Yolanda Lehner

Pesticides and honey bees: nectar and pollen contamination in alfalfa treated with dimethoate.

Medicago sativa L. (Leguminosae) sprayed withO,O-dimethylS-(N-methylcarbamoylmethyl) phosphorodithioate (dimethoate) had only 0.5 ppm of dimethoate in pollen one day later, but 3 ppm in nectar one week later, and 1 ppm in nectar two weeks later. As little as 1 ppm added to syrup fed to caged workers ofApis mellifera L. (Apidae) inhibited cholinesterase and reduced survival. Bees given a choice between treated and untreated syrups showed no preference; this suggests that the levels of dimethoate found in nectar are toxic and not repellent.

Free amino acids in thoraces of flown honey bees, Apis mellifera L. (Hymenoptera: Apidae)

Abstract 1. 1. The free amino acids were compared in the thoraces of flown and unflown honey bees, Apis mellifera L. Both workers and drones were tested. 2. 2. The amino acids showed little change with flight detectable by thin-layer chromatography on silica gel. By spectrophotometric analysis, a slight depletion in proline content with flight was observed. 3. 3. Evidently, proline is a minor source of flight energy in bees fed sucrose.

24-methylenepollinastanol and 24-dehydropollinastanol—two sterols of pollen

Abstract The esterified and unesterified sterol fractions of bee-gathered mixed pollens were examined, and total sterol composition was determined. Two new sterols of pollens, 14α-methyl-9β,19-cyclo-5α-cholest-24-en-3β-ol (24-dehydropollinastanol) and 14α-methyl-5α-ergost-24(28)-en-3β-ol (24-methylenepollinastanol) were isolated and identified. Both sterols were found primarily in the esterified sterol fraction, and 24-methylenepollinastanol accounted for 43% of the sterols of this fraction. 24-Dehydropollinastanol and four other sterols which also contain a 9β,19-cyclopropane ring were found only in the esterified sterol fraction. 24-Methylenecholesterol was the major sterol of the unesterified sterol fraction.

The Constancy of Cholinesterase Activity in Adult Honeybees

SummaryAlthough published data show the Cholinesterase level in adult worker honeybees found in hives to be more than double that in foraging honeybees, no significant change with age or activity was found when bees from indoor cages or free-flying outdoor colonies were assayed. It is concluded that when Cholinesterase levels are only half normal, poisoning of the bees should be suspected.

Pesticides and Honey Bees: The Danger of Microencapsulated Formulations

Abstract Microcapsules designed to improve the safety and persistence of pesticides are about the same size as pollen. Foraging bees collect pollen contaminated with such microcapsules and pack both together into hive combs. Sustained release formulations remain toxic in food stores of the colony. This combination of accumulation and persistence produces prolonged toxicity for bee colonies.