Showing papers in "Journal of The American Mosquito Control Association in 1991"

Botanical derivatives in mosquito control: a review.

Abstract: A review on the reported uses of chemicals derived from botanical sources is presented, along with the part of the plant used for extraction, the mosquito species studied and the bioactivity observed for 344 plant species. Examples of phytochemicals evaluated against mosquitoes as general toxicants, growth and reproduction inhibitors, repellents and ovipositional deterrents are given. The effects of mosquito species and life stage specificity, solvents used for extraction, phototoxic activity and the geographical source from where the plant compounds are derived are discussed.

Enhancement of the CDC ovitrap with hay infusions for daily monitoring of Aedes aegypti populations.

Abstract: An ovitrap containing hay infusion and a second ovitrap adjacent to it containing a 10% dilution of the infusion in tap water together yielded 8 times more Aedes aegypti eggs than single CDC ovitraps containing tap water. These "enhanced pairs" were significantly more attractive than pairs with other combinations of infusion, water or methyl propionate, and have proven useful for daily monitoring of Ae. aegypti populations. Our results shed light on the oviposition behavior of Ae. aegypti in the field.

Larvicidal activity of Tagetes minuta (marigold) toward Aedes aegypti.

Abstract: The steam distilled oils of 3 species of marigold, Tagetes patula, T. erecta and T. minuta, were tested for larvicidal activity toward third instar Aedes aegypti; activity at 10 ppm was demonstrated only for T. minuta. The larvicidal property of the whole oil dispersed in water persisted for at least 9 days. The terpene, ocimenone, which is a part of the whole oil, was found to be larvicidal only at a higher concentration than the whole oil and to lose its activity within 24 h after dispersal in water. These results suggest a potential utilization of oil of T. minuta or its components for the control of Ae. aegypti and other species of mosquitoes.

Replacement of Aedes aegypti by Aedes albopictus in Mobile, Alabama.

Abstract: Aedes albopictus was first detected in Mobile, AL, in 1987 during a CDC sponsored ovitrap survey in the Historic District. A comparison of ovitrap and larval surveys, done in 1957, 1984, 1987 and 1990, indicates that Ae. albopictus had replaced Aedes aegypti in urban Mobile. Possible explanations of this replacement, including displacement, are discussed.

Vector competence of North and South American strains of Aedes albopictus for certain arboviruses: a review.

Abstract: Since the introduction of Aedes albopictus into North and South America, 18 viruses in 3 families have been used in vector competence studies involving 10 North American and 4 South American geographic strains of Ae. albopictus. This review summarizes the results of these studies and discusses the potential of Ae. albopictus to become a vector of arboviruses of public health importance in areas of the Western Hemisphere where it has recently become established.

Aedes albopictus in Africa? First records of live specimens in imported tires in Cape Town.

Abstract: Live larvae of Aedes albopictus have been found entering South Africa in used tire casings imported from Japan on 3 separate occasions. This is the first evidence that this mosquito is entering Africa and underlines the value of mosquito monitoring programs to detect the importations of this important vector. It is suggested that undetected populations of Ae. albopictus may have already become established in Africa.

Measuring mosquito dispersal for control programs.

Abstract: Simple and economic methods were developed for control programs to demonstrate the movement of mosquitoes from a breeding source to residential areas. Using mark-release-recapture methods and examples, mean, median and maximum distances traveled were estimated or observed and compared for 11 species produced in a wastewater treatment facility near Lakeland, FL. The applicability of these methods and data interpretation for operational mosquito control programs are discussed.

Field trials with Vectolex (Bacillus sphaericus) and Vectobac (Bacillus thuringiensis (H-14)) against Anopheles gambiae and Culex quinquefasciatus breeding in Zaire.

