Field Evaluation of Indoor Thermal Fog and Ultra-Low Volume Applications For Control of Aedes aegypti in Thailand.

Efficacies of a handheld thermal fogger (Patriot™) and a backpack ultra-low volume (ULV) sprayer (Twister™) with combinations of 2 different adulticides (pyrethrin, deltamethrin) and an insect growth regulator (pyriproxyfen) were field-tested and compared for their impact on reducing indoor Aedes aegypti populations in Thailand. The effectiveness of the indoor space sprays was evaluated by sampling the natural Ae. aegypti population in houses and determining their physiological status, by monitoring mortality of sentinel caged mosquitoes (AFRIMS strain) and by assessing larval mortality in laboratory bioassays using water exposed to the spray. A total of 14,742 Ae. aegypti were collected from Biogents Sentinel traps in this study. The combination of ULD® BP-300 (3% pyrethrin) and NyGuard® (10% pyriproxyfen) sprayed either by the Patriot or Twister significantly reduced some Ae. aegypti populations up to 20 days postspray relative to the control clusters. The addition of pyriproxyfen to the adulticide extended how long household mosquito populations were suppressed. In 2 of the 4 products being compared, the Twister resulted in higher mortality of caged mosquitoes compared with the Patriot. However, neither machine was able to achieve high mortality among Ae. aegypti placed in hidden (protected) cages. The larval bioassay results demonstrated that the Twister ULV provided better adult emergence inhibition than the Patriot (thermal fogger), likely due to larger droplet size.

Relationship between mosquito (Diptera: Culicidae) landing rates on a human subject and numbers captured using CO2-baited light traps.

Capture rates of insectary-reared female Aedes albopictus (Skuse), Anopheles quadrimaculatus Say, Culex nigripalpus Theobald, Culex quinquefasciatus Say and Aedes triseriatus (Say) in CDC-type light traps (LT) supplemented with CO2 and using the human landing (HL) collection method were observed in matched-pair experiments in outdoor screened enclosures. Mosquito responses were compared on a catch-per-unit-effort basis using regression analysis with LT and HL as the dependent and independent variables, respectively. The average number of mosquitoes captured in 1 min by LT over a 24-h period was significantly related to the average number captured in 1 min by HL only for Cx. nigripalpus and Cx. quinquefasciatus. Patterns of diel activity indicated by a comparison of the mean response to LT and HL at eight different times in a 24-h period were not superposable for any species. The capture rate efficiency of LT when compared with HL was ≤15% for all mosquitoes except Cx. quinquefasciatus (43%). Statistical models of the relationship between mosquito responses to each collection method indicate that, except for Ae. albopictus, LT and HL capture rates are significantly related only during certain times of the diel period. Estimates of mosquito activity based on observations made between sunset and sunrise were most precise in this regard for An. quadrimaculatus and Cx. nigripalpus, as were those between sunrise and sunset for Cx. quinquefasciatus and Ae. triseriatus.

Efficacy of commercial mosquito traps in capturing phlebotomine sand flies (Diptera: Psychodidae) in Egypt.

Four types of commercial mosquito control traps, the Mosquito Magnet Pro (MMP), the Sentinel 360 (S360), the BG-Sentinel (BGS), and the Mega-Catch Ultra (MCU), were compared with a standard Centers for Disease Control and Prevention (CDC) light trap for efficacy in collecting phlebotomine sand flies (Diptera: Psychodidae) in a small farming village in the Nile River Valley 10 km north of Aswan, Egypt. Each trap was baited with either carbon dioxide (CO2) from combustion of butane gas (MMP), dry ice (CDC and BGS traps), light (MCU and S360), or dry ice and light (CDC). Traps were rotated through five sites in a5 x 5 Latin square design, repeated four times during the height of the sand fly season (June, August, and September 2007) at a site where 94% of sand flies in past collections were Phlebotomus papatasi (Scopoli). A total of 6,440 sand flies was collected, of which 6,037 (93.7%) were P. papatasi. Of the CO2-baited traps, the BGS trap collected twice as many P. papatasi as the MMP and CDC light traps, and at least three times more P. papatasi than the light-only MCU and S360 traps (P < 0.05). Mean numbers (+/- SE) of P. papatasi captured per trap night were as follows: BGS 142.1 (+/- 45.8) > MMP 56.8 (+/- 9.0) > CDC 52.3 (+/- 6.1) > MCU 38.2 (+/- 6.4) > S360 12.6 (+/- 1.8). Results indicate that several types of commercial traps are suitable substitutes for the CDC light trap in sand fly surveillance programs.

