Rhipicephalus sanguineus is a canine tick that infests dogs throughout the world and is frequently found in homes and dog kennels. Management of this tick species is complicated by the presence of resistance to commonly utilized acaricides. Fungal formulations could provide a valuable alternative tool for management and are especially relevant indoors where detrimental environmental effects on fungal spores are of less concern. Two commercially available fungal formulations, one containing Metarhizium anisopliae and the other containing Beauveria bassiana, were compared for time to death and sporulation in nymphal ticks exposed for 60 min in treated filter paper packets. Beauveria bassiana exposure killed ticks faster than M. anisopliae exposure and B. bassiana was more likely to sporulate on tick cadavers than M. anisopliae. To determine whether infected ticks could disseminate fungus to their conspecifics, ticks were marked and treated with fungus before being placed with untreated ticks. Fungus was successfully transmitted from treated to untreated ticks. Mortality of ticks exposed to B. bassiana-exposed conspecifics occurred sooner than for those exposed to M. anisopliae-exposed conspecifics, indicating faster dissemination in the former. Therefore, although both formulations resulted in decreased longevity of ticks compared with the controls, the B. bassiana formulation holds the most promise for direct or indirect application with respect to brown dog tick management.
Bed bugs as pests of public health importance recently experienced a resurgence in populations throughout the U.S. and other countries. Consequently, recent research efforts have focused on improving understanding of bed bug physiology and behaviour to improve management. While few studies have investigated the visual capabilities of bed bugs, the present study focused specifically on eye morphology and spectral sensitivity. A 3-D imaging technique was used to document bed bug eye morphology from the first instar through adult and revealed morphological characteristics that differentiate the common bed bug from the tropical bed bug as well as sex-specific differences. Electrophysiological measurements were used to evaluate the spectral sensitivity of adult bed bugs. Male bed bugs were more responsive than females at some wavelengths. Electrophysiological studies provided evidence for at least one photoreceptor with a spectral sensitivity curve peak in the green ((max) 520nm) region of the spectrum. The broadened long wavelength portion of the spectral sensitivity curve may potentially indicate another photoreceptor in the yellow-green ((max) 550nm) portion of the spectrum or screening pigments. Understanding more about bed bug visual biology is vital for designing traps, which are an important component of integrated bed bug management.
The mixing of an insecticide with sugar solution creates an oral toxin or insecticidal sugar bait (ISB) useful for reducing adult insect populations. The ability of ISBs to kill the biting midge Culicoides sonorensisWirth and Jones (Diptera: Ceratopogonidae), a vector of bluetongue virus, epizootic hemorrhagic disease and vesicular stomatitis viruses, was tested. The commercial insecticide formulations (percentage active ingredient) tested included bifenthrin, cyfluthrin, deltamethrin, permethrin, dinotefuran, imidacloprid, thiamethoxam and spinosad. Mortality rates were determined for various concentrations of commercial formulations (0.01, 0.05, 0.1, 1, 2 and 3%) and observed at 1, 4, 10 and 24h post-exposure to the ISB. In the first set of assays, laboratory-reared midges were fed sugar ad libitum and then exposed to insecticide-treated sugar solutions to measure mortality. The second assay assessed competitive feeding: midges were provided with a control sugar solution (10% sucrose) in one vial, and a sugar and insecticide solution in another. Pyrethroid treatments resulted in the greatest mortality in the first hour at the lowest concentrations and spinosad consumption resulted in the least mortality. Biting midges were not deterred from feeding on the 1% ISB solutions despite the presence of an insecticide-free alternative source of sugar.
