Bait Matrix Research Articles

Developing A Solid Termite Bait Matrix and Conducting Efficacy Trials Under Lab and Semi Field Conditions

The study on development of solid termite bait matrix and its efficacy against the Heterotermes indicola was performed in Peshawar, during 2023. The study was performed with completely randomized design (CRD) with different treatments i.e., developed bait, patent bait, popular wood and blotting paper. Each treatment was replicated three times. The laboratory experiment consisted of no-choice, free choice and aggregation test. While the semi-field experiment consisted of free choice test. During the no-choice test of the laboratory experiment, H. indicola showed a consumption rate of 6.29% for the popular wood and developed bait. However, in the blotting paper treatment, the termites consumed only 2.81%. In terms of choice test conducted in the lab, the popular wood exhibited the highest weight consumption percentage of 2.87%, while the patent bait displayed the lowest weight consumption percentage of 2.25%. Under the choice test maximum number of termites were attracted towards popular wood (77.00 Number of termites) while minimum number of termites were attracted towards patent bait (54.66 Number of termites). Whereas, in aggregation test, of the lab experiment, maximum number of termites were also aggregated towards popular wood (37.77 Number of termites) while minimum termites were aggregated for patent bait (25.22 Number of termites). In the case of free choice under semi-field conditions, the highest number of termites were observed on popular wood i.e., 380.00 followed by the developed bait, which recorded 293.50 termites. On the other hand, the lowest number of termites were recorded on the patent bait i.e., 231.50. Similarly, when considering the maximum consumed weight in percentage, popular wood exhibited the highest value at 16.24%, closely followed by the developed bait at 15.67% while the patent bait displayed minimum consumed weight percentage of 12.89%. In overall experiments it is concluded that among all the tested treatments, termites mostly consumed popular wood and developed bait. Since the developed bait showed promising results in attracting termites, it is recommended to continue refining its formulation. Conduct additional research to identify the key components or additives that enhance its attractiveness and consumption by termites. This optimization process can help maximize the effectiveness of the bait as a termite control strategy. Adding more popular wood saw dust in the bait may achieve more significant and desired results and can also prove to be cost efficient rather than adding more cellulosic material.

Development of Solid Termite Bait Matrix; Its Efficacy Trials in Lab and Semi Field Condition

The study on development of solid termite bait matrix and its efficacy against the Heterotermes indicola was performed in the Termite Laboratory, Entomology Division, Nuclear Institute for Food and Agriculture (NIFA), Peshawar, during 2023. The study was performed with completely randomized design (CRD) with different treatments i.e., developed bait, patent bait, popular wood and blotting paper. Each treatment was replicated three times. The laboratory experiment consisted of no-choice, free choice and aggregation test. While the semi-field experiment consisted of free choice test. During the no-choice test of the laboratory experiment, H. indicola showed a consumption rate of 6.29% for the popular wood and developed bait. However, in the blotting paper treatment, the termites consumed only 2.81%. In terms of choice test conducted in the lab, the popular wood exhibited the highest weight consumption percentage of 2.87%, while the patent bait displayed the lowest weight consumption percentage of 2.25%. Under the choice test maximum number of termites were attracted towards popular wood (77.00 Number of termites) while minimum number of termites were attracted towards patent bait (54.66 Number of termites). Whereas, in aggregation test, of the lab experiment, maximum number of termites were also aggregated towards popular wood (37.77 Number of termites) while minimum termites were aggregated for patent bait (25.22 Number of termites). In the case of free choice under semi-field conditions, the highest number of termites were observed on popular wood i.e., 380.00 followed by the developed bait, which recorded 293.50 termites. On the other hand, the lowest number of termites were recorded on the patent bait i.e., 231.50. Similarly, when considering the maximum consumed weight in percentage, popular wood exhibited the highest value at 16.24%, closely followed by the developed bait at 15.67% while the patent bait displayed minimum consumed weight percentage of 12.89%. In overall experiments it is concluded that among all the tested treatments, termites mostly consumed popular wood and developed bait. Since the developed bait showed promising results in attracting termites, it is recommended to continue refining its formulation. Conduct additional research to identify the key components or additives that enhance its attractiveness and consumption by termites. This optimization process can help maximize the effectiveness of the bait as a termite control strategy. Adding more popular wood saw dust in the bait may achieve more significant and desired results and can also prove to be cost efficient rather than adding more cellulosic material.

