Honeybees are not butterflies, of course. But given the lack of research about the possible effects of herbicides on bee brood, I thought this study of the effect of two herbicides on butterfly larvae might be worthy of note:
Journal of Insect Conservation
February 2010, Volume 14, Issue 1, pp 53-63
Date: 29 Apr 2009
Effects of grass-specific herbicides on butterflies: an experimental investigation to advance conservation efforts
Cheryl Russell, Cheryl B. Schultz
ABSTRACT
Encroachment by invasive plants is a leading threat to rare butterflies. Restoration plans increasingly recommend herbicides to control invasive plants within butterfly habitats. Few studies address the effects of these herbicides on at-risk butterflies. The effects of two graminicides (fluazifop-p-butyl and sethoxydim) and a surfactant (Preference®) were evaluated on Icaricia icarioides blackmorei and Pieris rapae. The effects on butterfly larvae were assessed by mimicking recommended timing and mixture rates of field applications. Differences in survival to adult eclosure, development time, biomass, sex ratio and adult morphology were assessed. Survival of P. rapae was reduced by 32% with sethoxydim and 21% with fluazifop-p-butyl. Wing size and pupal weights of P. rapae were reduced by herbicide treatments. Icaricia icarioides blackmorei experienced a 21% reduction in development time from the date of treatment to eclosure. These results highlight the importance of careful consideration in the use of herbicides in habitats harboring at-risk butterfly populations.
Similiar losses have been reported by the lobbyists in Germany. Interesting - did they really ban neonics in the UK? I just wonder, since this is new to me.
Published data indicate that in most cases there is_ no_difference in soybean yield when soybean seed was_treated with neonicotinoids versus not receiving_any insect control treatment. Furthermore,_neonicotinoid seed treatments as currently applied_are only bioactive in soybean_foliage for a period_within the first 3-4_weeks of planting, which does_not overlap with typical_periods of activity for some target pests of concern.[]
In most cases, these alternatives are comparable in cost to one another and to neonicotinoid seed treatments. The cost of application was considered in this comparison, although because these alternatives can be tank-mixed with other chemicals that are typically applied to soybeans, additional passes over a field would not be necessary. In comparison to the next best alternative pest control measures, neonicotinoid seed treatments likely provide $0 in benefits to growers and at most $6 per acre in benefits (i.e., a 0%-1.7% difference in net operating revenue). Some neonicotinoid seed treatment usage could provide an insurance benefit against sporadic and unpredictable pests, particularly in the southern United States. However, BEAD did not find information to support the real-world significance of this benefit, and overall evidence indicates that any such potential benefit is not likely to be large orwidespread in the United States.
Concern about the survival of the European honeybee has blossomed into a media frenzy during the past several years, with activists declaring, “Beepocalypse”! Beekeepers have seen see some of their honeybee hives disappear in recent years, and concerned observers have blamed the losses on everything from cell phones to genetically modified crops. The most frequently alleged culprit, though, is a class of pesticides known as neonicotinoids. But such alarmism is not supported by the facts.
Conclusions To our knowledge, this study is the first to examine the chronic sublethal effects on whole honey bee colonies subjected to worse-case scenarios as well as normal dietary exposure (5μg/kg) to imidacloprid. We used spiked diet patties placed within colonies to deliver continuous direct exposure over multiple brood cycles to imidacloprid residues that were generally higher than levels found in bee-collected pollen and nectar under field conditions. Our results provide evidence that imidacloprid exposure doses up to 100 μg/kg had no significant effects on foraging activity or colony performance during and shortly after 12 weeks of exposure. However, several colony performance endpoints showed dose-response patterns, particularly higher Varroa infestations with increased dose, though not all patterns were statistically significant. The major finding was the higher rates of queen replacement and resulting broodless periods during the late summer in colonies exposed to 20 and 100 μg/kg of imidacloprid, which led to weaker colonies going into the winter. These exposure regimes sublethally affected colony health and significantly reduced overwintering success. However, the question remains as to whether doses of 100 or even 20 μg/kg exposed for 12 continuous weeks realistically represent imidacloprid residues in bee-collected food under agriculture settings. In certain field situations, residues of imidacloprid can reach or exceed 100 μg/kg in pollen of treated crops during several weeks of flowering [35] or in guttation droplets exuded from treated corn seedlings [45,46]. However, it is uncommon for honey bees to be exposed to these doses for extended periods. Furthermore, bees generally forage on different water and floral sources simultaneously and not all sources will contain residues; thus their foraging behavior tends to reduce the concentration of imidacloprid in food stored in the colony. The within-hive fate experiment demonstrated that imidacloprid residues of 100 μg/kg in diet patties or 20 μg/kg in sucrose syrup became diluted or non-detectable due to the processing of beebread and honey and the rapid metabolism of the chemical by bees. Given the weight of evidence presented here, we conclude that chronic exposure to imidacloprid at the higher range of field doses (20 to 100 μg/kg) in the pollen of certain treated crops could contribute to reduced overwintering success but the most likely encountered field doses of 5 μg/kg, especially relevant for seed-treated crops, have negligible effects on honey bee colony health. Currently there is wide agreement that sublethal exposure to imidacloprid can cause adverse effects on honey bees in laboratory studies [77] but no evidence that this widely used insecticide is the major stressor causing colony declines. Our findings agree with a causal analysis by Staveley et al. [37] that judged neonicotinoid pesticides to be an unlikely sole cause of colony declines. Finally, this study makes evident the importance of conducting risk assessment studies on honey bee colonies over longer periods to reveal the chronic sublethal effects on queen health and bee behaviors that can ultimately impair colony performance
test tube study, nothing that relates to the real world. Not realistic dosages of neonics.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Beesource Beekeeping Forums
1.8M posts
54.7K members
Since 1999
A forum community dedicated to beekeeping, bee owners and enthusiasts. Come join the discussion about breeding, honey production, health, behavior, hives, housing, adopting, care, classifieds, and more!