting dengue, chikungunya and yellow fever in coastal urban areas. National and international health authorities therefore need to take the findings into consideration and extend their vector control efforts, which are presently focused on urban freshwater habitats, to include brackish water larval development habitats.     

Observations on the seasonal prevalence and vertical distribution patterns of oviposition by Aedes aegypti (L.) (Diptera: Culicidae) in urban high-rise apartments in Trinidad, West Indies.

The seasonal prevalence and vertical distribution of oviposition of Aedes aegypti were studied for 53 wk in 1999--2000 using modified ovitraps located at several elevations. The ovitraps were positioned both indoors and outdoors in high-rise apartments in the urban township of John John, Port of Spain, Trinidad, West Indies. Of 988 ovitraps, 490 were collected during the months of the wet season, with 404 (84.4%) positive with 18,536 Ae. aegypti eggs. Of 498 ovitraps collected during the dry season, 335 (67.3%) were positive with 12,255 Ae. aegypti eggs. Data from different elevations showed that significantly more eggs were collected at 13-24 m elevations than any other elevation. The results suggest that the invasion of high rise ecosystems by Ae. aegypti can enhance transmission of dengue. This ecological shift in the Ae. aegypti population exploited new habitats associated with human activity, suggesting that strategies should be developed to educate householders as well as creating appropriate vector control measures to prevent future threats of dengue transmission.     

Ovicidal and larvicidal activity against Aedes aegypti and Anopheles gambiae complex mosquitoes of essential oils extracted from three spontaneous plants of Burkina Faso

Essential oils extracted from dried leaves of three spontaneous plants naturally growing in Burkina Faso, i.e. Cymbopogon proximus, Lippia multiflora and Ocimum canum, exhibited larvicidal activity by the WHO standard protocol against 3rd and 4th instar F1-larvae of field-collected mosquitoes vectors of human disease, namely Aedes aegypti and members of the Anopheles gambiae complex, An. arabiensis and An. gambiae. The median lethal concentration (LC50) for Ae. aegypti and An. gambiae s.l. larvae ranged between 53.5-258.5 ppm and 61.9-301.6 ppm, respectively. The LC90 estimates ranged 74.8-334.8 ppm for Ae. aegypti, and 121.6-582.9 ppm for An. gambiae s.l. Ovicidal activity against eggs of An. gambiae s.l. was also demonstrated. The LC50 values for An. gambiae s.l. eggs ranged between 17.1-188.7 ppm, while LC90 values ranged between 33.5-488 ppm. Lippia multiflora showed the highest activity against An. gambiae s.l. eggs and Ae. aegypti larvae, whereas no difference was found among C. proximus and L. multiflora in their activity against An. gambiae s.l. larvae. Of the three plants, essential oils from O. canum had the lowest activity against both eggs and larvae. Eggs were more susceptible than larvae. Ae. aegypti larvae were more susceptible than larvae of An. gambiae s.l.     

Dispersal of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in an urban endemic dengue area in the State of Rio de Janeiro,Brazil

Experimental releases of female Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus were performed in August and September 1999, in an urban area of Nova Igua u, State of Rio de Janeiro, Brazil, to estimate their flight range in a circular area of 1,600 m where 1,472 ovitraps were set. Releases of 3,055 Ae. aegypti and 2,225 Ae. albopictus females, fed with rubidium (Rb)-marked blood and surgically prevented from subsequent blood-feeding, were separated by 11 days. Rb was detected in ovitrap-collected eggs by atomic emission spectrophotometry. Rb-marked eggs of both species were detected up to 800 m from the release point. Eggs of Ae. albopictus were more numerous and more heterogeneously distributed in the area than those of Ae. aegypti. Eggs positively marked for Rb were found at all borders of the study area, suggesting that egg laying also occurred beyond these limits. Results from this study suggest that females can fly at least 800 m in 6 days and, if infected, potentially spread virus rapidly.     