Transcriptome Responses to Defined Insecticide Selection Pressures in the German Cockroach (Blattella germanica L.)

Cockroaches are important global urban pests from aesthetic and health perspectives. Insecticides represent the most cost-effective way to control cockroaches and limit their impacts on human health. However, cockroaches readily develop insecticide resistance, which can quickly limit efficacy of even the newest and most effective insecticide products. The goal of this research was to understand whole-body physiological responses in German cockroaches, at the metatranscriptome level, to defined insecticide selection pressures. We used the insecticide indoxacarb as the selecting insecticide, which is an important bait active ingredient for cockroach control. Six generations of selection with indoxacarb bait produced a strain with substantial (>20×) resistance relative to inbred control lines originating from the same parental stock. Metatranscriptome sequencing revealed 1,123 significantly differentially expressed (DE) genes in ≥two of three statistical models (81 upregulated and 1,042 downregulated; FDR P < 0.001; log2FC of ±1). Upregulated DE genes represented many detoxification enzyme families including cytochrome-P450 oxidative enzymes, hydrolases and glutathione-S-transferases. Interestingly, the majority of downregulated DE genes were from microbial and viral origins, indicating that selection for resistance is also associated with elimination of commensal, pathogenic and/or parasitic microbes. These microbial impacts could result from: (i) direct effects of indoxacarb, (ii) indirect effects of antimicrobial preservatives included in the selecting bait matrix, or (iii) selection for general stress response mechanisms that confer both xenobiotic resistance and immunity. These results provide novel physiological insights into insecticide resistance evolution and mechanisms, as well as novel insights into parallel fitness benefits associated with selection for insecticide resistance.

Valorization of discarded industrial fish processing wastes for the extraction of gelatin to use as biodegradable fish bait matrix using RSM

Extraction of gelatin from fish wastes and the development of artificial fish bait matrix using the extracted gelatin were attempted in the study. Biochemical composition of fish wastes (heads, skins, fins and scales) and the gelatin derived from the wastes of corresponding body parts and physicochemical properties of fish gelatin were analyzed. Considering high yield (19.8–22.4%), good gel strength (1.99–2.3 N), high melting point (27 °C) and simple extraction process, the scale gelatin was selected for the development of artificial fish bait matrix. To optimize the levels of gelling agent, cross linker and solvent for the preparation of bait matrix, RSM was adopted. Gel strength and insolubility ratio were analyzed to know the suitability of the bait. They were found to have the gel strength ranging from 1.3 N to 23.5 N, insolubility ratio from 55–83%, and melting point from 34.3 °C to 41.1 °C. The optimum levels of ingredients for the preparation of ideal bait matrix were standardized as: gelatin-25.5%, sucrose-22.5% and water-52%. The curing temperature and curing duration were optimized based on the optimum gel strength of 20.84 N and insolubility ratio of 74.5% was 5 °C and 25 h respectively. The study revealed that a developed fish bait matrix suitable for fishing can be made from gelatin derived from fish wastes.

Disappearance Rates of a Placebo Bait for the Small Indian Mongoose Across Different Habitats on St. Kitts

The small Indian mongoose (Urva aurpunctata) is a non-indigenous wildlife reservoir for rabies virus on several Caribbean islands. Oral rabies vaccination (ORV) has been suggested to prevent the spread of rabies in mongooses, but there are limited data on ORV bait survival in maritime/tropical climates. We compared disappearance rates of an egg-flavored bait block vs. a control (canned tuna) and for bait blocks, we assessed if season, habitat, and day/night would influence the disappearance rate. On the island of St. Kitts, West Indies, we baited 45 stations (n=35 bait blocks, n=10 controls) at dawn and checked them twice daily for 4 consecutive days. This procedure was repeated after a two-day period, for each combination of season (dry and wet) and habitat type (mixed grassland, littoral and dry forest). We used the Kaplan-Meier method to estimate bait survival at 12 and 36 hours after baiting. Across all sites, control baits were removed faster than bait blocks, but by 36 hours, over 90% of all baits had disappeared. For bait blocks only, the disappearance rate was higher during the dry season and in the dry forest habitat compared to the other habitats. There was no difference between diurnal and nocturnal disappearance rates. While the exact species that consumed the baits remain uncertain, we found that mongooses readily remove bait blocks, along with non-native mammals (e.g., dogs and cats) and land crabs in littoral habitats. We suggest that the bait blocks used in this study may be suitable for use as an external bait matrix for ORV baits.

