Analysis of the ribosomal DNA sequences of the microsporidia Thelohania and Vairimorpha of fire ants.

Sequences of the 16SrRNA gene of three microsporidia pathogenic to imported fire ants, Solenopsis invicta and Solenopsis richteri, were determined and compared to each other and 15 other species of microsporidia. The sequences of 2 Thelohania species are nearly identical (99.2% identity), supporting light-microscopic and ultrastructural evidence that Thelohania solenopsae and Thelohania sp. are closely related but probably not conspecific. Sequence comparisons further revealed that Vairimorpha sp. has a sequence identity of about 73% with the two Thelohania species and Vairimorpha necatrix, the type species of the genus Vairimorpha. This, together with information on spore morphology, suggests that Vairimorpha sp. represents a genus distinct from that of the fire ant Thelohania. Its placement in the genus Vairimorpha must also be reevaluated. Two new sister taxa, one containing T. solenopsae and Thelohania sp. and one containing Vairimorpha sp., were found to have diverged early in the microsporidian lineage.

Host grooming efficiency for regulation of cat flea (Siphonaptera: Pulicidae) populations.

Grooming efficiency was studied by infesting domestic short-hair cats, Felis catus L., with known numbers of cat fleas, Ctenocephalides felis felis Bouché, then collecting the cat feces and extracting the fleas to determine how many had been groomed off, varying the infestation level. Some hosts were found to be significantly more efficient at grooming fleas than others, with the best groomer removing 17.6% of its flea burden daily, compared with only 4.1% removed by the poorest groomer. Cats were more efficient at grooming fleas at infestations of < 50 fleas and > 150 fleas. Mean on-host flea longevity was 7.8 d.

Body-surface map models for early diagnosis of acute myocardial infarction.

The standard 12-lead ECG is only 50% sensitive for the detection of acute myocardial infarction (AMI). The majority of leads for optimal classification of AMI probably lie outside the area covered by the 6 precordial leads. Thus, body-surface mapping (BSM) may be more helpful, as a larger thoracic area is sampled. We recorded 64-lead anterior BSMs in 635 patients with chest pain suggestive of AMI and abnormal electrocardiograms (ECGs), and 125 controls without chest pain. Of the 635 patients, 325 had AMI according to World Health Organization (WHO) criteria (203 presenting with ST segment elevation, and 122 with nondiagnostic ECG), and 310 had an "abnormal ECG but not AMI." QRS and ST-T isointegrals and variables describing map shape were derived. Subjects were randomly allocated to a training set (63 controls, 321 patients) and a validation set (62 controls, 314 patients). Multiple logistic regression was used in the training set to identify which variables gave best discrimination between groups. A model with these variables was then tested prospectively in the validation set. In stage 1 (all subjects), controls were compared with patients. In the training set, a model containing 21 variables classified 58/63 controls (specificity 92%) and 316/321 patients (sensitivity 98%). In the validation set, the model classified 48/62 controls (specificity 77.4%) and 302/314 patients (sensitivity 96%). In stage 2 (studying patients only), patients with AMI were compared with patients who had an abnormal ECG-not AMI. In the training set, a model containing 28 variables classified 132/165 patients (sensitivity 80%) with AMI and 134/156 patients (specificity 86%) with an abnormal ECG-not AMI. In the validation set, the model classified 123/160 patients (sensitivity 77%) with AMI and 131/154 patients (specificity 85%) with an abnormal ECG-not AMI. Combining results of both stages in a two-step algorithm gave an overall classification in the training set of controls 92%, abnormal ECG-not AMI 84%, AMI 80%, and in the validation set of controls 77%, abnormal ECG-not AMI 82%, AMI 74%. Thus, in conclusion, when compared with the 12-lead ECG, BSM models results in higher sensitivity and specificity for detection of AMI, particularly in patients presenting with chest pain and nondiagnostic ECG changes. The use of BSM models in such patients, may lead to the earlier detection of AMI and appropriate administration of fibrinolytic therapy and/or anti-platelet agents.

A microcomputer-based system for real-time analysis of animal movement.