Abstract: Under field conditions in Kinshasa, Zaire, an aqueous suspension of Bacillus thuringiensis (H-14), Vectobac (12-AS), lost most of its larvicidal activity at all concentrations after 48 h against Culex quinquefasciatus breeding in polluted gutter water and Anopheles gambiae breeding in clear water irrigation ponds. However, good control of Cx. quinquefasciatus was obtained using a granular formulation of B. sphaericus, Vectolex-G (ABG-6185), at concentrations of 10-30 kg/ha. High concentrations of Vectolex-G gave excellent control of An. gambiae breeding in irrigation ponds. The Vectobac-G was less active against An. gambiae than Vectolex-G, in spite of good dispersion of Vectobac-G particles.

Laboratory studies of a Brazilian strain of Aedes albopictus as a potential vector of Mayaro and Oropouche viruses.

Abstract: The vector efficiency of colonized Aedes albopictus from Brazil was assessed for Mayaro (MAY) and Oropouche (ORO) viruses. Female mosquitoes, 3-4 days old, were fed on a MAY-infected hamster with a viremia level of 5.3 log10 Vero cell plaque-forming units (PFU) of virus/ml or an ORO-infected hamster circulating 7.3 log10 PFU/ml. Mayaro infection rates among fed mosquitoes were 16.9 and 11% at 6, 13 and 20 days postfeeding, respectively, and 1/2 and 2/2 infected mosquitoes transmitted virus on days 13 and 20, respectively. Only 13, 5 and 3% of mosquitoes were infected with ORO virus at 6, 13 and 20 days, respectively, and no transmission occurred. Mosquitoes were also fed on 3 dilutions of MAY virus-blood suspensions in membrane feeders. The infection rate among mosquitoes fed the highest concentration (7.7 log10 PFU/ml) was 11/13 (85%), and 5/11 (46%) infected mosquitoes transmitted virus.

Controlled release repellent formulations on human volunteers under three climatic regimens.

Abstract: Two controlled-release repellent formulations containing 33% (3M) and 42% (Biotek) deet and an Army repellent containing 75% deet were evaluated in 3 different climatic regimens (tropical forested, tropical open and basic hot environments). The 3 repellents provided similar protection for different time periods after application under all 3 climates against Aedes aegypti, Ae. taeniorhynchus and Anopheles stephensi whereas there was no difference in protection period against An. albimanus.

Emergency control of Aedes aegypti as a disease vector in urban areas.

Abstract: Techniques for the emergency control of adult Aedes aegypti populations and their development are reviewed. Larviciding and environmental measures provide only delayed control of adult populations. Large-scale field trials of the ultra-low volume application of insecticide concentrates in Southeast Asia, South America and Africa, using aerial, ground, vehicle-mounted and hand-carried equipment, have, in most cases, resulted in satisfactory levels of control of adult populations. Sequential or indoor ULV applications of fenitrothion have provided immediate control and sustained reduction of the adult populations, often lasting well through normal peak transmission periods of dengue. Many ULV application trials in the Caribbean have not produced satisfactory control, but it is considered that this was due to the type of house construction, to the lower dosage rates of the malathion 96% ULV concentrates used, or to inappropriate droplet sizes. While ULV applications can provide rapid and effective emergency control of vectors at the time of outbreaks of disease in urban and periurban areas, they should not be used as a routine mosquito control measure nor as an alternative to reducing vector populations by environmental measures.

Evaluation of 1-octen-3-ol and carbon dioxide as attractants for mosquitoes associated with irrigated rice fields in Arkansas.

Abstract: Field studies were conducted to determine the responses of mosquitoes associated with irrigated riceland in Arkansas to 1-octen-3-ol (octenol), carbon dioxide (CO2) and combinations of both. Octenol was released at 4.1 (wick in) and 41.1 (wick out) mg/h and CO2 at 200, 500 and 1,000 ml/min. Octenol alone did not result in a significant (P greater than 0.05) increased response for any species relative to unbaited traps. An increase in CO2 release rate generally resulted in an increase in collection size. All octenol + CO2 combinations increased the collections of Coquillettidia perturbans, Culex salinarius and Psorophora columbiae relative to equivalent CO2 release rates alone. Mixed responses for these same treatment combinations were obtained for Anopheles crucians, An. quadrimaculatus and Cx. erraticus.

