Mean number of days taken by Bombus terrestris queens to undertake oviposition during pulsed exposure to dietary imidacloprid.

Oviposition occurred in standardised experimental colonies (queen and four workers) during either the 14-day ‘on dose’ period of pulsed exposure (during which bees fed on syrup dosed with dietary imidacloprid at the given concentration) or the subsequent 14-day ‘off dose’ period (when all imidacloprid dosages were removed from the bees' diet).

Oviposition did not occur during the ‘on dose’ period in colonies exposed at 98.4 ppb.