Right combination of host instar and parasitoid age optimizes mass production of Tamarixia lyciumi, the nymphal parasitoid of goji berry psyllid Bactericera gobica

Goji berries are widely renowned for their nutritional and medicinal properties and are typically sold as dried fruit for their long shelf-life. Tamarixia lyciumi Yang is a nymphal parasitoid of the psyllid Bactericera gobica Loginova, a destructive pest of goji berry plants. The use of T. lyciumi for rapid impact through inundative biological control is gaining more attention. Understanding the relationship between parasitoid efficiency and host instar or parasitoid age can help improve the mass production of T. lyciumi. Here, we examined the influences of B. gobica nymphal instar (3rd-, 4th-, and 5th-instar) and female T. lyciumi age (1-, 2-, 3-, and 4-day-old), and their interactions on the parasitism capacity, offspring performance, and host-handling time of T. lyciumi. As host instars increased, we observed a decrease in the proportions of parasitized psyllids, parasitoid emergence, and emerging female parasitoids, as well as an increase in the developmental time of parasitoid larvae. A higher parasitism capacity and a shorter larval development time were found in 3- and 4-day-old parasitoids compared to 1- and 2-day-old ones, while the proportions of parasitoid emergence and emerging female parasitoids were unaffected by parasitoid age. Host-handling time, including probing, drilling, oviposition, and total time, increased with host instars but decreased with parasitoid age. Thus, combining 3rd- and 4th-instar psyllid nymphs with 3- and 4-day-old parasitoids may optimize the mass production of T. lyciumi.