Oviposition activity and seasonal pattern of a population of Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) in subtropical Argentina

Monthly oviposition activity and the seasonal density pattern of Aedes aegypti were studied using larvitraps and ovitraps during a research carried out by the Public Health Ministry of Salta Province, in Tartagal, Aguaray and Salvador Mazza cities, in subtropical Argentina. The A. aegypti population was active in both dry and wet seasons with a peak in March, accordant with the heaviest rainfall. From May to November, the immature population level remained low, but increased in December. Ae. aegypti oviposition activity increased during the fall and summer, when the relative humidity was 60% or higher. Eggs were found in large numbers of ovitraps during all seasons but few eggs were observed in each one during winter. The occurrence and the number of eggs laid were variable when both seasons and cities were compared. The reduction of the population during the winter months was related to the low in the relative humidity of the atmosphere. Significant differences were detected between oviposition occurrences in Tartagal and Aguaray and Salvador Mazza cities, but no differences in the number of eggs were observed. Two factors characterize the seasonal distribution pattern of Ae. aegypti in subtropical Argentina, the absence of a break during winter and an oviposition activity concomitant of the high relative humidity of the atmosphere.     

Ecological traps for dragonflies in a cemetery: the attraction of Sympetrum species (Odonata: Libellulidae) by horizontally polarizing black gravestones

1. We observed that the dragonfly species Sympetrum flaveolum, S. striolatum, S. sanguineum, S. meridionale and S. danae were attracted by polished black gravestones in a Hungarian cemetery. 2. The insects showed the same behaviour as at water: (i) they perched persistently in the immediate vicinity of the chosen gravestones and defended their perch against other dragonflies; (ii) flying individuals repeatedly touched the horizontal surface of the shiny black tombstones with the ventral side of their body; (iii) pairs in tandem position frequently circled above black gravestones. 3. Tombstones preferred by the dragonflies were in the open and had an area of at least 0.5 m² with an almost horizontal, polished, black surface and with at least one perch in their immediate vicinity. 4. Using imaging polarimetry, we found that the black gravestones, like smooth water surfaces, reflect highly and horizontally polarized light. 5. In double‐choice field experiments with various test surfaces, we showed that the dragonflies attracted to shiny black tombstones display positive polarotaxis and, under natural conditions, detect water by means of the horizontally polarized reflected light. This, and the reflection‐polarization characteristics of black gravestones, explain why these dragonflies are attracted to black tombstones. 6. If females attracted to the black gravestones oviposit on them, the latter constitute ecological traps for dragonflies that are not close to water.     

Laboratory and field evaluation of the effects of the neonicotinoid imidacloprid on the oviposition response of Aedes (Stegomyia) aegypti Linnaeus (Diptera: Culicidae)

In this paper, we assessed the suitability of using the neonicotinoid imidacloprid with standard ovitraps by evaluating the ovicidal properties of imidacloprid and its influence on the oviposition response of gravid females of Aedes (Stegomyia) aegypti Linnaeus (Diptera: Culicidae). First, we calculated the imidacloprid lethal dose 99 (LD(99)) by exposing third instar larvae of the target species to different concentrations of the insecticide. Next, Ae. aegypti eggs were exposed to the imidacloprid LD(99) for 24 h and hatching inhibition was recorded. Finally, we investigated any potential repellent effect of the imidacloprid solution on the oviposition response of gravid Aedes females in field and laboratory conditions. The LD(99) obtained from larvae tests proved to be sufficient to keep any exposed eggs from hatching. No repellent effect was observed; females laid as many eggs in imidacloprid-treated ovitraps as in traps containing either clean water or temephos-treated water in both field and laboratory conditions. Our results indicate that imidacloprid is a suitable insecticide for treating ovitraps against Ae. aegypti.     