Selection, Reversion, and Characterization of House Fly (Diptera: Muscidae) Behavioral Resistance to the Insecticide Imidacloprid.

Insecticide resistance in pest populations is an increasing problem in both urban and rural settings caused by over-application of insecticides and lack of rotation among chemical classes. The house fly (Musca domestica L.) is a cosmopolitan fly species implicated in the transmission of numerous pathogens, and which can be extremely pestiferous when present in high numbers. The evolution of insecticide resistance has long been documented in house flies, with resistance reported to all major insecticide classes. House fly resistance to imidacloprid, the most widely used neonicotinoid insecticide available for fly control, has been selected for in field populations through both physiological and behavioral resistance mechanisms. In the current study, house flies collected from a southern California dairy were selectively bred for behavioral resistance to imidacloprid, without increasing the physiological resistance profile of the selected flies. Flies were also successfully selected for behavioral susceptibility to imidacloprid. The rapid selection for either behavioral resistance or behavioral susceptibility suggests that inheritable alleles conferring behavioral resistance were already present in the wild-type fly population collected from the dairy site. The methods used for the specific selection of behavioral resistance (or susceptibility) in the fly population will be useful for further studies on the specific mechanisms conferring this resistance. House fly behavioral resistance was further investigated using behavioral observation and feeding preference assays, with resistance determined to be both contact-dependent and specific to the insecticide (imidacloprid) rather than to a non-insecticidal component of a bait matrix as previously documented.

Analysis of Iophenoxic Acid Analogues in Small Indian Mongoose (Herpestes Auropunctatus) Sera for Use as an Oral Rabies Vaccination Biological Marker.

The small Indian mongoose (Herpestes auropunctatus) is a reservoir of rabies virus (RABV) in Puerto Rico and comprises over 70% of animal rabies cases reported annually. The control of RABV circulation in wildlife reservoirs is typically accomplished by a strategy of oral rabies vaccination (ORV). Currently no wildlife ORV program exists in Puerto Rico. Research into oral rabies vaccines and various bait types for mongooses has been conducted with promising results. Monitoring the success of ORV relies on estimating bait uptake by target species, which typically involves evaluating a change in RABV neutralizing antibodies (RVNA) post vaccination. This strategy may be difficult to interpret in areas with an active wildlife ORV program or in areas where RABV is enzootic and background levels of RVNA are present in reservoir species. In such situations, a biomarker incorporated with the vaccine or the bait matrix may be useful. We offered 16 captive mongooses placebo ORV baits containing ethyl-iophenoxic acid (et-IPA) in concentrations of 0.4% and 1% inside the bait and 0.14% in the external bait matrix. We also offered 12 captive mongooses ORV baits containing methyl-iophenoxic acid (me-IPA) in concentrations of 0.035%, 0.07% and 0.14% in the external bait matrix. We collected a serum sample prior to bait offering and then weekly for up to eight weeks post offering. We extracted Iophenoxic acids from sera into acetonitrile and quantified using liquid chromatography/mass spectrometry. We analyzed sera for et-IPA or me-IPA by liquid chromatography-mass spectrometry. We found adequate marking ability for at least eight and four weeks for et- and me-IPA, respectively. Both IPA derivatives could be suitable for field evaluation of ORV bait uptake in mongooses. Due to the longevity of the marker in mongoose sera, care must be taken to not confound results by using the same IPA derivative during consecutive evaluations.