A microcomputer-based video system for tracking, recording, and analyzing the movement of animals in two dimensions on variegated background in real-time has been developed and validated, both mechanically and with moving animals. Hardware and software (donationware) costs are low. Specimens visualized as small as 3 pixels long may be tracked in an arena that is 240 x 320 pixels in size. The results of tracking a mechanical moving spot are compared with a theoretical circular path. Comparisons between frame-by-frame human observation and computer generated X-Y coordinates are also presented. Applications of the tracking system include insect toxicology and pheromone bioassay, vertebrate locomotion studies, and basic research on taxes and kineses.

Host-location kairomone fromPeriplaneta americana (L.) for parasitoidAprostocetus hagenowii (Ratzeburg).

Chemically mediated host location in the eulophid parasitoidAprostocetus hagenowii (Ratzeburg) was investigated. In Y-tube bioassays 77.6% of female parasitoids responded to aPeriplaneta americana (L.) ootheca; parasitoids did not respond to air with no volatile stimuli. Frass from adult cockroaches was as attractive as an ootheca. Bioassay of one ootheca equivalent of five lipid fractions (eluted with hexane and 1, 5, 10, and 30% ether in hexane) from silica gel column chromatography indicated that the active component was a hydrocarbon. Further separation and bioassay of oothecal hydrocarbons by AgNO3-impregnated silica gel column chromatography indicated that the biological activity was in one fraction. Gas chromatographic (GC) analysis of this fraction revealed a single peak; this peak was identified by researchers in 1963, 1969, and 1972 as (Z,Z)-6,9-heptacosadiene. Qualitative and quantitative GC analyses of total hydrocarbons from oothecae, frass, and adult females were essentially identical; 6,9-heptacosadiene was the dominant hydrocarbon from each source. The alkadiene was 37 times more abundant in frass than on the ootheca. The volatilization of the alkadiene from oothecae was demonstrated by aeration and trapping on Super Q adsorbent. The current study is the first evidence for biological activity of (Z,Z)-6,9-heptacosadiene, a major hydrocarbon component on adult female American cockroaches, on their oothecae, and in their frass.

Residual effectiveness of insect growth regulators applied to carpet for control of cat flea (Siphonaptera: Pulicidae) larvae.

Three insect growth regulators, fenoxycarb, methoprene, and pyriproxyfen, formulated as total release aerosols, were tested for their residual effectiveness on carpet in bioassays with cat flea, Ctenocephalides felis (Bouché), larvae. All treatments except methoprene produced significant mortality for the 7-mo duration of the test. In general, fenoxycarb and the higher rates of pyriproxyfen reduced adult flea emergence by > 80%.

Larvicidal effects of boric acid and disodium octaborate tetrahydrate to cat fleas (Siphonaptera: Pulicidae).

Borate products varied in efficacy against larval cat fleas, Ctenocephalides felis felis Bouché, with some effective at rates of 23 micrograms/cm2 when larvae were exposed to the compounds in sand. Powdered boric acid, granular boric acid, and disodium octaborate tetrahydrate (Polybor) at rates of 200 micrograms/cm2 produced < or = 90% mortality of larvae exposed in carpet for 96 h. LC50 values of larvae exposed in treated carpets for 96 h were 23 micrograms/cm2 for powdered boric acid, 40 micrograms/cm2 for granular boric acid, and 47 micrograms/cm2 for polybor.

Oral toxicity of boric acid and other boron compounds to immature cat fleas (Siphonaptera: Pulicidae).

Oral toxicity was characterized in first-instar cat fleas, Ctenocephalides felis felis (Bouché), feeding on dried blood treated with boric acid. LC50 values ranged from 2.11% after 24 h to 0.21% after 7 d. In carpet tests with five different boron compounds and a number of different formulations, significant mortality for first instars was observed in all cases. In similar tests with prepupae and cocoons, there was no significant effect on mortality. The importance of these results is discussed in light of current application procedures for boron compounds, and suggestions are made for future research.

Rearing improvements for the German cockroach (Dictyoptera: Blattellidae).

