Gary R. Mullen

10 – Biting Midges (Ceratopogonidae)

Biting midges are minute blood-sucking flies. They are commonly known as “no-see-ums” owing to their small size and the fact that they often go unnoticed despite the discomforting bites, which they cause. There are 78 genera and 4000 described species of biting midges. Ceratopogonid larvae are typically long and slender, ranging from 2─5 mm in length when mature. Adult females typically require a blood meal to develop their eggs. Some are autogenous and carry over enough nutrients from the larval stage to develop eggs during the first gonotrophic cycle without feeding on blood. Ceratopogonid larvae develop in a wide range of aquatic and semiaquatic habitats. Biting midges are most abundant in proximity to productive breeding sites. They are annoying pests for humans and both domestic and wild animals. They also serve as vectors of a number of viruses, protozoans, and nematodes. Among the more important viral diseases are Oropouche fever in humans, bluetongue disease and epizootic hemorrhagic disease (EHD) in ruminants, and African horsesickness (AHS) in equines. Blood protozoans that are transmitted by biting midges cause diseases in poultry; and certain nematodes are the cause of mansonellosis in humans and onchocerciasis in various domestic and wild animals. . Proper maintenance of farm ponds and fluctuation of the water level in dairy ponds and waste lagoons helps to reduce the number of adult biting by midges.

Borrelia sp. in Ticks Recovered from White-tailed Deer in Alabama

Six hundred sixty-five hunter-killed white-tailed deer (Odocoileus virginianus) from 18 counties in Alabama (USA) were examined for ticks. Most of the collections were made at state-operated wildlife management areas. Four species of ticks (n = 4,527) were recovered: the lone star tick Amblyomma americanum (n = 482); the Gulf Coast tick A. maculatum (n = 11); the winter tick Dermacentor albipictus (n = 1,242); and the black-legged tick Ixodes scapularis (n = 2,792). Fifty-six percent of the ticks (n = 2,555) were examined for Borrelia sp. spirochetes using an immunofluorescent, polyclonal antibody assay. Spirochetes were detected in I. scapularis (five females, seven males) from Barbour, Butler, Coosa, and Lee counties and A. americanum (four males, four nymphs) from Hale, Lee, and Wilcox counties. Area-specific prevalences in ticks were as high as 3.3% for I. scapularis and 3.8% for A. americanum.

16 – MYIASIS (Muscoidea, Oestroidea)

Myiasis is the invasion of a living vertebrate animal by fly larvae. This invasion may or may not be associated with feeding on the tissues of the host. Myiasis-causing flies are represented by a diversity of species. Some are rarely involved in myiasis. Myiasis is classified based on the degree to which fly species are tied to a host. Three types of myiasis generally are recognized: accidental, facultative, and obligatory myiasis. Myiasis also can be categorized in relation to the site of maggot invasion or subsequent development in the host. These include gastrointestinal, urogenital, ocular, nasopharyngeal, auricular, and cutaneous myiasis. Myiasis apparently has evolved along different lines in different groups of flies. The vast majority of species involved in myiasis are the members of two superfamilies and six families of calypterate flies. The life history of muscoid and oestroid flies follows the typical holometabolous and cyclorrhaphous pattern of four stages: egg, larva (three instars), pupa (in a puparium), and adult. Livestock and wildlife are at greater risk of attack by myiasis-causing flies than are people. There are three major approaches for controlling myiasis: (1) Avoiding contact between potential hosts and myiasis causing flies; (2) early treatment of wounds to prevent myiasis; and (3) reduction or elimination of myiasis fly populations.

