Repellent efficacy of wood vinegar against Culex pipiens pallens and Aedes togoi (Diptera: Culicidae) under laboratory and semi-field conditions

The repellent efficacy of wood vinegar was assessed against mosquitoes under laboratory conditions at 1, 5, 10, 20, 40, 60 and 80% concentrations. The study evaluated whether wood vinegar is able to repel Culex pipiens pallens Coquillet and Aedes togoi (Theobald) from the human body and if so at what concentrations. The tests were conducted using the arm-in-cage method in 80 × 40 × 40 cm screened mosquito cages. The data were analyzed and compared with those of N,N-Diethyl-3-methylbenzamide (deet) at 10.3% concentration. The results showed that wood vinegar provided mosquito repellence of varying degree depending on the concentration used. The observed repellence averaged from as low as 39.6% at 5.0% concentration to as high as 100% at 80% concentration against Ae. togoi. Repellence against Cx. pipiens pallens was high being 90.3% at 20% concentration, 92.2% at 40% concentration, 93.9% at 60% concentration and 100% at 80% concentration. The duration of protection time tests showed that the 40% and 60% concentrations of the wood vinegar give protection from landing of Ae. togoi for a period of up to 7 h, though the lower concentration gave lower protection after the first five hours. The results indicated that wood vinegar has mosquito repellent characteristics that tend to vary with the concentration used and the species of mosquitoes. Wood vinegar in this case was very effective in repelling Cx. pipiens pallens, even at lower concentrations while higher concentrations were required to repel Ae. togoi.     

Predation on the invasive mosquito Aedes japonicus (Diptera: Culicidae) by native copepod species in Germany

Some limnic copepod species are predators of mosquito larvae. Seven species belonging to the order Cyclopoida, family Cyclopidae, were collected in the field in Germany and tested for the first time in laboratory bioassays for their potential to serve as biological control agents of the invasive Asian bush mosquito Aedes japonicus (Theobald), a vector of various pathogens causing disease. Females of Diacyclops bicuspidatus (Claus) did not attack 1^st instar larvae of Ae. japonicus, but Macrocyclops distinctus (Richard), Cyclops divergens Lindberg, and C. heberti Einsle predated a mean of 14, 18, or 19 1^st instar larvae, respectively. Acanthocyclops einslei Mirabdullayev and Defaye killed 30 larvae, and high predation rates with a mean of 39 or 46 larvae, respectively, were obtained by Megacyclops viridis (Jurine) and M. gigas (Claus). In regression analyses, predation rates by M. viridis correlated with body size, with specimens of 1.8 mm length being more effective than smaller or bigger ones. Based on the presented data, the two Megacyclops species seem to be promising candidates for use in field studies on the biological control of Ae. japonicus.     

Genetics of glucosephosphate isomerase in Aedes togoi (Diptera: Culicidae)

The genetics of glucosephosphate isomerase (E.C. 5.3.1.9) in two strains (Malaysian and Taiwan) of Aedes togoi is reported. Three electrophoretic phenotypes were present in both sexes. The zymogram patterns were identical in both strains of A. togoi. The phenotypes were governed by a pair of codominant alleles. The allele frequency of the slow-moving band was 0.63 in the Malaysian strain and was 0.86 and 0.82 in F161 and F169 generations, respectively, of the Taiwan strain. The sample studied was in good accord with Hardy-Weinberg expectations.     

Lethal and repellent effects of transfluthrin and metofluthrin used in portable blowers for personal protection against Ochlerotatus togoi and Aedes albopictus (Diptera: Culicidae)

