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Biomedical subjects

R C Axtell

Publications and source records attributed to R C Axtell.

At least 37 records · Page 2Linked to original sources
PubMed1990

Temperature-dependent development and parasitism rates of four species of Pteromalidae (Hymenoptera) parasitoids of house fly (Musca domestica) pupae.

Parasitoid development, parasitoid-induced host mortality and parasitoid progeny emergence were determined at five constant temperatures for Muscidifurax raptor Girault and Sanders, Muscidifurax zaraptor Kogan and Legner, Spalangia cameroni Perkins and Spalangia endius Walker using pupae of the house fly, Musca domestica L., as hosts. At temperatures of 20, 25, 30 and 35 degrees C the median development times (days from oviposition to adult emergence), respectively, were M. raptor (28.4, 20.7, 14.3, 14.5), M. zaraptor (30.6, 22.8, 14.1, 14.2), S. cameroni (55.6, 35.2, 21.8, 25.0) and S. endius (52.4, 31.5, 16.3, 14.6). All species failed to emerge at 15 degrees C. Using densities of five parasitoids and 100 hosts and a 24 h exposure period, Muscidifurax species oviposited at a greater rate over a wider range of temperatures than Spalangia species. At 15, 20, 25, 30 and 35 degrees C the mean number of pupae killed per parasitoid were, respectively, M. raptor (1.4, 7.4, 10.5, 13.7, 14.1), M. zaraptor (0.0, 3.3, 8.9, 14.4, 15.0), S.cameroni (0.0, 7.8, 11.0, 11.9, 7.4), S.endius (0.6, 4.0, 7.5, 12.0, 11.7), and means of the number of parasitoid progeny per parasitoid were, respectively, M.raptor (0.2, 5.2, 7.9, 11.8, 11.6), M.zaraptor (1.3, 4.4, 8.2, 13.0, 13.7), S.cameroni (0.0, 2.4, 4.7, 5.1, 1.0), S.endius (0.0, 0.9, 3.4, 7.5, 4.9). Development and ovipositional activity in S.cameroni was strongly inhibited at 35 degrees C. The model by Sharpe & DeMichele (1977) was used to describe temperature-dependent development and the number of parasitoid progeny produced per parasitoid at temperatures of 15-30 degrees C in all species.

Animals↗
PubMed1990

Ecology and management of arthropod pests of poultry.

The worldwide spread of modern, high-density confined poultry production systems under the direction of integrators has intensified the importance of a select number of arthropod ectoparasites and habitat pests. This concentrated production of poultry provides artificial ecosystems that are sometimes ideal for the development of large populations of arthropod pests. At the same time the systems are amenable to integrated pest management involving a multipest and multimethod approach to reducing or eliminating arthropod pests. Since rodents are major pests, they should be included in an integrated pest management program to make the program most cost-effective and attractive to the integrators and producers (5). Quantitative data are scarce on economic effects, and the concept of economic thresholds is difficult to apply either to ectoparasites or to habitat pests. The risk of transporting ectoparasites among flocks is difficult to evaluate and necessitates treatment after early detection of the arthropods. Flies and litter beetles present a threat of disease transmission and the potential for lawsuits from neighbors or public health agencies that are factors not subject to easy cost estimates. The monetary losses of a flock devastated by disease or a farm forced to close are so great that the risks are unacceptable. Production losses from lowered feed conversion ratios and insulation damage are likely to be detected by the sophisticated record-keeping of the integrators. Minimal use of pesticides and other chemicals on poultry and in poultry housing is an objective of the integrators and, consequently, an integrated pest management (IPM) approach that reduces the need for pesticides is attractive. The key to further development of effective arthropod management programs for poultry is the implementation of pest and disease monitoring programs for the complete system. Improvements in arthropod sampling methods and more attention to monitoring the biosecurity systems to minimize ectoparasite dispersal are needed. The integrators have servicemen who regularly visit the production facilities and can be trained to perform monitoring functions and to instigate and supervise integrated pest management measures. With the increasing use of computers by the integrators, the prospects for utilizing the monitoring data in predictive computer simulation models for pest management decision-making justify more efforts to develop such tools (64, 102, 168). Future poultry pest management programs must be based on sound data, which presently is too limited, and must be flexible enough to adjust rapidly to evolving pest problems in rapidly changing production systems.