In repeated behaviours such as those of feeding and reproduction, past experiences can inform future behaviour. By altering their behaviour in response to environmental stimuli, insects in highly variable landscapes can tailor their behaviour to their particular environment. In particular, female mosquitoes may benefit from plasticity in their choice of egg-laying site as these sites are often temporally variable and clustered. The opportunity to adapt egg-laying behaviour to past experience also exists for mosquito populations as females typically lay eggs multiple times throughout their lives. Whether experience and age affect egg-laying (or oviposition) behaviour in the mosquito Stegomyia aegypti (=Aedes aegypti) (Diptera: Culicidae) was assessed using a wind tunnel. Initially, gravid mosquitoes were provided with a cup containing either repellent or well water. After ovipositing in these cups, the mosquitoes were blood-fed and introduced into a wind tunnel. In this wind tunnel, an oviposition cup containing repellent was placed in the immediate vicinity of the gravid mosquitoes. A cup containing well water was placed at the opposite end of the tunnel so that if the females flew across the chamber, they encountered the well water cup, in which they readily laid eggs. Mosquitoes previously exposed to repellent cups became significantly more likely to later lay eggs in repellent cups, suggesting that previous experience with suboptimal oviposition sites informs mosquitoes of the characteristics of nearby oviposition sites. These results provide further evidence that mosquitoes modify behaviour in response to environmental information and are demonstrated in a vector species in which behavioural plasticity may be ecologically and epidemiologically meaningful.
A better understanding of the visual attraction of house flies to colors and patterns is needed to improve fly trap performance. This study combined physiological responses measured with electroretinogram studies of the house fly's compound eyes and ocelli with behavioral attraction of flies to reflective colors and patterns in light tunnel assays. Compound eye and ocellar electroretinogram responses to reflected light were similar, with the largest responses to white and blue followed by yellow, red, green, and black. However, data from light tunnel behavioral assays showed that flies were attracted to white and blue light but were repelled by yellow. The addition of a black line pattern enhanced the attractiveness of blue visual targets, whereas yellow lines decreased attractiveness. Sensory input from the compound eye and the ocellus seems to be integrated to direct fly behavior. There is a direct correlation of house fly attractiveness to visual targets and the intensity of electrophysiological response, except for the yellow targets, which repel flies despite of intense electrophysiological response.
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.
We evaluated the oviposition response of gravid Aedes albopictus (Skuse) to six organic infusions. Laboratory and field-placed oviposition cups baited with water oak (Quercus nigra L.), longleaf pine (Pinus palustris P. Mill), or St. Augustine grass (Stenotaphrum secundatum (Walt.) Kuntze), as well as binary infusion mixtures of each, were used. In addition, a triple-cage, dual port olfactometer was used to measure upwind response of gravid individuals to these infusions. We found that Ae. albopictus deposited more eggs in infusion-baited cups compared with water alone. Moreover, significantly more eggs were laid in the water oak and a water oak-pine mixture as compared with the St. Augustine grass infusion in laboratory bioassays. However, a negative upwind response was observed with longleaf pine infusion in the olfactometer. In field cages, significantly more eggs were deposited in infusion-baited cups as compared with water alone and a greater percentage of eggs were deposited in cups containing a water oak and the water oak-longleaf pine mixture as compared with cups containing single infusions or their mixtures.
A sampling study using a BG-Sentinel trap baited with CO(2), a gravid trap baited with an oak-pine infusion, a human subject, and a vegetative aspirator was conducted to compare their reliability at detecting Aedes albopictus Skuse in suburban and sylvatic habitats. We collected 73,849 mosquitoes, representing 29 species from 11 genera over a 20-wk period. The BG-Sentinel trap accounted for over 85% of all Ae. albopictus captured and was significantly more effective at detecting the presence of Ae. albopictus compared with the other three techniques. Landing counts provided the fewest mosquito species (n = 10), yet provided a quick and effective weekly assessment of the major biting species and were the most effective method for sampling Ae. albopictus within a 10-min period. Fewer Ae. albopictus were sampled from sylvatic habitats compared with suburban ones. Sampling criteria advantageous for surveying Ae. albopictus and other mosquito species are discussed.
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.
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.
Abstract 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 × 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.
ABSTRACT 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.