The lethal efficacy of three vaporizing insecticides – 0.6% transfluthrin and 0.6% metofluthrin in portable battery‐powered blowers and 2.5% bioallethrin in electric mats – was assessed in unventilated and ventilated screened room conditions against Ochlerotatus togoi (Theobald) females. The mosquitoes were highly susceptible to transfluthrin and metofluthrin. Mean mortality rates of mosquitoes exposed to transfluthrin and metofluthrin in portable blowers ranged from 95 to 100% at a distance of 10 cm from mosquito cages in both room conditions; this was a >2.4‐fold greater mortality rate than for mosquitoes exposed to bioallethrin in electric mats under the same conditions (mean 40%). The three insecticides showed a decrease in mortality rate at a distance of 70 cm: rates were <5.0, 32.5, 85.0 and 90.0% for 10, 30, 60, and 120 min after exposure, respectively, for the same exposure periods in a closed room. In semi‐field repellent tests with human volunteers, 0.6% concentrations of transfluthrin and metofluthrin provided mean biting protection of 76.1 and 59.9% on legs, 68.5 and 52.1% on arms, 63.4 and 63.1% on the chest, and 87.1 and 52.9% on the face, respectively. In field tests, 0.6% transfluthrin effectively repelled Armigeres subalbatus and Aedes albopictus, with mean biting protection of 85.4 and 89.3% on exposed legs and arms, respectively, of the human volunteers. Metofluthrin at 0.6% also effectively repelled Ar. subalbatus, with mean biting protection levels of 71.8 and 73.5% on the legs and arms, respectively. There was no significant difference of repellent activity between the two vaporizing insecticides in the field.     

Frequency of pyrethroid resistance in Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in Thailand

Thirty‐two Aedes aegypti populations collected throughout Thailand and five populations of Aedes albopictus from southern Thailand were subjected to standard WHO contact bioassays to assess susceptibility to three commonly used synthetic pyrethroids: permethrin, deltamethrin, and lambda‐cyhalothrin. A wide degree of physiological response to permethrin was detected in Ae. aegypti, ranging from 56.5% survival (Lampang, northern Thailand) to only 4% (Kalasin in northeastern and Phuket in southern Thailand). All 32 populations of Ae. aegypti were found to have evidence of incipient resistance (62.5%) or levels of survival deemed resistant (37.5%) to permethrin. Four populations of Ae. albopictus were found with incipient resistance (97 – 80% mortality) and one with resistance (< 80%) to permethrin. The majority of Ae. aegypti populations (68.7%) was susceptible (> 98% mortality) to deltamethrin, with incipient resistance (observed 97–82% mortality) in other localities. In contrast, all populations of Ae. aegypti were completely susceptible (100% mortality) to the recommended operational dosage of lambda‐cyhalothrin. All five populations of Ae. albopictus were found completely susceptible to both deltamethrin and lambda‐cyhalothrin. Evidence of defined incipient or resistance to synthetic pyrethroids mandates appropriate response and countermeasures to mitigate further development and spread of resistance. In light of these findings, we conclude that routine and comprehensive susceptibility monitoring of dengue mosquito vectors to synthetic pyrethroids should be a required component of resistance management policies and disease control activities.     

State‐wide survey of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in Florida

Aedes aegypti and Aedes albopictus are invasive mosquito species with geographic ranges that have oscillated within Florida since their presence was first documented. Local transmission of dengue, chikungunya, and Zika viruses serves as evidence of the public health importance of these two species. It is important to have detailed knowledge of their distribution to aid in mosquito control efforts and understand the risk of arbovirus transmission to humans. Through a partnership involving the University of Florida Institute of Food and Agricultural Sciences Cooperative Extension Service and the Florida Medical Entomology Laboratory; the Florida Department of Health; and mosquito control agencies throughout Florida, a container mosquito surveillance program involving all life stages was launched in the summer of 2016 to detect the presence of Ae. aegypti and Ae. albopictus. Results from this survey were mapped to provide a picture of the current known distribution of Ae. aegypti and Ae. albopictus in Florida. Aedes aegypti and/or Ae. albopictus were detected in the 56 counties that were part of the survey. Only Aedes albopictus was detected in 26 counties, primarily in the panhandle region of Florida. The results of this work underscore the importance of maintaining container mosquito surveillance in a state where chikungunya, dengue, and Zika viruses are present and where there is continued risk for exotic arbovirus introductions.     