Argentine Ant (Linepithema humile, Mayr) Eradication Efforts on San Clemente Island, California, USA

The Argentine ant, Linepithema humile (Mayr), is a highly invasive ant species that has spread into urban, agricultural, and natural areas worldwide. The pervasive expansion of this species is detrimental both ecologically and economically, resulting in the allocation of vast amounts of resources for control. New efforts are underway to control the Argentine ant in ecologically sensitive habitats, such as those on the California Channel Islands. We tested the efficacy of thiamethoxam liquid bait at a concentration of 6 ppm on San Clemente Island, California, where the Argentine ant has spread into natural areas hosting protected endemic species. Applied by hand, helicopter, and ATV, hygroscopic polyacrylamide beads were used as a bait matrix to deliver the liquid bait (thiamethoxam and sucrose) for Argentine ant infestations at 5 sites (totaling 177 ha) on San Clemente Island. Treatments reduced the number of monitoring points at which the Argentine ant was detected 1 year posttreatment (17.91% vs. 3.65%), suggesting that these methods are a promising conservation tool. Continued monitoring to detect remaining infestations will be necessary for eventual eradication of the Argentine ant from San Clemente Island.

Subterranean Termites Feeding on CSI Baits for a Short Duration Still Results in Colony Elimination.

Termite baits using chitin synthesis inhibitors can protect structures from subterranean termite damage by eliminating colonies. One of the potential shortcomings of baits is that termites may have to feed extensively on a bait station for the colony to be eliminated. If disturbances occur during this critical feeding time, termites may abandon the site, which could prevent colony elimination. We exposed whole laboratory colonies of Coptotermes gestroi (Wasmann) containing an average of 59,000 termites to 0.5% noviflumuron baits, from 1 to 10 d, to simulate a temporary access to the bait as a result of disturbances. Our results show that colonies which fed for a single day and consumed as little as 1.1 g of bait matrix (=5.5 mg noviflumuron) were eliminated within 90 d. This study indicates that only a fraction of the bait matrix is necessary for elimination of large laboratory colonies, and that hypothetical disturbance reducing the access to a bait station would likely have little impact on the effect of the bait. Within 1 d, colonies had already acquired a lethal dose, which is shared by trophallaxis to all individuals of the colony, and colonies inevitably died despite short exposure to noviflumuron. It is estimated that if a field mature colony of 1 million individuals consumes more than 18.6 g of bait (=93 mg noviflumuron) in a relatively short period, it would already have acquired a colony-wide lethal dose and reached a point of no-return for colony elimination.

The efficacy of Vespex® wasp bait to control Vespula species (Hymenoptera: Vespidae) in New Zealand

ABSTRACTTransitioning from trials to pest control tool, the efficacy of controlling wasps Vespula vulgaris and V. germanica using Vespex® wasp bait was tested in 2015. Vespex® is a protein-based bait matrix with 0.1% fipronil. Five sites ranging <300 to >2000 ha and over 5500 ha in total had bait stations placed 300 × 50 m apart and received one application of Vespex®. Wasp nest traffic rates declined 93% in four days at one site, and over 97% after 20–38 days at all other sites. Measured honeydew availability also improved post wasp control. Further demonstrating feasibility, five different agencies worked closely with government leading many programme aspects. Vespex® was made more widely available in New Zealand towards the end of 2015. Web page information showed ∼30% of all territorial authorities nationally are engaging in pest wasp problems. This signals a future potential in the way that pest wasps might be managed in a community context for social, economic and biodiversity conservation objectives.

Combinatorial Potential of bait matrix against subterranean termites under lab and field conditions

Bait matrix of different treatments were evaluated against two termite species i.e. Odontotermes obesus and Coptotermes heimi both under laboratory and field conditions. Mean wood consumption in laboratory bioassays were investigated for 2, 4 and 6 weeks with maximum consumption was noted after 4 weeks. While, field experiment was conducted for 24 there was greater consumption of the loosely bound bait matrix compared to the tightly bound matrix. However, feeding was comparatively high in combinations with attractants. Overall, treated colonies experienced a 90-95% decrease in population size after 24 weeks of baiting. The queen in the royal chamber of the mound was found dead.

Bait Preference of Free-Ranging Feral Swine for Delivery of a Novel Toxicant.

