Cytochrome P450 monooxygenase activity levels in phytoplasma-infected and uninfected Amplicephalus curtulus (Hemiptera: Cicadellidae): possible implications of phytoplasma infections

The process of pass-through and multiplication of phytoplasma in host-insect tissues could cause some pathogenic effects in insect vectors and may increase the susceptibility to some insecticides. We propose that ‘Candidatus phytoplasma ulmi'-infected Amplicephalus curtulus had reduced cytochrome P450 (P450s) activity compared with uninfected leafhoppers. P450s activity and phytoplasmas were quantified in adult A. curtulus at 25, 35 and 45 days after the access acquisition period (AAP) in the head-thorax and abdomen sections. Real-time PCR analysis showed that 67 and 78 % of insect samples were positive to phytoplasma at 35 and 45 days after the AAP, respectively. None of the samples tested positive to phytoplasma at 25 days after the AAP. P450s activity did not change at 35 days of incubation, but 45 days after the AAP, the enzymatic activity remained 112 % higher in phytoplasma-infected than in noninfected leafhoppers. P450s activity in the abdomen and head-thorax sections in phytoplasma-infected leafhoppers was 28 and 81 % more than in uninfected leafhoppers, respectively. Females had a higher concentration of phytoplasma than males, with 38 % more in the abdomen than in the head-thorax section. These results indicate that infection with ‘Ca. Phytoplasma ulmi' alters A. curtulus P450s activity because of phytoplasma invasion in the host, and it is recognized as probably being an exogenous agent for a specific time period in the life of the insect vector.