Increased sensitivity of honey bees to ivermectin (1ug/ml) following oral exposure to standard and tested inhibitors (1mM) and LC50 of ivermectin following treatment of bees with 1 mM inhibitor solution.

<p>All inhibitor + ivermectin treatments had significantly higher mean mortality than the ivermectin treatment (p < 0.0001).</p

Mortality of honey bees (24 h ±SE) pretreated with a series of concentrations of candidate inhibitors.

<p>Bees were fed verapamil, quercetin, fumagillin or Pristine before and during oral exposure to 1 μg/ml ivermectin.</p

Transporter function assays.

<p>Bees treated with a series of dosages of the MDR transporter-inhibitor verapamil before and after ingestion of the fluorescent substrate Rhodamine B solution, and assayed at two times (24 and 48 h post ingestion) show greater fluorescence at increased verapamil concentrations in both tissues.</p

Mean 24 h mortality (±SE) of honey bees fed 1 μg/ml ivermectin treated with low concentrations of inhibitors.

<p>Bees fed Pristine (Prist), quercetin (Querc), fumagillin (Fumag) and verapamil (Verap) in sucrose syrup. All inhibitor/doses shown had significantly greater mortality than the ivermectin-only control (P < 0.002).</p