Meeting Abstract
Protozoa in the order Neogregarinorida (Gregarinea: Apicomplexa) infect the fat body, hypodermis, intestine or Malpighian tubules of insect hosts. All known Mattesia species infect the fat body or Malpighian tubules of beetles, moths, and fleas, with the exception of two species, which develop in the hypodermis of ants. Additionally, all species of Ophryocystis infect the Malpighian tubules of beetles, except for O. elektroscirrha, which develops in the hypodermis of Danaid butterflies. Using histological techniques and SEM, we examined the distribution of oocysts and their associated pathology of an undescribed Mattesia sp., in adult red imported fire ants, Solenopsis invicta and O. elektroscirrha in adult monarch, Danaus plexippus and queen, Danaus gilippus, butterflies. Our results indicate that oocysts of the Mattesia sp. were always located within the hemocoel of their ant hosts. Oocysts were distributed throughout the head, thorax and abdomen, and thousands of oocysts were observed surrounding the brain of infected ants. In contrast, oocysts of O. elektroscirrha were distributed on the surface of the abdomen, inside the aedeagus of male and within the vulva, ductus bursary and ovipore of female monarch and queen butterflies. Importantly, no oocysts were ever embedded in the cuticle of queen butterflies, however oocysts were commonly embedded in the cuticle of female monarch butterflies. These observations may be important as previous studies indicate that female monarchs lose weight at a faster rate than uninfected monarchs; suggesting O. elektroscirrha infections may increase the rate of water loss through the cuticle. It is currently unclear what effects, if any, the occurrence of Mattesia sp. oocysts surrounding the brain of infected fire ants may have on ant fitness or behavior.
