Exploration of the Role of Florida Zombie Ant Fungus Enterotoxin in Carpenter Ant Behavioral Manipulation

The fungus Ophiocordyceps camponoti-floridani (Ophcf) infects Camponotus floridanus carpenter ants and manipulates them to climb to a high tree branch, bite down on foliage and die. Post ant death, the fungus grows out of the ant and spreads spores for reproduction. I investigated the function of an Ophcf gene product highly activated during the behavioral manipulation of these “zombie ants”; an enterotoxin. I have created an expression vector and heterologously expressed this enterotoxin in Cordyceps bassiana (Cbass), a related fungus that does not normally manipulate behavior. This process includes gene amplification, Golden Gate vector cloning in E. coli, A. tumefaciens-mediated transformation to Cbass, and RT-qPCR to verify heterologous gene expression. This was followed by carpenter ant infections with transgenic Cbass (EntB), wildtype Cbass (infected control), and sham (non-infected control) infected ants. Subsequent behavioral observations using tracking system MARGO (Werkhoven et al., 2019) have detected changes in activity levels of ants infected with both transgenic and WT Cbass compared to sham infected ants. This supports previously qualitative descriptions of increased activity caused during infection with WT Cbass (Trinh, 2020). There is a slight but insignificantly higher activity response from EntB compared to WT infected ants over the course of the trial that may be indicative of Ophcf induced changes that are different from general sickness behavior. Additional replicates are necessary to discern if these findings are statistically robust. Future studies should administer this enterotoxin expressing Cbass to observe inter-social behaviors of Carpenter ants. If the enterotoxin is sufficient to elicit one of the side effects of typical Ophcf infection, this would justify further characterization of the proteins and their functions in altering C. floridanus behavior. This characterization could yield information applicable to other parasite-host relationships as well

HABscope: A tool for use by citizen scientists to facilitate early warning of respiratory irritation caused by toxic blooms of Karenia brevis.

Blooms of the toxic microalga Karenia brevis occur seasonally in Florida, Texas and other portions of the Gulf of Mexico. Brevetoxins produced during Karenia blooms can cause neurotoxic shellfish poisoning in humans, massive fish kills, and the death of marine mammals and birds. Brevetoxin-containing aerosols are an additional problem, having a severe impact on beachgoers, triggering coughing, eye and throat irritation in healthy individuals, and more serious respiratory distress in those with asthma or other breathing disorders. The blooms and associated aerosol impacts are patchy in nature, often affecting one beach but having no impact on an adjacent beach. To provide timely information to visitors about which beaches are low-risk, we developed HABscope; a low cost (~$400) microscope system that can be used in the field by citizen scientists with cell phones to enumerate K. brevis cell concentrations in the water along each beach. The HABscope system operates by capturing short videos of collected water samples and uploading them to a central server for rapid enumeration of K. brevis cells using calibrated recognition software. The HABscope has a detection threshold of about 100,000 cells, which is the point when respiratory risk becomes evident. Higher concentrations are reliably estimated up to 10 million cells L-1. When deployed by volunteer citizen scientists, the HABscope consistently distinguished low, medium, and high concentrations of cells in the water. The volunteers were able to collect data on most days during a severe bloom. This indicates that the HABscope can provide an effective capability to significantly increase the sampling coverage during Karenia brevis blooms