Location: Beneficial Insects Introduction Research Unit
Project Number: 8010-22000-031-094-I
Project Type: Interagency Reimbursable Agreement
Start Date: May 1, 2024
End Date: Sep 30, 2025
Objective:
The goal of this agreement is to continually evaluate D. sinicus. This will be done in close collaboration with APHIS, University of Delaware (UD) project partners, and collaborators in China.
Objective 1. Quarantine evaluations of SLF parasitoids collected in China.
Approach:
This includes (1) rearing and maintaining a colony of D. sinicus, (2) developing and improving simple rearing methods; (3) running quarantine assays to evaluate various aspects of the parasitoid reproductive biology, host age preference, and foraging efficiency; (4) providing APHIS cooperators with non-target stinkbugs; (5) and supporting and assisting UD cooperators to complete studies of SLF parasitoids in our quarantine.
This study will investigate the parasitoid’s reproductive biology. Newly emerged male and female wasps will be paired. Each pair will be provided with honey + nymphs (10-15 first instar and 10-15 second instar every 2-3 days) until the female is died (20 replicates). All exposed hosts will be examined for oviposition or feeding, and all parasitized hosts (pool from the same week exposure) will be reared separately for each instar on potted plants in small cage (also, separately rear parasitized hosts with different number of eggs for each instar) (developmental time on each instar will be precisely measured from the second study). We will record the longevity of male and female adults, number and sex of formed cocoons or emerged wasps. All dead females will be dissected to measure their body sizes (hind tibia length) and residual mature eggs. In another set (depend on the availability of wasps and nymphs), newly emerged males and females will be housed for 24h for mating and each female will be provided with (1) honey only; and (2) honey + nymphs (10 or 15 first instars every 2-3 days) in small deli container. Female wasps will be dissected at different times post-emergence (5, 10, 20 days) or until they have died to determine the number of mature eggs (also measured for the body size). All exposed first instar will be checked for oviposition or host feeding and all parasitized hosts will also be reared in potted trees as procedures 3&4).
ARS will determine host stage preference and suitability. There will be three treatments: (1) choice test with experienced females; (2) choice test with unexperienced females and (3) no choice test. Body size of female wasp likely affects the host stage selection. For the test, each female wasp will be exposed to (a) two nymphs of each 1st, 2nd and 3rd instars simultaneously (choice test) or (b) 6 nymphs of either 1st, 2nd, or 3rd instar alone (no-choice test) in one container with one TOH leaf for 1h at 20 C (n =20). For the choice test, testing females are either naïve or experienced by providing each with 10 first instar nymphs for 24h prior to the test. All exposed nymphs will be examined for the oviposition or host feeding. All parasitized nymphs will be reared separately for each instar on a potted plant in a small cage at 20 °C. We will record the offspring survival and developmental time (for various stages), sex of all emerged wasps, and measure the body size of a sub-sample (at least 10) of emerged female wasps from different instars and superparasitized hosts. We will collect extra data especially for the survival and fitness on different instars and superparasitized hosts.
