First off, systemic seed treatments are hardly a new thing:
Since the late 1940s, and perhaps even earlier, pesticidal compositions to
treat seeds prior to planting, for the control of certain fungi as well as soil insects, have
been developed and manufactured. Until the late 1960s, organo-mercury compounds
dominated the seed treatment field, especially in the treatment of cereals (wheat. barley,
etc.). With the banning of organo-mercury compounds for seed treatment use by various
governments throughout the world, a new breed of fungicidal compounds was developed
for treating seed, with many of these having systemic properties. This paper describes
briefly a protocol for the development of seed treatment formulations which has been used
successfully by the author over the last 15 years. The protocol outlines the desirable physical
and chemical properties of these types of pesticide formulations as well as laboratory
storage and field tests which it is felt are required.
REFERENCE: Halliday, C. G., "Seed Treatment Formulations: Denlopment of a Protocol,"
Pesticide Formulations and Application Systems: Fourth Symposium, (1985)
* * *
The potential of seed treatments to harm bees was looked into well before the media blitz and by the well-respected honey bee biologist Mark Winston:
Recently developed insect control techniques, such as genetically modified crops with insecticidal proteins and systemic chemical seed and soil treatments, are often safer for nontarget species than broad-spectrum insecticidal sprays (Betz et al. 2000). However, potential harm could come to pollinators if the insecticide is expressed in or transported to pollen or nectar.
In 1999, the French Ministry of Agriculture suspended use of the imidacloprid product Gaucho on sunflower crops because of a suspected relationship between honey bee losses and imidacloprid use. Analyses of residue levels of imidacloprid in canola and sunflower pollen have shown levels always less than 8 ppb, and usually at undetectable quantities below one ppb.
Two experiments were conducted testing for lethal and sublethal effects of the transgenic proteins Cry1Ac and chitinase, and the chemical seed and soil treatment imidacloprid on bumble bees (Bombus occidentalis Greene and B. impatiens Cresson, Hymenoptera: Apidae). Colonies were received on 18 May 2001 and monitored until 8 August 2001.
In the first experiment, B. occidentalis colonies were exposed to realistic residue levels of Cry1Ac, chitinase, and imidacloprid found in pollen. There were no effects on pollen consumption, bumble bee worker weights, colony size, amount of brood, or the number of queens and males produced.
In the second experiment, using B. impatiens, we tested the effects of Cry1Ac and two levels of imidacloprid. Similar colony health measures were collected as in the first experiment, but in addition foraging ability of individual bees was tested on complex artificial flowers. There were no differences in colony characteristics among treatments.
No lethal, sublethal colony, or individual foraging effects of these novel pesticides were found at residue levels found in the field, suggesting that bumble bee colonies will not be harmed by proper use of these pesticides.
The conclusion of our study suggests that levels of imidacloprid at or below 7 ppb in pollen will not harm bumble bee colony health or foraging ability, whereas concentrations of 30 ppb, approximately four times the highest residue level recorded in any study to date, may have sublethal effects on foraging.
Effects of Novel Pesticides on Bumble Bee (Hymenoptera: Apidae) Colony Health and Foraging Ability
LORA A. MORANDIN AND MARK L. WINSTON
Environ. Entomol. 32(3): 555-563 (2003)
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