Provisioning predatory mites with entomopathogenic fungi or pollen improves biological control of a greenhouse psyllid pest

Effects of the entomopathogenic fungus Clonostachys rosea on mortality rates and gene expression profiles in Diaphorina citri adults

Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a serious pest of citrus. The insect also transmits Candidatus Liberibacter asiaticus, the pathogen of a devastating citrus disease called Huanglongbing. Clonostachys rosea is a versatile fungus that possesses nematicidal and insecticidal activities. The effect of C. rosea against D. citri remains unclear. Here we examined the pathogenicity of C. rosea against D. citri adults. A mortality rate of 46.67% was observed in adults treated with 1 × 10⁸ conidia/mL spore suspension. Comparative transcriptomic analyses identified 259 differentially-expressed genes (DEGs) between controls and samples treated with fungi. Among the DEGs, 183 were up-regulated and 76 down-regulated. Genes with altered expression included those involved in immunity, apoptosis and cuticle formation. Our preliminary observation indicated that C. rosea is virulent against ACP adults and has the potential as a biological control agent for ACP management in the field.

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.

Deleterious effects of electron beam irradiation on development and reproduction of tomato/potato psyllids, Bactericera cockerelli

The potato/tomato psyllid Bactericera cockerelli causes serious damage to several solanaceous crops by direct feeding and vectoring Candidatus Liberibacter solanacearum, a bacterial pathogen. Electron beam (eBeam) irradiation is an environmentally friendly, chemical-free alternative method that is increasing in use for disinfestation of insect pests. We hypothesize that this irradiation technology will have detrimental effects on potato psyllid and thus impede its disease vectoring. To this end, we explored the effects of eBeam treatment ranging from 50 to 500 Gy on survival, development and reproduction of this pest. Impact on psyllids was apparently dose-dependent. When irradiated at 350 Gy, eggs could not hatch, 1st instar nymphs failed to emerge, and although a small portion of irradiated 5th instar nymphs survived, the emerged adults were mostly deformed. Abnormality in eclosed adults suggests harmful effects of eBeam on metamorphosis. Reproduction was seriously impaired when female psyllids were exposed to eBeam at the 5th instar nymphal or young adult stage, presumably due to inability to form oocytes. In addition, reciprocal crosses between irradiated and untreated psyllids indicated that female psyllids were more radiosensitive than males to eBeam. Taken together, these findings indicate that eBeam negatively impacted potato psyllid development and reproduction, which would inevitably compromise its disease transmission capacity. A dose of 350 Gy can be considered as a reference dose for effective control of potato psyllids.