Search

The little fire ant, Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae), was first detected in plant nurseries in the Puna district of Hawaii island in 1999. W. auropunctata has since spread throughout Hawaii island, and is reported in homes, landscapes, plant nurseries and orchards, and forested areas. This study evaluated: 1) the attractiveness of several granular, liquid, gel, and paste insecticidal ant baits for homeowner and commercial use as compared with the standard granular baits containing hydramethylnon known to be attractive to and effective against W. auropunctata, and 2) the effects of weathering on granular bait attractiveness. Field attractiveness choice tests were conducted in an infested 37.2-m² plot, and worker ant foraging and recruitment were recorded at 15-min intervals for 2 h. Granular and paste products that were as attractive as standard granular baits (Amdro Fire Ant Bait, Probait) included others formulated with hydramethylnon, abamectin, hydramethylnon and S-methoprene, indoxacarb, fipronil, and metaflumizone. None of the gel or liquid ant bait products evaluated (active ingredients hydramethylnon, sodium tetraborate pentahydrate, thiamethoxam, fipronil or indoxacarb) were attractive to foraging workers. Attraction of these baits could possibly be improved with inclusion of preferred food sources, such as peanut butter or animal-based protein. Attractiveness of granular ant baits exposed to 7 and 14 days of weathering fell by 40 to 96% as compared to fresh deposits. Corn grit baits should be formulated to preserve attractiveness in tropical environments with high rainfall. [ABSTRACT FROM AUTHOR]

The little fire ant, Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae), a highly successful, destructive invasive ant, is potentially the greatest ant species threat to the Pacific region. Once established, W. auropunctata is extremely difficult to control. This study was conducted to observe the effects of ant baits containing insect growth regulators (IGR) on W. auropunctata colonies during a five-month observation period. Baits containing both methoprene and hydramethylnon achieved 100% mortality by six weeks after treatment, possibly because of the metabolic inhibitor, hydramethylnon, rather than the IGR, methoprene. The IGR pyriproxyfen-exposed queens were unable to produce worker brood or replacements at 20 weeks after treatment. In methoprene-treated colonies three distinct effects on queen fecundity were observed with either continued or cessation of production of viable worker brood and worker replacements, or production of sexual brood exclusively. With its consistent interference with production of replacement workers and viable sexual brood as compared to methoprene, pyriproxyfen shows potential to be an effective IGR for controlling W. auropunctata. [ABSTRACT FROM AUTHOR]

Solenopsis papuana is one of the few introduced ant species that have widely infiltrated undisturbed mesic and wet forests in Hawaii. This may be problematic since many endemic Hawaiian insects are limited to mountain forests, and methods for monitoring and controlling S. papuana would be useful. Four non-toxic monitoring baits (corn syrup, SPAM®, peanut butter, and tuna/ corn syrup blend) and five ant pesticide baits (Advion® Fire Ant Bait™, Amdro® Ant Block®, Extinguish™ Plus, MaxForce® Complete Brand Granular Insect Bait, and Siesta™) were tested for attractiveness to S. papuana in choice tests at Lyon Arboretum and Pahole Natural Area Reserve (NAR) on the island of Oahu. Amdro® Ant Block® and Siesta™ were also tested for efficacy against S. papuana in field plots at Pahole NAR. SPAM® and peanut butter were the most attractive monitoring baits at both locations. There were few significant differences in attractiveness among the five ant pesticides, but Amdro® Ant Block® attracted the highest or second highest number of ants at both sites, while rankings among the other baits were inconsistent. Amdro® Ant Block® presented in bait stations 2.5 m apart greatly reduced the number of ants at monitoring cards in field plots, by an average of 96% from pre-treatment levels over the course of the 246-day trial. Ant numbers also declined in the Siesta™ plots (by 77%), but more closely mirrored fluctuations in the untreated control plots. These methods were effective for monitoring and suppressing S. papuana populations in localized natural areas in the Waianae Mountain Range. [ABSTRACT FROM AUTHOR]

The islands of Hawaii have been the battleground for successive "invasion waves" by exotic ants for over a century. The arrival of Pheidole megacephala (Fabricius) (the big headed ant) in the late nineteenth century, was followed in 1939 by Linepithema humile (Mayr) (the Argentine ant) and Anoplolepis gracilipes (fr. Smith), (the longlegged Ant) in 1953. The most recent arrival is the little fire ant (Wasmannia auropunctata Roger) which was first recorded in 1999. This paper chronicles the subsequent spread of W. auropunctata through the Hawaiian archipelago. Initially introduced and spread via the import and sale of nursery plants, W. auropunctata is now well-established on the island of Hawaii. Ubiquitous on the windward side of Hawaii island, W. auropunctata are now being transported not only via nursery plants but also via non-agricultural products. The prevention, detection and response to W. auropunctata introductions is addressed by informal and ad hoc partnerships between a number of agencies, each contributing to preventing and reducing spread of this species. The draft Hawaii Inter-Agency Biosecurity Plan recognizes and strengthens these partnerships and will contribute positively to Hawaii's biosecurity system. [ABSTRACT FROM AUTHOR]