Predators and Parasitoids-in-First: From Inundative Releases to Preventative Biological Control in Greenhouse Crops

Repeated mass introductions of natural enemies have been widely used as a biological control strategy in greenhouse systems when the resident population of natural enemies is insufficient to suppress the pests. As an alternative strategy, supporting the establishment and population development of beneficials can be more effective and economical. The preventative establishment of predators and parasitoids, before the arrival of pests, has become a key element to the success of biological control programs. This “Predators and parasitoids-in-first” strategy is used both in Inoculative Biological Control (IBC), and in Conservation Biological Control (CBC). Here, we provide an overview of tools used to boost resident populations of biocontrol agents.

Number of attacks by Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae) affects the successful parasitism of Ostrinia furnacalis (Lepidoptera: Crambidae) eggs

In laboratories, the parasitism rate of Ostrinia furnacalis (Güenée) (Lepidoptera: Crambidae) eggs by Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) is low; however, efforts to control O. furnacalis with T. dendrolimi in the field have been successful. In this study, the effects of the number of attacks by T. dendrolimi against O. furnacalis eggs and diet of O. furnacalis larva on wasp development were investigated. The results indicated that more attacks increased significantly not only the successful parasitism rate of O. furnacalis eggs by T. dendrolimi, but also the percentage of host eggs that failed to develop into either O. furnacalis larvae or T. dendrolimi. Both the size and female proportion of T. dendrolimi offspring decreased as the number of attacks increased. The number of T. dendrolimi eggs laid in per host egg increased significantly as the ratio of wasps to host eggs increased from 1:5 to 3:5. Host diet also significantly affected the developmental time of immaturity and the emergence rate of adults of T. dendrolimi. These results illustrate how inundative releases of T. dendrolimi can successfully control O. furnacalis despite the fact that pest parasitism by the subsequent wasp generation decreases sharply in the field. The suitability of O. furnacalis eggs to T. dendrolimi and the superparasitism effects on offspring of T. dendrolimi are discussed.

First report of pupal parasitoids of filth-breeding flies (Diptera) from bovine manure in northeastern Mexico

A total of 2702 individuals representing nine species of Pteromalidae (Chalcidoidea) plus at least one species of Diapriidae, Trichopria haematobiae (Ashmead) (Diaprioidea), were reared as pupal parasitoids of filth-breeding flies in bovine manure during a 2-year study in northern Tamaulipas, Mexico. The Pteromalidae included two undescribed species of Spalangia Latreille plus Spalangia cameroni Perkins, S. drosophilae Ashmead, S. endius Walker, S. nigroaenea Curtis, Muscidifurax raptor Girault and Sanders, M. zaraptor Kogan and Legner, and Pachycrepoideus vindemiae (Rondani). Spalangia nigroaenea accounted for 71% of all the pupal parasitoids and all six Spalangia species for 94% of the parasitoids over the 2 years. Based on its preponderance, S. nigroaenea is recommended as a candidate for inundative releases within integrated pest management programs to help control fly pests of cattle in northeastern Mexico.