Volatile Infochemicals from Rhyzopertha dominica Larvae and Larval Feces Involved in Theocolax elegans Host Habitat Location

Abstract

The development of biologically based approaches for stored product pest control is needed to reduce chemical inputs. Bioassays were performed to investigate host habitat location in the trophic interaction durum wheat/Rhyzopertha dominica/Theocolax elegans. GC-MS analyses were carried out to identify some chemical compounds produced by the host-related substrates. Choice and no-choice experiments demonstrated that female parasitoids were poorly attracted to intact kernels with respect to the infested substrates. Furthermore, T. elegans females performed longer residence time on infested wheat, and they generally displayed a short-term like fidelity for this cue, remaining on it during the whole observation. Infested wheat emitted one chemical (fenchone), which is possibly linked to host larvae presence, while the feces produced by host larvae emitted some other characteristic compounds. Results demonstrated that the presence of host larvae is a key factor for T. elegans host habitat location, considering that the attractiveness of the undamaged wheat is irrelevant. Furthermore, parasitoid females tended to stay on attractive cues, limiting the risk of contamination of other commodities. Biological control tools may be useful to improve the efficiency of pest management programs, but their application should be carefully evaluated.

The power of poop: Defecation behaviors and social hygiene in insects

“…Several species of caterpillars, which live in stationary leaf shelters, have also evolved behaviors such as “ballistic frass ejection,” shooting fecal pellets ( Fig 1 ) to remarkable distances, successfully avoiding accumulation of fecal material and subsequent need for removal [ 3 ]. While feces avoidance mostly seems to benefit invertebrates by preventing disease, it is not the only benefit—predatory and parasitic wasps seem to have the ability to use volatile chemicals from frass to locate their host species [ 4 , 5 ], and some lepidopteran and coleopteran species have shown oviposition avoidance in areas that have been treated with feces-associated volatiles of their own species and that of others, potentially saving their offspring from future competition [ 6 , 7 ].…”