Sampling subterranean termite species diversity and activity in tropical savannas: an assessment of different bait choices

Abstract.  1. Cellulose baits are commonly used for semi-quantitative sampling of subterranean wood-feeding termites, with a single food choice sampling programme implemented most often. In most situations, however, the composition and feeding preferences of the subterranean termite assemblage remain unknown.
2. The diversity, frequency, foraging activity, and intensity of attack of termites were assessed regularly at 144 baits representing 12 different bait choices over 8.5 months, in two northern Australian tropical savanna sites that differed in vegetation structure (closed vs open). Baits differed in type (paper rolls, cardboard, wooden stakes), position (surface, buried), and moisture status at installation (wet, dry).
3. Sixteen species were recorded, including 11 wood-feeders. Average species diversity, foraging activity, and bait consumption were greater at buried baits than at surface baits. Wooden baits were most attractive early in the experiment, and paper baits more attractive later. Mean species diversity was greatest at wooden stakes in the closed site. Species frequency of occurrence varied across bait choices.
4. A composite bait sampling protocol of stakes and paper rolls installed above and below ground gave an accurate assessment of the activity, diversity, and structure of the termite guild sampled across all baits over 8.5 months.
5. The choice of bait, its presentation, and time of examination are critical to the success of a termite baiting programme. If the aim is to characterise the structure and foraging activity of the subterranean termite assemblages that are attracted to baits, composite baiting protocols should be implemented.     

白蚁纤维素粉饵料成型技术研究

为研究白蚁饵料成型工艺,比较了9种胶黏剂对白蚁纤维素饵料成型效果、耐水性能以及对白蚁取食的影响。结果表明:20%、40%剂量糊精;50%、100%剂量三聚氰胺甲醛树脂,10%、20%、40%田菁胶、卡拉胶、壳聚糖、明胶;10%、50%、100%聚乙烯醇、硅酸钠对微晶纤维素的成型效果较好,经上述剂量胶黏剂处理后,纤维素饵块的邵氏硬度(HD)极显著高于对照。耐水性能试验至第30天时,50%聚乙烯醇、100%聚乙烯醇、100%三聚氰胺甲醛树脂处理的纤维素饵块的溃散程度指数分别为1.33、1.00、2.00,其余饵块的溃散程度指数均达3级。生测结果显示,在7 d的室内强迫取食试验中,白蚁对50%聚乙烯醇、100%聚乙烯醇、100%三聚氰胺甲醛树脂处理的块状纤维素饵料的取食率均极显著低于对照,说明饵块中添加的上述胶黏剂对白蚁的取食具有一定的影响。综上,50%聚乙烯醇、100%聚乙烯醇、100%三聚氰胺甲醛树脂适用于白蚁纤维素饵料成型,但若想获得白蚁喜食的饵块仍需对配方做进一步的优化。     

Do colours that deter birds affect cereal bait acceptance by possums (

Poisonous baits used for pest control in New Zealand commonly contain green dye and cinnamon oil to make them less attractive to birds. Research aimed at reducing the impact of poison based pest control on birds has shown that some birds are initially deterred from feeding on blue or, to a lesser extent, green coloured food and are attracted to yellow or red food. We determined whether colours that deter or attract birds affected the acceptance of non-toxic and toxic cereal baits by captive brushtail possums (Trichosurus vulpecula). Individual possums were offered, daily, a choice between a standard green dyed non-toxic cereal bait and either a blue dyed(17 possums) or yellow dyed non-toxic bait (16 possums) for 10 days. Following this, for the first group of 17 possums, 1080 toxin was added to either the green bait (9 possums) or blue bait (8 possums) and possums were offered the green versus blue choice again. Two additional groups that had not previously been fed cereal baits were also given a choice between blue and green baits, one of which was toxic. All possums offered non-toxic bait ate less on the first day of presentation than on subsequent days. There was no difference in acceptance of either blue or yellow coloured non-toxic bait compared to the standard green non- toxic bait on any days. Bait colour appeared to be unimportant in cereal bait choice and did not deter possums from eating any of the baits. The addition of toxin to baits did not significantly alter bait choice in any groups, although some individuals which had no previous experience with baits ate more toxic than non-toxic bait. These data suggest that adding a stronger bird deterring colour (i.e., blue) to poisonous baits is unlikely to adversely affect the acceptance of baits by possums.     