Efficacy assessment of Quwenling, a mosquito repellent from China.

Abstract: Quwenling, an insect repellent product of China derived from extracts of the lemon eucalyptus plant (Eucalyptus maculata citriodon), was evaluated. Laboratory tests compared Quwenling with deet against Anopheles albimanus, An. quadrimaculatus, Aedes aegypti, Ae. albopictus and field tests with Ae. taeniorhynchus. Cloth treated with Quwenling at greater than 2x the dosage of deet was effective against 2 of 4 species tested (Ae. albopictus 29 days, An. quadrimaculatus 28 days). On the skin of volunteers at 2x the dosage of deet, the duration of protection for Quwenling was significantly less than deet with Ae. aegypti and Ae. taeniorhynchus, and was not significantly different with Ae. albopictus. Both repellents were ineffective against the anopheline species. As a topically applied mosquito repellent, Quwenling has a shorter duration of effectiveness than deet.

Effect of body size on the vector competence of field and laboratory populations of Aedes triseriatus for La Crosse virus.

Abstract: Aedes triseriatus females collected as pupae from 2 tireyards and one woodlot were tested for susceptibility to La Crosse virus infection and ability to transmit the virus to suckling mice. Rates of disseminated infection and oral transmission were inversely correlated with mean body size. The smallest population developed disseminated infections and transmitted virus at significantly higher rates than the 2 larger populations. Adults derived from F1 eggs of the largest and smallest populations showed no significant differences in rates of disseminated infection and transmission, suggesting that the differences between the field populations were primarily caused by larval rearing conditions. When pupae of 2 strains of Ae. triseriatus were arranged into discrete size groups and tested for susceptibility to virus, an inverse relationship was observed between rate of disseminated infections and mean pupal wet weight. In contrast, Ae. hendersoni exhibited low transmission rates (7-10%) regardless of body size.

Insecticide susceptibility of Aedes aegypti from Santo Domingo, Dominican Republic.

Abstract: The insecticide susceptibility of Aedes aegypti adults and larvae from Santo Domingo, Dominican Republic, was investigated using World Health Organization standard procedures. A field strain was more resistant to insecticides than a colony strain that originated from the same place. Larvae produced from ovitrap-collected eggs were resistant to temephos (78.2% mortality on exposure to 0.025 mg/liter). Mortality rates after exposure of adults to discriminating concentrations showed that wild populations were resistant to DDT, malathion, propoxur, permethrin and deltamethrin. The problem of resistance was considered serious enough to warrant consideration of control measures other than the use of chemicals.

Aedes aegypti infestation characteristics in several Caribbean countries and implications for integrated community-based control.

Abstract: Periodic larval surveys for Aedes aegypti were conducted in 11 Caribbean countries between 1983 and 1989. On average, there were 24 potential larval habitats per house including 4.9 which held water at the time of examination. Breteau indices for the various islands ranged from 34.7 to 121.6. In descending order of importance, water storage drums, house plants, buckets, used tires and miscellaneous small discarded containers accounted for 84% of all foci. Highest rates of infestation were found in tires (38.4%) and drums (33.8%). For the development of integrated community-based vector control programs, not only should consideration be given to the larval ecology of Ae. aegypti, but also to the sociological significance of the various container habitats and the selection of control strategies most appropriate for their management.

Resistance in Anopheles culicifacies sibling species B and C to malathion in Andhra Pradesh and Gujarat States, India.

