C. Dayton Steelman

Reservoir Competence of Lesser Mealworm (Coleoptera: Tenebrionidae) for Campylobacter jejuni (Campylobacterales: Campylobacteraceae)

Abstract The lesser mealworm, Alphitobius diaperinus (Panzer), is a carrier of Campylobacter spp. in poultry facilities; however, the beetle’s importance in the epidemiology of campylobacteriosis is not known. A series of laboratory experiments were designed to test the vector and reservoir competence of the lesser mealworm for Campylobacter jejuni. In the first experiment, C. jejuni was swabbed onto the outer surface of adult and larval beetles to determine how long bacteria can survive on the beetles’ exterior. Next, adult and larval mealworms were allowed to drink from a solution containing C. jejuni and the duration of internal carriage was monitored. For the third experiment, beetles drank from a Campylobacter suspension and the duration of fecal shedding of bacteria was determined. In the last experiment, 3-d-old chickens were fed either one or 10 infected beetles, and cloacal swabs were tested periodically for Campylobacter. C. jejuni was detected on the exterior of larval beetles for 12 h, from the interior of larvae for 72 h, and from the feces of larvae for 12 h after exposure. Ninety percent of the birds that consumed a single adult or larval beetles became Campylobacter-positive, whereas 100% of the birds that consumed 10 adults or larvae became positive. These experiments demonstrated that the lesser mealworm could acquire and harbor Campylobacter from an environmental source. We found that the lesser mealworm was capable of passing viable bacteria to chickens that consumed the beetle. The beetle should be included in attempts to maintain Campylobacter-free poultry facilities.

Mitochondrial and Ribosomal Internal Transcribed Spacer 1 Diversity of Cimex lectularius (Hemiptera: Cimicidae)

Abstract Understanding genetic variation among populations of medically significant pest insects is important in studying insecticide resistance and insect dispersal. The bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), is widespread hematophagus insect pest around the world, including North America, and it has recently been identified as an emerging resurgent pest. To date, no studies have been conducted on genetic variation of this species. For this study, 136 adult bed bugs representing 22 sampled populations from nine U.S. states, Canada, and Australia were subjected to genetic analysis using polymerase chain reaction (PCR) to amplify and sequence a region of the mitochondrial DNA (mtDNA) 16S rRNA gene and a portion of the nuclear rRNA internal transcribed spacer (ITS) 1 region. For the 397-bp 16S marker, a 12 nucleotide sites in total were polymorphic, and 19 unique haplotypes were observed. Heterozygosity was observed within many of the sampled populations for the mtDNA marker. This suggests that bed bug populations did not undergo a genetic bottleneck as one would expect from insecticide control during the 1940s and 1950s, but instead, that populations may have been maintained on other hosts such as birds and bats. In contrast to the high amount of heterozygosity observed with the mitochondrial DNA marker, no genetic variation in the 589-bp nuclear rRNA marker was observed. This suggests increased gene flow of previously isolated bed bug populations in the United States, and given the absence of barriers to gene flow, the spread of insecticide resistance may be rapid.

Susceptibility of the Bed Bug Cimex lectularius L. (Heteroptera: Cimicidae) Collected in Poultry Production Facilities to Selected Insecticides 1

Abstract Cimex lectularius L. is a widespread hematophagus insect pest around the world and is currently experiencing a reemergence as a public health pest of concern. One possible source of bed bugs to the human environment is the movement of bed bugs from poultry facilities to human structures by poultry workers. No recent studies have been conducted on the susceptibility of this insect to a wide range of insecticides. In addition, populations of bed bugs from poultry facilities have not been screened against insecticides for over 15 yr. Adult bed bugs collected from three poultry facilities in northwest Arkansas were exposed for 24 or 48 h (25°C) to glass vials treated with various dilutions of 12 insecticides dissolved in acetone to determine the concentration–response relationship. The order of toxicity, from most to least based on the LC50s was: λ-cyhalothrin, bifenthrin, carbaryl, imidacloprid, fipronil, permethrin, diazinon, spinosyn, dichlorvos, chlorfenapyr, and DDT. Significant differences in LC50 and LC90 values for diazinon was observed among the three populations due to the previous history of repeated exposure to a mixture of tetrachlorvinphos and dichlorvos over a 10 yr period when compared to the LC50s of two populations that had been exposed to the tetrachlorvinphos and dichlorvos mixture during 2–3 flock cycles. Bed bugs in each of the three populations exhibited high levels of DDT resistance, LC50 > 100,000 ppm, which confirms that resistance to this insecticide continues in bed bug populations. This study documents baseline toxicological data for 12 insecticides in three populations of bed bugs and provides the first data on bed bug susceptibility to fipronil, spinosyn, and imidacloprid.