First record and spreading of the invasive mosquito Aedes japonicus japonicus (Theobald, 1901) in Croatia

Aedes (Hulecoeteomyia) japonicus japonicus (Theobald, 1901) has recently established across North America and Central Europe. A 3‐year survey was conducted in northwestern Croatian regions from 2013 to 2015 using mosquito ovitraps at possible points of entry and house yards, occasionally complemented by larval collections from cemetery vases. In the first year, the survey investigated the county bordering Slovenia, where the first detection of Ae. j. japonicus had taken place on 28 August 2013. During the next 2 years, Ae. j. japonicus was detected in this area from early May until late October. In 2015, several counties further to the east were included in the survey, leading to the detection of Ae. j. japonicus approximately 100 km eastward from the initially surveyed region. Given a moderate continental climate and homogeneous climatic conditions in this part of Europe, the eastward spread of Ae. j. japonicus can be expected to continue.     

Distribution of the eggs of Aedes punctor (Diptera: Culicidae)

ABSTRACT.

• 1 Eggs of the mosquito Aedes punctor Kirby were found to be aggregated in a horizontal band within woodland depressions.
• 2 The height of the peak of egg density above the lowest point in the depression varied from 24 to 39 cm in six transect studies.
• 3 One depression, 2 m in diameter, was analysed in detail and found to contain a total of 9231 eggs with a maximum density of 944 eggs in a 250 cmz area.

     

Insecticide susceptibility status of Aedes aegypti (Diptera: Culicidae) from Townsville

Insecticide susceptibility of a 1995 Townsville Aedes aegypti (L.) population was investigated in the laboratory according to World Health Organization guidelines. Using baseline data from two Townsville populations (1955 and 1989), larval bioassays detected significant increases in susceptibility to synthetic pyrethroids and malathion, and significant reductions in susceptibility to most organophosphates and propoxur. Adult bioassays detected significant resistance to bendiocarb and DDT. Comparison of larval data with the international reference ROCK strain showed substantial resistance to have developed to malathion and fenthion. Further analysis revealed the presence of distinct substrains in the baseline 1989 population, which displayed varying levels of temephos susceptibility. We concluded that susceptibility investigations should assess mosquito populations collected from many sites within an area rather than taking a single population from one site, and that the 1989 Ae. aegypti colony would be unsuitable for use as a susceptible reference population.     

Bionomics of Aedes aegypti subpopulations (Diptera: Culicidae) from Argentina

Differences in biological features of immature and adult Aedes aegypti, as well as variability in vector competence, seem consistent with the existence of genetic variation among subpopulations and adaptation to local conditions. This work aims to compare the bionomics of four Ae. aegypti subpopulations derived from different geographical regions reared under temperate conditions. Life statistics of three Ae. aegypti subpopulations from the provinces of Córdoba, Salta, and Misiones were studied based on horizontal life tables. The Rockefeller strain was used as a control. The development time required to complete the larva and pupa stages varied from 6.91 to 7.95 and 1.87 to 2.41 days, respectively. Significant differences were found in mean larval development time between the Córdoba and Orán subpopulations. The larva‐pupa development time was similar in all the subpopulations. However, survival values varied significantly between the Orán and San Javier subpopulations. The proportion of emergent males did not differ from females within each subpopulation nor among them. Adult longevity was similar among the subpopulations. The average number of eggs laid by each female was significantly different. The Rockefeller strain laid a significantly greater number of eggs (463.99 eggs/female) than the rest of the subpopulations. Moreover, differences in the demographic growth parameter R_o were detected among the four subpopulations. The differences obtained in larval development time, larva‐pupa survival values, and net reproductive rates among the subpopulations might reflect underlying genetic differences as a result of colonization from different regions that probably involve adaptations to local conditions.     