Abstract: Studies conducted in Warangal, Khammam and Mahabubnagar districts in Andhra Pradesh and Surat district in Gujarat have revealed that Anopheles culicifacies sensu lato (s.l.) populations were resistant to malathion. In the absence of indoor spraying of malathion in public health programs in the 3 districts of Andhra Pradesh, resistance is attributed to the extensive use of pesticides in agriculture. Species B and C were sympatric in all areas surveyed, and both the species were resistant to malathion. In most of the surveys carried out in Mahabubnagar, Khammam and Warangal, levels of resistance were higher in species C than in B. In Mahabubnagar district an increase in resistance from 5.5 to 64% was observed from 1985 to 1987 in An. culicifacies s.l. The proportion of species C was low in the initial 2 surveys, and in the later surveys the proportion was almost equal to that of species B; the resistance level was also significantly higher than in species B. In Surat district, where resistance ranged from 74 to 93%, the level of resistance in the 2 species was almost the same.

Perspectives on management of pestiferous Chironomidae (Diptera), an emerging global problem.

Abstract: In recent years, adult Chironomidae emerging from some urban natural or man-made habitats have increasingly posed a variety of nuisance and economic problems, and in some situations medical problems to humans in different parts of the world. Although there are an estimated 4,000 or more species of chironomid midges worldwide, less than 100 species have been reported to be pestiferous. Among midge control methods, numerous laboratory and field studies have been conducted on the use of organochlorines, organophosphates (OPs), pyrethroids and insect growth regulators (IGRs). Field use of OP insecticides such as chlorpyrifos, temephos and others in the USA and Japan has generally resulted in larval control for 2-5 wk or longer with application rates below 0.56 kg AI/ha (USA) and less than 1-5 ppm (Japan). Frequent use of some OP insecticides in the USA and Japan has caused their increased tolerance in several midge species. The IGRs, diflubenzuron and methoprene, provide alternate means for midge control. These IGRs in some situations suppressed adult midge emergence by greater than 90% at rates less than 0.3 kg AI/ha. A number of parasites and pathogens have been reported from midges in different parts of the world. Bacillus thuringiensis serovar. israelensis is effective against some midge species, but at rates at least 10x or higher established for mosquito larvicidal activity. The flatworm, Dugesia dorotocephala, and some fish species offer a good potential for midge control in some situations. In large habitats covering hundreds or thousands of ha, information on the basic ecology of larval midges and adult behavior is essential for formulating midge control criteria. More research is needed on the biological and physical and cultural control of these pestiferous insects.

Design for a canopy trap for collecting horse flies (Diptera: Tabanidae).

Abstract: A design for a canopy trap for collecting horse flies is described. The collecting heads can easily be changed since the collar is fixed in place and supports the trap. The collar allows an unobstructed pathway to the collecting head. The center pole has a sliding steel rod that allows adjustment of canopy height upon installation in one operation.

A new method for monitoring mosquito oviposition in artificial and natural containers

Abstract: A new method is described for the direct measurement of Aedes albopictus, Ae. atropalpus, Ae. triseriatus and Orthopodomyia signifera oviposition in artificial and natural containers. Seed germination papers were mounted on the insides of can-traps, tree holes and discarded tires to obtain a direct measure of mosquito oviposition. This durable paper substrate was removed weekly while minimizing the disruption of the oviposition habitat. After the germination papers were dried, the aforementioned mosquito eggs were hatched successfully and reared in the laboratory through the adult stage.

Temperature effects on the gonotrophic cycle of Culicoides variipennis (Diptera: Ceratopogonidae).

Abstract: The duration of oogenesis and time to oviposition after blood feeding was studied in Culicoides variipennis held at constant laboratory temperatures. As assessed by daily dissection of ovaries, the time required for greater than or equal to 80% of females to complete egg development at 13, 17, 21, 27, 30 and 34 degrees C was 10, 5, 4, 3, 2 and 2 days, respectively. Mean times to oviposition at these temperatures were 13.8, 8.2, 4.9, 3.6, 3.0, and 2.6 days, while modal values were 13, 6, 4, 3, 3 and 3 days, respectively. Allowing 7 days after onset of oviposition in groups of 100-150 females, cumulative eggs laid/live female were 4.4, 62.6, 68.9, 63.5, 66.5 and 62.4, respectively. These data should prove helpful in estimating the duration of the gonotrophic cycle and deriving daily survivorship estimates from seasonal parity studies in the field.