MONITORING OF CULICOIDES SPP. AT A SITE ENZOOTIC FOR HEMORRHAGIC DISEASE IN WHITE-TAILED DEER IN GEORGIA, USA

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) were monitored at a Georgia (USA) site where epizootic hemorrhagic disease (EHD) and bluetongue (BT) viruses are enzootic among white-tailed deer (Odocoileus virginianus). Collections were made using a captive white-tailed deer and light traps from June 1993 through November 1994. We collected 210,482 females from the captive deer during morning and evening periods. Predominant species were C. lahillei (73%), C. stellifer (16%), C. biguttatus (6%), C. niger (3%), C. spinosus (2%), and C. paraensis (0.2%). Other species were C. venustus, C. obsoletus/sanguisuga, C. haematopotus, C. guttipennis, and C. arboricola, which together represented <0.1% of the specimens collected. No C. variipennis, a known vector of EHD and BT viruses, were collected from the deer. An estimated 953,299 females were collected in 695 light-trap nights. The most common species in light-trap collections were C. spinosus (45%), C. biguttatus (27%) and C. stellifer (24%). Culicoides variipennis was rare in the light-trap samples, representing <0.01% of the total collections. There was serological evidence from hunter-killed deer that local deer were infected with EHD and BT viruses during the study, particularly during 1994. A primary suspect vector was C. lahillei, which attacked the bait deer in large numbers during the summer and early fall of both 1993 and 1994. Based on their seasonality, relative abundance, and host-seeking activity, C. stellifer and C. spinosus also were considered as possible vectors. However, virus isolation attempts on 113,716 Culicoides, including 62,530 C. lahillei and 32,769 C. stellifer, were negative.

LARVAL SURVEY OF TIRE-BREEDING MOSQUITOES IN ALABAMA

ABSTRACT A state-wide survey of tire-breeding mosquitoes in Alabama was conducted in 2004 and 2005. Tire sites in all 67 counties in the state of Alabama were sampled for mosquito larvae. A total of 13,022 mosquito larvae, representing 12 species in 7 genera, was collected. The most frequently collected species were Aedes albopictus (70.4%), Culex territans (8.0%), and Ochlerotatus triseriatus (7.1%). The following species were also collected: Cx. restuans (6.0%), Cx. salinarius (2.7%), Orthopodomyia signifera (2.4%), and Cx. quinquefasciatus (1.4%). Ochlerotatus atropalpus, Toxorhynchites rutilus, Anopheles punctipennis, An. quadrimaculatus, and Psorophora columbiae each represented <1.0% of the total larval collections. No Ae. aegypti or Oc. japonicus were collected from tires during this survey. The first known collection of Ps. columbiae breeding in water-filled tires is reported.

FIELD COMPARISON OF BERMUDA-HAY INFUSION TO INFUSIONS OF EMERGENT AQUATIC VEGETATION FOR COLLECTING FEMALE MOSQUITOES

ABSTRACT Field experiments were conducted in east-central Alabama in 2003 and 2004 to compare the attractiveness of selected gravid-trap infusions to ovipositing female mosquitoes. Comparisons were made among infusions of the following plants: Bermuda hay, Cynodon dactylon, and 3 species of emergent aquatic plants typical of Culex larval habitats, i.e., soft rush, Juncus effusus; a common sedge, Rhynchospora corniculata; and broad-leaf cattail, Typha latifolia. Experiments were conducted at a site in Lee County, AL, with an abundance of common nuisance mosquitoes, including Culex quinquefasciatus and Aedes albopictus. Carbon dioxide–baited miniature light traps were operated concurrently with gravid traps to provide an activity index of mosquito species at the site. Gravid traps with hay infusion collected the greatest numbers of Cx. quinquefasciatus and Culex restuans females (2003). The results indicate that hay infusion is highly attractive to Cx. quinquefasciatus and is the infusion of choice for collecting females of this species in gravid traps. In the case of Ae. albopictus, infusions were not determined to be significantly different from one another in their attractiveness to gravid females. In general, females of Cx. quinquefasciatus and Cx. restuans demonstrated selectivity when choosing an oviposition site, whereas Ae. albopictus females did not. Factors associated with the oviposition biology of the latter species most likely account for their lack of preference for any single infusion type.