Use of a bait impact index to assess effects of bait application against populations of Formosan subterranean termite (Isoptera: Rhinotermitidae) in a large area

The effects of bait applications on the overall activity of the Formosan subterranean termite, Coptotermes formosanus Shiraki, in a town of 1.2 km2 were assessed between 2001 and 2003 by using a bait impact index. The index incorporated the amount of baits applied and the distance between bait application loci and the monitoring stations from which termite activity was measured. Even with the collaboration of only 35% of the residents and incomplete treatment records, the bait impact index demonstrated that more baits applied in proximity to monitoring loci significantly caused the decline of C. formosanus activity.     

Colored bait preferences of house Fly (Musca domestica L.) (Dipetera: Muscidae)

The housefly, Musca domestica L. (Dipetera: Muscidae) transmits disease, contaminates laboratories, hospitals, equipment and can be annoying to people and animals. They are considered a serious urban pest worldwide. An important tool used to control houseflies is baiting. This study was undertaken to review the preference of housefly for different colored baits. Various colored baits were prepared and evaluated under laboratory conditions. These were colored blue, white, yellow, red, purple and green. Among the different colored baits used, the blue bait was preferred the most by the houseflies, followed by the white and yellow baits, and the red, purple and green baits were least attractive to the houseflies. Similarly, the blue bait was detected faster by the houseflies and was consumed significantly more than the red, purple or green baits. Also, the blue bait attracted a significantly higher number of flies than the red, purple and green baits.     

Oral rabies vaccine (ORV) bait uptake by captive striped skunks

Aerial delivery of oral rabies vaccine (ORV) baits has proven effective in large-scale efforts to immunize wildlife against rabies, and in North America this strategy currently is being used to immunize foxes (Urocyon cinereoargenteus and Vulpes vulpes), raccoons (Procyon lotor), and coyotes (Canis latrans). Skunks are also a major reservoir and vector of rabies, but at present oral vaccines for use in skunks are not licensed. Furthermore, given differences in morphology (smaller jaws) and behavior (food handling and consumption), it is unknown if baits currently used in ORV campaigns would be effective for skunks. Because oral vaccine delivery is contingent upon puncture of the vaccine container (VC), baits need to be sufficiently attractive to elicit selection and consumption. Manipulation of the bait to facilitate vaccine ingestion by the target species is a critical element for an effective ORV bait. The objectives of this study were to assess manipulation and consumption of current ORV baits by striped skunks (Mephitis mephitis). We conducted four independent trials with penned animals and various baits to assess bait selection frequency, VC puncture frequency, and consumption. Video recorded trials were used to assess attractiveness of baits and consumption behavior of skunks. Bait characteristics, such as texture, size, and flavor influenced selection and consumption. Fish and chicken flavors were preferred and vaccine containers within selected baits were likely to be punctured. Vaccine ingestion seemed more likely if VCs were directly coated with the bait matrix. To make baits attractive to skunks and to ensure puncture of the VC, modifications to current baits should consider a smaller size, a meat-flavored matrix, a slightly pressurized VC, and a direct coating of matrix on the VC.     

