1. Potential biological control agent discovered in South American fire ants. Natural enemies for fire ant control are largely absent in U.S. populations of fire ant resulting in unchecked population growth and expansion. ARS researchers at Gainesville, Florida, have discovered a virus in South American populations of fire ants with potential to provide sustainable control of this invasive ant pest in the U.S. This discovery represents the first opportunity for virus-based classical biological control of fire ants in the U.S.
2. Virus-containing baits found effective against fire ants in the laboratory. Natural alternatives to traditional insecticides are not available for fire ant control. ARS researchers at Gainesville, Florida, have determined that fire ant-specific viruses can control fire ant colonies when incorporated into baits and fed to the colonies. Additional studies are underway to improve formulations and increase impacts on fire ant colonies. The discovery represents the first virus-based biopesticide for fire ant control.
3. Gene expression patterns identified for founding fire ant queen behavioral phenotypes. Little is known about the effect of social environment on gene expression during the crucial newly mated queen colony foundation stage. ARS researchers at Gainesville, Florida, determined that social environment played a major role in the determination of the patterns of gene expression, while the physiological state and the social rank of founding queens are only secondary. These results highlight the powerful influence of social environment on regulation of gene expression patterns, physiology and, ultimately, social behavior.
4. The genomic region responsible for single and multiple queen social organizational forms in fire ants identified. Introduced fire ants exhibit two colony social forms that differ in the number of reproductive queens per colony as well as a host of other traits. Remarkably, many individual and life-history traits allied to social organization also are associated with allelic variation at the single gene Gp-9. ARS researchers at Gainesville, Florida, found Gp-9 is embedded in an epistatic network of genes that are resistant to being broken up and that regulate various aspects of the complex social syndrome (i.e., a “supergene”). The newly discovered non-recombining genomic region (part of a pair of heteromorphic chromosomes) has many of the key properties of sex chromosomes and comprises most of the genes with demonstrated expression differences between individuals of the two social forms. These findings highlight how genomic rearrangements can maintain divergent adaptive social phenotypes involving many genes acting in concert by locally limiting recombination.
5. Multiple uses of fire ant alarm pheromone. The alarm pheromone in ants is usually associated with the rapid movement of workers after disturbance, but female and male sexuals (winged forms) also produce the alarm pheromone, suggesting additional functions. ARS researchers at Gainesville, Florida, determined that male and female sexuals initiate mating flights with the alarm pheromone and that males exhaust their pheromone supply while maintaining a lek into which the females fly for mating. In contrast, newly mated queens accumulate large amounts during colony growth that dissipates to insignificant amounts in mature colonies. Results support a diverse multifunctional role for the alarm pheromone in fire ants.
6. New low-cost diet for rearing fire ants. Laboratory studies of fire ants require healthy growing colonies. ARS researchers at Gainesville, Florida, discovered that fire ant colonies can be successfully reared on raw beef liver and sugar water. This diet is not as good as domestic crickets, but it is about 1/4 the cost, easily available, more effective than any artificial diet, better than mealworms and other cricket species, and sufficient for rearing and maintaining stock colonies. A liver and sugar water diet may also prove very useful to researchers around the world because this diet is also effective at rearing many other kinds of ants.
7. Insect growth regulator reduces invasive crazy ant colony growth. The tawny crazy ant is an invasive pest that is spreading in the southern U.S. Ant baits are an efficient and environmentally compatible method of control, but most commercial baits are ineffective against this species. ARS researchers at Gainesville, Florida, demonstrated that bait containing an insect growth regulator significantly reduced colony growth of the tawny crazy ant. An effective insect growth regulating bait has the potential to be more effective than standard bait toxicants because it can be more easily distributed by the ants among their numerous colonies.Valles, S.M., Strong, C.A., Buss, E.A., Oi, D.H. 2012. Non-enzymatic hydrolysis of RNA in workers of the ant Nylanderia pubens. Journal of Insect Science. 12(146):1-8.