BIOLOGY, GENOMICS, AND INTEGRATED PEST MANAGEMENT OF INVASIVE ANTS
Location: Imported Fire Ant and Household Insects
Title: RNA Interference of the PBAN/Pyrokinin Gene: Impact on Ant, Solenopsis invicta, and Moth, Helicoverpa zea, Development
Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 5, 2012
Publication Date: June 13, 2012
Citation: Choi, M.Y., Vander Meer, R.K., Coy, M.R., Scharf, M.E. 2012. RNA Interference of the PBAN/Pyrokinin Gene: Impact on Ant, Solenopsis invicta, and Moth, Helicoverpa zea, Development. Journal of Insect Physiology. 58:1159-65.
Interpretive Summary: The red imported fire ant, S. invicta, is among the world’s 100 worst invasive alien species. In the United States this ant species infests more than 320 million acres in 13 southern tier states and Puerto Rico and are spreading northward. It is estimated to be responsible for almost $7 billion annually in damage repair, medical care, and control costs. In the last decade S. invicta has changed from an invasive pest ant in the United States to a global problem. Many moth species are also of significant economic importance, e.g. Helicoverpa zea, the corn ear worm. There is a need to develop novel species-specific control methods that do not utilize classical insecticides. Scientists from the Imported Fire Ant and Household Insect Unit at the Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS, Gainesville, FL and from The University of Florida, Entomology and Nematology Department have investigated phenotypic changes that occur in fire ants and H. zea, when expression of the neurohormone producing PBAN/Pyrokinin gene is suppressed with RNAi. The results show a negative impact on fire ant immatures, pupae and adults. Importantly, feeding the RNAi to workers tending brood lead to high mortality of the brood. This suggests that currently used bait methodologies could be adapted for use of RNAi control methods. Results with H. zea showed delayed melanization and pupal mortality, and those treated female pupae that made it to adult produced significantly less sex pheromone. This work illustrates that targeting an insect neurohormone system with RNAi could be an effective strategy for the discovery of the next generation insect pest control, as well as a strategy to identify specific physiological functions.
Recently, an emerging RNA interference (RNAi) technology has shown high potential for development of novel biologically-based control agents as alternatives to insecticides. This represents a paradigm shift that will avoid many problems associated with conventional insecticides. Insect neuropeptide hormones represent more than 90% of all insect hormones. These species-specific neuropeptides are involved in many important functions that could be used for species-specific targeted pest control. The PBAN/pyrokinin family is a major group of insect neuropeptides, and they are expected to be found from all insect groups, and to have multiple functions during insect development. PBAN is well understood in moth species relative to pheromone biosynthesis and developmental physiology. Recently, we investigated the PBAN/pyrokinin gene and peptides in the fire ant, which is one of the most destructive invasive pest ants in the World. In this study, we selected the PBAN gene as a target neuropeptide system for RNAi using two different insect model species, fire ant, S. invicta, a pest invasive social insect, and the corn earworm, H. zea, a serious lepidopteran crop pest. We also report negative impacts, increased adult and larval mortality, delayed pupal development and decreased sex pheromone production, during developmental period of both species when treated with PBAN dsRNAs. This is the first demonstration of the application of PBAN/pyrokinin gene suppression using RNAi for two different insect groups. This work illustrates that targeting an insect neurohormone system with RNAi could be an effective strategy for the discovery of the next generation insect pest control, as well as a strategy to identify specific physiological functions.