Elimination of subterranean termite (Isoptera: Rhinotermitidae) colonies using a refined cellulose bait matrix containing noviflumuron when monitored and replenished quarterly

Using a quarterly (3-mo) monitoring and bait-replenishment interval, 122 subterranean termite colonies throughout the United States were baited with a refined cellulose bait matrix containing 0.5% noviflumuron. All colonies were eliminated in less than 1 yr after initiation of baiting as determined by long-term monitoring and genetic markers. Sixty-three percent of the colonies were eliminated during the first quarter after the initiation of baiting and 77% of colonies were eliminated after consuming two bait tubes or less. This suggests that a single baiting cycle and bait installed in response to a single active monitoring device were sufficient to eliminate the majority of colonies. Although termites temporarily abandoned stations after depleting bait, workers resumed feeding when baits were replenished. Colonies that consumed large amounts of bait before elimination foraged into multiple stations, thus allowing adequate amounts of bait to sustain feeding. The time to eliminate termite colonies with bait replenished quarterly was similar to that previously reported for laminated cellulose bait replenished monthly. Our data support the conclusion that extending the bait replenishment interval from monthly to quarterly for bait tubes with refined cellulose containing 0.5% noviflumuron did not adversely impact colony elimination.     

Development of a toxic bait for control of eastern lubber grasshopper (Orthoptera: Acrididae)

This study assessed baits for eastern lubber grasshopper, Romalea guttata (Houttuyn). When offered a choice among several grain-based baits (rolled oats, wheat bran, oat bran, yeast, corn meal, cornflakes) and vegetable oils (canola, corn, peanut, soybean), eastern lubber grasshopper adults preferred bait consisting of wheat bran carrier with corn oil as an added phagostimulant. Other carriers were accepted but consumed less frequently. Discrimination by eastern lubber grasshoppers among oils was poor. Similarly, addition of flavorings (peppermint, anise, lemon, banana) resulted in few significant effects. The carbaryl, wheat bran, and oil bait developed in this study was effective at causing eastern lubber grasshopper mortality in field-cage studies. Significant mortality occurred even though grasshoppers had to locate dishes of bait in a large cage, and could feed on daylilies, or grass growing through the bottom of the cage, rather than on the bran flakes. Consumption of as little as a single carbaryl-treated bran flake could induce mortality, although individuals varied greatly in their susceptibility. The bait matrix developed in this study was readily consumed when in the presence of some plant species. We expect that wheat bran and corn oil bait would be most effective as protection for less preferred plants (tomato, pepper, eggplant, leek, parsley, fennel, daylily, lily of the Nile, and canna lily) because baits were readily consumed in the presence of these plants. Plants that are readily consumed in the presence of bait (preferred plants) included butter crunch lettuce, carrot, yellow squash, cauliflower, collards, green onion, chive, cucumber, cabbage, cantalope, endive, red leaf lettuce, society garlic, caladium, and amaryllis. Baits are likely to be less effective in the presence of such plants. On average, vegetables in Solanaceae (i.e., tomato, pepper, and eggplant) and Apiaceae (i.e., fennel and parsley) elicited high levels of bait-feeding activity, indicating that these vegetables were not highly preferred. The plants tested from Liliaceae, Cucurbitaceae, Asteraceae, and Brassicaceae elicited an intermediate-to-low level of bait feeding.     

A new flavor-coated sachet bait for delivering oral rabies vaccine to raccoons and coyotes