Known-age cohorts of three strains of German cockroach, Blattella germanica (L.), were mass-reared by establishing one rearing container each week (so that cockroaches within a container would be of known age). An average of 330-443 females was placed in oviposition units within these rearing containers. Percentage hatch of oothecae was 77.49-84.63%, resulting in an average of 12,258-16,359 nymphs per rearing container. Development of nymphs was similar for the three strains. Survivorship of nymphs to the adult stage was 19.95-29.56%; survivorship was significantly higher for the strain most recently colonized from the field. Adult emergence occurred at 6-7 wk, and average production per container was 2,834-3,971 cockroaches.

Harborage width preferences of German cockroach (Dictyoptera: Blattellidae) adults and nymphs.

Adults and nymphal cohorts of the German cockroach, Blattella germanica (L.), were allowed 24 h to select preferred harborage widths from eight harborages between 1.59 and 12.72 mm (increments of 1.59 mm) in both individual and combined cohort studies. In individual cohort studies, 1- and 2-wk-old nymphs significantly preferred 1.59-mm-wide harborage, with 74 and 68%, respectively; 3- and 4-wk-old nymphs significantly preferred 3.18-mm-wide harborage, with 63 and 45%, respectively; 5-wk-old nymphs selected the 4.77-mm-wide harborage; and 6-wk-old nymphs were evenly distributed in 3.18- to 9.54-mm-wide harborages. Males were in 6.36- to 12.72-mm-wide harborages. Nongravid females (81%) were in 4.77-, 6.36-, and 11.13-mm-wide harborages; gravid females (94%) preferred 4.77- and 6.36-mm-wide harborages. The percentage of nymphs outside harborages decreased as cockroach age increased from 1 to 5 wk. In combined cohort studies, preferred harborage widths for all cohorts and sexes were 6.36-7.95 mm and 11.13-12.72 mm. The percentage of nymphs outside harborages was low and constant (< 4.57%) irrespective of age or sex.

Oral toxicity and repellency of borates to German cockroaches (Dictyoptera: Blattellidae).

The oral toxicities of boric acid and disodium octaborate tetrahydrate (DSOBTH) in dry-mixed, wet-mixed, and water-based solution baits were determined for German cockroaches, Blattella germanica L., in choice and nonchoice experiments. In dry-mixed, nonchoice bait tests, all cockroaches died within 1 wk. Time to mortality decreased as the concentration of boric acid increased. The LT50s for DSOBTH were not significantly different for any concentrations tested. In choice tests, the order of LT50s of boric acid and DSOBTH were 6.25% = 12.5% > 25% = 50% and 25% > 12.5% > 50% > 25%, respectively. Consumption of treated and control baits and the differences between the LT50s of the nonchoice and choice tests indicate repellency of the toxicants. Most German cockroaches died in 3-6 d in wet-mixed nonchoice tests, but all cockroaches survived the wet-mixed choice tests except at the lowest concentration of boric acid. This result indicated repellency. In nonchoice tests with water-based solutions, all cockroaches died in 5 d. In choice tests with boric acid solutions, mortality did not increase at concentrations > 1%. Choice/nonchoice ratios indicate no repellency of water-based solutions. In addition, consumption of treated and blank solutions was not significantly different for any concentration except 4% DSOBTH.

Age- and sex-related effects in German cockroaches fed an allopurinol diet (Dictyoptera: Blattellidae).

The effects of feeding several ages of adult and nymphal German cockroaches a laboratory rat chow diet containing 0.10% allopurinol were investigated. All cockroaches fed the allopurinol diet suffered increased mortality. The range of LT50 values (the time required to kill 50% of an experimental cohort) for four ages of nymphs (1-8, 16-23, 21-28, and 28-35 d old following hatch) continuously fed the allopurinol diet was 1.36 wk (4.72-6.08 wk). Regardless of sex, young adult (1-7 d old following eclosion) cockroaches fed the allopurinol diet died significantly sooner than older adults (28-35 d old following eclosion); males died significantly sooner than females. All females fed the allopurinol diet as nymphs aborted their oothecae. Although an initial ootheca were hatched from cockroaches fed the allopurinol diet as adults, all subsequent oothecae were aborted. Untreated females mated with allopurinol-fed males experienced successful reproduction, but allopurinol-fed females mated with either allopurinol- or control diet-fed males failed to reproduce. Evidence suggests that cockroaches suffer increased mortality and reproductive failure from increased levels of hypoxanthine and xanthine.