云南伊蚊属奈蚊亚属一新种及二新记录种记述

报道了云南省伊蚊属奈蚊亚属Aedes subgen. Kenknightia Reinert,1990至今所发现的种类,其中包括1新种类异形伊蚊Ae.（Ken.） dissmilierodes sp. Nov.和2种中国新记录,讨论了新种与近缘种的鉴别特征,简述了2种新记录的形态特征。新种模式标本保存于云南省疟疾防治研究所。     

Geographical distribution of the Aedes Triseriatus Group (Diptera: Culicidae) in Mexico

Aedes brelandi Zavortink is reported for the first time outside of the United States, where it has been found in northern and central parts of Mexico. Ae. triseriatus (Say) is reported in northern and central Mexico and Ae. zoosophus Dyar and Knab is recorded in southern Mexico. Collection records for these species in northern, central, and southern Mexico showing the current distribution of the Aedes Triseriatus Group are included.     

The effect of photoperiod on life history and blood‐feeding activity in Aedes albopictus and Aedes aegypti (Diptera: Culicidae)

Several studies have examined how climatic variables such as temperature and precipitation may affect life history traits in mosquitoes that are important to disease transmission. Despite its importance as a seasonal cue in nature, studies investigating the influence of photoperiod on such traits are relatively few. This study aims to investigate how photoperiod alters life history traits, survival, and blood‐feeding activity in Aedes albopictus (Skuse) and Aedes aegypti (Linnaeus). We performed three experiments that tested the effects of day length on female survival, development time, adult size, fecundity, adult life span, and propensity to blood feed in Ae. albopictus and Ae. aegypti. Each experiment had three photoperiod treatments: 1) short‐day (10L:14D), 2) control (12L:12D), and 3) long‐day (14L:10D). Aedes albopictus adult females were consistently larger in size when reared in short‐day conditions. Aedes aegypti adult females from short‐day treatments lived longer and were more likely to take a blood meal compared to other treatments. We discuss how species‐specific responses may reflect alternative strategies evolved to increase survival during unfavorable conditions. We review the potential impacts of these responses on seasonal transmission patterns, such as potentially increasing vectorial capacity of Ae. aegypti during periods of shorter day lengths.     

The hatching stimulus for eggs of Aedes punctor (Diptera: Culicidae)

ABSTRACT.

• 1 Eggs of the British woodland mosquito, Aedes punctor (Kirby), were subjected to a variety of media in an attempt to determine the hatching stimulus.
• 2 It was found that continuous immersion in distilled water evoked almost no hatching (0.2%); intermittent removal from the water gave low hatching (8.9%).
• 3 Slow deoxygenation of the medium by either bacterial growth or the introduction of nitrogen produced the highest level of hatching (26.0–90.0%). Eggs of A.punctor were shown to hatch within a 4 h period of the oxygen concentration in the medium reaching zero.

     

我国伊蚊—新亚属及—新种(双翅目:蚊科)

1985年6月,在进行滇西类业区系调查中采获一批伊蚊,经鉴定,发现1新亚属,现将该亚属及1新种描述如下。华蚊亚属Sinoaedes,新亚属 亚属特征:雌蚊 中型,暗黑色,具银白鳞饰。触须暗色。喙暗色。前胸前背片平覆宽白鳞。中胸盾片平覆褐色窄鳞;小盾片三叶状,具宽鳞;后背片光裸。有气门后鬃;有1根中胸下后鬃。翅鳞暗色。各足除股节腹面具白色区外,一致暗色。腹节暗色。第     

Pathogenicity of entomopathogenic fungus,Metarhizium anisopliae MET-GRA4 isolate on dengue vectors,Aedes albopictus and Aedes aegypti mosquito larvae (Diptera: Culicidae)

