Meanwhile, Kathirithamby observed Strepsiptera actually entering a host. She found that the first-instar infective larva of the Strepsiptera jabs itself between the outer shell and the skin of the host. Once the entire body has penetrated its layers, it remains in constant motion for 24 to 36 hours until it is enclosed by the host.
The host's skin forms a bag, which at this point is suspended by a thin stalk. Later, the larva develops into another stage and the stalk eventually pinches off from the overlying epidermal layer. The second-instar larva moves passively through the host, eventually residing into the abdomen. It goes through two more molts and develops into the fourth-instar larva, all the while deriving its nutrients from the host, Johnston said.
The female develops no further, except to harden an anterior portion (the cephalothorax), which squeezes out between abdominal segments and emits a male attractant.
The male develops within the ant, and the day it is to emerge, it elicits a strange behavior in its host: The ant will leave the colony and climb to the top of any grass or twig it encounters.
"I'd love to know how a pupae enclosed in a bag in the abdomen does that," Johnston said.
The short-lived male Strepsitera emerges from the ant, finds and mates with a female. She develops up to 800,000 eggs and lays live young, which emerge from the female to start the cycle all over again.
The research gets to a fundamental problem, Johnston said. "How does a parasite attack whether it is you or I or any other organism w
'"/>
Contact: Edith Chenault
e-chenault1@tamu.edu
979-845-2886
Texas A&M University - Agricultural Communications
8-Aug-2003