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This study investigated the effects of the permethrin-impregnated plastic on ant mortality and foraging rates, and tested its potential for preventing ants from colonizing potted soil. Direct exposure to the plastic for as short as 1 min caused significant mortality of both red imported fire ants, Solenopsis invicta Buren, and Argentine ants, Linepithema humile (Mayr); however, red imported fire ants were more susceptible than Argentine ants. Knockdown of virtually all ants initially occurred within 15 min after exposure. However, some moribund ants recovered from the effects within 24 h. For example, after 1 min of direct exposure to the permethrin-impregnated plastic, 70% of Argentine ants and 5% of red imported fire ants recovered from the treatment. In established colonies of Argentine ants, significantly fewer ants foraged for food up posts treated with the plastic compared with untreated posts. In addition, colonies responded to introduction of the treatment by significantly reducing their overall foraging rates, even on untreated posts. When pots filled with moistened soil were introduced into established ant colonies, 82% of Argentine ants and 99% of red imported fire ants moved into the soil. In contrast, when a 1-cm-wide coil of the plastic was placed under the pot, no ants moved into the soil. The potential for use of these materials in nursery production is discussed.

Cat fleas are the most important ectoparasite of cats and dogs worldwide. During the past ten years, topical and oral applications of insecticides such as fipronil, imidacloprid, lufenuron and, most recently, selamectin have revolutionized cat-flea control. Recent studies show that these therapies eliminate the need to treat indoor and outdoor environments, and their use markedly reduces the severity and prevalence of flea allergic dermatitis. Surveys have yet to reveal the development of insecticide resistance to these chemical compounds. Extending the longevity of these effective host-targeted therapies should be a major goal of the veterinary community.

The effects of hexaflumuron consumption on the mortality of workers of the Western subterranean termite, Reticulitermes hesperus Banks, were observed following various exposures to a substrate treated with 14C-labeled hexaflumuron at 5 g kg−1. Uptake of hexaflumuron by workers was rapid, peaking at approximately 280 ng hexaflumuron per termite 12 days after exposure. The onset of mortality began at day 8, with cumulative mortality reaching approximately 96% by day 45. Excretion of hexaflumuron from worker termites was rapid following various exposure periods, half-lives ranging from 2.1 to 4.7 days. Trophallaxis among worker termites was efficient, hexaflumuron levels in recipient termites approaching two-thirds of levels present in donor termites feeding continuously on hexaflumuron-treated filter paper. The effect of donor-to-recipient group ratios was negligible on the amounts of hexaflumuron transferred from donors to recipients. In laboratory tests, hexaflumuron diffused from a feeding source within 7 days. The presence of additional food sources appeared to inhibit movement of hexaflumuron. Movement of hexaflumuron by cannibalism and coprophagy occurred, but was significant only when termites were starved. Hexaflumuron also appeared to adversely affect egg development by preventing hatch. Hexaflumuron was readily transferred through termite groups, effectively suppressing laboratory populations of R hesperus. Variable efficacy in field situations employing baiting with hexaflumuron in southern California may be a consequence of sporadic feeding at bait stations, the rapid clearance of hexaflumuron from individual termites, and the difficulties in bait presentation (low foraging activity, poor bait station foraging fidelity) inherent in the foraging characteristics of the Western subterranean termite. Copyright © 2005 Society of Chemical Industry

Brief exposures of Argentine ants to four different insecticide treatments, bifenthrin, beta-cyfluthrin, bifenthrin + beta-cyfluthrin, and fipronil, were conducted to determine Kaplan-Meier product limit survivorship percentiles (SPs) at 21-23 and 27-29 degrees C. Bifenthrin, beta-cyfluthrin, and bifenthrin + beta-cyfluthrin provided rapid kill at 21-23 degrees C with SP10 values ranging from 11.2 to 33.7 min. Fipronil provided delayed toxicity at 21-23 degrees C with SP10 values ranging from 270 to 960 min. At 27-29 degrees C, all of the SP10 values significantly decreased. Field tests in which Argentine ants were induced to forage across insecticide-treated surfaces were used to determine the effect that speed of action has on foraging and recruitment ability, and whether these insecticides are repellent. The slower-acting fipronil allowed a greater amount of foraging and consequently a greater fraction of the colony to be exposed, whereas fast-acting bifenthrin, beta-cyfluthrin, and bifenthrin + beta-cyfluthrin inhibited recruitment, resulting in fewer ants being exposed and killed. Implications for controlling ants by using perimeter barrier treatments are discussed.

Horizontal transfer of three contact insecticides, bifenthrin, beta-cyfluthrin, and fipronil, was tested in laboratory colonies. Donor ants were exposed for 1 min to insecticide-treated sand substrates and placed with unexposed ant colonies at two different temperatures. Mortality was monitored to compare the ability of donors to transfer lethal doses of these insecticides to untreated individuals. Treated donor insects, live or dead, were added into colonies to determine the importance of donor behavior on lethal transfer. Fipronil was readily transferable between individuals, resulting in high mortality rates. Bifenthrin and beta-cyfluthrin were less transferable, exhibiting moderate-to-low mortality rates similar to the controls. Greater mortality occurred at 27-29 degrees C than at 21-23 degrees C for bifenthrin, but not the other treatments or controls. Colony mortality did not significantly increase when adding live donors, suggesting that necrophoresis was probably an important donor behavior in addition to grooming and trophallaxis on horizontal transfer.