Abstract Field studies were conducted at wooded wetlands in Gainesville, FL, U.S.A., to assess responses of natural populations of adult mosquitoes (Diptera: Culicidae) to American Biophysics MM‐X™ and Coleman MD‐2500™ traps baited with enantiomers of 1‐octen‐3‐ol, a naturally occurring compound, and 1‐octyn‐3‐ol, a closely related synthetic compound. Overall, the same species of mosquitoes were attracted by all enantiomers, although the (R)‐(+) isomer of octenol generally attracted more species, and it is the isomer produced in greatest proportion in nature. Traps baited with the R‐enantiomer caught greater numbers of mosquitoes than those baited with the S‐enantiomer of each compound, whereas traps baited with S‐enantiomers were equally or slightly less attractive than those baited with carbon dioxide only.
The impact of the attractants 1-octen-3-ol (octenol) and L-lactic acid (Lurex (TM)) on collection of Aedes albopictus in Suburban backyards was assessed in Mosquito Magnet (TM) 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, Psorophora ferox, 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.
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.
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.
The responses of scapularis (Acari: Ixodidae) nymphs and adults to extracts of cast larval skins were tested in a Petri dish bioassay. Assembly was elicited in nymphs and adults in the presence of skins, exudate from ticks, and filter paper exposed to ticks compared to untreated controls. Assembly was noted by 1 hr after exposure with little change between 1 and 24 hr. The assembly response increased in the presence of an increased number of skins. Similar assembly was elicited in nymphs and adults in the presence of cast larval skins and a saline (0.95% NaCl) skin extract. Methanol and hexane extracts were not attractive. When chemical standards were tested against nymphs, they responded to guanine, uric acid, hypoxanthine, xanthine, inosine, and hematin. Adults were tested against guanine, inosine, and xanthine, and all elicited significant assembly. Responses of nymphs increased significantly with increase in dose of uric acid and guanine. Responses of nymphs to a mixture of guanine, xanthine, and adenine (25:1:1 ratio) were similar to responses to cast skins. This study provides the first evidence of an assembly pheromone in I. scapularis.
Efficacy of commercially available formulations of desiccants (Drione, Dri-dic, diatomaceous earth) and insecticidal soap (Safer's) comprised of active ingredients were evaluated against Ixodes scapularis Say immatures in petri dish and grass turf bioassays. In petri dish bioassays at label rate, all products, except diatomaceous earth, provided a high degree of control by 24 and 48 h (71–100% mortality). Mortality of larvae exceeded 94% by 4 h after treatment with Drione (10× label rate held at 85% RH), Dri-die (label rate held at both 85% and 98% RH) and Safer's insecticidal soap (10× label rate held at 98% RH). Nymphal mortality was highest by 4 h after treatment with Safer's insecticidal soap (up to 96%). Larvae were more susceptible than nymphs to desiccants, however, nymphs were more susceptible than larvae to Safer's insecticidal soap. Immature ticks treated with Safer's insecticidal soap exhibited sublethal effects with significantly decreased attachment to hosts and no engorgement. In grass turf bioassays, mortality of nymphs was equivalent (85–95%) between treatments of chlorpyrifos (0.6 kg [AI]/ha, Safer's insecticidal soap, and Drione. In the same bioassays, nymphal mortality was moderate after treatment with Dri-die (23–29%) and low following application with diatomaceous earth (16%) and for untreated controls (6%).
Lyme disease was reproduced in specific pathogen-free beagle dogs by exposure to Borrelia burgdorferi-infected ticks (Ixodes dammini). Seroconversion and disease frequency were higher after exposure to infected adult ticks than to infected nymphs. Young pups developed clinical disease more readily than older dogs. The incubation period lasted 2-5 months. Acute recurrent lameness with fibrinopurulent arthritis was the dominant clinical sign. Dogs recovered but developed persistent mild polyarthritis. B. burgdorferi persisted in recovered dogs for at least 1 year. Isolation of B. burgdorferi and detection by polymerase chain reaction was most successful from skin biopsies at the site of the tick bite. Antibody to B. burgdorferi antigens was first detected by ELISA and Western blots by 4-6 weeks after exposure. High serum levels persisted during 17 months of observation. In contrast to infection from ticks, inoculation of dogs with cultured B. burgdorferi resulted in seroconversion with a shorter duration of antibody persistence and no clinical disease.