Spatial Analysis of Alphitobius diaperinus (Coleoptera: Tenebrionidae) in Broiler Production Facilities

Abstract The lesser mealworm, Alphitobius diaperinus (Panzer), is an important economic pest in poultry production systems. Spatial analysis of the beetle population and environmental parameters can aid the integrated management of this pest species. A mealworm population was monitored weekly using tube traps in a broiler facility for five consecutive flock grow-outs ranging from 5 to 8 wk each. Litter temperature, pH, and relative humidity were measured concurrently at six of the same locations as tube trap placement. A geographic information system was used to display weekly spatial relationships of adult and larval beetles during each flock grow-out. Spatial maps of beetle populations showed that low numbers of the beetles were found in the half of the facility used to initiate each flock grow-out during weeks 1–3. Beetle numbers increased continuously in all areas of the facility in latter weeks of each grow-out. Using ranges of environmental conditions considered favorable to the beetles, we developed a model to predict locations of high beetle densities. A comparison of the predictive model to actual counts of adult and larval beetles showed percentages of agreement ranging from 20.0 to 86.7%. The accuracy of the predictive model had limits imposed by house environmental conditions and by beetle movement restrictions. Spatial maps of beetle occurrence based on trap counts display areas in the facility where control efforts would have the greatest impact on beetle numbers, whereas modeling is a less costly alternative than conventional sampling methods for finding areas of high beetle occurrence.

Survey of Borreliae in ticks, canines, and white-tailed deer from Arkansas, U.S.A.

BackgroundIn the Eastern and Upper Midwestern regions of North America, Ixodes scapularis (L.) is the most abundant tick species encountered by humans and the primary vector of B. burgdorferi, whereas in the southeastern region Amblyomma americanum (Say) is the most abundant tick species encountered by humans but cannot transmit B. burgdorferi. Surveys of Borreliae in ticks have been conducted in the southeastern United States and often these surveys identify B. lonestari as the primary Borrelia species, surveys have not included Arkansas ticks, canines, or white-tailed deer and B. lonestari is not considered pathogenic. The objective of this study was to identify Borrelia species within Arkansas by screening ticks (n = 2123), canines (n = 173), and white-tailed deer (n = 228) to determine the identity and locations of Borreliae endemic to Arkansas using PCR amplification of the flagellin (flaB) gene.MethodsField collected ticks from canines and from hunter-killed white-tailed were identified to species and life stage. After which, ticks and their hosts were screened for the presence of Borrelia using PCR to amplify the flaB gene. A subset of the positive samples was confirmed with bidirectional sequencing.ResultsIn total 53 (21.2%) white-tailed deer, ten (6%) canines, and 583 (27.5%) Ixodid ticks (252 Ixodes scapularis, 161 A. americanum, 88 Rhipicephalus sanguineus, 50 Amblyomma maculatum, 19 Dermacentor variabilis, and 13 unidentified Amblyomma species) produced a Borrelia flaB amplicon. Of the positive ticks, 324 (22.7%) were collected from canines (151 A. americanum, 78 R. sanguineus, 43 I. scapularis, 26 A. maculatum, 18 D. variabilis, and 8 Amblyomma species) and 259 (37.2%) were collected from white-tailed deer (209 I. scapularis, 24 A. maculatum, 10 A. americanum, 10 R. sanguineus, 1 D. variabilis, and 5 Amblyomma species). None of the larvae were PCR positive. A majority of the flaB amplicons were homologous with B. lonestari sequences: 281 of the 296 sequenced ticks, 3 canines, and 27 deer. Only 22 deer, 7 canines, and 15 tick flaB amplicons (12 I. scapularis, 2 A. maculatum, and 1 Amblyomma species) were homologous with B. burgdorferi sequences.ConclusionsData from this study identified multiple Borreliae genotypes in Arkansas ticks, canines and deer including B. burgdorferi and B. lonestari; however, B. lonestari was significantly more prevalent in the tick population than B. burgdorferi. Results from this study suggest that the majority of tick-borne diseases in Arkansas are not B. burgdorferi.