The phylogenetic relationships among 31 different flea isolates representing seven different species were studied by nucleotide sequence comparison of the internal transcribed spacer 1 (ITS1), internal transcribed spacer 2 (ITS2) and/or mitochondrial 16S ribosomal RNA gene (mt16S-rDNA) to examine the patterns of variation. Results show that all regions are useful in discriminating among flea species. In Ctenocephalides felis and Tunga penetrans, some differences in these gene regions occurred among different isolates within the same species. In the latter case, the differences are in the mt16S-rDNA region, with one isolate showing 48% divergence in nucleotide sequence. The taxonomic implications of this result are unclear at present. The gene regions revealed differences between C. felis isolates only after DNA sequencing the PCR products. Further differentiation among C. felis isolates was obtained using four different random binding primers (decamers) and primers for mammalian aldolase to amplify narrow differences in the genome. Using these primers we were able to discriminate between different C. felis isolates and determine that some of the genetic variation coincided with minor differences in response to the control agent imidacloprid. However, overall findings do not support the existence of subspecies of C. felis.

Nitenpyram (Capstar) is a fast acting, orally administered flea treatment that is absorbed into the blood of the host animal and is readily available for uptake by feeding fleas. We examined the efficacy of a single dose of nitenpyram against adult cat fleas, Ctenocephalides felis (Bouché), over several days. We recorded adult flea mortality and flea egg production on treated and untreated cats. Nitenpyram provided 100% kill of all fleas on the host at the time of treatment and for up to 24 h after treatment. Between 24 and 48 h after treatment, there was a 98.6% reduction in adult flea numbers. From 48 to 72 h, there was a 5% reduction in adult fleas. There was a 97% reduction and 95.2% reduction in the number of flea eggs collected from treated versus untreated animals during the first 48 h and from 48 to 72 h, respectively. In addition, we quantified three distinct behavioral responses of infested adult cats treated with nitenpyram to determine the extent of any immediate, overt behavioral responses in treated animals. A significant increase in scratching, biting, licking, and twitching occurred for 5 h. The biting and licking continued for 7 h after treatment. Administration of nitenpyram provides an effective mechanism to eliminate adult fleas from hosts for up to 48 h after treatment.

The foraging range and distribution of Argentine ant, Linepithema humile (Mayr), colonies in urban areas of southern California extended at least 61 m (200 feet) from feeding stations and structures. Ants were fed at 25% sucrose feeding stations containing 0.01% fluorescent brighter (FB28). Within 14 d, from 77-90% of the ants sampled next to the feeding stations were positive for FB28. The percentage of ants with FB28 declined gradually to approximately 55% 61 m away from the feeding station. The percentage of marked ants in the controls didn't change over the 4-wk-test period. There were approximately 290,000 ants visiting the monitored stations each night before treatments. The 0.0001% fipronil baits and 0.06% fipronil SC sprays provided significant reductions in at least 4 wk. The percentage of ants marked with FB28 decreased significantly in both bait and spray treatments over 4 wk suggesting that the resurgence of ants in treated areas were because of immigration from untreated areas. It is likely that much larger areas will need to be treated to control Argentine ants in urban settings, especially if baits are being used.

Appropriate particle size may be a critical characteristic for effective granular ant baits. We examined the particle size preference of six species of pest ants to an anchovy-based bait. We also examined head capsule widths of Argentine ants, Linepithema humile (Mayr) (mean = 0.54 mm), California harvester ants, Pogonomyrmex californicus (Buckley) (mean = 1.63 mm), red imported fire ants, Solenopsis invicta Buren (mean = 0.9 mm), and southern fire ants, Solenopsis xyloni McCook (mean = 0.76 mm) and compared them with the first and second most preferred particle size. There were differences between particle size of which the most mass was removed and of which there were more particles removed by ants. California Argentine ants, southern fire ants, and Alabama Argentine ants removed more 840 to 1,000-microm particle mass of the anchovy diet but had more visits to dishes containing 420 to 590 microm particles. California harvester ants and Allegheny mound ants, Formica spp., removed more2,000 microm particle mass but visited dishes containing 1,000 to 2,000 microm particles more often. Red imported fire ants also removed more2,000 microm particle mass but visited dishes with 590 to 840-microm particles most often. Pharaoh ants, Monomorium pharaonis (L.), removed and visited 420 to 590-microm particles more than any other size. A linear regression model determined that particle size preferred by each ant species relates to forager head width. The majority of particles of commercial ant bait, including Amdro, Ascend, Award, Bushwhacker, Max Force with fipronil, and old and new formulations of Max Force with hydramethylnon, were 1,000 to 2,000 microm, but the majority of Niban particles were420 microm. Altering the size of particles of toxic ant baits to fit the particle size preference of each pest ant species may increase the efficacy of ant baits.

Assimilation of boron by Argentine ants, Linepithema humile (Mayr), fed boric acid—sucrose water solutions was affected by the addition of sorbitol. Concentrations of 10 and 20% sorbitol reduced boron assimilation by 38 and 67%, respectively, thereby significantly reducing the toxicity of the solutions. The effect of solution pH on mortality indicated that the ionized borate molecule was less toxic than the neutral boric acid species. Electron microscopy revealed that ants fed low concentrations of boric acid (0.5%) show gross abnormalities in the microvilli and cells lining the midgut.

The development of effective baits to control the Argentine ant, Linepithema humile (Mayr), has been problematic because foragers prefer sweet liquids, while many toxicants are insoluble in water and liquid baits are generally difficult to deliver. The incorporation of thiamethoxam and sucrose solutions into a water-absorbing polyacrylamide hydrogel provides a unique and novel carrier and method of application for liquid baits. Formulations of thiamethoxam affected the size of the hydrogels, and sucrose solutions containing 0.0003% technical thiamethoxam provided hydrogels as large as those made with 25% sucrose solution or deionized water. Concentrations of thiamethoxam as low as 0.000075% in the hydrogels provided 50% kill of workers within 3 d in a laboratory setting. In small colony studies, baiting with 0.00015 and 0.000075% thiamethoxam hydrogels provided 100% mortality of workers and queens within 8 d. An enzyme-linked immunosorbent assay indicated that thiamethoxam was absorbed into the interior of the polyacrylamide matrix. The water loss rates of the hydrogels were dependent upon the relative humidity. Polyacrylamide hydrogels with >50% water loss were less attractive to ants. Field studies in highly infested areas indicated that concentrations of 0.0006 or 0.0018% thiamethoxam were more effective than 0.00015%. Hydrogels may provide a cost-effective alternative to providing aqueous baits to control Argentine ants.

