A New Spider Host Association for Ogcodes eugonatus (Loew) (Diptera, Acroceridae)

Abstract

Acrocerid flies are internal parasitoids of spiders during their larval stages (Schlinger, 1987). Females of Ogcodes species lay their eggs on or near the tips of dead twigs. Upon emergence the first-instar planidial larva either attaches itself to the substrate by means of a caudal disc and waits for a spider host, or actively searches for one. When a suitable host is encountered, the planidium attaches itself to one of the spider's legs, and usually progresses to the anterodorsal part of the abdomen. During this migration, however, the planidium moves only when the spider moves (Schlinger, 1960). To gain entry, the planidium makes a small hole in the host's body wall, enters, and migrates to and attaches to one of the book lungs. After a period of diapause, the planidium undergoes three larval molts and becomes an actively feeding, fourth instar larva which consumes most of the spider host. Members of the genus Ogcodes usually emerge from the epigastric furrow region of their respective spider hosts (Schlinger, 1987). On 26 April 1989, an immature female spider, Agelenopsis sp. (Agelenidae) was taken from a funnel web in a wooded area in Nashville, Davidson County, Tennessee. The spider died during early May and a yellow acrocerid larva was discovered on its web. An adult Ogcodes eugonatus (Loew) emerged from its pupal case several weeks later. 0. eugonatus is a widespread species found in scattered localities from southern Mexico to Canada, and from New York to California (Schlinger, 1960). It has been reared from eleven host species distributed among four spider families: Lycosidae (Pardosa banksi, P. distincta, P. milvina, P. sternalis), Oxyopidae (Oxyopes salticus), Thomisidae (Xysticus sp.) and Salticidae (Pellenes hallani, Phidippus johnsoni, P. principes, P. clarus, Sassacus sp.) (Schlinger, 1987). The current observation adds the family Agelenidae to this spider host list. Specimens were deposited in the University of Kansas Snow Entomological Museum.