Research was conducted during 1996-2000 to develop baits for delivering an oral rabies vaccine to raccoons (Procyon lotor) and coyotes (Canis latrans). A bait was sought that: (1) was attractive to the target species, (2) could be distributed by aircraft, (3) was as effective (or more so) than the currently used fish meal polymer bait, and (4) could be produced in large numbers by automated procedures and could be purchased by user groups at substantially lower cost. Ten field trials were conducted to document raccoons' bait flavor preferences, evaluate a new vaccine sachet bait coated with various attractants, and determine if the sachet bait would effectively deliver Raboral V-RG oral rabies vaccine (Merial Limited, Athens, Georgia, USA) to this species. Raccoons preferred fish and crustacean-based flavors over those derived from plant materials. Raccoon visits to tracking stations, frequency of bait removals, and percent of sachets discarded by this species that were emptied of placebo vaccine indicated efficacy of the new bait was equal or superior to the currently used fish meal polymer bait. A field trial conducted in fall 1998 compared aerially distributed vaccine-laden sachet and polymer baits and showed there was no difference between the percent of raccoons from the test and reference areas subsequently found positive for rabies antibody. Four bait trials to determine coyote response to sachet baits were conducted in 1997-98. The propensity for canids to gulp or bolt smaller food items is well known. Thus, a first trial involved offering fish-flavored sachet baits of different sizes to 30 captive coyotes to determine if smaller size baits were more frequently swallowed intact. Two field trials were also conducted in fall 1997 to determine if free-ranging coyotes discriminated among sachet baits coated with different attractants. Finally, Raboral V-RG-laden poultry-flavored sachet baits were aerially dropped and the percent of seropositive coyotes was compared with coyotes from surrounding areas where fish meal polymer vaccine baits had been distributed. Captive coyotes did not swallow sachet baits intact, regardless of size. Bait preference field trials indicated that coyotes preferred poultry, cheese/beef tallow, and fish-flavored sachet baits and that such baits were taken at the same rate as polymer baits. A sample of coyotes from the area baited with vaccine-laden sachet baits had a markedly higher (P = 0.01) seropositivity rate than coyotes from areas where vaccine was distributed in polymer baits. Sachet bait production could be facilitated by automated technology and sachet baits used either as an alternative vaccine delivery device or in combination with the fish meal polymer bait.     

The use of alarm pheromones to enhance bait harvest by grass-cutting ants

The enhancement of bait for the control of grass-cutting ants was investigated using two species of grass-cutting ant, Atta bisphaerica (Forel) and Atta capiguara (Gon?alves) (Hymenoptera: Formicidae). Bait was applied in loose piles to obtain a direct relationship between ant attraction and bait harvest. Enhancement with alarm pheromone compounds significantly increased the attractiveness and harvest of bait under certain conditions. A large proportion of the ants attracted to the enhanced bait were minor workers. These ants rarely transport bait because of their small size, and so it may be possible to increase the effect of bait enhancement by using smaller bait granules. Foragers of A. capiguara were less inclined to transport citrus-pulp bait than were those of Atta laevigata (Fr. Smith), a species that also harvests dicotyledonous plants. This emphasizes the importance of developing a bait matrix that is more acceptable to grass-cutting species. Nevertheless, the results suggest that alarm pheromone compounds have significant potential to improve the efficacy of baits for the control of grass-cutting ants.     

Elimination of field colonies of a mound-building termite Globitermes sulphureus (Isoptera: Termitidae) by bistrifluron bait

The efficacy of Xterm, which contains 1% bistrifluron, in the form of cellulose bait pellets was evaluated for its efficacy in eradicating field colonies of the mound-building termite Globitermes sulphureus (Haviland) (Isoptera: Termitidae). The termite mounds were dissected at the end of the experiment to determine whether the colonies were eliminated. By approximately 2 mo postbaiting, the body of termite workers appeared marble white, and mites were present on the body. The soldier-worker ratio increased drastically in the colonies, and the wall surface of the mounds started to erode. Colony elimination required at least a 4-mo baiting period. Mound dissection revealed wet carton materials (food store) that were greatly consumed and overgrown by fast-growing fungi. Decaying cadavers were scattered all over the nests. On average, 84.1 +/- 16.4 g of bait matrix (68.9 +/- 13.4%, an equivalent of 841 +/- 164 mg of bistrifluron) was consumed in each colony. Moreover, we found that a mere 143 mg of bistrifluron was sufficient to eliminate a colony of C. sulphureus.     