Two species of velvety tree ants, Liometopum luctuosum Wheeler, and Liometopum occidentale Emery (Hymenoptera: Formicidae), are commonly found in the western Unites States from Washington to southern California. L. luctuosum is restricted to coniferous forests in the mountains in the southern range, whereas L. occidentale is found in the lowlands. The survivorship of workers of both species exposed to several temperatures and relative humidity (RH) was determined. As temperature increased, survival of both species decreased. As the RH increased, survival of both species increased. However, L. luctuosum had higher overall survival in all treatment groups. The cuticular permeability (CP) and the rates of body water loss for each species were determined. Both species had similar CPs. Increased physiological tolerances of L. luctuosum may be an explanation for its broader distribution.

We have developed an oral bioassay to determine the toxicity of hydramethylnon to individual workers and queens of the Argentine ant, Linepithema humile. We fed seven concentrations of hydramethylnon in suspension to individual workers or queens, determined the amount of hydramethylnon ingested and evaluated the individual ants for mortality 14 days later. At concentrations ≥0.37 g liter−1, the amount of liquid the queens ingested decreased dramatically, indicating that Argentine ant queens may detect hydramethylnon. Significantly larger volumes of the two highest concentrations of the hydramethylnon suspension were ingested by the workers, compared to the lower concentrations, suggesting that hydramethylnon may act as a feeding stimulant for the workers. Worker mortality was higher than queen mortality at the highest concentrations tested. The highest worker mortality resulted when the ants ingested 1.03 µg of hydramethylnon per mg of ant tissue. At the highest concentration (1.0 g liter−1) tested, workers ingested almost 12 times as much active ingredient per mg of body weight as did queens, suggesting that, in order to increase mortality of queens, multiple feedings must occur. © 2001 Society of Chemical Industry

Three species of fleas, Oropsylla montana (Baker), Hoplopsyllus anomalus (Baker), and Echidnophaga gallinacea (Westwood), occur seasonally on the California ground squirrel, Spermophilus beecheyi (Richardson). Few studies have focused on the biology and ecology of these fleas despite their importance in the epidemiology of sylvatic plague. To best duplicate a natural parasite-host relationship in the laboratory, a novel nest box was developed that facilitated housing wild-caught S. beecheyi, was conducive to rearing fleas, and met modern standards for laboratory animal hygiene. This flexible system allowed adult fleas with different feeding strategies to be colonized successfully while providing sufficient flea eggs for both colony maintenance and biological research. The techniques described could be adapted to work with other species of rodents and their fleas.

Comprehensive laboratory baiting studies with the 4 insecticides abamectin, boric acid, fipronil, and hydramethylnon were conducted against Argentine ant, Linepithema humile (Mayr). Serial dilutions of each insecticide prepared in a 25% sucrose solution were provided for 24 h or 14 d to groups of workers and queens. Sucrose-water baits containing 1 x 10(-5)% fipronil and 0.1% hydramethylnon provided complete mortality of L. humile workers baited for 24 h. Baits containing 1 x 10(-4) and 1 x 10(-5)% fipronil provided 100% kill of queens. In the continuous baiting, 0.5% boric acid, 1 x 10(-6)% fipronil, and 0.025% hydramethylnon provided 100% mortality of workers. The queens and workers provided baits containing 1 x 10(-5)% fipronil and 0.5% boric acid all died within 14 d. Low concentrations of fipronil and boric acid in sucrose may be promising candidates for Argentine ant control.

Differences in feeding and trophallaxis among castes of the western drywood termite, Incisitermes minor (Hagen), were determined using rubidium (Rb) as a tracer. Both 5th- and 6th-instar nymphs and 3rd- and 4th-instar larvae fed directly on Rb-treated paper and acted as both donors and recipients in trophallactic exchanges with other larvae and nymphs, and as donors for soldiers and alates. Soldiers and alates did not feed on Rb-treated paper suggesting that they do not feed directly on wood and are completely dependent on nymphs for their nutritional needs. Larvae paired with Rb-fed nymphs received the greatest amount of Rb suggesting that there may be a hierarchy of trophallaxis in drywood termites. Transfer efficiency, the percentage of the total Rb intake of donors that is passed to the recipients, ranged from 1.1 % (nymphal donors to alate recipients) to 16.6 % (larval donors to nymphal recipients).

Insecticide resistance often is blamed for failures of insecticides to control cat fleas, Ctenocephalides felis (Bouche). Yet the genetics and adaptive advantage of resistance traits remain unexamined. Lethal doses of insecticides that kill 50% of the population fluctuate 7-fold within a cat flea strain. Many reports of flea resistance may be attributable to variable mortality from effects of solvents, substrates, humidities, temperatures, colonization, and ages of fleas. Resistance ratios (ratios of lethal doses of a resistant to a susceptible strain) are < 690-fold in fleas; lower than many other arthropods. This, plus strain variability, hinders resistance detection. Relationships between resistance levels, control failures, and health threats are unclear. Insensitive acetylcholinesterase, knockdown recovery, glutathione transferase conjugation, and mixed function oxidase/cytochrome P450 are demonstrated resistance mechanisms in cat fleas. Ecological genetics of resistance in cat fleas probably involves flea transfer among hosts, host movements, refugia, founder effects, and mortality from abiotic factors. Understanding cat flea resistance requires population monitoring before, during, and after insecticide treatments using conventional and rapid molecular bioassays. Sustained insecticide release devices such as flea collars and long-lived insecticide residues for premises possibly contribute to the development of resistance. New systemic and topical insecticides, especially when given prophylactically, may act similarly. Eliminating insecticides prevents insecticide resistance but necessitates application of biorational tactics incorporating mechanical, environmental, and cultural controls. Using high temperatures, low humidities, host grooming and such tactics as decreasing doses, increasing action thresholds, rotating insecticides, and leaving spatial and temporal refugia may suppress cat flea resistance.

