Olfactory attraction of egg parasitoids to virgin females of noctuid stemborers

Abstract

To locate hosts, egg parasitoids rely on infochemicals of the adult host stage, e.g. pheromones, rather than cues emitted by the inconspicuous egg themselves. Here, we show that three different egg parasitoid species the scelionids Telenomus busseolae Gahan and Telenomus isis Polaszek and the trichogrammatid Trichogramma bournieri Pintureau & Babault were attracted to both calling and non-calling females of the noctuids Busseola fusca (Fuller), Sesamia calamistis (Hampson) and Sesamia nonagrioides (Lefebvre). In Y-tube olfactometer experiments this study revealed a preference of all three parasitoids for non-calling (general odors of virgin females) and calling moth (sex pheromone) over the control (clean air), and for calling over the non-calling moth. However, the three parasitoids were equally attracted to calling moth of B. fusca and S. calamistis indicating low host specificity. The findings indicated that all three parasitoids used the pheromones released by the calling moth in host finding. It is suggested that the low host specificity may affect egg parasitism of the target pest in crop fields.

Interspecific extrinsic and intrinsic competitive interactions in egg parasitoids

“…Interspecific competition between introduced and local parasitoid species should also be considered since it may affect the establishment, as well as the efficiency and efficacy of the parasitoids success (Agboka et al 2002). For example, a detailed study of the extrinsic and intrinsic competition between egg parasitoids of noctuid stemborers, especially between T. busseolae and T. isis, has been undertaken in order to evaluate the chance of establishment of T. isis in eastern Africa (Schulthess et al 2001;Agboka et al 2002;Fiaboe et al 2003;Bruce et al 2009). Whereas T. busseolae is widespread in Africa, T. isis is not present in East and South of Africa.…”

“…However, the differences in the interspecific extrinsic competition between egg parasitoids sharing a common host cannot always be explained in terms of host breadth specificity (Bruni et al 2000;Bruce et al 2009;Laumann et al 2009) and sometimes the generalist parasitoid species respond to kairomonal cues while the specialist one does not (Battisti 1989) Fatouros et al (2005aFatouros et al ( , 2005bFatouros et al ( , 2007Fatouros et al ( , 2008aFatouros et al ( , 2009 Thomson and Stinner (1990) ( Table 1). Laumann et al (2009) evaluated the response of the platygastrids T. podisi Ashmead and T. basalis towards the blends of volatiles released from the metathoracic glands of five adult stink bug host species.…”