Control of Culex quinquefasciatus in a storm drain system in Florida using attractive toxic sugar baits.

Attractive toxic sugar baits (ATSBs) were used to control mosquitoes in the storm drains of a residential area on the outskirts of St Augustine, Florida. The drainage system was newly constructed and no mosquitoes were breeding inside it. The area covered by the storm drains was divided in half; 10 drains served as control drains and 16 drains served as experimental drains. The baits, which consisted of a mixture of brown sugar, fruit juice, green dye marker and boric acid, were presented at the entrances of the treated drains and exit traps were positioned over the drain openings and the connecting tubes leading to retention ponds. Similar baits with orange dye and without toxin were presented at the entrances of control drains. A total of 220 pupae of Culex quinquefasciatus (Diptera: Culicidae) were released in each control and toxin-treated drain, and the numbers of recovered mosquitoes were examined to determine the effectiveness of ATSBs in the storm drain system. An average of 178.2 mosquitoes exited each drain in the control area; 87.0% of these had fed on the baits and were stained orange, whereas 13.0% were unstained. In the toxin-treated drains, 83.7% of hatched females and 86.6% of hatched males were controlled by the baits.

Transfluthrin Spatial Repellent on US Military Camouflage Netting Reduces Tabanids in a Warm-Temperate Environment.

We investigated the capability of transfluthrin on US military camouflage netting to reduce collections of tabanid biting flies in a warm-temperate field environment on the Gulf Coast of Florida. We found that transfluthrin significantly reduced collections of a variety of medically and veterinarily important tabanids inside protected areas by up to 96% upon initial treatment and up to 74% after 20 days posttreatment. These results suggest that transfluthrin could be an effective element in the US Department of Defense integrated pest management system and leveraged in civilian scenarios to protect livestock and humans from potential mechanical transmission of pathogens and disruption of activities caused by painful bites.

Transfluthrin Spatial Repellent on US Military Materials Reduces Culex tarsalis Incursion in a Desert Environment.

Standard residual pesticides applied to US military materials such as camouflage netting can reduce mosquito biting pressure in the field but may contribute to the evolution of resistance. However, residual applications of a spatial repellent such as transfluthrin could allow mosquitoes the opportunity to escape, only inducing mortality if insects linger, for example after becoming trapped in a treated tent. In this study we investigated the capability of transfluthrin on 2 types of US military material to reduce natural populations of disease vector mosquitoes in a cool-arid desert field environment in southern California. We found that transfluthrin could reduce Culex tarsalis incursion into protected areas by up to 100% upon initial treatment and up to 45% for at least 16 days posttreatment, showing that this compound could be an effective element in the US Department of Defense integrated vector management system appropriate for further study.

Kidney: primary source of plasminogen after acute depletion in the cat.

The kidney was the primary source of plasminogen to restore normal plasma levels, after acute plasminogen depletion was produced by injection of streptokinase in cats. The concentration of plasminogen in the hepatic vein remained below that in the artery during the time when concentrations in the artery and renal vein were returning to normal.

Host-seeking height preferences of Aedes albopictus (Diptera: Culicidae) in north central Florida suburban and sylvatic locales.

The response of Aedes albopictus to the BG-Sentinel, Omni-directional-Fay-Prince, and Mosquito MagnetX traps was evaluated in four suburban and four sylvatic habitats in north-central Florida to ascertain potential height preference of this species. These traps, which are primarily designed to attract diurnal mosquitoes, were set at 1 and 6 m and were evaluated during 40 trapping periods over 4 mo. We collected 45,640 mosquitoes, representing 26 species from 10 genera, the most common being Aedes albopictus, Ae. vexans, Coquilletidia perturbans, Culex nigripalpus, Aedes infirmatus, Ae. triseriatus, and Psorophora ferox. Although significantly more Ae. albopictus were captured at 1 m above ground than at 6 m, fewer were captured in sylvatic habitats than suburban habitats. Although not statistically different, the BG-Sentinel caught more Ae. albopictus compared with the other two traps regardless of locale. These results suggest that, although Ae. albopictus was captured as high as 6 m, the majority seek hosts at or below 1-m heights. This further supports prior research that, although Ae. albopictus has been shown to disseminate West Nile virus, it has not been implicated as a major vector for the virus, which is likely because of its propensity to feed on ground-dwelling hosts. The study also shows how trap type, trap heights, and environments influence sampling estimates when determining species abundance.