The first reported case of a non-native termite species being introduced and established in California was the Formosan subterranean termite, which was discovered in San Diego County in 1992. Because this termite can exact tremendous damage within a relatively short time, the affected area was defined and an attempt was made to eradicate it. Intensive baiting with the insect growth regulator hexaflumeron over 12 months appears to have eliminated the original infestation. New infestations have recently been discovered in and around homes about 1/4 mile away, and winged Formosan subterranean termites have been caught nearly 3/4 mile away. Measurements of workers and soldiers and dating of damage suggest that the new colonies are 6 to 8 years old, and that new colonies established from winged reproductives before baiting took effect at the original site. If left unabated, this pest may become increasingly more serious in California.

Structural insect pests may be killed by exposure to freezing temperatures. The critical thermal minimum (CTmin) is the threshold low temperature at which an insect succumbs from momentary exposure to temperatures decreasing at 1°C/min. The CTmin was —21.3°C for the western drywood termite, lncisitermes minor (Hagen); —17.2°C for workers of lncisitermes snyderi (Light); and —13.9°C for workers of the Formosan subterranean termite, Coptotermes formosanus Shiraki. The CTmin for the southern lyctus beetle, Lyctus planicollis LeConte, was —35.6°C for eggs, —26.2°C for small larvae, —30.0°C for medium larvae, and —24.3°C for large larvae. The effectiveness of liquid nitrogen (N2) to chill wall voids below the CTmin values for these structural pests was tested in a mock-up wall. The time to the CTmin was affected by the rate at which liquid N2 was released into the void and the vertical location of the release point. Fiberglass insulation in the wall affected the pattern of cooling by deflecting the liquid N2 around the insulation. Plumbing and electrical fixtures in the wall were not damaged by liquid N2, even though they were exposed to temperatures as low as —50°C. However, liquid N2 cracked vinyl floor tiles adjacent to the wall. The oxygen level in confined spaces where liquid N2 was released rapidly dropped below 19.5%, the minimum acceptable level for worker safety. Consequently, fans probably should be used to circulate fresh air into the areas where liquid N2 is used, and electronic monitoring should be done to ensure safe oxygen level. Because insects survive if they are not exposed to at least their CTmin it is important to monitor accurately the internal temperature of target wood with thermocouples to ensure that the CTmin has been reached where the insect actually occurs. To achieve an effective low temperature throughout a structure, virtually every void would need to be treated. Otherwise, it is unlikely that isolated pockets of termites could survive by escaping exposure to the CTmin Proper placement of thermocouples could be extremely important.

We investigated foraging patterns of the southern fire ant, Solenopsis xyloni (McCook), using combinations of readily available foods that might be incorporated into a bait mixture. Choice tests conducted to determine the most attractive diet for S. xyloni included preference tests for each of 4 particle sizes. Freeze-dried diets were more attractive than oven-baked diets, and diets made with freeze-dried chicken eggs and anchovies were the most attractive. A particle size of diet of 11-20 mesh (840-2,000µn) resulted in the largest amount of diet removed by the colony. The smallest particle size, 40 mesh (420-590µm), had the most particles removed by workers but yielded the least amount of diet brought into the ant colony. S. xyloni is primarily a nocturnal forager, whose foraging begins ≈4 h before sunset and whose maximal foraging occurs between 2 and 7 h after sunset. There was considerable seasonal intracolony variation, but the maximal amount of diet was taken in June, August, and October.

▪ Abstract The cat flea, Ctenocephalides felis felis, is the most important ectoparasite of domestic cats and dogs worldwide. In addition to its annoyance to pets and humans, C. felis felis is responsible for flea bite allergy dermatitis and the transmission of dog tapeworm. The abiotic and biotic factors that affect the development of immature stages are reviewed with special emphasis given to those aspects directly affecting control. Factors influencing host selection and feeding by adults are summarized. Recent studies concerning mating and oviposition, especially as they impact the likelihood of survival by immatures, are discussed. There has been an increase in the number of reports of insecticide resistance in the past ten years. Greater attention has been placed on disrupting larval development in modern IPM programs. The immature stages of the cat flea are extremely susceptible to environmental factors such as temperature and relative humidity and insect growth regulators (IGRs). In recent years, the control of cat fleas has increasingly relied on the use of IGRs applied to the host or to the indoor environment. Finally, we discuss advances in pesticide chemistry that provide tools for better control of adult fleas on the host.

A bioassay was developed to determine the efficacy of insecticides against adult cat fleas, Ctenocephalides felis (Bouché), on turfgrass. Activity was assessed by exposing adult fleas to treated and untreated disks of turf for 24 h, 1 and 7 d after treatment. Filter paper, a representative nonwaxy, porous substrate was bioassayed in similar fashion 1 d after treatment to confirm insecticide activity. Results demonstrated the relative efficacy of insecticides applied to turf at different rates as well as differences among insecticides. Of 10 insecticides tested, chlorpyrifos wettable powder and emulsifiable concentrates consistently provided greatest kill of adult fleas. Although initially active, pyrethroid insecticides and diazinon generally showed significant declines in residual activity by day 7. Possible reasons for differences in activity are discussed.