Field evaluation of an insect growth regulator, pyriproxyfen, against Anopheles punctulatus on north Guadalcanal, Solomon Islands.

Abstract: Five pools containing immature stages of Anopheles punctulatus were treated with pyriproxyfen at 4 different dosages. Inhibition of adult emergence was observed in pupae collected from the test pools and/or those obtained by rearing of the 4th instar larvae. Adult emergence was inhibited completely for 2 months at a dosage of 0.1 ppm, for one month at 0.05 ppm and 0.01 ppm, and for 20 days at 0.02 ppm. Death of test insects were observed at the pupal stage and at adult emergence. The mortality rate at adult emergence increased with the duration of larval rearing and with the elapse of time after application.

Effectiveness of mist-blower applications of malathion and permethrin to foliage as barrier sprays for salt marsh mosquitoes.

Abstract: Permethrin and malathion were applied as salt marsh mosquito barrier sprays by mist-blower to the shrub border of a park. At one and 24 h after treatment, mosquito landing counts in both insecticide treated areas declined by 80-90% relative to counts in an untreated control area. After 48 h, in the malathion-treated area, mosquito activity returned to levels observed in the control area. From 2 to 8 days post-treatment, mosquito landing counts in the permethrin-treated area remained depressed and significantly (P less than 0.01) different from the malathion-treated and control areas. On days 9 and 10 post-treatment, mosquito landing rates returned to high levels in the insecticide-treated and control areas.

Potential for resistance to pyriproxyfen: a promising new mosquito larvicide

Abstract: An organophosphorus-resistant strain of Culex quinquefasciatus was pressured with pyriproxyfen for 17 generations. Egg viability began declining in the F7 generation and became lower as the selection process continued; by the F17 generation egg viability was too low to proceed further. Susceptibility tests on larvae of the F5, F10, F15, and F17 generations showed no indication of increased tolerance to pyriproxyfen.

Comparison of four membranes for artificially bloodfeeding mosquitoes.

Abstract: Four species of mosquitoes, Aedes aegypti, Ae. triseriatus, Culex pipiens and Cx. tarsalis, were allowed access to defibrinated rabbit blood via 4 different membranes and a standard membrane feeder. Natural animal skins (mouse or quail) were the most effective. More than 50% of the Aedes mosquitoes fed within 5 min and approximately 90% fed within 20 min on either mouse or quail skin. Culex species fed best on quail skin, but the difference in feeding on quail skin and sheep intestine was not significant at 10 or 20 min. In general Culex mosquitoes fed less readily on natural animal skins than Aedes.

Permethrin and dimethyl phthalate as tent fabric treatments against Aedes aegypti.

Abstract: Tests were conducted to determine the persistence of compounds applied to tents to protect against mosquitoes. Interiors of 2 camping tents were treated by the manufacturer--one with the repellent dimethyl phthalate (DMP) and one with the insecticide permethrin. A third tent was untreated. Tents were set up outdoors and exposed to weathering for one year. Weekly tests were conducted by releasing Aedes aegypti into the tents, then recording knockdown (KD) and biting behavior during a 3-h period. Weather data were collected 24 h/day during the study. Year-long mean KD of mosquitoes exposed in the tent to permethrin was 58.6%, to DMP 2.7% and the control 0.9%. Mean biting was 11.9, 43.8 and 58%, respectively. Under constant exposure to weathering, the permethrin-treated tent gave best results with average protection from bites greater than 96% for 9 months (DMP was less than 31%). Although preliminary, the data suggest permethrin would be effective as a tent treatment to reduce annoyance of mosquitoes.