Infusion-baited ovitraps to survey ovipositional height preferences of container-inhabiting mosquitoes in two Florida habitats.

To ascertain mosquito species-specific oviposition height preferences, a study was conducted evaluating the response of field populations of container-inhabiting mosquitoes to water, oak (Quercus spp.),or oak-pine (Pinus spp.) infusion-baited ovitraps in four suburban and four sylvatic habitats in north central Florida. In total, 48 ovitraps, 24 suspended at each height of 1 or 6 m (near the ground or tree canopy, respectively), were monitored weekly for 5 mo. Throughout our study, we collected 13,276 mosquito eggs, representing five species from four genera, the most common being Aedes triseriatus (Say), Aedes albopictus Skuse, and Orthopodomyia signifera (Coquillett). Significantly more Ae. triseriatus and Ae. albopictus eggs were oviposited in containers with oak and oak-pine infusions compared with water alone. Significantly more Ae. albopictus eggs were recovered from traps at 1 m in suburban habitats, whereas more Ae. triseriatus eggs were recovered at 6 m in sylvatic habitats.

Evaluation of six mosquito traps for collection of Aedes albopictus and associated mosquito species in a suburban setting in north central Florida.

We compared 6 adult mosquito traps for effectiveness in collecting Aedes albopictus from suburban backyards with the goal of finding a more suitable surveillance replacement for the Centers for Disease Control and Prevention (CDC) light trap. Trap selection included 2 commercial propane traps (Mosquito Magnet Professional trap and Mosquito Magnet Liberty trap), 2 Aedes-specific traps (Fay-Prince Omnidirectional trap and Wilton trap), 1 experimental trap (Mosquito Magnet-X trap), and a standard surveillance CDC light trap that served as a control. Traps that did not generate carbon dioxide were provided with bottled CO2 at a flow rate of 500 ml/min. Those traps designed for use with chemical attractants (Mosquito Magnet traps) were baited with Lurex (L-lactic acid) and octenol (1-octen-3-ol) commercial baits, known attractants to Ae. albopictus. Three repetitions of a 6 x 6 Latin square test yielded a total of 37,237 mosquitoes, of which 5,280 (14.2%) were Ae. albopictus. Significantly more (P < 0.05) Ae. albopictus were collected from the experimental and commercial traps (4,244/5,280; 80.3%) than from the CDC light trap and Aedes-specific traps. The Mosquito Magnet Liberty collected the most Ae. albopictus (1,591), accounting for 30.1% of the total take, followed closely by the Mosquito Magnet-X (1,468) and the Mosquito Magnet Pro (1,185). The omnidirectional Fay-Prince trap performed better than the CDC or Wilton trap. Twenty-seven mosquito species were collected during these trials, 9 species in large enough numbers for meaningful analysis. Aedes albopictus was the second most common mosquito trapped. The results of these trials indicate that propane-powered commercial traps would serve as useful substitutes in lieu of CDC traps in Ae. albopictus surveillance efforts. Trap features advantageous for collecting Ae. albopictus and other mosquito species are discussed.

Evaluation of two commercial traps for the collection of Culicoides (Diptera: Ceratopogonidae).

Two types of commercial propane-powered traps, mosquito magnet (MM) (American Biophysics Corporation) MM-Freedom (Freedom) and MM-Liberty Plus (Liberty Plus), were evaluated for the collection of Culicoides. Trap preference and seasonal characteristics for the 3 major species, Culicoides furens, Culicoides barbosai, and Culicoides mississippiensis, were recorded from July 7, 2005, to July 24, 2006. Over 35 million Culicoides were captured during our study. When species were evaluated separately, analysis of overall mean trap collections yielded 5 months (February, March, June, September, and October) with significant trap effects. The Freedom trap captured more C. furens in June and October; the Liberty Plus trap captured more C. mississippiensis in February, March, and April, and more C. barbosai in September. The high numbers of Culicoides captured during our study suggest that the number of host-seeking Culicoides could potentially be reduced by continuous trapping during times when they are prevalent. Results of these investigations will be used to guide future control efforts.