Laboratory cats were infested with a known number of cat fleas, Ctenocephalides felis (Bouché), to determine the effects of photoperiod on flea egg production. Photoperiods of 8:16, 12:12, and 16:8 (L:D) h were chosen to represent winter, spring/fall, and summer, respectively. There were no significant differences in daily or total flea egg production among the 3 photoperiods. To determine the effects of photoperiod on development of immature stages and subsequent adult emergence from cocoons, eggs collected during each photoperiod experiment were reared under the 3 described light and dark conditions. Resulting differences suggest that photoperiod may influence the emergence behavior of adults from cocoons.

The hypothesis that western drywood termite, Incisitermes minor (Hagen), nymphs are negatively phototactic was tested. Significantly more nymphs were found under the covered half of a petri dish than under the uncovered half exposed to either incandescent or fluorescent light, whereas there was no significant preference for either the covered or uncovered side when exposed to red darkroom light. The behaviors of I. minor nymphs when placed on temperature gradients for 24 h at 10, 30, or 50% RH were videotaped, analyzed, and quantified to test the hypothesis that I. minor nymphs actively avoid and move away from hot and cold temperatures. I. minor nymphs avoided temperatures >45°C and

Insecticide was applied to the perimeter of homes and adjacent areas likely to be visited by Argentine ants, Iridomyrmex humilis (Mayr). Treatment configuration consisted of a 1.8- to 2.4-m-wide band of spray around the exterior of the structure. Margins of sidewalks and pathways and around stepping stones, bases of trees, potted plants, and garbage cans were sprayed with 1.2-to 1.8-m-wide bands. Based on monitoring with traps, significant and relevant control was achieved when the number of ants trapped post treatment declined at least 80%. Barrier sprays of 237 mg (AI)/m2 chlorpyrifos, 14.5 mg (AI)/m2 cyfluthrin and 67.2 mg (AI)/m2 cypermethrin provided >80% reductions in the number of ants trapped at 7 d. Chlorpyrifos provided >82% reductions for at least 30 d. The combination of cyfluthrin spray + granules provided >85% reductions in ant trap counts at day 7. Only the combination treatment provided >80% reductions at 60 d. Cypermethrin and permethrin sprays failed to provide >80% reductions for 30 d. Factors that likely contribute to decreased performance of barrier sprays against ants include heavy irrigation, dense ground cover, exposure to direct sunlight, alkaline nature of the stucco and concrete surfaces, and extremely high temperatures.

Colony size, foraging activity, foraging phenology, and selected physiological parameters were evaluated on colonies of the western subterranean termite, Reticulitermes hesperus Banks, in urban and undisturbed habitats. The greatest foraging activity occurred from May to October at the University of California, Riverside urban site, and from late November to January at the Motte–Rimrock natural study site. Foraging activity was related to minimum temperatures at the urban site, and minimum temperatures and precipitation at the undisturbed site. Foraging population was greater in the urban habitat, with estimates ranging from 85,752 to 830,581 foragers compared with 78,930 to 103,758 at the native site. Termites at the urban site had greater initial and dry body weights, but less body fat than their counterparts from undisturbed habitats. No difference in the cuticular permeabilities of termites occurred between locations.

Insect growth regulators (IGRs) such as lufenuron, methoprene, and pyriproxyfen have been important tools in the integrated pest management of cat fleas, Ctenocephalides felis (Bouche), for the past two decades. Other IGRs have been registered for the control of termite, dipteran, and lepidopterous pests including chlorfluazuron, cyromazine, dicyclanil, and precocene I, but have been not tested against C. felis. The intrinsic activity of IGRs was determined by exposing larvae to treated larval rearing media. The LC50s of chlorfluazuron, cyromazine, dicyclanil, lufenuron, and precocene I against cat fleas were 0.19, 2.66, 0.04, 0.20, and 10.97 ppm, respectively. The LC95s of chlorfluazuron, cyromazine, dicyclanil, lufenuron, and precocene I were 0.78, 51.24, 0.30, 0.62, and 175.05, respectively. The regression slopes of chlorfluazuron and lufenuron were 2.65 ± 0.24 and 3.40 ± 0.45 (SEM), respectively, and considerably steeper than the other IGRs tested (1.51 to 1.74). The intrinsic activity of IGRs tested is summarized as dicyclanil > chlorfluazuron = lufenuron > cyromazine > precocene I. The responses of the laboratory UCR strain to these IGRs can serve as a baseline of susceptibility until a more susceptible cat flea strain is found. Chlorfluazuron and dicyclanil look like promising candidates against cat fleas.

A population of the Formosan subterranean termite, Coptotermes formosanus Shiraki, was discovered in La Mesa, San Diego County, in February 1992. This is the first instance of a non-native termite species being introduced and established in California. Due to the extremely destructive nature of this termite, a study was initiated to attempt to eradicate or control it using an insect growth regulator (hexaflumuron). Preliminary results suggest the product suppresses the population, but evaluation of this control is continuing. In the meantime, removal of excess wood reduces the food sources available to the termites and may help limit the growth and expansion of the colony.

Urban and residential concrete surfaces are often treated with pesticides to control ants. Run-off from irrigation/rainfall can remove pesticides from concrete and contaminate urban waterways. Recent regulations and mitigations in regions such as California aim to reduce insecticide run-off (e.g. pyrethroids), but are often proposed without adequate consideration of their impact on ant control efficacy.We carried out an outdoor study with a side-by-side comparison between pesticide run-off potential and residual ant toxicity after exposing treated concrete to summer conditions and simulated precipitations.Treatments with bifenthrin, permethrin or fipronil all showed fast ant knockdown initially, and over 50% of ants were killed within 16 h after 1-min contact with the treated surfaces. Shorter ant median lethal time (LT50) was observed on concrete treated with over-the-counter (OTC) granule/dust formulations than OTC liquid or professional formulations. However, the treated surfaces rapidly lost ant control efficacy after outdoor exposure and repeated precipitations. Except for OTC solid permethrin treatment, the ant toxicity disappeared after 20 days for all other formulation treatments. In contrast, pesticides were detected in run-off water from simulated precipitations even 89 days after the treatment, with levels above 0.5 µg L(-1) for bifenthrin, 30 µg L(-1) for permethrin and 0.15 µg L(-1) for fipronil. Pyrethroid run-offs from OTC solid formulations were10 times higher than the other two formulations.The results suggested viable options for run-off mitigation include decreasing use on concrete such as using crack/spot treatments instead of broadcast applications, limiting pesticide use on hardscapes away from water contact, and avoiding using dust/granule formulations on hardscapes.