Detection of insecticide resistance in the German cockroach (Dictyoptera: Blattellidae) with glue-toxin traps.

Glue that contained an insecticide was evaluated for its ability to yield useful toxicological data for German cockroaches, Blattella germanica (L.). Toxicities of three classes of insecticides were evaluated by topical applications (LD50) and exposure to insecticide-impregnated glue (LC50). Cockroaches that were resistant to topical insecticide applications were also resistant to the glue formulation. Reliability was greatest when mortality was scored 40 to 48 h after the cockroaches were placed on the glue. This method should be adaptable for insecticide resistance monitoring of German cockroaches.

Susceptibility of cockroaches (Dictyoptera: Blattellidae, Blattidae) to infection by Steinernema carpocapsae.

The susceptibility of American cockroaches, Periplaneta americana (L.); smoky brown cockroaches, P. fuliginosa (Serville); oriental cockroaches, Blatta orientalis L.; German cockroaches, Blattella germanica (L.); and brownbanded cockroaches, Supella longipalpa (F.), to Steinernema carpocapsae Weiser (All strain) was evaluated under laboratory conditions. A 1-ml water suspension containing 500,000 nematodes was placed on filter paper in a petri dish or the pad of a bait station. German, brown-banded, oriental, and smoky-brown cockroaches died within 1 d after placement in the petri dishes. The relative order for the LT50s were American greater than oriental greater than smoky-brown greater than brown-banded = German. All cockroaches actively groomed nematodes from legs and antennae of forced (petri dish) exposure. The LT50s for S. carpocapsae for nonforced (bait station) exposure were significantly greater than those for forced exposure. The LT50s were 3.25, 4.13, 9.86, and 11.38 d for brown-banded, German, oriental, and smoky-brown cockroaches, respectively. The relative order of the LT50s after forced (American greater than oriental greater than smoky-brown greater than German = brown-banded) and nonforced (American greater than smoky-brown greater than oriental greater than German greater than brown-banded) exposure to S. carpocapsae was inversely related to the moisture of their preferred habitats.

Diel patterns of cat flea (Siphonaptera: Pulicidae) egg and fecal deposition.

The quantity of eggs and feces deposited by replicate populations of cat fleas, Ctenocephalides felis (Bouché), from domestic house cats. Felis catus, were recorded at 1-h intervals over a 24-h period, in a photoperiod of 12:12 (L:D) (photophase, 0600-1800 hours [EST]). Egg production averaged 23.96 +/- 0.83 eggs per female per day and was greatest from 2400 to 0300 hours and lowest from 0700 to 0900 hours and from 1700 to 1900 hours. Daily fecal deposition was 0.77 +/- 0.03 mg feces per flea and did not vary significantly among hours. Flea eggs and adult feces were dropped continuously from infested cats, but significantly more eggs were shed at times of day when cats normally rest. More feces are concentrated in the small areas where cats rest than over the large areas they roam. Consequently, eggs and feces would not be deposited uniformly throughout the hosts home range, resulting in a clumped distribution of larval development sites at host resting areas.

Spectrophotometric method of quantifying adult cat flea (Siphonaptera: Pulicidae) feces.

Cat flea, Ctenocephalides felis felis (Bouché), feces are an essential part of larval nutrition under natural conditions. The mass values of adult flea feces can be measured by dissolving samples of flea feces in Drabkin's reagent, filtering, centrifuging, and measuring absorbance spectrophotometrically at 540 nm. Either flea feces or air-dried host blood can be used to generate the standard curve used to convert absorbance (optical density) values into mass values. Debris collected from flea-infested house cats averaged 23.02 mg debris per cat per h with an average of 10.41 mg flea feces per cat per h. Flea feces deposited in the environment serve as potential larval food. Adult flea feces comprised an average of 44.28% of the debris deposited from infested domestic house cats in this study.

