Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/1997
Publication Date: N/A
Citation: Interpretive Summary: The polka dot wasp moth, Syntomeida epilais (Walker), is a major pest of oleander, a flowering ornamental shrub that is grown throughout much of Florida. A parasitic fly, Lespesia aletiae (Riley), attacks this and other lepidopterous pest insects. Scientists at the Insect Attractants, Behavior and Basic Biology Research Laboratory in Gainesville, Florida, in collaboration with the Department of Entomology and Nematology, University of Florida, evaluated the use of fall armyworm as a host for laboratory rearing and compared parasite development in fall armyworm versus polka dot wasp moth caterpillars. Lespesia aletiae adults obtained from polka dot wasp moth caterpillars readily oviposited on fall armyworms and fall armyworms appeared to be better host for the development of the immature stages of this parasitoid. Parasitoid developmental times were shorter, and both percent parasitism and parasitoid survival were higher in fall armyworms than in S. epilais. This research indicates that this parasitoid may be laboratory-reared and could provide an environmentally safe tool for the control of the immature stages of fall armyworm, polka dot wasp moth and other pest lepidopterans.
Technical Abstract: The tachinid Lespesia aletiae (Riley) was obtained from parasitized larvae of Syntomeida epilais (Walker), which is an arctiid pest of oleander, Nerium oleander (L.). Development of L. aletiae in fifth and sixth instars of S. epilais and of a noctuid, the fall armyworm, Spodoptera frugiperda (Smith) was determined in laboratory studies. Female L. aletiae flies lived an average of 23.9 d., 14 days longer than males, and were observed to oviposit membranous eggs directly on the host body. First instars cut their way out of the egg and into the host within 2 min of oviposition. The percent parasitism in laboratory assays ranged from 36% in fifth instar S. epilais to 65% in sixth instar fall armyworms. Puparial size was found to increase with increasing host instar and to decrease with increasing number of maggots per host. The time between exposure to parasitoids and host death was longer in fifth than sixth instars of the same host, and was significantly longer in fifth instars S. epilais than in any of the other host instar/species combination tested. The parasitoid puparial stage was approximately one day longer for females than it was for males. Both the fifth and sixth instars of the fall armyworm and S. epilais were suitable for the parasitoid's development. However, parasitism and parasitoid survival were higher in parasitized fall armyworms.