Efektivitas Air Rendaman Jerami Alang-Alang (Imperata cylindrica) sebagai Atraktan terhadap Jumlah Telur Aedes aegypti

The use of ovitrap with attractants modification has been known as an alternative method in controlling DHF vectors. Attractant material will be better if it uses natural ingredients that are cheap and easy to obtain and easy to manufacture. Attractant material is recommended to use natural ingredients that are cheap and easy to obtain and are easy to make. Imperata plants can be easily obtained and easily processed as attractant material. This study aims to determine the effectiveness of attractants on a laboratory scale in the form of immersion water from the straw of the Imperata cylindrica plants in various concentration levels to Aedes aegypti eggs number. Research with an experimental design using a completely Randomized Design (CRD) was conducted at the Entomology Laboratory of the Tanah Bumbu Research and Development Center, in July 2019. Treatment concentrations consisted of 5%, 10%, 15%, and 20%, control using akuades. Samples for testing using Ae. aegypti gravid mosquitoes. Treatment with 5 repetitions, carried out for 7 days. Data analyzed by normality test, Anova test, and Least Significant Differences (LSD) test. The average number of eggs at concentrations of 5%, 10%, 15%, and 20% respectively was 45.00; 78.60; 129.40; and 174.00. Anova test showed Imperata cylindrica straw soaking attractant had a significant effect on oviposition of Ae. aegypti mosquitoes. LSD test results showed attractant 15% is the optimal concentration in increasing the number of eggs in the ovitrap.

Vertical Distribution, Biodiversity, and Some Selective Aspects of the Physicochemical Characteristics of the Larval Habitats of Mosquitoes (Diptera: Culicidae) in Chaharmahal and Bakhtiari Province, Iran

Background and aims: Mosquitoes (Diptera: Culicidae) are still a focus of research because of their role in the transmission of diseases and annoying biting behavior. Source reduction is an effective measure to control mosquito populations, which is based on good knowledge of larval habitats. This study was conducted to obtain that basic knowledge in Chaharmahal and Bakhtiari province. Methods: This study was carried out in 2011 and 2012. Geographical coordinates, altitude, pH, temperature, and the dissolved oxygen level of larval habitats were recorded by relevant devices, followed by documenting physical attributes by direct observation. In addition, the indices of biodiversity were calculated to analyze the vertical biodiversity of species. Finally, the affinity index was calculated to elucidate species co-occurrence. Results: Eighteen species were recovered from 92 larval habitats. Low- (≤ 1400 m), mid- (1401–2000 m), and high- (≥ 2001 m) altitudes lodged 7, 17, and 14 species, respectively. Further, the indices of the species richness and biodiversity for these altitudinal categories were 0.93, 1.94, and 1.58, as well as 1.54, 2.13, and 1.96, respectively. Larval habitats were mostly natural, temporary, with standing but clear water, muddy substrate, sunlit, and with vegetation. Other physicochemical characteristics and affinity of species were described and discussed as well. Conclusion: To the best of our knowledge, this is the first report of vertical distribution and biodiversity of mosquito larvae in Iran. The relative uniformity of physicochemical characteristics of larval habitats was attributed to prevailing water resources in the studied area and sampling design. The oviposition site selection of gravid mosquitoes is still an unresolved problem which needs further investigations.

Gravid Culex pipiens Exhibit A Reduced Susceptibility to Ultra–Low Volume Adult Control Treatments Under Field Conditions

ABSTRACT In July and August of 2018, a field trial was conducted to examine the effectiveness of the North Shore Mosquito Abatement District's operational ultra–low volume (ULV) adulticide program. Two study sites were selected in Skokie, IL, and treated by truck-based ULV with d-phenothrin and prallethrin synergized with piperonyl butoxide over the course of a month. Natural mosquito populations were sampled via Biogents (BG)-counter baited with CO2 or Alfalfa infusion. The results from this study demonstrate that host-seeking mosquitoes were reduced by 65.3% after ULV treatment while gravid mosquitoes were reduced by only 29.2%. In addition, host-seeking mosquitoes rebounded dramatically (303.1%) 3 days posttreatment while gravid mosquitoes did not (5.7%). Based on the differential effect between gravid and host-seeking mosquitoes, we concluded that the gonotrophic cycle and timing of ULV adulticide operations are important factors affecting the resistance of West Nile virus vectors to pyrethroid exposures.

