Egg-parasitoids

By means of an international project, Argentinian and Italian researchers are carrying out joint research to study biological and ecological aspects of Tuta absoluta biological control.
This paper lists indigenous natural enemies reported for T. absoluta, as well as the current results on T. absoluta egg and larval parasitoids in both countries. Parasitoid species that
conformed to different guilds are shown to coexist in cropping conditions, and some show positive characteristics as potential biocontrol agents against T. absoluta by means of augmentative
releases. Future laboratory and field evaluations of the efficacy of biological control programs in Argentina and Italy are proposed.

Emergence and survival of adults for 24 h was compared for Trichogramma chilonis Ishii reared on eggs of Corcyra cephalonica (Stainton) adults whose larval growth and development had been monitored on broken grains of four different cereals: finger millet (Eleusine coracana L. Gaertn),
soft white wheat (Triticum aestivum L), short-grained white rice (Oryza sativa L.), and durra sorghum (Sorghum bicolor L. Moench). For C. cephalonica, the percentage adult emergence and several fifth-instar food use indices (consumption index, relative growth rate, and efficiencies of conversion of ingested and digested food) were significantly higher for millet-reared than for sorghum-reared larvae. The nutritional indices for wheat- and rice-reared C. cephalonica larvae were intermediate
between the indices for larvae reared on millet and sorghum. The percentage adult emergence and percentage 24-h survival of T. chilonis were significantly higher on eggs of C. cephalonica hosts reared on millet than on eggs of those reared on sorghum. These results suggest that the rearing of
C. cephalonica larvae on a high-quality nutritional source resulted in high-quality eggs, which ultimately resulted in high-quality T. chilonis reared on those eggs. Such an effect has been modeled in ecological theory as a “bottom up cascade.” Improved knowledge of the nutritional ecology of parasitoids and hosts can lead to improved understanding of the ecological mechanisms affecting host plant, host, and parasitoid abundance, as well as to improved efficiency and quality of Trichogramma production in mass rearing programs.