Invasive feral swine (Sus scrofa) cause extensive damage to agricultural and wildlife resources throughout the United States. Development of sodium nitrite as a new, orally delivered toxicant is underway to provide an additional tool to curtail growth and expansion of feral swine populations. A micro-encapsulation coating around sodium nitrite is used to minimize detection by feral swine and maximize stability for the reactive molecule. To maximize uptake of this toxicant by feral swine, development a bait matrix is needed to 1) protect the micro-encapsulation coating so that sodium nitrite remains undetectable to feral swine, 2) achieve a high degree of acceptance by feral swine, and 3) be minimally appealing to non-target species. With these purposes, a field evaluation at 88 sites in south-central Texas was conducted using remote cameras to evaluate preferences by feral swine for several oil-based bait matrices including uncolored peanut paste, black-colored peanut paste, and peanut-based slurry mixed onto whole-kernel corn. These placebo baits were compared to a reference food, whole-kernel corn, known to be readily taken by feral swine (i.e., control). The amount of bait consumed by feral swine was also estimated using remote cameras and grid boards at 5 additional sites. On initial exposure, feral swine showed reduced visitations to the uncolored peanut paste and peanut slurry treatments. This reduced visitation subsided by the end of the treatment period, suggesting that feral swine needed time to accept these bait types. The black-colored peanut paste was visited equally to the control throughout the study, and enough of this matrix was consumed to deliver lethal doses of micro-encapsulated sodium nitrite to most feral swine during 1–2 feeding events. None of the treatment matrices reduced visitations by nontarget species, but feral swine dominated visitations for all matrices. It was concluded that black-colored peanut paste achieved satisfactory preference and consumption by feral swine, and no discernable preference by non-target species, compared to the other treatments.

Optimization of termite in-ground monitoring stations: An evaluation trial

Subterranean termites are serious pests of wood in service in much of the world. One of the most popular techniques for monitoring and controlling termites is the use of in-ground monitoring stations. Different cellulosic matrices were evaluated in terms of mass loss, moisture content variation and termite presence, accounting for spatial coordinates and monitoring station conditional variables, including: type of cellulosic matrix, matrix treatment and meteorological conditions, during one year in field conditions, both in Portugal and in the USA. A multivariate redundancy analysis was performed resulting in 60.4% of data variability being explained by the variables considered in this analysis. Spatial variables were responsible for the highest amount of variance observed in the response variables monitored for the termite monitoring stations, followed by the type of cellulosic matrix, from which cellulose and Hevea brasiliensis were the most influential variables. The optimization of termite in-ground monitoring stations should be performed through correct evaluation of termite feeding preferences and decay resistance, in order to choose an adequate bait matrix and a proper bait design. The termite species biology and the geographical location where control programs will be applied should also be taken into account.

Field Trials With 0.5% Novaluron Insecticide Applied as a Bait to Control Subterranean Termites (Reticulitermes sp. and Coptotermes formosanus [Isoptera: Rhinotermitidae]) on Structures.

A field study was initiated in 2009 with 0.5% novaluron the BASF Advance Termite Bait System, which was 100% effective in controlling Reticulitermes sp. Holmgren and Coptotermes formosanus Shiraki infestations on 11 structures in the Texas City, TX area. Stations with inspection cartridges (cellulose tablets) and monitoring bases (southern yellow pine) and independent monitoring devices were installed in an alternating pattern around each structure and were inspected every 30 d postinstallation. When subterranean termite activity was confirmed on the inspection cartridge or the monitoring base, the inspection cartridge was removed and replaced with a bait cartridge containing 0.5% novaluron insecticide on a proprietary matrix (124 g/cartridge) in a station. Once the novaluron-treated bait was inserted, inspections of that station were made on a 4-mo cycle until no termite activity was observed. The mean time to achieve control of the subterranean termites on the structures was 10.5 mo post initial installation of bait. Mean time to achieve control of the termites on the structures after the baits were installed was 5.4 mo. Control of the termites on the structures required consumption of a mean of 1.3 bait cartridges (166.2 g) of 0.5% novaluron bait matrix per structure. These results indicate that the baits with 0.5% novaluron were effective in controlling termites on the structures used in this study.

Nontarget mortality of New Zealand lesser short-tailed bats (Mystacina tuberculata) caused by diphacinone.