Animals↗
PubMed1990

Efficacy of encapsulated Lagenidium giganteum (Oomycetes: Lagenidiales) against Culex quinquefasciatus and Aedes aegypti larvae in artificial containers.

Presporangial mycelia of Lagenidium giganteum cultured on sunflower seed extract were encapsulated in calcium alginate and added once (July 18) to outdoor (Raleigh, NC) caged tires, wood and concrete containers populated with first instars of Culex quinquefasciatus or Aedes aegypti. First instars were added twice weekly (for 10 wk) to simulate natural oviposition. The fungus persisted for 10 wk and recycled in the mosquito larvae of both species. The overall reductions of Cx. quinquefasciatus and Ae. aegypti immatures were higher in tires (55 and 45%, respectively) and wood (67 and 38%) than in concrete containers (17 and 14%). There were low correlations of the numbers of mosquito immatures with measurements of water quality (chemical oxygen demand, ammonia nitrogen and conductivity) in the containers.

Aedes↗
PubMed1990

Comparisons of different types and concentrations of alginates for encapsulation of Lagenidium giganteum (Oomycetes: Lagenidiales), a fungal pathogen of mosquito larvae.

Six different types of alginates used to encapsulate Lagenidium giganteum gave similar levels of fungal infection in Culex quinquefasciatus larvae. Initial infection levels when the capsules were immersed in water after 6 days of storage (15 and 25 degrees C) were 100% for all types of alginate and after 42 days of storage was 62-100%, depending on the type of alginate. Infectivity was 24-100% after the encapsulated fungus were left in water for 7 days and after 15 days was 0 to 26%, depending on the alginate. When 2 of the alginates were tested at different concentrations to give high, medium and low viscosity solutions, the fungus encapsulated using lower concentration alginate solutions usually gave the highest level of infectivity.

Alginates↗
PubMed1987

Efficacies of mixtures of disinfectants and insecticides.

Efficacies of mixtures of diluted commercial formulations of selected insecticides and disinfectants were evaluated. Insecticides tested included representative pyrethroids (fenvalerate [Ectrin WDL and WD] and permethrin [Ectiban EC]), organophosphates (dichlorvos [Vapona EC], tetrachlorvinphos [Rabon WP] and dichlorvos/tetrachlorvinphos [RaVap EC], and a carbamate (carbaryl [Sevin S]). Disinfectants tested included representatives of cresylic acid (Biolene), cresylic acid/phenol (BioGuard X-185), phenol (1-Stroke Environ), quaternary ammonium (BioGuard S-3 and PFP-4), quaternary ammonium/formalin (DC & R), and formalin classes of disinfectants. Mixtures were tested for toxicity to two target insects (Musca domestica on plywood, Alphitobius diaperinus in litter) and two bacteria (Pseudomonas aeruginosa and Staphylococcus aureus). Of 56 mixtures evaluated, 24 showed reduced insecticidal toxicity and 35 showed reduced bactericidal activity compared with insecticides or disinfectants alone.

Animal Husbandry↗
PubMed1987

Encapsulation of the mosquito fungal pathogen Lagenidium giganteum (Oomycetes:Lagenidiales) in calcium alginate.

The asexual stages (presporangial mycelia) of Lagenidium giganteum cultured on sunflower seed extract were encapsulated in calcium alginate and remained infective to mosquito larvae, Culex quinquefasciatus, after storage at 15 degrees C for up to 75 days. Survival and zoospore release from the encapsulated mycelia persisted for up to 24 days after immersion in water. Encapsulated sexual stages (oospores), held at 23-26 degrees C for up to 35 days or frozen for 8-10 days, were infective to mosquito larvae for up to 48 days after immersion in water and during that time over 50% of the oospores germinated. In outdoor pools, encapsulated mycelia gave 100% control of Cx. quinquefasciatus at 6-7 days after treatment while encapsulated oospores gave 100% control at 11 days posttreatment.

Alginates↗
PubMed1987

Temperature and water quality effects in simulated woodland pools on the infection of Culex mosquito larvae by Lagenidium giganteum (Oomycetes: Lagenidiales) in North Carolina.

