Aggregation Patterns of Sensory Sensillae in the Food Canal and Cibarium of Haematobia irritans (Diptera: Muscidae).

Although mean body lengths of females were significantly greater than males in individuals drawn from two Haematobia irritans (L.) sample populations (n = 20 females and n = 20 males from West Virginia; n = 20 females and n = 20 males from Georgia), there were no significant differences in food canal lengths for females versus males at either site. Variable numbers (21-37) of setiform sensillae occurred throughout the length of the food canal, but such sensillae were significantly aggregated in the distal-most canal region of both sexes at both sites. There was no significant difference in mean numbers of food canal setiform sensillae between females and males. Four basiconic (campaniform) sensillae were consistently observed in the food canal of every fly; always aggregated in the distal-most canal region. Setiform sensillae in the cibarium also varied in number (6-13), but were significantly aggregated in the median and proximal cibarial regions. Four (occasionally three) peg-like basiconic sensillae were also observed in the cibarium of sample individuals; always in the distal and distal median regions of both sexes. Sensory sensillae (both setiform and basiconic) in both the food canal and cibarium were similarly aggregated for both sexes at both sites. Aggregation of setiform and basiconic sensillae in the food canal suggests that the distal canal region is most critical for sensory input regarding monitoring blood flow, and stress forces brought to bear on the cuticle as the labrum tip penetrates the host's skin.

Putative Sensory Structures Associated With the Food Canal of Tabanus atratus (Diptera: Tabanidae).

Putative sensory structures in the food canal, and distal vestibule region entering the canal of Tabanus atratus F., are described. Two pairs of sensilla were observed in the walls of the vestibule-a distal pair of the basiconic type, and a pair of setifiorm sensilla at the base of the vestibule. Vestibular sensilla were constant in type, number, and position. Conversely, setiform sensilla in right and left walls of the food canal varied in number from one fly specimen to another, and lacked evidence of pairing (i.e., sensilla in one wall did not necessarily have a counterpart in the other wall). Food canal sensilla were of setiform design, with the exception of a single basiconic sensilla in each lateral wall of the food canal in every fly. When the food canal was partitioned into four equidistant regions, setiform sensilla were aggregated in the two distal-most regions, with relatively few sensilla observed in the two proximal canal regions. This aggregation was significant, leading to rejection of the null hypothesis that setiform sensilla were evenly distribution throughout the length of the food canal. Basiconic sensilla were always located in the distal-most region of the food canal.

Sensory Trichites Associated With the Food Canal of Chrysops callidus (Diptera: Tabanidae).

Twelve pairs of putative sensory trichites (= sensilla) in the food canal of Chrysops callidus Osten Sacken are described. Eight paired trichites are located in the distal half of the food canal of all flies in the sample population (n = 26 females), but paired trichites 9 through 12 were found in variable numbers in the proximal half of the canal. Trichites were more closely spaced in the distal half of the food canal, and more widely spaced in the proximal half of the canal, indicating that monitoring blood flow is more critical in the distal region of the canal. Moreover, trichites were not precisely paired, with mean position for each right wall trichite 1 through 8 being slightly anterior to its counterpart in the left wall. A short, funnel-shaped vestibule was evident at the labrum terminus, opening distally to the outside and proximally into the food canal (the vestibule/food canal junction). There were two pairs of sensilla (one pair of basicone design, the other setiform) observed at the base of the vestibule just anterior to the junction of the vestibule with the food canal. These vestibular sensilla were constant in type, number and position, in every member of the sample population.

Prevalence of dog intestinal nematode parasites in south central West Virginia, USA.