Influence of toxic bait type and starvation on worker and queen mortality in laboratory colonies of Argentine ant (Hymenoptera: Formicidae)

The efficacy of toxic baits should be judged by their ability to kill entire ant colonies, including the colony queen or queens. We studied the efficacy of four toxic baits to the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae). These baits were Xstinguish that has the toxicant fipronil, Exterm-an-Ant that contains both boric acid and sodium borate, and Advion ant gel and Advion ant bait arena that both have indoxacarb. Experimental nests contained 300 workers and 10 queen ants that were starved for either 24 or 48 h before toxic bait exposure. The efficacy of the toxic baits was strongly influenced by starvation. In no treatment with 24-h starvation did we observe 100% worker death. After 24-h starvation three of the baits did not result in any queen deaths, with only Exterm-an-Ant producing an average of 25% mortality. In contrast, 100% queen and worker mortality was observed in colonies starved for 48 h and given Xstinguish or Exterm-an-Ant. The baits Advion ant gel and Advion ant bait arena were not effective against Argentine ants in these trials, resulting in <60% mortality in all treatments. Because of the strong influence of starvation on bait uptake, control efficacy may be maximized by applying bait when ants are likely to be starved. Our results suggest queen mortality must be assessed in tests for toxic bait efficacy. Our data indicate that of these four baits, Xstinguish and Exterm-an-Ant are the best options for control of Argentine ants in New Zealand.     

Resurgence and persistence of Dorymyrmex flavus after reduction of Solenopsis invicta buren with a broadcast bait

The effects of bait treatment(s) on population dynamics of Solenopsis invicta and Dorymyrmex flavus were studied, and various factors underlying the resurgence and persistence of D. flavus to reinvasion by S. invicta were studied in more detail. Pitfall traps, bait vials, transect sampling, and direct inspections were used to monitor densities of these two species, and inspections of D. flavus midden contents, video monitoring of D. flavus colonies, and studies of the fate of marked S. invicta were used to further clarify interactions of these two species, D. flavus abundance increased after the reduction of S. invicta with baits. D. flavus was also observed to sustain higher densities for an extended period (2 yr) after cessation of bait treatment and to exhibit antagonistic behaviors toward S. invicta, showing an ability to resist reinvasion of the treated area by S. invicta. Given these findings, D. flavus may retard domination of the ant assemblage by S. invicta. Additional studies are justified regarding how to enhance the role of this species in affected ecosystems.     

Field evaluation of the bait toxicant chlorfluazuron in eliminating Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae)

Two aspects of the Exterra Termite Interception and Baiting System (Ensystex, Fayetteville, NC) were evaluated in a field experiment using 13 termite mounds near Townsville, Australia. First, a cellulose-acetate powder containing either 0.05% wt:wt or 0.25% wt:wt chlorfluazuron (Requiem, Ensystex, Fayetteville, NC) was tested for its efficacy in eliminating colonies of the xylophagous mound-building subterranean termite Coptotermes acinaciformis (Froggatt). The moist bait matrix was replenished during the first inspection of 10 mounds (five mounds by two treatments) used in the experiment. Second, a single application of the moist bait matrix was used on three additional mounds to test termite responses and the effectiveness of 0.25% wt:wt chlorfluazuron. Although there was no evidence of repellence, there was little removal of replenished bait. Five colonies were eliminated by 0.05% wt:wt chlorfluazuron and five colonies by 0.25% wt:wt chlorfluazuron: another colony was moribund, and elimination appeared imminent. Colony decline was first suspected some 12 wk after bait application, and colony elimination was confirmed, by destructive sampling, about 5 wk later. Colony elimination may have occurred within 12 wk. One colony was an anomaly and did not succumb to the effects of the toxicant. Another colony was not eliminated because of invasion of the baiting system by ants. Ants, principally Iridomyrmex purpureus (F. Smith) group and Papyrius nitidus (Mayr) group, occurred commonly in the stations during the experiment. Microcerotermes sp. was found in five of the C. acinaciformis mounds, after colony elimination. Inspections of small sections of mounds and wooden dowels inserted into mounds were reliable methods for monitoring colony health.     

