Gravid Periplaneta americana (Blattodea: Blattidae) Fails to Detect or Respond to the Presence of the Oothecal Parasitoid Aprostocetus hagenowii (Hymenoptera: Eulophidae)

Abstract

Several families of parasitic Hymenoptera have evolved traits that allow them to exploit cockroach oothecae. Cockroaches may bury and conceal their oothecae to prevent parasitoid attack. However, these protective measures require additional investment by females. We hypothesized that gravid cockroaches would reduce parental care in the absence of oothecal parasitoids and increase care when parasitoids were detected. Behavior bioassays consisted of glass jars containing a gravid American cockroach, Periplaneta americana (L.) (Blattodea: Blattidae), expanded polystyrene (EPS), and a dog food pellet. A fruit fly (Drosophila melanogaster Meigen) (Diptera: Drosophilidae) or parasitoid Aprostocetus hagenowii (Ratzburg) (Hymenoptera: Eulophidae) was added for the fly and parasitoid treatments, respectively. There was no significant difference among treatments in the proportion of oothecae buried or in mean cover of oothecae with EPS particles. Cover had no effect on parasitism success or failure. Electroantennogram (EAG) assays using P. americana antennae were also conducted. The EAG responses to dead parasitoid stimuli (0.111–0.124 mV) were significantly (p < 0.05) greater than the negative control, but responses to living parasitoid stimuli (0.075–0.089 mV) were nonsignificant. These findings suggest that burial and concealment of oothecae is a general defensive behavior employed regardless of the presence or absence of a natural enemy. The results also indicate that gravid P. americana are unable to detect, and therefore, differentiate A. hagenowii from other insects and that A. hagenowii can successfully locate and parasitize oothecae completely concealed with EPS particles.

Potential of the oothecal parasitoid Aprostocetus hagenowii (Hymenoptera: Eulophidae) as a biological control agent for the Turkestan cockroach (Blattodea: Blattidae)

“…Aprostocetus hagenowii wasps were obtained from Dr. Barry Pawson (PNE, Inc., Tipp City, OH; Retired), have been maintained at Auburn University since 2020, and were reared according to Smith et al (2022). The colony was held in 100 × 15 mm polystyrene Petri dishes on the oothecae of P. americana .…”

“…as well as B. orientalis , Eurycotis floridana (Walker), and Neostylopyga rhombifolia (Stoll) (Narasimham 1984, LeBeck 1991, Pawson and Gold 1993). This species is simple to rear under laboratory conditions, and its gregarious nature and high fecundity are conducive for mass rearing (Narasimham 1984, Smith et al 2022). Introduction of A. hagenowii can support immediate and long-term cockroach suppression as they actively seek out and destroy oothecae concealed in hard to access areas (e.g., wall voids and pipe chases) or within materials such as expanded polystyrene (Styrofoam) (Pawson and Gold 1993, Smith et al 2022).…”

“…This species is simple to rear under laboratory conditions, and its gregarious nature and high fecundity are conducive for mass rearing (Narasimham 1984, Smith et al 2022). Introduction of A. hagenowii can support immediate and long-term cockroach suppression as they actively seek out and destroy oothecae concealed in hard to access areas (e.g., wall voids and pipe chases) or within materials such as expanded polystyrene (Styrofoam) (Pawson and Gold 1993, Smith et al 2022). Furthermore, the presence of A. hagenowii appears to go unnoticed by cockroaches, and their use should not affect the responses of cockroaches to other treatment methods (e.g., baits, repellants, traps, etc.)…”

“…Furthermore, the presence of A. hagenowii appears to go unnoticed by cockroaches, and their use should not affect the responses of cockroaches to other treatment methods (e.g., baits, repellants, traps, etc.) (Smith et al 2022). Aprostocetus hagenowii may aid in B. lateralis management, but there has yet to be an investigation of whether this parasitoid can successfully utilize B. lateralis as a host.…”