Enhanced ovicidal activity of an oil formulation of the fungus Metarhizium anisopliae on the mosquito Aedes aegypti

Abstract.  The effect of humidity on the activity of Metarhizium anisopliae IP 46 (Metsch.) Sorokin (Hypocreales: Clavicipitaceae) formulated in sunflower oil against Aedes aegypti (L.) (Diptera: Culicidae) eggs was examined. After exposure of eggs at 75% relative humidity (RH) for ≤ 25 days, ovicidal activity was not increased by oil-in-water formulated conidia, hyphal bodies or pure-oil formulated conidia, compared with conidia or hyphal bodies prepared in water only. At optimal > 98% RH, eclosion was ≤ 13.7% after treatment with oil-in-water formulated propagules in ≤ 10% oil, and it was completely inhibited when conidia were applied in pure oil. At 86–100% RH, new conidia were found on eggs treated with oil-formulated conidia and incubated down to 91% RH. Ovicidal activity was still detected at 93% RH and was augmented with increasing humidity and time of exposure of eggs. Eclosion of larvae was distinctly reduced by IP 46 pure-oil formulated conidia after a minimal initial exposure of 3 days at > 98% RH, followed by: (a) a 12-day exposure at 75% RH before submersion in water; (b) a minimal 5-day exposure at > 98% RH and direct subsequent transfer of treated eggs to water, or (c) a minimal daily 20-h exposure at > 98% RH alternating with 4 h at 75% RH for 10 days. We demonstrate that oil-based formulations of conidia of M. anisopliae enhance ovicidal activity at high humidities and conclude that these formulations have potential in the integrated control of Ae. aegypti .     

Distribution and habitats of mosquito larvae in the Kingdom of Tonga

Abstract  Mosquitoes are a significant pest and human health issue in the Kingdom of Tonga. The occurrence of species and habitats used by mosquito larvae were investigated to determine the potential for control through larval habitat management. Forty-two sites, including 22 villages and 20 farm plantations on the six islands of Tongatapu, Pangaimotu, Vava'u, Pangaimotu (Vava'u group), 'Utungake and Nuku, were surveyed in April 2006. A total of eight mosquito species were collected: Aedes aegypti (Linnaeus), Ae. horrescens (Edwards), Ae. nocturnus (Theobold), Ae. tongae (Edwards), Culex albinervis (Edwards), Cx. annulirostris (Skuse), Cx. quinquefasciatus (Say) and Cx. sitiens (Wiedemann). Several species were widespread, particularly Ae. aegypti and Ae. nocturnus on the main island of Tongatapu, whereas Ae. aegypti dominated sites on islands of the Vava'u group. Comparative sampling of 17 village and 17 rural sites showed that larval habitat was more abundant in towns than in rural areas. Larvae were found in a wide range of habitats but were particularly abundant in artificial water bodies (e.g. disused concrete water tanks, 44-gallon drums and used car tyres). In rural sites, habitats were generally sparse except in rain-filled branch stems of giant taro plants. Mosquito populations in artificial habitats could be markedly reduced by seeding disused water tanks with aquatic predators already present in Tonga, using mesh-net covers over 44-gallon drums, and drilling holes in used car tyres.     

Preliminary data on the performance of Aedes aegypti and Aedes albopictus immatures developing in water-filled tires in Rio de Janeiro

A monthly survey of Aedes aegypti and Aedes albopictus immatures in discarded tires at a site in metropolitan Rio de Janeiro showed that Ae. albopictus was much more abundant in the rainy season, but Ae. aegypti abundance showed a less clear seasonal pattern. Pupal masses for Ae. albopictus showed a seasonal trend. In contrast, Ae. aegypti pupae did not show any clear trend in weight. Large Ae. albopictus pupae were found in the warmer months, when water volume was higher, pH lower and larval abundance lower. Further studies should be carried out to assess how seasonal variations in body size may impact vector competence of these species in Brazil.     