Oviposition Behavior of Culex tarsalis (Diptera: Culicidae) Responding to Semiochemicals Associated with the Western Mosquitofish, Gambusia affinis (Cyprinodontiformes: Poecilliidae)

Considerable previous research has focused on predator-associated semiochemicals and how they affect mosquito oviposition behavior. However, most of this work has been done without taking into consideration either the natural density of the predators or how other semiochemicals in aquatic environments might affect the responses of gravid mosquitoes. The influence of mosquitofish density, source water (tap vs pond), presence of freshly laid egg rafts, and removal of a putative source of semiochemicals (bacteria) on oviposition by Culex tarsalis Coquillett (Diptera: Culicidae) was studied in laboratory bioassays. Culex tarsalis females were deterred from laying egg rafts on water that contained semiochemicals associated with Gambusia affinis (Baird & Girard), but this deterrence was not strongly associated with the density of fish used to condition aged tap water. The number of egg rafts laid onto Gambusia-exudate water made with either tap water (density < 1 fish per liter) or pond water was typically ≥ 50% of that onto water that did not house mosquitofish. Gravid mosquitoes tested individually did not reduce oviposition onto Gambusia-exudate water as compared to controls. Likewise, oviposition by females with ablated wings did not differ significantly between Gambusia-exudate water and controls. Oviposition onto filter-sterilized Gambusia-exudate water was reduced relative to unfiltered water, suggesting that semiochemicals deterring egg-laying were still present after bacteria were removed. Taken together, these findings suggest that the responses of gravid Cx. tarsalis to chemicals from habitats containing mosquitofish are complex and the origin of the semiochemicals present in the Gambusia-exudate water needs to be elucidated.

Conspecific and allospecific larval extracts entice mosquitoes to lay eggs and may be used in attract-and-kill control strategy

One of the strategies of integrated vector management is to lure gravid mosquitoes for surveillance purposes or to entice them to lay eggs in water containing toxins that kill the offspring (attract-and-kill or trap-and-kill). Typically, the major challenge of this approach is the development of a lure that stimulates oviposition plus a toxin with no deterrent effect. Bacillus thuringiensis var. israelensis (Bti) satisfies the latter criterion, but lures for these autocidal gravid traps are sorely needed. We observed that gravid Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus laid significantly more eggs in cups with extracts from 4th-stage larvae (4 L) of the same or different species. No activity was found when 4 L were extracted with hexane, diethyl ether, methanol, or butanol, but activity was observed with dimethyl sulfoxide extracts. Larval extracts contained both oviposition stimulant(s)/attractant(s) and deterrent(s), which partitioned in the water and hexane phases, respectively. Lyophilized larval extracts were active after a month, but activity was reduced by keeping the sample at 4 °C. In the tested range of 0.1 to 1 larvae-equivalent per milliliter, oviposition activity increased in a dose-dependent manner. In field experiments, Ae. aegpti laid significantly more eggs in traps loaded with larval extracts plus Bti than in control traps with water plus Bti.

Conspecific larval extracts along with biotoxin to attract-and-kill mosquitoes

One of the strategies of integrated vector management is to lure gravid mosquitoes for surveillance purposes or to entice them to lay eggs in water containing toxins that kill the offspring (attract-and-kill or trap-and-kill). Typically, the major challenge of this approach is the development of a lure that stimulates oviposition plus a toxin with no deterrent effect. Bacillus thuringiensis var. israelensis (Bti) satisfies the latter criterion, but lures for these autocidal gravid traps are sorely needed. We observed that gravid Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus laid significantly more eggs in cups with extracts from 4th-stage larvae (4L) of the same or different species. No activity was found when 4L were extracted with hexane, diethyl ether, methanol, or butanol, but activity was observed with dimethyl sulfoxide extracts. Larval extracts contained both oviposition stimulant(s)/attractant(s) and deterrent(s), which partitioned in the water and hexane phases, respectively. Lyophilized larval extracts were active after a month, but activity was reduced by keeping the sample at 4°C. In the tested range of 0.1 to 1 larvae-equivalent per milliliter, oviposition activity increased in a dose-dependent manner. In field experiments, Ae. aegpti laid significantly more eggs in traps loaded with larval extracts plus Bti than in control traps with water plus Bti.

Comparing Effectiveness of Hay Infusion and Sugar Fermentation Solution as Ovitrap's Attractans to Aedes aegypti

Dengue Hemorrhagic Fever (DHF) is still one of the major public health problems in the world and Indonesia. There are several methods of mosquito vector control, one of them is the use of ovitrap and the addition of attractants which is a compound that may attract gravid mosquitoes to lay eggs. Some examples of attractants are hay infusion and sugar fermentation solution. This research aimed to compare effectiveness of hay infusion and sugar fermentation solution as Aedes aegypti attractants. This research type was true experimental laboratory with complete randomized design which is divided into 3 groups of ovitrap containing aquades as control, 20% hay infusion and 20% sugar fermentation solution. Ovitraps with those attractants were put into a mosquito coop containing 25 gravid female mosquitoes. Mosquito’s eggs counting was done after 2 days with 9 times repetition. The data were then analyzed using Kruskal-Wallis and Mann-Whitney test. It was found that the difference of mosquito’s eggs number in the ovitrap containing the fermentation solution of sugar and hay infusion had a significance value of 0.000 (p> 0,05). It means that hay infusion is more effective compared with sugar fermentation. Keywords : DHF, ovitrap, attractant, hay infusion, sugar fermentation solution