Asexual stages of the California (CA) isolate of Lagenidium giganteum cultured on sunflower seed extract (SFE)-agar, were applied to outdoor pools containing Culex larvae near Raleigh, NC in August and September 1984. Infection rates among the larvae ranged from 19 to 74% at 2-4 days posttreatment and subsequent epizootics eliminated most of the newly hatched larvae for at least 10 days posttreatment. Substantial reductions in numbers of larvae and adult emergence were achieved from a single application of the fungus. Water quality and temperature data are presented. From laboratory assays of organically polluted water, the percent infection of Culex quinquefasciatus by the fungus was correlated with water quality and temperature. A logistic model of water quality (COD and NH3-N) effects on infectivity rates by the CA isolate is described.

Animals↗
PubMed1987

Population dynamics of Culex quinquefasciatus and the fungal pathogen Lagenidium giganteum (Oomycetes: Lagenidiales) in stagnant water pools.

The fungal pathogen Lagenidium giganteum (California isolate), cultured on sunflower seed extract (SFE) and agar, was introduced once (May 15) into outdoor caged replicated stagnant water pools containing all instars of larval Culex quinquefasciatus. Subsequently, first-instar larvae were added daily (May 15-September 30) to simulate natural oviposition. The fungus persisted for the entire 138-day study period, which corresponded with the season of Cx. quinquefasciatus breeding in this region of North Carolina, and recycled in the mosquito larvae producing an 82% reduction of adult mosquitoes produced in comparison to untreated pools. The cycles of fungal activity varied among the pools with 2-4 major epizootics occurring during the study period. Data are presented on the cycling of populations of fungal zoospores, mosquito larvae, pupae and adults during the entire mosquito breeding season.

Animals↗
PubMed1986

Effect of nutrient concentration in culturing three isolates of the mosquito fungal pathogen, Lagenidium giganteum (Oomycetes: Lagenidiales), on sunflower seed extract.

The requirements for soluble protein concentration in sunflower seed extract (SFE) cultures were similar for 3 isolates of Lagenidium giganteum from North Carolina, Louisiana and California. Sunflower seed extract agar containing soluble protein in the range of 1.0 to 4.0 mg/ml was satisfactory for high levels of zoospore production. It is recommended that the protein concentration be 2.0 mg/ml for both SFE agar and liquid SFE culturing media, and the protein assay be with the Bradford method using bovine serum albumin as the standard.

Chytridiomycota↗
PubMed1986

Factors affecting storage of mycelial cultures of the mosquito fungal pathogen Lagenidium giganteum (Oomycetes: Lagenidiales).

Sunflower seed extract (SFE) agar cultures (in petri dishes) of Lagenidium giganteum (California isolate) were evaluated for zoospore production and ability to infect mosquito larvae, Culex quinquefasciatus, after periods of storage up to 93 days at 15 degrees C. Rates of decrease in zoospore production and infectivity were related to soluble protein concentration in the SFE-agar media but at all concentrations (0.7-6.0 mg/ml) about 50% of the initial levels were lost after 40-50 days of storage. Water loss from the SFE-agar did not affect zoospore production or infectivity except at extremely high levels (about 98% water loss).

Animals↗
PubMed1984

Evaluations of sampling methods for darkling beetles (Alphitobius diaperinus) in the litter of turkey and broiler houses.

Materials placed on the litter in turkey and broiler houses were evaluated as sampling devices for the larvae and adults of Alphitobius diaperinus (lesser mealworm or darkling beetle). Insects harbored in, on, and between pieces of the materials were counted after 1-week exposure. Pan traps consisting of two stacked pieces of 1.3-cm thick foil-covered polyisocyanurate insulation (Celotex) placed under a protective metal pan staked to the litter surface was a more effective sampling device than pan traps using thicker (5 cm) Celotex, 3.8 cm thick polystyrene (Styrofoam), or two stacked pieces of wood. A tube trap consisting of rolled fluted corrugated cardboard inserted in a section of polyvinyl chloride pipe was as effective a sampling device as the two pieces of Celotex in a pan trap and was more convenient to use. Six pieces of corrugated cardboard stacked under a pan caught larger numbers of beetle larvae and adults but was awkward to handle and impractical. Placement of sampling devices in the major subhabitats (open center, near walls, near feeders, and near waterers) in turkey and broiler houses affected catches of beetle larvae and adults. The open center area was satisfactory and most convenient.

Animals↗