Improving liquid bait programs for Argentine ant control: bait station density

Argentine ants, Linepithema humile (Mayr), have a positive effect on populations of mealybugs (Pseudococcus spp.) in California vineyards. Previous studies have shown reductions in both ant activity and mealybug numbers after liquid ant baits were deployed in vineyards at densities of 85-620 bait stations/ha. However, bait station densities may need to be <85 bait stations/ha before bait-based strategies for ant control are economically comparable to spray-based insecticide treatments-a condition that, if met, will encourage the commercial adoption of liquid baits for ant control. This research assessed the effectiveness of baits deployed at lower densities. Two field experiments were conducted in commercial vineyards. In experiment 1, baits were deployed at 54-225 bait stations/ha in 2005 and 2006. In experiment 2, baits were deployed at 34-205 bait stations/ha in 2006 only. In both experiments, ant activity and the density of mealybugs in grape fruit clusters at harvest time declined with increasing bait station density. In 2005 only, European fruit lecanium scale [Parthenolecanium corni (Bouché)] were also present in fruit clusters, and scale densities were negatively related to bait station density. The results indicate that the amount of ant and mealybug control achieved by an incremental increase in the number of bait stations per hectare is constant across a broad range of bait station densities. The results are discussed in the context of commercializing liquid ant baits to provide a more sustainable Argentine ant control strategy.     

Evaluation of non-toxic bait interference for indexing brushtail possum density

Percentage non-toxic bait interference is currently used by local authorities to monitor brushtail possum control operations but the validity of the method has not been established. Two models have been proposed to estimate an index of possum density (possums per bait) from a log-transformation of percentage bait interference. In two trials, percentage bait interference and the density index derived from percentage bait interference using the Bamford (1970) model usually increased from night to night. Variation in the number of possums per bait was reduced by dividing the Bamford index by the number of nights baits were put out, as proposed by Jane (1981). The spatial distribution of bait interference along lines of bait stations was random for the first night and usually for at least 5 nights. Rhodomine dye and cyanide poison, alternated at bait stations after at least 5 nights non-toxic baiting, showed that about 83% of possums in one trial and 29% of possums in the other trial interfered with more than one bait on the same night. Increasing the spacing between bait stations reduced the proportion of possums interfering with more than one bait. The number of possums per line killed by cyanide baits after at least 5 nights of non-toxic baiting was strongly correlated with percentage bait interference, with and without logarithmic transformation, on the first night. The possums' apparent ability to remember the location of bait stations from one night to the next means that, in the absence of better advice, the original Bamford (1970) model should be modified as proposed by Jane (1981) to estimate possum density and change in possum density (e.g., from pre- to post-poison).     

Field evaluation of a fipronil bait against subterranean termite Odontotermes formosanus (Isoptera: Termitidae)

The subterranean termite Odontotermes formosanus Shiraki is an important pest of agronomic crops, plantations, and forestry, and it endangers earthen dikes and dams in China. A fipronil bait consisting of straw pulp and white sugar was evaluated against field colonies of O. formosanus. Triple mark-capture with Nile blue dye was used to delineate foraging territories and to estimate foraging populations of four O. formosanus colonies locating in the campus of Huazhong Agricultural University, Wuhan, China. Termite activity was monitored by number of termite workers and straw board consumption in underground monitoring stations. Consumption of bait matrix and fipronil was estimated for each testing site. The results showed that approximately 3-5 mg of fipronil could suppress foraging populations of O. formosanus containing 0.4-0.7 million foragers per colony. Baits containing fipronil seem to be a feasible alternative for controlling O. formosanus.     