Evaluation of carbon dioxide, 1-octen-3-ol, and lactic acid as baits in Mosquito Magnet Pro traps for Aedes albopictus in north central Florida.

The impact of the attractants l-octen-3-ol (octenol) and L-lactic acid (LurexTM) on collection of Aedes albopictus in suburban backyards was assessed in Mosquito Magnet Pro traps. These carbon dioxide-producing traps were additionally baited with commercial formulated lures with octenol, lactic acid, octenol + lactic acid, or no attractant (control) and evaluated in 4 residential sites. Three repetitions of the study resulted in the total collection of 1,321 Ae. albopictus. Significantly more Ae. albopictus were captured in traps baited with octenol + lactic acid than in traps baited only with octenol. Lactic acid-baited and control trap captures were not significantly different from octenol + lactic acid- or octenol-baited trap totals. Octenol- + lactic acid-baited traps collected 36.2% and 52.0% more Ae. albopictus than lactic acid-baited and control traps, respectively. Male Ae. albopictus accounted for 26.7% of the total capture. Other mosquito species collected in sufficient numbers for analysis included Cx. nigripalpus, Ochlerotatus infirmatus, Psorophoraferox, and Cx. erraticus. Larger numbers of these species were collected in traps that were unbaited or baited with only octenol than in traps baited with lactic acid or octenol + lactic acid.

Laboratory evaluation of avian odors for mosquito (Diptera: Culicidae) attraction.

Attraction of Culex quinquefasciatus Say, Culex tarsalis Coquillett, Culex nigripalpus Theobald, and Aedes aegypti (L.) to avian and other host odors was investigated in a dual-port olfactometer. Although attraction to a human arm was high for Ae. aegypti (>80%) and low for all Culex spp. (<25%), all species responded similarly to a chicken (55.3-73.6%). Responses of Ae. aegypti, Cx. quinquefasciatus, and Cx. nigripalpus to feathers were low (<20%) but greater than to controls. There was no difference in attraction of Cx. tarsalis to feathers or controls. Responses to CO2 (5 ml/min) were low for all species (<15%) except Cx. tarsalis, which were moderate (24.5%). When feathers were combined with CO2, the resulting attraction was additive or lower than responses to feather and CO2 alone for all species except for Cx. tarsalis, which had responses that were three-fold greater than expected if responses were additive. The CO2-feather treatments were less attractive than a chicken for all species. When olfactometer assays were extended from 3 to 20 min, responses by Ae. aegypti significantly increased to a chicken and CO2 and attraction of Cx. quinquefasciatus significantly greater to chickens, CO2, and feathers. None of the volatile compounds previously identified from feathers or uropygial glands tested were attractive. Both feather-rubbed cotton balls and hexane extracts of feathers were attractive and as attractive as feathers; however, ether extracts were not attractive. Feathers clearly contribute to the attraction of host-seeking Culex spp., and future studies will focus on identification of the attractant compounds.

Laboratory evaluation of a dyed food marking technique for Culex quinquefasciatus (Diptera: Culicidae).

A method of marking adult Culex quinquefasciatus by feeding the larvae commercial hog chow dyed with methylene blue, Giemsa, and crystal violet was evaluated under laboratory conditions. Of 243 mosquitoes fed the dyed food, 230 had visible marks (94.6%). The dyed food increased the egg-adult development time from 11.4 to 12.1 d. After 9 d, 82.5% of adult mosquitoes dyed as larvae could be identified, and remained detectable for up to 15 d, their maximum laboratory life.

Attraction of mosquitoes to volatiles associated with blood.

Responses of the mosquitoes Aedes aegypti, Culex quinquefasciatus, and Culex nigripalpus to volatiles and compounds associated with bovine and avian blood that were presented in collagen membranes were evaluated in olfactometer and landing assays. The presence of attractants produced by blood was supported by more attraction of all species to blood than water controls in the olfactometer. Females of Ae. aegypti and Cx. quinquefasciatus were more attracted to bovine blood than to avian blood, but there was no difference in Cx. nigripalpus responses. In landing assays, significantly more females of all species landed on casings with blood than on water controls. There was no difference in landing of Ae. aegypti on bovine or avian blood. However, significantly more females of Cx. quinquefasciatus and Cx. nigripalpus landed on avian blood compared to bovine blood. Blood presented in collagen casings was an effective method for evaluating in-flight attraction and landing in all three species. In the olfactometer, several individual compounds elicited attraction in all species, but none were as attractive as blood for all species. In landing assays, several organic acids and sulfides elicited landing, with Ae. aegypti responding to the greatest number of compounds. These assay methods are effective for evaluation of volatile compounds from blood, and although responses were obtained to several compounds, none were as effective as blood in the olfactometer and landing assays.