Coprological examination was used to determine prevalence of gastrointestinal helminthes in a sample of 231 dogs (117 females and 114 males) during the summer of 2009 at a veterinary clinic in south central West Virginia, USA. Clinical signs (e.g., diarrhea, vomiting, weight gain or loss) were noted in addition to a history of anthelmintic usage. A total of 79 dogs (33.6%) were infected with one or more intestinal nematodes. Most dogs (58) were parasitized with a single species, 19 were parasitized with 2 species, and 2 were parasitized by 3 species. There was no significant difference (i.e., X(2)<3.84; P>0.05) in prevalence of infection between female and male dogs for any of the identified nematode species. The chi-square test for equality of proportions was used to determine prevalence of infection in 3 age categories of dogs (females and males combined): young dogs (≤12 months of age); mature dogs (13-83 months); and old dogs >83 months. Prevalences of infection for Ancylostoma caninum and Toxocara canis were significantly (P<0.005) higher in young dogs, whereas there was no significant difference (P>0.05) in prevalence by age category for Trichuris vulpis. Dogs exhibiting clinical signs were no more likely to harbor intestinal nematodes than dogs that were asymptomatic. Additionally, dogs receiving heartworm treatment were significantly less likely to be parasitized than dogs receiving no heartworm prophylaxis.

Adaptation of Haplobothrium globuliforme (Cestoda: Pseudophyllidea) to the intestinal architecture of the bowfin (Amia calva L).

Haplobothrium globuliforme maintains its position in the proximal mid-gut epithelium of Amia calva with the aid of tentacles, i.e., proboscides, everted from scolices of a primary strobila and craspedote proglottids of a secondary strobila. Weakly developed scolices of the secondary strobila appear to have little holdfast action, but the distinctly craspedote proglottids of these individuals project into the intestinal mucosa, altering the configuration of gut epithelial cells and pushing the tapeworm deeper into mucosal crypts. The basement membrane underlying the epithelium appears to act as a barrier that prevents tapeworms from penetrating into the deeper tissue layers of the lamina propria, muscularis mucosa, or submucosa. Scolex tegument modification occurs at the point of contact with host basement membrane. A mild background infiltrate of lymphocytes and granulocytes was evident adjacent to the scolex and proglottid tegument. There was no evidence of blood vessel proliferation, edema, mast cell degranulation, eosinophilia, or subsequent collagen formation associated with tapeworm activity.

Carrion fly (Diptera: Calliphoridae) larval colonization of sunlit and shaded pig carcasses in West Virginia, USA.

Two pig (Sus scrofta L.) carcasses were placed in sunlit and shaded plots in September 2003, and again in May 2004. Mean ambient temperatures between sunlit and shaded plots were not significantly different in either September or May, but mean ambient temperatures at sunlit and shaded plots in 2004 were significantly higher than corresponding means for sunlit and shaded plots in 2003. Mean maggot mass temperatures were significantly higher than ambient plot temperatures for all four experimental plots (i.e., sunlit and shaded carcasses in both 2003 and 2004). In addition, maggot mass temperatures on sunlit carcasses were positively, and significantly, correlated with ambient temperatures, whereas there was no significant correlation between maggot mass and ambient temperatures at shaded plots. Carcass decomposition proceeded more rapidly in 2004 in the presence of higher ambient temperatures, and sunlit carcasses decomposed faster than shaded ones in both 2003 and 2004 experiments. Phaenecia coeruleiviridis (Macquart) and Phormia regina (Meigen) third instars dominated collections on all four carcasses, but there was little temporal overlap between these species with third instars of the former dominating collections in the early portion (approximately 40%) of each experimental period (with the exception of the shaded carcass in 2004 where both species were co-dominant), and the latter assuming dominance in the latter portion (approximately 60%). Lower accumulated degree hour values were calculated for instar development on 2004 carcasses subjected to higher ambient temperatures.

Occurrence of tire inhabiting mosquito larvae in different geographic regions of West Virginia.