Development of virtual bait stations to control Argentine ants (Hymenoptera: Formicidae) in environmentally sensitive habitats

A novel bait station referred to as a virtual bait station was developed and tested against field populations of the invasive Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), at White Beach, Camp Pendleton, in Oceanside, CA. White Beach is a nesting habitat for an endangered seabird, the California least tern (Sterna antillarum browni Mearns). The beach is heavily infested with Argentine ants, one of the threats for the California least tern chicks. Conventional pest control strategies are prohibited because of the existence of the protected bird species and the site's proximity to the ocean. The bait station consisted of a polyvinyl chloride pipe that was treated on the inside with fipronil insecticide at low concentrations to obtain delayed toxicity against ants. The pipe was provisioned with an inverted bottle of 25% sucrose solution, then capped, and buried in the sand. Foraging ants crossed the treated surface to consume the sucrose solution. The delayed toxicity of fipronil deposits allowed the ants to continue foraging on the sucrose solution and to interact with their nestmates, killing them within 3-5 d after exposure. Further modification of the bait station design minimized the accumulation of dead ants in the sucrose solution, significantly improving the longevity and efficacy of the bait station. The virtual bait station exploits the foraging behavior of the ants and provides a low impact approach to control ants in environmentally sensitive habitats. It excluded all insects except ants, required only milligram quantities of toxicant, and eliminated the problem of formulating toxicants into aqueous sugar baits.     

Field evaluation of potential control strategies against the invasive eastern subterranean termite (Isoptera: Rhinotermitidae) in Chile

Four different termite control strategies consisting of two soil treatments with cypermethrin and fipronil and two bait treatments with hexaflumuron and sulfluramid were evaluated for their efficacy and potential for controlling the invasive eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), in Quillota and Valparaiso, Chile. Monitoring stations were installed at all sites to measure the overall termite activity next to and at distances up to 30 m away from infested structures, most being 3-5 m. Foraging activity was extremely seasonal with the maximum consumption rates occurring from January to April. Termite foraging activity was low from July to September. After treatments in January 2003, there was a significant decrease in wood consumption, percentage of active stations, and numbers of termites in traps for the first 6 mo with hexaflumuron baits. No significant change in R. flavipes foraging activity was observed on wood consumption and percentage of active stations for sulfluramid bait or cypermethrin and fipronil soils treatments. The seasonal pattern of foraging activity remained unchanged for all treatments in 2004 and 2005, except structures baited with hexaflumuron. Feeding activity at the monitors in the area surrounding the hexaflumuron baits declined to 0 after January 2004. Alate flights occurred in approximately 38% of the structures treated with cypermethrin and sulfluramid bait in 2003 and in approximately 40% of the structures treated with cypermethrin, fipronil, and sulfluramid bait in 2004. Sulfluramid baits and cypermethrin soil treatments did not have any impact within a 15-m radius of the structures. Soils treatments of fipronil and cypermethrin prevented termites access in 75% of the homes. The number of active monitoring stations only declined within 2 m of the fipronil-treated zone. Hexaflumuron exhibited a reduction in activity for at least a 15-m radius.     

Laboratory and field performance of an indoxacarb bait against German cockroaches (Dictyoptera: Blattellidae)

Experimental indoxacarb powder and gel baits were evaluated in the laboratory, and a gel bait was evaluated in subsequent field studies against the German cockroach, Blattella germanica (L.). In continuous exposure tests, LT50 values were 1.90 and 1.10 d for 0.25 and 1% indoxacarb powder baits, respectively. However, 0.25% indoxacarb gel bait had an LT50 value of 0.68 d, similar to a 0.05% abamectin gel bait formulated with the same bait base. There was no difference in toxicity between fresh and 7-d-old gel bait deposits. A pyrethroid-resistant strain of German cockroaches was significantly resistant to both abamectin and indoxacarb gel baits. Gel bait contained approximately 40% water, desiccated rapidly at 25-28 degrees C and 30-45% RH, but did not rehydrate when held at 56.7% RH for 3 d. Powder indoxacarb baits contained <1% water and did not desiccate or gain water. Indoxacarb gel bait (0.25%) was relatively nonrepellent (approximately 30%) and had positive maximum performance index values (approximately 100) in Ebeling choice box experiments. In field experiments in cockroach-infested kitchens, the 0.25% indoxacarb gel bait significantly reduced visual counts of German cockroaches approximately 74% at 3 d and >95% at 14 d. Indoxacarb baits are toxic, relatively nonrepellent, and can significantly reduce German cockroach populations.