Considering the rapid transmission of the dengue virus, substantial efforts need to be conducted to ward-off the epidemics of dengue viruses. The control effort is depending on chemical insecticides and had aroused undesirable conflicts of insecticide resistance. Here, we study the entomopathogenic fungus, Metarhizium anisopliae as a promising new biological control agent for vector control. The pathogenicity effects of Metarhizium anisopliae against field and laboratory strains of Aedes albopictus and Aedes aegypti larvae were tested using the larvicidal bioassay technique. The results demonstrate that the treatments using M. anisopliae isolate MET-GRA4 were highly effective and able to kill 100% of both Ae. albopictus and Ae. aegypti mosquito larvae at a conidia concentration of 1 × 10?/ml within 7 days of the treatment period. The fungus displayed high larvicidal activity against laboratory and field strain of Ae. aegypti larvae with LC₅₀ values (9.6 × 10³/ml, 1.3 × 10³/ml) and LC₉₅ values (1.2 × 10?/ml, 5.5 × 10⁵/ml) respectively. For Ae. albopictus, LC₅₀ values for laboratory and field strains were (1.7 × 10⁴/ml, 2.7 × 10⁴/ml) and the LC₉₅ values were (2.1 × 10?/ml, 7.0 × 10⁵/ml) respectively. Interestingly, the susceptibility of field strain towards M. anisopliae was higher as compared to the laboratory strain Aedes larvae. In which, the causative agents of all the dead larvae were verified by the virulence of M. anisopliae and caused morphological deformities on larval body. The findings from this study identify this isolate could be an effective potential biocontrol agent for vector mosquitoes in Malaysia.     

Density-dependent regulation of Aedes cantans (Diptera: Culicidae) in natural and artificial populations

Abstract.

• 1 Mortality and size variation (siphon length) in Aedes cantans larvae were examined in natural populations in northern England in 1989 and 1990.
• 2 Under crowded conditions, density-dependent competition led to reduction in the size of both larvae and adults and increased larval mortality.
• 3 Larvae were also maintained in cages in the field at different densities. Results paralleled those for the natural populations in the ponds; larvae maintained at high densities showed increased mortality and reduced size.
• 4 Possible density-dependent factors leading to mortality and size reduction include cannibalism and contact inhibition leading to food shortages.
• 5 The main density-independent factor contributing to larval mortality was habitat desiccation.

     

Seasonal surveillance confirms the range expansion of Aedes japonicus japonicus (Theobald) (Diptera: Culicidae) to the Hawaiian Islands of Oahu and Kauai

The Asian bush mosquito, Aedes japonicus japonicus (Theobald) was not known to occur in the Hawaii archipelago until it was identified on the island of Hawaii in 2003. This mosquito species remained undetected on the neighboring islands for 8?years before it was discovered at the Honolulu International Airport on Oahu in 2012. By 2015, four Ae. j. japonicus mosquitoes were collected in the western mountains of Oahu and one was collected in the central mountains of Kauai. The collection of this invasive mosquito species across the neighboring Hawaiian Islands of Oahu and Kauai indicated the need for increased seasonal surveillance on these islands. Following nearly four years of surveillance, Ae. j. japonicus was also confirmed to occur in the eastern mountains of Oahu and in the central mountainous region of Kauai. To expand the knowledge of the spread of invasive mosquitoes species further surveillance is necessary to identify all possible areas where populations of Ae. j. japonicus and other invasive mosquito species occur in Hawaiian archipelago.     

Forest canopy,water level,and biopesticide interact to determine oviposition habitat selection in Aedes albopictus

Understanding how interacting abiotic and biotic factors influence colonization rates into different habitat types is critical for both conserving and controlling species. For example, the rapid global spread of Asian tiger mosquitoes, Aedes albopictus, has reduced native species abundances and produced disease outbreaks. Fortunately, bacterial endospores of two Bacillus species (biospesticide) are highly lethal to Ae. albopictus larvae and have been commercially developed to reduce populations. Oviposition habitat selection is the first defense Ae. albopictus females possess against any control substance added to breeding sites, and considerable variation exists in their response to biopesticides. In a field experiment, I crossed the presence/absence of biopesticides, with two canopy (open, closed) and water (high, low) levels at 64 breeding sites, to examine if these interacted to influence oviposition site choice. Avoidance of biopesticide was most pronounced in closed canopy sites and those with low water levels, as all main effects and two‐way interactions influenced oviposition. Oviposition habitat selection represents a possible mechanism of resistance to biopesticides and other methods used to kill mosquito larvae. Future experiments examining how larval density and mortality modify these results should allow for more effective control of this highly invasive species.