Water Level Flux in Household Containers in Vietnam - A Key Determinant of Aedes aegypti Population Dynamics

We examined changes in the abundance of immature Aedes aegypti at the household and water storage container level during the dry-season (June-July, 2008) in Tri Nguyen village, central Vietnam. We conducted quantitative immature mosquito surveys of 171 containers in the same 41 households, with replacement of samples, every two days during a 29-day period. We developed multi-level mixed effects regression models to investigate container and household variability in pupal abundance. The percentage of houses that were positive for I/II instars, III/IV instars and pupae during any one survey ranged from 19.5-43.9%, 48.8-75.6% and 17.1-53.7%, respectively. The mean numbers of Ae. aegypti pupae per house ranged between 1.9-12.6 over the study period. Estimates of absolute pupal abundance were highly variable over the 29-day period despite relatively stable weather conditions. Most variability in pupal abundance occurred at the container rather than the household level. A key determinant of Ae. aegypti production was the frequent filling of the containers with water, which caused asynchronous hatching of Ae. aegypti eggs and development of cohorts of immatures. We calculated the probability of the water volume of a large container (>500L) increasing or decreasing by ≥20% to be 0.05 and 0.07 per day, respectively, and for small containers (<500L) to be 0.11 and 0.13 per day, respectively. These human water-management behaviors are important determinants of Ae. aegypti production during the dry season. This has implications for choosing a suitable Wolbachia strain for release as it appears that prolonged egg desiccation does not occur in this village.     

Laboratory experiments on factors affecting oviposition site selection in Toxorhynchites amboinensis (Diptera: Culicidae), with a report on the occurrence of egg cannibalism

Laboratory experiments tested the effects of water quality and the presence of conspecific and heterospecific immatures on oviposition by Toxorhynchites amboinensis (Doleschall). The females showed a highly significant preference for oak leaf infusion water over distilled water. When twenty starved third and fourth instar Tx.amboinensis larvae were present in the water, substantially fewer eggs were counted from pots containing these conspecifics, than from controls in which no larvae were present. Numbers of eggs from pots containing starved second instar larvae did not differ significantly from controls. Observations of larval behaviour while oviposition was occurring suggested that egg numbers were reduced in containers because of egg cannibalism with third and fourth instar larvae, and not because the larvae caused a deterrent effect. Subsequent experiments confirming the occurrence of substantial egg cannibalism by third and especially fourth instar larvae are described. As with larvae, the presence of Tx.amboinensis pupae in the water had little effect on oviposition. If placed in the water 24 h prior to test, pupae very slightly enhanced its attractiveness, but if introduced immediately before test there appeared to be a slight deterrent effect. With heterospecific larvae, twenty fourth instar Ae.aegypti larvae introduced into infusion water 24 h before test rendered the water slightly attractive, while water in which Ae.aegypti larvae had been reared for 48 h proved highly repellent.     

Polarized light pollution of matte solar panels: anti-reflective photovoltaics reduce polarized light pollution but benefit only some aquatic insects

Photovoltaic solar panels represent one of the most promising renewable energy sources, but are strong reflectors of horizontally polarized light. Polarized light pollution (PLP) associated with solar panels causes aquatic insects to prefer to oviposit on panels over natural water bodies, with potential to negatively impact their global populations as solar energy expands. We evaluate the hypothesis that anti-reflective coatings (ARCs) used to increase the energy efficiency of solar panels will reduce the amount of PLP they reflect, and their attractiveness to aquatic insects. We created artificial test surfaces that mimicked the optical properties of coated and uncoated solar panels and exposed them to wild populations of polarotactic mayflies (Ephemeroptera), horseflies (Tabanidae) and non-biting midges (Chironomidae) used as indicators of PLP. We evaluated the reflection-polarization properties of test surfaces from four different angles of view and under sunny and overcast skies in the visible and ultraviolet parts of the spectrum. Matte (i.e. ARC-coated) sunlit solar panels were strong sources of horizontally polarized light only when the sun was afront and behind, in contrast to uncoated panels which exceeded common polarization-sensitivity thresholds for aquatic insects from all four viewing directions. As predicted by these polarization patterns, horsefly numbers and water-seeking behaviors were significantly reduced by ARCs. Under overcast skies, both matte and shiny (i.e. uncoated) panels were insect-detectible sources of PLP. Matteness modestly reduced the degree of polarization of reflected light, but not sufficiently such that fewer chironomids were attracted to them. Mayflies actually preferred matte panels under overcast skies. ARCs are most likely to reduce PLP and benefit aquatic insects under sunny skies and when used in conjunction with white non-polarizing gridding, but may actually exacerbate the severity of their negative effects under overcast conditions. Consequently, even current ARC technology has a role to play in aquatic insect conservation, but strategic deployment of solar panels away from water bodies and temperate regions may trump these benefits.     