Model based on weather variables to predict seroconversion to bluetongue virus in Alabama cattle

Abstract A model for the prediction of bluetongue virus seroconversion was developed using weather variables and results from serum samples collected from a research herd of Hereford, Angus, Holstein and mixed breed beef cows at 12 different times over 2 years. The six weather variables analyzed were: mean daily air temperature; mean daily soil temperature at a depth of 10 cm; mean daily hours of wet vegetation; total days of rainfall ≥ 0.13 cm; total rainfall for each 7 day period; mean daily solar energy (W m −2 ). A maximum R 2 multiple linear regression technique was applied to meteorological data collected during the four weekly intervals prior to each sample collection date (48 sets of weekly meteorological data). The best predictors for seroconversion were mean daily hours of wet vegetation and total rain days during the second weekly period prior to sample collection. The bluetongue virus seroconversion was related to mean daily hours of wet vegetation, total rain days, and total precipitation as expressed by the equation: Seroconversion=7.1+4.0 (mean daily hours of wet vegetation)−1.3 (total precipitation) (R 2 =0.62, P

23 – MITES (Acari)

More than 250 species of mites are recognized as the cause of health-related problems for humans and domestic animals. Types of problems include: (1) temporary irritation of the skin due to bites or feeding on host skin, fur, and feathers; (2) persistent dermatitis in response to mites that invade the skin or hair follicles; (3) mite-induced allergies; (4) transmission of pathogenic microbial agents and metazoan parasites; (5) intermediate hosting of parasites, notably tapeworms; (6) invasion of respiratory passages, ear canals, and occasionally internal organs; (7) an abnormal fear of mites, or “acarophobia;” and (8) delusory acariosis , a psychological condition in which individuals are convinced that they are being attacked by mites when, in fact, no mites are involved. The general term for infestations of animals by mites is called “acarinism,” whereas any disease condition caused by mites is called “acariasis.” Mites comprise the arachnid subclass “ Acari ,” which is divided into two major groups: the Antactinotrichida and Actinotrichida . These are further subdivided into seven orders. The body is divided into two major regions: the anterior gnathosoma , bearing the pedipalps and chelicerae; and the idiosoma , the remainder of the body, bearing the legs and eyes. The basic developmental stages in the life history of mites are the egg, prelarva, larva, protonymph, deutonymph, tritonymph, and adult. Mites can adversely affect human health in many ways. They can infest homes including carpets, mattresses and bedding, clothing, stored food products, and household pets. The most widely recognized mite problems that affect human health are respiratory allergies caused by mites, infesting house dust.

Tick infestations of white-tailed deer in Alabama.

Four species of ticks were collected from 537 white-tailed deer (Odocoileus Virginianus), examined during the hunting seasons (November to January) of 1988–89 and 1989–90 at selected locations in Alabama (USA). Ixodes scapularis was the most common tick recovered (2,060 specimens) and infested 54% of the deer. Dermacentor albipictus was the second most frequent tick (1,253 specimens) and infested 15% of the deer. Amblyomma americanum was the third most frequent tick (315 specimens) and infested 24% of the deer; this was the only species of tick collected from deer at all sampling locations. Amblyomma maculatum was an infrequent parasite (five specimens) and infested only 1% of the deer; this tick species was only recorded during the 1989–90 season. Year-to-year and geographical differences in tick infestation parameters were noted. The data are compared with those reported for previous surveys of ticks infesting white-tailed deer in Alabama and adjacent states.

Seroprevalence of Borrelia burgdorferi in dogs in Alabama, USA.

A random sample of private small-animal practices in Alabama submitted sera from dogs with known tick contact. A total of 579 samples from the three geographic regions of the state were collected (58% of the targeted sample size). Sera were screened for antibodies to Borrelia burgdorferi using an indirect fluorescent antibody (IFA) test which had a sensitivity and specificity of greater than 90%. Anti-B burgdorferi titers of > or = 1:64 were considered to be positive, based on results from B. burgdorferi-inoculated dogs. Ten of the 579 samples (1.7%) were positive, and titers ranged from 1:64 to 1:512. Seropositive dogs were found throughbout the state, and there was no significant difference in seroprevalence by region (Mantel-Haenszel chi 2, P = 0.85). These results indicate that the seroprevalence for canine Lyme disease in Alabama is low and that use of the canine Lyme disease vaccine is not justified.