Microbial larvicides for the control of nuisance aquatic midges (Diptera: Chironomidae) inhabiting mesocosms and man-made lakes in California.

Abstract: Bacillus thuringiensis var israelensis (Bti) and B sphaericus were evaluated for chironomid larvicidal activity in freshwater mesocosms Of two Bti formulations, the technical powder ABG-6164 provided excellent control of chironomines (94%) at the rate of 112 kg/ha whereas the liquid concentrate, Vectobac 6 AS, achieved only moderate control (57%) at the rate of 224 kg/ha In contrast, similar rates of B sphaericus products, ABG-6184 technical powder and BSP-2 flowable concentrate, produced no significant reduction Lake studies were initiated to determine which Bti formulations were practical and effective in large-scale situations Two sinking granular corn grit formulations worked with varying degrees of success but were deemed too bulky for extensive applications Bti technical powder preparations with high potency ratings of 5,000 and 12,430 ITU/mg gave excellent control of Chironomus spp (100% and 87%) when used at the rates of 67 and 28 kg/ha, respectively None of the treatments reduced larval populations of the tanypodines, Procladius and Tanypus

Age structure and abundance levels in the entomological evaluation of an insecticide used in the control of Anopheles albimanus in southern Mexico.

Abstract: Applications of bendiocarb produced a high insecticidal residual effect lasting up to 3 months on the most common indoor house surfaces No significant decreases in mosquito man-biting rate levels were observed between treated and untreated villages It was shown that almost equal proportions of intra- and peridomicillary mosquitoes came into contact with the insecticide, indicating that mosquitoes commonly enter houses, rest on treated surfaces and return to bite both indoors and outdoors Although the insecticide was found to have a significant effect on the percentage parity (interpreted as abundance of older individuals) of intra- and peridomicillary Anopheles albimanus mosquitoes, parity recovered and continued a normal cyclic pattern that appeared to be dependent on relative abundance The proximity of a treated village to an untreated village (12 km) can affect the age structure of mosquito populations through shared common resting and breeding sites

Poor vector efficiency of Culex quinquefasciatus following infection with Dirofilaria immitis.

Abstract: The vector efficiency of the Haiti and Covington strains of Culex quinquefasciatus after feeding on dog blood infected with Dirofilaria immitis (approximately 110 microfilariae (mf)/20 microliters of blood) was 1.2 and 0.3%, respectively, versus nearly 20% for the Vero Beach strain of Aedes taeniorhynchus. At a much higher microfilaremia (approximately 400 mf/20 microliters), it was 1.6, 0.5 and 31.5%, respectively. The poor vector efficiency of the 2 Cx. quinquefasciatus strains probably was due to the formation of long, needle-like oxyhemoglobin crystals in the blood meal, which prevented the migration of microfilariae to the Malpighian tubules. Crystals did not form when Cx. quinquefasciatus ingested D. immitis microfilariae mixed in human blood.

Mosquito species collected from a marsh in western Kenya during the long rains.

Abstract: A total of 475,431 mosquitoes representing 8 genera and 43 species were collected from a marsh in the western Kenya highlands to determine species composition and succession in relation to the epidemiology of Rift Valley fever virus. Culex piplens was the most common species, totalling 92.3% of the collection, followed by Cx. zombaensis &2.2%&, Anopheles coustani &1.1%&, An. &0.8%&, Mansonia uniformis &0.6%&, Coquillettidia microannulatus &0.5%&, Uranotaenia mashonaensis &0.5%&, Ma. africana &0.4%& and Cq. aurites &0.4%&. Aedes quasiunivittatus was the'first floodwater species to emerge from newly flooded areas and was the most abundant Aedes collected, representing 88% of all Aedes specimens. Culex guiarti and Cx. zombaensis colonized newly flooded areas soon after the areas