Primary and secondary poisoning of nontarget wildlife with second-generation anticoagulant rodenticides has led to restrictions on their use and to increased use of first-generation anticoagulants, including diphacinone. Although first-generation anticoagulants are less potent and less persistent than second-generation compounds, their use is not without risks to nontarget species. We report the first known mortalities of threatened New Zealand lesser short-tailed bats (Mystacina tuberculata) caused by diphacinone intoxication. The mortalities occurred during a rodent control operation in Pureora Forest Park, New Zealand, during the 2008-09 Austral summer. We observed 115 lesser short-tailed bat deaths between 9 January and 6 February 2009, and it is likely that many deaths were undetected. At necropsy, adult bats showed gross and histologic hemorrhages consistent with coagulopathy, and diphacinone residues were confirmed in 10 of 12 liver samples tested. The cause of mortality of pups was diagnosed as a combination of the effects of diphacinone toxicity, exposure, and starvation. Diphacinone was also detected in two of 11 milk samples extracted from the stomachs of dead pups. Eight adults and 20 pups were moribund when found. Two adults and five pups survived to admission to a veterinary hospital. Three pups responded to treatment and were released at the roost site on 17 March 2009. The route of diphacinone ingestion by adult bats is uncertain. Direct consumption of toxic bait or consumption of poisoned arthropod prey could have occurred. We suggest that the omnivorous diet and terrestrial feeding habits of lesser short-tailed bats make them susceptible to poisoning with the bait matrix and the method of bait delivery used. We recommend the use of alternative vertebrate pesticides, bait matrices, and delivery methods in bat habitat.

Colony Size Affects the Efficacy of Bait Containing Chlorfluazuron Against the Fungus-Growing Termite Macrotermes gilvus (Blattodea: Termitidae).

The efficacy of chitin synthesis inhibitors (CSIs) against fungus-growing termites is known to vary. In this study, 0.1% chlorfluazuron (CFZ) cellulose bait was tested against medium and large field colonies of Macrotermes gilvus (Hagen). The termite mounds were dissected to determine the health of the colony. Individual termites (i.e., workers and larvae) and fungus combs were subjected to gas chromatography-mass spectrometry (GC-MS) analysis to detect the presence of CFZ. In this study, 540.0 ± 25.8 g (or equivalent to 540.0 ± 25.8 mg active ingredient) and 680.0 ± 49.0 g (680.0 ± 49.0 mg active ingredient) of bait matrix were removed by the medium- and large-sized colonies, respectively, after baiting. All treated medium-sized colonies were moribund. The dead termites were scattered in the mound, larvae were absent, population size had decreased by 90%, and the queens appeared unhealthy. In contrast, no or limited effects were found in large-sized colonies. Only trace amounts of CFZ were detected in workers, larvae, and fungus combs, and the population of large-sized colonies had declined by only up to 40%. This might be owing to the presence of large amount of basidiomycete fungus and a drastic decrease of CFZ content per unit fungus comb (a main food source of larvae) in the large-sized colonies, and hence reduced the toxic effect and longer time is required to accumulate the lethal dose in larvae. Nevertheless, we do not deny the possibility of CSI bait eliminating or suppressing the higher termite if the test colonies could pick up adequate lethal dose by installing more bait stations and prolonging the baiting period.

Comparative Evaluation of Three Chitin Synthesis Inhibitor Termite Baits Using Multiple Bioassay Designs

Use of chitin synthesis inhibitors has revolutionized the potential impact of termite baiting systems. Several chitin synthesis inhibitors have been used or tested against subterranean termites. We evaluated the effect of lufenuron on bait matrix consumption and mortality of Coptotermes formosanus and compared it with 2 other chitin synthesis inhibitors presently used for termite control: diflubenzuron and noviflumuron. Laboratory no-choice and multi-chamber bioassay designs were employed. At the end of 6 weeks, in both the no-choice and multi-chamber tests, mortality was significantly higher in all the chitin synthesis inhibitor treatments as compared to the controls; however, lufenuron treatment had significantly higher mortality than the other chitin synthesis inhibitors. Multi-chamber tests suggested no sign of feeding deterrence with any of the chitin synthesis inhibitors at the concentrations tested. Consumption of lufenuron cardboard or noviflumuron bait matrix was similar to that of control cardboard in the no-choice tests. We conclude that, based on the overall bait consumption and mortality data, lufenuron was at least as effective as noviflumuron and diflubenzuron.

