Novel transinfections of Rickettsiella do not affect insecticide tolerance in Myzus persicae, Rhopalosiphum padi, or Diuraphis noxia (Hemiptera: Aphididae).

Aphids (Hemiptera: Aphidoidea) are economically important crop pests worldwide. Because of growing issues with insecticide resistance and environmental contamination by insecticides, alternate methods are being explored to provide aphid control. Aphids contain endosymbiotic bacteria that affect host fitness and could be targeted as potential biocontrol agents, but such novel strategies should not impact the effectiveness of traditional chemical control. In this work, we used a novel endosymbiont transinfection to examine the impact of the endosymbiont Rickettsiella viridis on chemical tolerance in 3 important agricultural pest species of aphid: Myzus persicae (Sulzer) (Hemiptera: Aphididae), Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphididae), and Diuraphis noxia (Mordvilko ex Kurdjumov) (Hemiptera: Aphididae). We tested tolerance to the commonly used insecticides alpha-cypermethrin, bifenthrin, and pirimicarb using a leaf-dip bioassay. We found no observed effect of this novel endosymbiont transinfection on chemical tolerance, suggesting that the strain of Rickettsiella tested here could be used as a biocontrol agent without affecting sensitivity to insecticides. This may allow Rickettsiella transinfections to be used in combination with chemical applications for pest control. The impacts of other endosymbionts on insecticide tolerance should be considered, along with tests on multiple aphid clones with different inherent levels of chemical tolerance.