Surveillance of the mosquito Aedes aegypti and its biocontrol with the copepod Mesocyclops aspericornis in Australian wells and gold mines

Abstract. A survey of the dengue vector mosquito Aedes aegypti was undertaken using runnel traps to detect immature stages (larvae and pupae) in flooded disused mine shafts and wells in Charters Towers, Queensland, Northern Australia. The town has a history of dengue fever since 1885 when goldminers were the first recorded victims. During the latest dengue epidemic in 1993, 2% of the population had laboratory-confirmed dengue virus Type 2, despite source reduction of Ae.aegypti breeding-sites at ground level or above. This led to suspicions that dengue vector Ae.aegypti breeding-sites might be below ground level. When surveyed in March 1994, Ae.aegypti immatures were found in 9/10 wells and 1/6 mine shafts. The water in wells and mines had similar characteristics -except that turbidity was higher in the mines, which more often contained predators of mosquito immatures.
The copepod Mesocyclops aspericornis was collected from water in 1/10 wells and 2/6 mine shafts. Laboratory predation trials resulted in 95.5–100% predation by 25 copepods/1 on Ae.aegypti first-instar larvae up to 200 larvae/1. Five wells containing Ae.aegypti in the survey were inoculated with fifty indigenous M.aspericornis , and five wells (one positive and four negative in the survey) were left untreated as controls. Nine months later, in December 1994, Ae.aegypti had been eliminated from all five treated wells but all untreated control wells contained Ae.aegypti , except for one well that contained a natural population of M.aspericornis. The role of wells and mines as winter/ dry season refuges of Ae.aegypti in northern Australia is reviewed, and we recommend the use of M.aspericornis as a cost-effective, environmentally acceptable and persistent agent for the sustainable control of Ae.aegypti , especially in inaccessible breeding sites.     

The influence of larval density, food stress, and parasitism on the bionomics of the dengue vector Aedes aegypti (Diptera: Culicidae): implications for integrated vector management

New larval control strategies for integrated vector management of Aedes aegypti are in high demand, including the use of biological control agents. Exposure of Aedes aegypti to parasites, starvation, and overcrowded conditions during larval development reduces the probability of survival to eclosion, can directly affect fitness parameters such as adult size and fecundity, and can affect the size, provisioning, and viability of eggs produced by females. We compared these parameters after exposing larvae to 1) abundant food at low larval densities, 2) food deprivation and high larval density, and 2) infection with the endoparasite Plagiorchis elegans, an entomopathogenic digenean trematode. Female mosquitoes that eclosed from larval conditions of starvation and overcrowding were smaller and laid fewer and smaller eggs than controls. The proportion of females to complete an oviposition cycle was reduced in the P. elegans-infected treatment group. Parasite load was negatively correlated with wing length and egg size. Infection of Ae. aegypti with P. elegans has sublethal effects and may reduce population-level reproductive output, but one-time low-density P. elegans exposure does not have sufficient effect on Ae. aegypti fitness parameters to be considered a viable biocontrol option.     

