First Observation of Egg Sac Predation of the Mantisfly, Mantispa interrupta (Neuroptera, Mantispidae) upon the Wolf Spider, Gladicosa gulosa (Araneae, Lycosidae)

Abstract

Although adult mantisflies of the subfamily Mantispinae prey upon a variety of insect species, during the larval stage they are obligate predators of spider eggs (Redborg and MacLeod, 1985; Hoffman and Brushwein, 1989). The mobile, campodeiform larvae gain entrance to spider egg sacs by either directly burrowing into an egg sac, or by boarding a female spider and entering the egg sac as it is being produced. Some species (Mantispa viridis Walker) are obligate egg sac penetrators, whereas others, such as Mantispa sayi Banks, can utilize both methods (Redborg and MacLeod, 1985). Inside the egg sac, the larva passes through three instars and transforms into a pupa. The pharate adult then emerges from both the pupal case and the spider egg sac. Soon after emergence it sheds one more time, transforming into a fully functional adult mantisfly (Hoffman and Brushwein, 1990). On 8 March 1997, a female Gladicosa gulosa (Walckenaer) (Araneae, Lycosidae) was captured in a mesic woodland on the Red Buffalo Ranch, in Chautauqua County, Kansas. The spider was maintained at room temperature in a laboratory of the Department of Entomology, University of Kansas. An egg sac was produced on 15 March, and a pharate adult Mantispa interrupta Say emerged at sunset on 17 April. Within an hour, it shed to the adult stage. No live spiderlings occurred in the egg sac after the mantispid's emergence. Instead of characteristically carrying the egg sac attached to her spinnerets, the female wolf spider ignored her egg sac for approximately one week prior to the mantispid's emergence. The emergence of the mantispid at sunset is consistent with Brushwein's observations of the emergence of M. interrupta between 1900 and 2200 hours EST (Brushwein, Culin, and Hoffman, 1995). Spider host associations for Mantispa interrupta have been summarized by Hoffman and Brushwein (1990). A laboratory study by Viets (1941) first demonstrated M. interrupta larvae boarding a female lycosid and the subsequent emergence of an adult mantisfly from the spider's egg sac. Pharate adults of M. interrupta have been recorded emerging from egg sacs of: Gnaphosa muscorum (C. L. Koch) (Gnaphosidae) (Kaston, 1940), Rabidosa rabida (Walckenaer) [reported as Lycosa rabida Walckenaer] (Lycosidae) (Rice, 1985), Eris militaris (Hentz) [reported as Philaeus militaris (Hentz)]