Seasonal shifts in macronutrient preferences in supercolonies of the invasiveYellowCrazyAntAnoplolepis gracilipes(Smith, 1857) (Hymenoptera:Formicidae) onChristmasIsland,IndianOcean

AbstractThe timing and duration of sexual brood production in ants can affect their rate of spread and colony growth. Because protein is key to larval growth, queen survival and fecundity, macronutrient collection by foraging workers is expected to favour protein prior to and throughout gyne production. However, food preference driven by the production of gynes may be overridden by a preference associated with worker production, especially if investment in workers vastly outweighs that of sexual brood and workers are produced on different schedules. Food preferences alone may not indicate the availability of that food type in the environment. OnChristmasIsland,IndianOcean, sexual brood of the invasiveYellowCrazyAnt,Anoplolepis gracilipes(Smith, 1857), was produced annually during a single period associated with the onset of the wet season. However, workers were produced continuously throughout the year and colony investment to worker production measured by the standing biomass of eggs, larvae and pupae, typically exceeded 98%. High, aseasonal investment in worker production, together with aseasonal worker activity, would suggest that there should be no seasonal preference shown by workers at food stations containing both protein and carbohydrate. However, workers showed a preference for one food type over another on 46 of 61 occasions at one site and on 31 of 41 occasions at another. When a preference was shown, it was predominantly for protein‐rich food during the dry season and almost always for carbohydrate at the onset and during the wet season. We suggest that these preferences reflect seasonal shortages in key resources when invertebrates (protein‐rich) are scarce during the dry season and honeydew from scale insects (carbohydrate) is depleted by rain during the wet season. OnChristmasIsland, timing and duration of the dry season preference for protein has been exploited by the control program forA. gracilipessupercolonies, which deploys a toxin in a proteinaceous bait matrix during dry periods.

Bait Matrix Flavor Preference by Mongoose (Herpestes auropunctatus) in Puerto Rico: Implications for Oral Rabies Vaccination

The small Indian mongoose (Herpestes auropunctatus) is the primary rabies vector in Puerto Rico. Mongooses are implicated in up to 74% of rabies cases on the island, and pose a threat to domestic animals and human health and safety. No rabies management program exists in Puerto Rico and development of an oral rabies vaccination program requires determining which flavors on the vaccine's bait coating matrix that are attractive to mongooses. Our objective was to evaluate preference among three flavors (cheese, coconut and fish) in the Ultralite bait matrix that is used for delivery of Rabies Vaccine, Live Adenovirus Vector (ONRAB ® ). Placebo baits were offered to free-ranging mongooses in two different ecological environments. The study was conducted at El Yunque National Forest and Cabo Rojo National Wildlife Refuge. At each site we established bait stations with three bait flavors offered simultaneously. We placed a remote camera at each station to monitor bait fate. Cheese ranked higher than fish flavor (W = 1473, P = 0.0273) and cheese and fish both ranked significantly higher than coconut (W = 2180.5, P < 0.0001 and W = 2065.0, P = 0.0008, respectively). These results suggest cheese and fish flavors should perform better than coconut flavor in attracting free-ranging mongooses to consume ONRAB ® baits in Puerto Rico.

Optimization of Formulations for the Lethal Control of Feral Pigs

Author(s): Foster, Justin A.; Martin, James C.; VerCauteren, Kurt C.; Phillips, Greg E.; Eisemann, John D. | Abstract: Feral pig populations continue to increase and disperse into unoccupied habitats in North America. Associated damages and control efforts cost U.S. taxpayers as much as $1.5 million/year. Toxicants show promise for feral pig control programs and may be more cost-effective than contemporary methods (i.e., trapping, aerial gunning, and dog-hunting). However, no toxicants are registered for feral pig control in the U.S. Development of sodium nitrite as an active ingredient in pig toxicants is ongoing in Australia, and a registration has been granted in New Zealand. Sodium nitrite is a strong oxidizer and is unpalatable to feral pigs, and thus it must be masked and stabilized to ensure effective dosing. We researched 3 different formulations of sodium nitrite loaded in a single bait matrix to evaluate mortality and acceptance in the context of U.S. registry requirements. Formulations were accepted by feral pigs but did not cause acceptable mortality rates in subjects. One formulation (TX1) produced mean mortality rates of 50%, which was well below our stated goal of 90%. Bait acceptance and mortality were diminished by insufficient masking of sodium nitrite. However, results indicate that our sodium nitrite formulation improved acceptance and mortality rates in feral pigs and could be the basis for improvements. Future investigations will focus on masking the taste of sodium nitrite.