The brown widow spider, Latrodectus geometricus C. L. Koch, has become newly established in southern California during the first decade of the 21st century. Brown widows and egg sacs were collected within the urban Los Angeles Basin using timed searches. We also collected and compared the abundance and distribution of the native western black widow spider, Latrodectus hesperus Chamberlin & Ivie, to brown widows. Brown widows were very common around urban structures especially outside homes, in parks, under playground equipment, in plant nurseries and landscaping areas, greatly outnumbering native western black widows, and were very rare or nonexistent in garages, agricultural crops, and natural areas. Western black widows predominated in xeric habitats and were less prevalent around homes. Neither species was found in the living space of homes. In southern California, envenomation risk exists because brown widows are now common in urban areas and the spiders hide where people place their fingers and exert pressure to move objects (e.g., under the curled lip of potted plants, in the recessed handle of plastic trash bins). Nonetheless, brown widow spider bites are less toxic than those of native western black widow spiders and, hence, if they are displacing black widows, overall widow envenomation risk may actually be lower than before brown widow establishment.

The western subterranean termite, Reticulitermes hesperus Banks, exposed to temperature gradients of 26–47°C, preferred temperatures between 29–32°C. Termites were never found at temperatures >40°C. When exposed to temperature gradients of 5·8–43·6°C, workers preferred temperatures between 14 and 19°C. Soil temperatures varied with depth, exposure to sunlight, and season of the year. Surface soil temperatures in the sunlight exceeded 40°C only during post meridian readings from April through to October. Soil temperatures to a depth of 120 cm exceeded 14°C from April through to October, indicating adequate temperatures for foraging activity. Surface soil temperatures were below optimal foraging temperatures from November through to March, especially during the night and early morning. No thermal shadows existed at the 0800 h reading. Within 4 h, the soil underneath the centre of the stone was significantly cooler than was the soil at the edge or exposed to sunlight. By late afternoon even the soil under the centre of the stone had increased to above 40°C. Thermal shadows provide refuge for surface foraging termites to avoid high temperatures.

Adult cat fleas, Ctenocephalides felis (Bouché), marked with orange-red or green fluorescent dye were released on one cat to study movement to another cat over a 7-d period. When the cats were separated, 3-8% of the marked fleas moved to the other cat. When the cats were allowed to remain together, 2-15% of the fleas moved. The percentage of fleas unaccounted for ranged from 8-47%. When both cats lived together, 8-15% movement occurred no matter which cat was infested. The percentage of female and male fleas unaccounted for was 8-32 and 30-47%, respectively, highlighting the importance of host grooming. Significantly fewer female cat fleas moved from one host to another than did males. The likelihood of establishing new infestations by adult fleas transferring from one host to another exists. However, visitations to environments capable of supporting immature stages of fleas seem a more important source of flea infestations.

Intensive residential use of insecticides has resulted in their ubiquitous presence as contaminants in urban surface streams. For pest eradication, urban hard surfaces such as concrete are often directly treated with pesticides, and wind/water can also carry pesticides onto hard surfaces from surrounding areas. This study expanded on previous bench-scale studies by considering pesticide runoff caused by irrigation under dry weather conditions and rain during the wet season, and evaluated the effects of pesticide residence time on concrete, single versus recurring precipitations, precipitation intensity, and concrete surface conditions, on pesticide transferability to runoff water. Runoff from concrete 1 d after pesticide treatment contained high levels of bifenthrin (82 μg/L) and permethrin (5143 μg/L for cis and 5518 μg/L for trans ), indicating the importance of preventing water contact on concrete after pesticide treatments. Although the runoff transferability quickly decreased as the pesticide residence time on concrete increased, detectable residues were still found in runoff water after 3 months (89 d) exposure to hot and dry summer conditions. ANOVA analysis showed that precipitation intensities and concrete surface conditions (i.e., acid wash, silicone seal, stamping, and addition of microsilica) did not significantly affect the pesticide transferability to runoff. For concrete slabs subjected to natural rainfalls during the winter wet season, pesticide levels in the runoff decreased as the time interval between pesticide application and the rain event increased. However, bifenthrin and permethrin were still detected at 0.15–0.17 and 0.75–1.15 μg/L in the rain runoff after 7 months (221 d) from the initial treatment. In addition, pesticide concentrations showed no decrease between the two rainfall events, suggesting that concrete surfaces contaminated by pesticides may act as a reservoir for pesticide residues, leading to sustained urban runoff contamination.

Although on-animal topical treatment with compounds such as imidacloprid has revolutionized the control of the cat flea, Ctenocephalides felis (Bouche) (Siphonaptera: Pulicidae), the development of insecticide resistance is a continuing threat. As part of a highly co-ordinated and unprecedented resistance monitoring programme for C. felis, 1437 flea isolates were collected by veterinary clinics in Australia, Germany, France, the U.K. and 29 states in the U.S.A. from 2002 to 2009. About 65% of the collections were made from June to October each year and 71% of the collections were from cats. Collections of flea eggs were sent to one of five different laboratories, where they were tested with a diagnostic dose of imidacloprid (3 p.p.m.) applied to larval flea-rearing medium. Of the 1437 collections received, 1064 contained adequate numbers of eggs for testing. Of these isolates, untreated eggs failed to hatch in 22.7% and were not considered valid bioassays. Survival rates > 5% and development of adult fleas (a threshold for further testing) occurred in only 22 isolates. They were re-tested with the same diagnostic dose and none produced > 5% adult emergence. Complete dose-response bioassays were performed on three of the isolates that had triggered a second test and produced slopes, intercepts and LC(50) values similar to those for existing susceptible laboratory strains. Results confirmed sustained susceptibility of C. felis to imidacloprid, despite its widespread use for over a decade.

