The influence of the juvenile hormone analogue (S)-hydroprene on Aprostocetus hagenowii (Hymenoptera: Eulophidae), an oothecal parasitoid of the oriental cockroach Blatta orientalis (Dictyoptera: Blattidae)

The synthetic juvenile hormone analogue (S)-hydroprene can control populations of the oriental cockroach Blatta orientalis Linnaeus. Eradication of B. orientalis infestations, however, can take in excess of two years. In an attempt to reduce the time (S)-hydroprene takes to eliminate a population of oriental cockroaches, we explored the possibility of using the oothecal endoparasitoid Aprostocetus hagenowii Ratzeburg in combination with (S)-hydroprene. For such a strategy to be successful, it is important that the parasitoid remains substantially unaffected by (S)-hydroprene. When A. hagenowii was exposed to B. orientalis oothecae in the presence of (S)-hydroprene, female parasitoids showed no reduction in their capacity to attack hosts and their fecundity was not compromised. (S)-hydroprene, at dose rates of 18 mg/m and 100 mg/m, induced deformity in approximately 12% and 33% respectively of parasitoids that emerged. No reduction in reproductive viability was seen in morphologically normal F1 parasitoids. Deformed F1 parasitoids, exposed to the higher (S)-hydroprene dose, showed a 71% reduction in the number of oothecae attacked and a 50% reduction in the number of offspring produced. These results indicate that A. hagenowii could be used in combination with (S)-hydroprene in an integrated pest management programme against B. orientalis.