Streptokinase-dependent delayed activation of horse plasminogen.

Complete activation of purified horse plasminogen to plasmin was obtained with a 1:10 molar ratio of streptokinase to plasminogen after 5 min of incubation at 37 degrees C. At a 1:1 molar ratio, maximal activity did not appear until 15-30 min, while at a ratio of 6:1 complete activation was delayed for 120-180 min. Gel filtration studies of isotopically labeled streptokinase and horse plasminogen suggest that the delay was due to impaired formation of a streptokinase-plasminogen complex. The predominant streptokinase moiety within the streptokinase-plasmin complex which forms from the streptokinase-plasminogen complex had a molecular weight of about 25000. The streptokinase-horse plasmin complex activated bovine plasminogen and was relatively stable. Native streptokinase was rapidly modified by horse plasmin predominantly to a fragment with a molecular weight comparable to that of the streptokinase moiety within the horse streptokinase-plasmin complex, about 25000 daltons. Partial characterization of horse plasminogen revealed no striking differences from human plasminogen in terms of molecular weight, N-terminal analysis and amino acid composition. However, horse plasminogen did not react with antibodies to human plasminogen, and its isoenzymes were more acidic than those of the human. Further characterization of horse plasminogen will be required to ascertain whether activation by streptokinase can serve as a model for the altered kinetics which have recently been described for the activation of aberrant types of human plasminogen.

Insect repellent jacket tests against biting midges (diptera: Culicoides) in Panama.

Light-weight net jackets treated with N,N-diethyl-m-toluamide (deet) were field-tested in Panama against five species of biting midges, principally Culicoides furens (Poey) and C. barbosai Wirth and Blanton. The deet-treated jacket provided 87-93% protection. Time of day as well as season appeared to influence the proportionate numbers of species collected. The mean coefficient of protection was slightly lower during morning tests when C. barbosai was most abundant and higher during evening tests when C. furens was most abundant.

The effectiveness of permethrin and deet, alone or in combination, for protection against Aedes taeniorhynchus.

Field tests were conducted to compare the degree of protection from bites by the mosquito Aedes taeniorhynchus (Wiedemann) provided by wearing clothing treated with permethrin [(3-phenoxyphenyl)methyl (+/-) cis/trans 3-(2-dichloroethenyl)2, 2-dimethylcyclopropanecarboxylate] with that provided by applying deet (N,N-diethyl-m-toluamide) to exposed skin or by applying deet and wearing the treated clothing. Human test subjects were exposed to natural populations of mosquitoes for a 9-hour daytime period (total of 8 days/treatment) while using one or both protection methods. Unprotected test subjects were also exposed for short periods each day as a check to determine the overall biting rate of mosquitoes. The combined use of both protection methods was the most effective treatment in preventing bites, resulting in an average of 1.5 bites/9-hour day, compared with 53.5 and 98.5 bites on subjects protected only with treated clothing or deet, respectively, and 2,287 bites (extrapolated) on subjects who wore untreated clothing during the same time period. Measurements also indicated that the toxic effect of permethrin reduced biting rates by greater than 90% within the immediate area where subjects wore permethrin-treated uniforms for 9 hours.

Evaluation of personal protection methods against phlebotomine sand flies including vectors of leishmaniasis in Panama.

Three personal protection methods were evaluated against phlebotomine sand flies in Panama. Skin applications of five selected repellents including deet (N,N-diethyl-m-toluamide) provided a mean coefficient of protection (CP) of 99.2% against the attack of at least three sand fly species. Deet-treated net jackets also provided good protection, but it was concluded that an additional application of repellent to the unprotected face was necessary for maximum protection. Permethrin-treated clothing did not provide the protection expected. Apparently sand fly behavior and resistance to quick knock-down were responsible for the numbers of bites recorded, and therefore maximum protection from bites would require application of deet or another suitable repellent to the exposed skin when wearing permethrin-treated clothing.