Sands treated with solvent systems used to formulate commercially available termiticides, except for isofenphos, were toxic to western subterranean termites, Recticulitermes hesperus Banks, killing 24-86% after a 24-h exposure to sand air dried for 1 d. After air-drying deposits for 7 d, no solvent systems were still toxic. Irrigating solvent-treated sands with the equivalent of 1.27 cm of rainfall removed all toxicity, except for permethrin and cypermethrin solvent systems. After a second irrigation, all sands treated with the solvent systems were not toxic. Sands treated with solvent systems of all termiticides tested were repellent, except for that of isofenphos, and remained repellent after being air dried for 7 d. The loss of toxicity, but not repellency, after air drying suggests different chemical bases for the two effects or a concentration dependent effect. None of the termiticides tested were repellent after two rinses with water (equivalent of 2.54 cm rainfall). The effects of solvents must be considered when evaluating the repellency and toxicity of soils treated with commercially available termiticides.

BACKGROUND: Insecticides are commonly used for ant control around residential homes, but post-treatment runoff may contribute to contamination of surface water in urban watersheds. This study represents the first instance where runoff of insecticides was directly measured after applications around single family residences. During 2007, houses were treated with bifenthrinorfipronilsprays following standardpractices. During 2008,pin streamapplicators, spray-freezones andrestricting sprays to the house foundation were considered as management options. RESULTS: During 2007, the resulting runoff from the bifenthrin spray in the irrigation water had a mean concentration of 14.9 µ gL −1 at 1 week post-treatment and 2.5 µ gL −1 at 8 weeks, both high enough to be toxic to sensitive aquatic organisms. In comparison, treatments with bifenthrin granules resulted in no detectable concentrations in the runoff water after 8 weeks. The mean concentration for fipronil used as a perimeter spray was 4.2 µ gL −1 at 1 week post-treatment and 0.01 µ gL −1 at 8 weeks, with the first value also suggesting a potential for causing acute aquatic toxicity to sensitive organisms. During 2008, insecticide runoff was reduced by using spray-free zones and pin stream perimeter applications. CONCLUSIONS: It is shown that insecticide runoff from individual home treatments for ants can be measured and used to improve techniques that minimize runoff. The pin stream application and applications limited to the house foundation should be further evaluated for their potential to reduce pesticide runoff from residential homes. c � 2010 Society of Chemical Industry

In a previous experimental study, recluse spiders Loxosceles reclusa Gertsch and Mulaik and Loxosceles laeta (Nicolet) (Araneae: Sicariidae) preferred small cardboard refugia covered with conspecific silk compared with never-occupied refugia. Herein, we investigated some factors that might be responsible for this preference using similar cardboard refugia. When the two Loxosceles species were given choices between refugia previously occupied by their own and by the congeneric species, neither showed a species-specific preference; however, each chose refugia coated with conspecific silk rather than those previously inhabited by a distantly related cribellate spider, Metaltella simoni (Keyserling). When L. laeta spiders were offered refugia that were freshly removed from silk donors compared with heated, aged refugia from the same silk donor, older refugia were preferred. Solvent extracts of L. laeta silk were chosen approximately as often as control refugia when a range of solvents (methylene chloride:methanol, water, and hexane) were used. However, when acetone was used on similar silk, there was a statistical preference for the control, indicating that there might be a mildly repellent aspect to acetone-washed silk. Considering the inability to show attraction to chemical aspects of fresh silk, it seems that physical attributes may be more important for selection and that there might be repellency to silk of a recently vacated spider. These findings are discussed in regard to pest management strategies to control recluse spiders.

Publisher Summary This chapter expands on the use patterns of insecticides in and around structures to control the major urban insect pests. Environmental and health concerns have become an important consideration in urban pest management, especially as it relates to water quality issues. The detection of pesticides, particularly pyrethroids, in urban waterways has raised concerns about their use, especially for ant control. There has been an increased awareness of the potential hazards of pesticides in urban environments and demand for more integrated pest management (IPM) and so-called green pest control. Even though green pest control lacks a clear definition and is largely a marketing tool, it has generated considerable attention. It has revitalized urban IPM, especially strategies that utilize a smaller amount of insecticides, and has stimulated the development of several different training programs for pest management professionals (PMPs). There is an increasing database and public awareness of the medical importance and role of cockroaches and other arthropods in inducing asthma and related health issues. This development will likely result in major regulatory changes and use patterns of insecticides around urban structures and present challenges to the PMP and homeowner. The use of botanicals, fragrance oils, and inorganic compounds has increased dramatically. Other new chemistries such as the neonicotinoids, phenylpyrazoles, and pyrroles have largely replaced the organophosphate and some traditional uses of pyrethroid insecticides.

Topical toxicity of cypermethrin (LD50 = 1.6 μg/g) was approximately three times greater to Reticulitermes hesperus Banks than chlorpyrifos (LD50 = 4.5 μg/g) and ≈35 times greater than chlordane (LD50 = 56.8 μg/g) after 7 d. Water rinsed from soil treated with chlorpyrifos produced significantly greater kill than did soil treated with an aqueous rinse hom soil h’eated with cypermethrin. The rinse water from soil treated with chlordane did not produce significant kill when redeposited on untreated soil. Termiticidal amounts of chlorpyrifos, chlordane, or cypermethrin moved to soil depths of at least 30,7, and 7 cm, respectively. With cypenrmethrin, sublethal effects were detected to a depth of 42 cm.

