Crude Extracts and Alkaloids Derived from Symbiotic Association Cause Mortality of Asian Citrus Psyllid Kuwayama (Hemiptera: Psyllidae).

Asian citrus psyllid Kuwayama (Hemiptera: Psyllidae) is an important economic pest of citrus crops because it vectors the causal pathogen of huanglongbing (HLB; aka citrus greening). Population suppression of with insecticides has been disproportionally relied on for HLB management and a greater diversity of more sustainable tools is needed. spp. is a fungal endosymbiont (family Clavicipitaceae) that forms a mutualistic relationship with members of plants in family Convolvulaceae. This association results in the production of ergot alkaloids that were previously documented as having psyllicidal properties. We investigated the mortality and behavior of exposed to crude extracts from morning glories in the plant family Convolvulaceae, as well as synthetic ergot alkaloids. Nymphs and adults were exposed to the crude plant extracts from positive species of Convolvulaceae, as well as five synthetic ergot alkaloids. Treatments were prepared by exposing clippings of citrus to 100 ng/µL of crude extract from -positive species of (, , and ), and , and from one -negative species () (100 ng/µL). Mortality of adult and nymphal was significantly higher than the control after exposure to extracts from and . The synthetic ergot alkaloids, lysergol (10-100 ng/µL), ergonovine maleate (100 ng/µL), agroclavine (10-100 ng/µL), and ergosine (10-100 ng/µL) increased mortality of nymphs, while ergosine (100 ng/µL) and agroclavine (100 ng/µL) increased mortality of adults compared to water controls. Fewer adults settled on plants treated with crude extracts or synthetic ergot alkaloids than on water controls at 48 h after release. that fed on citrus leaves treated with 10 ng/μL solution of crude extract from the -positive species (, , , , and excreted significantly less honeydew compared with a negative water control and extract from -negative species (). Our results indicate that crude extracts and ergot alkaloids exhibit toxic and sub-lethal effects on that could be useful for management of this pest.