Comparative Susceptibility of Adult and Larval Lesser Mealworms, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), Collected from Broiler Houses in Arkansas to Selected Insecticides 1

Abstract Loss of insecticide susceptibility was suspected in lesser mealworms, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), in broiler chicken facilities in Arkansas due to reports of control failures. Bioassay tests using selected insecticides were conducted on adult and larval beetles collected from broiler chicken production farms having different insecticide application history. The residual and topical application tests showed that previous insecticide use had caused significant differences in the relative susceptibility of lesser mealworms. Topical application bioassay tests indicated that adult beetles had greater susceptibility to the insecticides tested than 8th instars collected from the same farm while in residual tests little difference was generally found in the susceptibility of adults and larvae exposed to the insecticides. Data suggested that the ability to de-toxify DDT and other organochlorine insecticides remained in some beetle populations due to spread of wood-shaving litter containing beetles over pastures among broiler production facilities, particularly involving facilities that have been in broiler production for over 40 y. A program utilizing integrated tactics that will reduce the dependency on insecticides is needed to manage litter beetles in poultry production facilities.

Sustained Mass Release of Pupal Parasitoids (Hymenoptera: Pteromalidae) for Control of Hydrotaea aenescens and Musca domestica (Diptera: Muscidae) in Broiler-Breeder Poultry Houses in Arkansas

Abstract Muscidifurax zaraptor Kogan and Legner, M. raptorellus Kogan and Legner, and Spalangia cameroni Perkins were released bi-weekly in two facilities at a broiler-breeder egg production farm in Arkansas during 2003 and 2004. Of the recovered house fly, Musca domestica L., sentinel pupae, 18.8% were parasitized in 2003, with M. zaraptor being the dominant species (66.8%) and M. raptorellus contributing 6.9% of the parasitism. The release of M. raptorellus did not result in substantial parasitism in sentinel house fly pupae until the second year of study when M. raptorellus was the most dominant species, contributing approximately 61.9% parasitism. At the non-release farm, 13.9% of the sentinel house fly pupae were parasitized, with S. cameroni and M. zaraptor dominating in 2003. Parasitism at the control farm decreased to 3.4% in 2004. It appeared that sustained releases of parasitoids at the release farm over two years provided a significant increase in house fly pupal parasitism when compared to the percentage of pupae parasitized at the non-release farm. Of the sentinel Hydrotaea aenescens (Wiedemann) pupae recovered from the release farm, 9.3% were parasitized in 2003. Filth fly data indicated that the combined predator activity of H. aenescens and sustained parasitoid releases reduced M. domestica to a level well below the treatment threshold. In addition, the sustained release of parasitoids reduced H. aenescens numbers to below the treatment threshold of 100 filth flies per sticky ribbon per week by 9 wk during the latter part of the filth fly season during 2003 and 2004.

Molecular assay for the detection of Cochlosoma anatis in house flies and turkey specimens by polymerase chain reaction

Abstract A 1520bp region of Cochlosoma anatis mtDNA 16S gene was subjected to DNA sequencing and a 466bp portion was compared with other protozoan 16S sequences to develop PCR primers specific for C. anatis. This PCR diagnostic method allowed identification of C. anatis from house flies, Musca domestica L., turkey gut, and fecal samples within 6h after field-collected samples reached the laboratory. House flies detected carrying C. anatis using the diagnostic 374bp amplicons represented the first record of this protozoan in house flies.

Survey of parasitoids (Hymenoptera: Pteromalidae) of house fly (Diptera: Muscidae) pupae from broiler-breeder poultry houses in northwest Arkansas

Abstract Parasitoids were collected from broiler-breeder poultry houses in northwest Arkansas using sentinel bags containing house fly, Musca domestica L., pupae. At least five species of Pteromalidae were collected over a two-year sampling period: Pachycrepoideus vindemiae (Rondani), Spalangia endius Walker, S. cameroni Perkins, Muscidifurax spp., and Nasonia vitripennis (Walker).

Infectivity of Steinernema spp. (Nematoda: Steinernematidae) to Adult Litter Beetles, Alphitobius diaperinus (Coleoptera: Tenebrionidae) in the Laboratory

Three species of Steinernema, S. carpocapsae, S. feltiae, and S. scapterisci consisting of 12 different strains, were tested for their infectivity towards adults of the litter beetle Alphitobius diaperinus. Of the five most promising nematode strains, LC50 values ranged from 1.5 to 77.0 nematodes per host in the filter paper assays. Assays in poultry litter material revealed LC50 values to be 5.8 and 14.6 nematodes per host for the Mexican S. carpocapsae strain and Pye S. feltiae strain.