Photoperiod affected the production of cat flea eggs by cats infested with cat flea, Ctenocephalides felis (Bouché). Cat flea eggs have a smooth chorion and do not adhere to the host. About 60% of fluorescing eggs placed in the pelage were recovered in collecting trays underneath the host in 2 h. An average of 87.7 eggs per cat was laid during the last 8 h of the scotophase compared with 49.9 and 59.1 eggs during the other 8-h periods. Significant variation in the number of eggs collected daily existed among the six cats. The activity budgets were similar for all the cats with the maximum sleep period during the photophase. The possible adaptive advantages of synchronizing egg production with photoperiod are discussed.

The oral toxicity of boron compounds to the Argentine ant, Linepithema humile (Mayr), was evaluated in laboratory tests. The ants were provided 25% sucrose water containing 0.5 and 1% boric acid, disodium octaborate tetrahydrate, and borax. Lethal times of these solutions were a function of the concentration of boron. In field tests, the ants showed no discrimination between disodium octaborate tetrahydrate and boric acid. There was a significant reduction in consumption of sucrose water with >1% boric acid.

Experiments tested the ability of newly emerged spiderlings of a black widow spider, Latrodectus hesperus Chamberlin & Ivie (Araneae: Theridiidae), to crawl through brass screen of various mesh size. The purpose was to determine whether immatures of these medically important spiders could be excluded from buildings. In horizontal orientation, black widow spiderlings were able to easily pass through mesh with openings of 0.83 mm and were prevented from passing in four of five tests with mesh of 0.59-mm openings. Spiderlings also readily pass through 0.83-mm mesh in vertical orientation. Our laboratory studies indicate that the mesh size sufficient for exclusion is too small for practical use in most cases, although there are some specialized situations where such small mesh might be useful. The results are discussed in regard to actual conditions found in typical commercial building situations.

Publisher Summary This chapter discusses cat fleas, which are small (2 mm), dark, reddish brown, wingless, bloodsucking insects. The cat flea is a cosmopolitan, eclectic species, having been recorded from more than three dozen species, including opossums, raccoons, kangaroos, and even birds. This wide host range explains this flea’ s ability to repopulate domestic animals after suppression efforts. Because it lacks host specificity and tends to feed on humans, the cat flea is a pest of both companion animals and humans with whom they share their abode. Once adult cat fleas locate a host, they tend to remain on that animal unless dislodged. They feed readily and mate on the host. Female fleas lay eggs while on the host and because the eggs are not sticky, they readily fall off into the host's environment, with large numbers accumulating in areas frequented by the animal. From the eggs emerge small, white, eyeless, legless larvae with chewing mouthparts. Flea larvae have three instars that, under favorable conditions, can be completed in as little as 10 days. The third instar voids its gut approximately 24 hours before initiation of cocoon construction. Within its cocoon, the prepupa molds to the pupa and continues metamorphosis to the adult flea within about 4 days, under favorable conditions. Because fleas must have blood from a mammalian host to survive, treating host animals is the most efficient and effective means of suppressing fleas.

Publisher Summary This chapter discusses how urban habitats are conducive to insect pest problems such as mosquitoes, flies, cockroaches, fleas, termites, and wooddestroying pests. In addition, crowding and waste also lead to vertebrate pest problems such as rats, mice, and pigeons. For example the Formosan subterranean termite, Coptotermes formosanus, has spread by marine commerce to semitropical and tropical seaports throughout the world. Once ashore, railroad ties provide a rapid method of moving and establishing large colonies of termites. The vast majority of insects, however, are not capable of adapting to the artificial and unnatural conditions created by humans in urban environments. A few pests such as the German cockroach, cat flea, and house fly have readily adapted, have been able to survive in close proximity to humans, and now are cosmopolitan. Humans can directly attribute the need for urban pest management in and around structures to the dislike of insects and arthropods. Some pests such as cockroaches, fleas, flies, and mosquitoes represent potential health risks. Others such as termites and wooddestroying pests can cause serious economic damage to structures. Pantry and fabric pests cause damage to foods, fabrics, and items made with furs, skins, and feathers.

We developed a laboratory method to determine the potential efficacy of baits formulated for control of the Argentine ant, Iridomyrmex humilis (Mayr). Possible effects as insect growth regulators were not examined. Of the 10 formulated baits tested, only mirex applied to granulated silkworm pupae had delayed toxicity. Hydramethylnon applied to granulated silkworm pupae also provided excellent kill of workers but did not exhibit delayed toxicity. In field tests, this bait provided faster control than did a chemical barrier of granular diazinon.

Dichlorvos and chlorpyrifos vapor from dried residual deposits produced significant numbers of moribund workers of the western subterranean termite, Reticulitermes herperus Banks. In some cases, lethal effects were not observed until 7 h after exposure. Tenhour exposure to vapor from deposits of chlordane, chlorpyrifos, cypermethrin, or dichlorvos aged for 12 h produced significantly greater numbers of moribund workers than did the control treatment. Vapor from deposits of chlordane, chlorpyrifos, or cypermethrin aged for 12h produced more moribund insects than did 1-h-old deposits, suggesting that older deposits release more toxicant than fresh deposits. Residual deposits of chlorpyrifos or dichlorvos redeposited from their vapor phase on foil surfaces produced 83–100% moribund termites within 24 h. Redeposition of toxicant or sorption of vapor might be responsible for lethal effects. Regardless of the insecticide used, toxic amounts did not move to dry untreated soil beneath treated soil. Toxic vapor from soil treated with dichlorvos moved down simulated termite tunnels. This phenomenon was not observed for other insecticide treatments.