Respiratory Pore Construction in the Host by the Nemestrinid Parasite Neorhynchocephalus sackenii (Diptera), With Notes on Respiratory Tube Characters

Abstract

After penetrating the grasshopper host in the unsclerotized tissue just below the rows of spiracles, the parasitic larva punctures and enters the main tracheal trunks, wandering there and feeding on the inner surface for about 2 days. It then punctures the trachea again to make a partial exit just under the host's integument, through which it cuts its respiratory pore while still maintaining contact with the host's spiracular trachea, usually in an abdominal segment. Upon completion of the pore, the larva severs connection with the trachea, and, reversing its position, brings its metapneustic spiracles to the pore, which it plugs with the posterior end of its body. The respiratory tube which then begins to develop maintains the larva's contact with the pore as the parasite moves deep into the host's body cavity. When artificially parasitized hosts molted, the parasite's respiratory pore and tube were shed with the exuviae, and new ones were developed which differed in manner of formation, appearance, and position. Another North American nemestrinid, Trichopsidea clausa, makes no external pore but attaches its respiratory tube to the host's spiracular tracheae, usually in the first abdominal segment. The African T. (Symmictus) flavopilosa, parasitic in a much larger grasshopper, makes its pore within 1 mm. of the host's mesothoracic spiracle and develops respiratory tubes that may be twice as long as the larvae themselves.