The persistence and residual contact toxicity of foliar dislodgeable
emamectin benzoate residues to
Apis
mellifera (L.) and Diglyphus
isaea (Walker) were studied following applications to foliage
at
maximum anticipated labeled use rate (0.0168 kg of active
ingredient/ha). Bee mortality from contact
exposure to dislodgeable alfalfa residues aged for 3, 8, and 24 h was
100, 46, and 3%, respectively.
This contact toxicity was directly correlated with the magnitude
of dislodgeable residues (9.1, 3.6,
and 1.3 ng/cm2, respectively), with a dissipation half-life
of about 10 h. Similarly, D. isaea
mortality
from contact exposure to dislodgeable residues aged for 0.5, 1.0, 3.5,
35, and 60 h was 75, 65, 50,
20, and 15%, respectively; these residues (5.2, 5.0, 4.5, 1.4, and
<0.2 ng/cm2, respectively) had a
dissipation half-life of about 15 h. Therefore, these beneficial
insects are expected to survive and
colonize treated crops within relatively short intervals (≤24 h) after
applications of emamectin
benzoate.
Keywords: Avermectin; foliar dislodgeable residues; beneficial insects;
residual contact toxicity;
emamectin benzoate