Eleven species of mosquito larvae were collected in 568 collection visits to 209 abandoned tire pile sites in 33 West Virginia counties from April through October of 2003. Ochlerotatus j. japonicus supplanted the native Oc. triseriatus as the most common tire-colonizing species in the state. In general, the exotic Oc. j. japonicus was a better colonizer of tires than Oc. triseriatus in peridomestic, sunlit conditions throughout the state, whereas both species were equally likely to colonize tires in nonperidomestic, shaded settings. Aedes albopictus competed effectively with Oc. triseriatus from mid-summer through October in low elevation western counties but was not well represented in central counties of the state. Aedes albopictus was seldom collected at higher elevations in eastern counties. Culex pipiens, like Ae. albopictus, was more likely to be in collections from the western portion of West Virginia throughout the study period. Frequency of occurrence of Cx. restuans peaked in early season collections and declined as the season progressed, but Anopheles punctipennis and the medically unimportant Cx. territans gradually increased in frequency each month through September. Typically, species in the genus Culex and An. punctipennis were predisposed to peridomestic, sunlit habitats. Larvae of the predatory Toxorhynchites rutilus septentrionalis were found mostly in nonperidomestic, shaded settings. This species initially appeared in mid-summer, and by August and September it was found in as many as 30% of the collection sites in western and eastern counties. Larvae of An. barberi, Oc. atropalpus, and Orthopodomyia signifera were poorly represented in collections.

Larval mosquitoes in abandoned tire pile sites from West Virginia.

Larvae of 13 mosquito species were collected from abandoned tire piles at peridomestic and nonperidomestic sites in 3 south-central West Virginia counties from May through September 2002. Ochlerotatus triseriatus was the most frequently collected species from May through August, whereas Aedes albopictus and Ochlerotatus japonicus were more prevalent in September. Prevalence of Oc. triseriatus and Culex restuans declined throughout the study period. Conversely, prevalences of Ae. albopictus, Oc. japonicus, Culex territans, and Toxorhynchites rutilus increased during the same period. Ochlerotatus atropalpus was significantly more likely to be encountered at nonperidomestic sites. None of the other species exhibited a significant predisposition for either peridomestic or nonperidomestic sites.

Spatial and temporal variation in the mosquitoes (Diptera: Culicidae) inhabiting waste tires in Nicholas County, West Virginia.

Larvae of 12 mosquito species were collected from abandoned tire piles at peridomestic and forested sites in Nicholas County, WV, from March through November of 2001. No larvae were found in March, but the numbers of species increased to 10 by July and remained relatively constant, at 9-11 in any given month, throughout November. Larvae of Ochlerotatus triseriatus (Say), the most commonly encountered species in every month of collection, were significantly more likely to be found in forested tire pile sites. Conversely, Culex restuans Theobald, Anopheles punctipennis (Say), Cx. territans Walker, and Aedes albopictus (Skuse) larvae were significantly more likely to be found in peridomestic tire piles. Larvae of the remaining seven species were either found in equal proportions at peridomestic and woodland sites, or there were too few collections to make statistical inferences. Opportunities for competitive interactions between Ae. albopictus and Oc. triseriatus in Nicholas County would be minimized because the peak occurrence of the two species differ temporally and spatially.

Larval fly activity on sunlit versus shaded raccoon carrion in southwestern West Virginia with special reference to the black blowfly (Diptera: Calliphoridae).

Larvae of Phormia regina (Meigen), Phaenicia sp., and Sarcophaga sp. were identified from raccoon carcasses placed in sunlit and shaded areas at a southwestern West Virginia site in May of 2000. Samples of larvae were taken from each carcass at 3-h intervals over a 153-h experimental period. Phormia regina was clearly the dominant species with large numbers of third instars observed at every 3-h collection period from 81 to 153 h on both carcasses. Mean lengths of third-instar P. regina larvae collected from the sunlit carcass were significantly greater than mean lengths of larvae collected from the shaded carcass. Third-instar Phaenicia sp. also appeared at 81 h on both carcasses, but relatively few (< or = 4) individuals were present in each 3-h collection sample from 81 through 126 h. Larvae of this species were not present in samples from either carcass in those 3-h intervals from 129 to 147 h. Sarcophaga sp. larvae were also collected, but only in samples taken from the sunlit carcass at 81 and 93 h. Ambient temperatures were recorded throughout the experimental period, whereas maggot mass temperatures were not recorded until the appearance of large numbers of second instars at 48 h. From 48 to 69 h, maggot mass temperatures were equivalent to ambient temperatures; but after 69 h, maggot mass temperatures were considerably elevated over ambient temperatures.