Septic Infection Experiment
Given the impact of infection route on immune gene expression , we
wanted to clarify whether the interaction between pesticides and
infection outcomes might be infection route-dependent. We selected two
populations, Coffee and Dorris, as representative populations that may
demonstrate interactions between pesticide resistance and exposure on
infection outcomes. Therefore, we exposed 14-day old larvae from
control- and OP-regimes to control and OP oral diets (as described
above) for three days, and then septically infected individuals withBtt and recorded their survival.
We produced a mixture of Btt cultures of vegetative cells from
both the logistic growth and early stationary phase for septic
infections as previously described , which caused around 50% mortality
in preliminary experiments. We pricked larvae laterally between the head
and second segment with an ultra-fine borosilicate needle dipped in the
bacterial suspension and recorded survival after 24 hours. We repeated
the experiment three times with 20 individuals per population (Coffee or
Dorris), selection regime (OP selected and control) and pesticide
treatment (OP exposure and control) each (n = 480).
Differences in survival between the control group (control selection
regime, no pesticide) and the other groups were analyzed in a GLMM with
experiment (block) and population as random factors and a binomial error
distribution .