Manure preferences and postemergence learning of two filth fly parasitoids, Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae)

Authors: TAYLOR, CAITLIN - University Of Florida; Machtinger, Erika; Geden, Christopher - Chris

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2016
Publication Date: 12/9/2016
Citation: Taylor, C.E., Machtinger, E.T., Geden, C.J. 2016. Manure preferences and postemergence learning of two filth fly parasitoids, Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae). PLoS One. 11(12):e0167893.

Interpretive Summary: House flies and stable flies are important pests associated with animals and humans and transmit many disease organisms. Biological control is an important element in successful fly management, and commercially available pupal parasitoids can kill these flies. Though previous research has shown that parasitoids are capable of learning from their environment after emergence as an adult, it is unknown if two common pupal parasitoids, Spalangia cameroni and Muscidifurax raptor, change habitat preferences for seeking pest fly pupae to parasitize based on their postemergence experience. In this study, conducted by scientists at the University of Florida and the USDA’s Center for Medical, Agricultural and Veterinary Entomology (Gainesville, FL), S. cameroni and M. raptor were exposed to host puparia in manures from horses and cattle, as well as clean puparia with no manure as they emerged as adults. They were then given a period of time to seek hosts provided in either manure, or without manure, and produce offspring. The results demonstrate that after postemergence exposure to different animal manures, these parasitoids did not significantly change preferences for microhabitats were offspring were produced, potentially suggesting somewhat innate microhabitat preferences.

Technical Abstract: The efficiency of host-seeking behavior is a crucial determinant of the reproductive performance of female parasitoids. Initially, parasitoids may use chemical information generated from the microhabitat in which they emerge to locate hosts. Spalangia cameroni and Muscidifurax raptor are commercially available parasitoids of filth flies, including house flies and biting stable flies. Postemergence exposure to manure may provide a way to increase parasitism in specific microhabitats upon release. In this study, female parasitoids of both species were exposed to equine manure, bovine manure, or clean pupae before releasing in an arena. Females from each emergence exposure were tested in choice experiences for progeny production in hosts located in bovine manure verses clean pupae, equine manure verses clean pupae, and equine manure verse bovine manure. There was no effect of postemergence exposure on S. cameroni. Females consistently produced more progeny in hosts found in manure over clean pupae, and in equine manure over bovine manure. The effect of postemergence exposure eon M. raptor was minimal with females producing equal numbers of progeny in bovine manure verses clean manure, as opposed to preferring to oviposit in clean manure as with all other treatments. Residual host mortality was moderately altered by exposure in both species. After postemergence exposure to different animal manures, these parasitoids were fairly inflexible to producing progeny in different manures, potentially suggesting innate microhabitat preferences. It does not appear as though postemergence exposure would increase host-seeking in specific microhabitats in the field, however more research is needed on the host-seeking behavior and interaction of these, and other commonly used pupal parasitoids of filth flies.