Population dynamics of Aedes aegypti and dengue as influenced by weather and human behavior in San Juan, Puerto Rico

Previous studies on the influence of weather on Aedes aegypti dynamics in Puerto Rico suggested that rainfall was a significant driver of immature mosquito populations and dengue incidence, but mostly in the drier areas of the island. We conducted a longitudinal study of Ae. aegypti in two neighborhoods of the metropolitan area of San Juan city, Puerto Rico where rainfall is more uniformly distributed throughout the year. We assessed the impacts of rainfall, temperature, and human activities on the temporal dynamics of adult Ae. aegypti and oviposition. Changes in adult mosquitoes were monitored with BG-Sentinel traps and oviposition activity with CDC enhanced ovitraps. Pupal surveys were conducted during the drier and wetter parts of the year in both neighborhoods to determine the contribution of humans and rains to mosquito production. Mosquito dynamics in each neighborhood was compared with dengue incidence in their respective municipalities during the study. Our results showed that: 1. Most pupae were produced in containers managed by people, which explains the prevalence of adult mosquitoes at times when rainfall was scant; 2. Water meters were documented for the first time as productive habitats for Ae. aegypti; 3. Even though Puerto Rico has a reliable supply of tap water and an active tire recycling program, water storage containers and discarded tires were important mosquito producers; 4. Peaks in mosquito density preceded maximum dengue incidence; and 5. Ae. aegypti dynamics were driven by weather and human activity and oviposition was significantly correlated with dengue incidence.     

The effect of host type on movement patterns of Aedes aegypti (Diptera: Culicidae) into and out of experimental huts in Thailand.

Flight behavior studies were carried out from December 2004 through February 2005 at two sites in Thailand to compare the movement patterns of Aedes aegypti into and out of experimental huts baited with a human host, dog host, or without a host using a mark-release-recapture study design. Studies were conducted in isolated villages of Kanchanaburi and Chiang Mai Provinces, Thailand. In the presence of a human host only 4.9% (39/800) of the Ae. aegypti females departed the hut as compared to 46.5% (372/800) when a dog was present. There was no significant difference in the numbers of Ae. aegypti exiting when comparing dog to no host. A peak in exiting behavior in the absence of any host (human or dog) was observed between 1400-1700 h. Ingress behavior was much stronger when a human host was present in the hut with the peak of entering occurring in the morning (0830-1130 h) compared to 1000-1200 h without a host. Overall, significant differences between the two host types were observed with Ae. aegypti females being more attracted to humans (p < 0.05) than dogs. There was no significant difference between numbers of Ae. aegypti entering the hut baited with a dog and the hut containing no host source. The experimental hut design used in the present study can serve as a protocol for testing the exiting and entering behavior of Ae. aegypti in response to chemical compounds.     

Effects of variations in a formulated protein meal on the fecundity and fertility of female mosquitoes

Abstract. A formulated protein meal developed by Kogan (1990) for adult female Aedes aegypti mosquitoes was evaluated and modified to increase egg and pupal yield. A vigorous laboratory colony was maintained with the females fed exclusively on this dietary formula for about twenty-five generations over more than 2 years. Extra modifications were made to produce a diet suitable for Anopheles arabiensis and Anopheles stephensi females to produce eggs. Both formulations contain bovine albumin, haemoglobin and globulin in a ringer based solution, plus ATP as a phagostimulant for Ae.aegypti. Compared to Kogan's original, our Aedes formula doubled the production of pupae per female after a single meal, although the yield was still significantly lower than from mosquitoes fed on animal hosts or defibrinated pig blood. In varying the proportions of different constituents during attempts to optimize the formula, no relationship was found between total protein content (within the range 80–220 mg/ml) and fecundity, percentage hatch or pupal yield of Ae.aegypti. Equivocal results were found when an isoleucine supplement was added to the formula.