Volatile effects of insect growth regulators against the German cockroach (Dictyoptera: Blattellidae).

Third-instar German cockroach nymphs were held to maturity in continuous proximity to test surfaces treated with hydroprene and fenoxycarb, which they were unable to contact directly. Surfaces tested were unfinished plywood, fiberboard, vinyl tile (absorbent surfaces), glass, stainless steel, ceramic tile, and formica (nonabsorbent surfaces). Number of oothecae, percent egg hatch, and survival did not differ between any fenoxycarb treatment and the untreated controls, but there was significant wing twisting (76-94%) for all nonabsorbent surfaces. Number of oothecae was significantly lower and percent wing twisting was significantly higher for all hydroprene-treated surfaces with respect to the untreated controls, although survival was not affected. These effects were less pronounced for the nonabsorbent surfaces. These results indicate that hydroprene, but not fenoxycarb, has significant biological activity through volatile action when applied at current label rates. This activity is likely to have important consequences for control, especially for "crack and crevice" applications in confined spaces.

Effect of methoprene and diflubenzuron on larval development of the cat flea (Siphonaptera: Pulicidae).

Cat flea larvae, Ctenocephalides felis Bouche, exposed to glass surfaces treated with methoprene concentrations from 0.127 to 1,270 ng/cm2 did not emerge as adults. Most larvae died in the third instar, but those exposed to the 0.127 ng/cm2 concentration formed larval-pupal intermediates. Larvae exposed to glass surface treated with diflubenzuron concentrations from 12.7 to 1,270 ng/cm2 died during the process of molting in all three instars. Exposure of larvae to 12.7 and 127 ng/cm2 diflubenzuron resulted in 15 and 5.2% adult emergence, respectively.

Dietary effects of allopurinol and sulfinpyrazone on development, survival, and reproduction of German cockroaches (Dictyoptera: Blattellidae).

Diets containing two gout medications, allopurinol and sulfinpyrazone, were fed ad libitum to first- or second-instar German cockroaches for 15 wk or until 100% mortality was reached. Cockroaches fed greater than or equal to 0.10% allopurinol diets weighed significantly less than those fed the control diet. Mortality of cockroaches fed diets containing greater than or equal to 0.05% allopurinol was significantly greater than those fed the control diet. The LT50 (6.1 wk) of cockroaches fed diets containing 0.10% allopurinol was significantly less than those fed any other diet containing allopurinol. LT50s and slopes were proportional and inversely related, respectively, to percentage of allopurinol in the diet. The addition of sulfinpyrazone to allopurinol diets minimally enhanced the blatticidal nature of the diets. Nymphs fed diets containing greater than or equal to 0.05% allopurinol experienced significant delays in adult emergence. Cockroaches fed greater than or equal to 0.01% allopurinol diets aborted a significantly greater percentage of their oothecae than those fed the 0.001% allopurinol or control diets. Hatched oothecae from cockroaches fed the 0.01% allopurinol diet had significantly fewer nymphs than those fed the 0.001% allopurinol or control diets. Percentage of oothecae aborted and number of nymphs per hatched ootheca from cockroaches fed a 2% sulfinpyrazone diet did not differ significantly from the control.

Biological response of German cockroaches fed diets containing allopurinol.

The acceptability of dietary allopurinol to German cockroaches, Blattella germanica (L.), was assessed. In diet choice tests between rat chow with or without 0.1% w/w allopurinol there were no significant differences in nymphal development, feeding duration, visits or consumption. The LT50 of cockroaches fed a choice of diets was 3 weeks greater (7.88) than those fed non-choice a 0.1% allopurinol diet. Female cockroaches provided a choice of diets aborted a significantly greater percentage of their oothecae (98.6%) than those fed the untreated diet (1.7%). Choice arena tests of 2% allopurinol in rat chow significantly reduced cockroach populations compared with untreated controls. After 6 weeks, populations were reduced by approximately 50%, and 97% after 14 weeks. These results indicate that allopurinol is acceptable to B. germanica as a dietary supplement which could be used in baits for cockroach control.