Alarming long-term effects of insecticides weaken ant colonies

Date:
July 1, 2020
Source:
University of Bern
Summary:
Scientists have shown how even low doses of neonicotinoid
insecticides, as they may realistically occur in contaminated
soils, adversely affect the development of black garden ants
(Lasius niger). This study highlights the need to overthink
current deployment and management of chemical pest control for
more sustainable agriculture.



FULL STORY ========================================================================== Scientists have shown how even low doses of neonicotinoid insecticides,
as they may realistically occur in contaminated soils, adversely affect
the development of black garden ants (Lasius niger). This study highlights
the need to overthink current deployment and management of chemical pest control for more sustainable agriculture.


========================================================================== "Ants are one of the most important animal groups on our planet. However,
they are also affected by the recently observed global declines in
abundance and diversity of insects," says Daniel Schla"ppi of the
Institute of Bee Health of the University of Bern, main author of
the study. Evidence suggests that pesticides are among the factors
responsible for the observed declines. "One problem of these substances
is their persistence and the potential to contaminate soils and water,
even in areas in which they are not applied," says co-author Gae'tan
Glauser from the University of Neucha^tel.

But so far, no data existed to show how exposure to low concentrations,
which do not induce direct mortality, affect ants in the long run. The
data, collected at the University of Bern in cooperation with Agroscope
and the University of Neucha^tel, clearly demonstrate previously
overlooked long-term effects, which are not detectable during the first
year of colony development.

The results are published in Communications Biology, an Open-Access
Journal of Nature. According to the authors, this study highlights the importance to develop sustainable agricultural practices that incorporate reduced use of agro-chemicals to prevent irreparable damages to natural ecosystems.

Worrying long-term impacts Thiamethoxam has a clear negative impact
on the health of ants. Thiamethoxam is a neonicotinoid insecticide
used to combat pest insects that threaten our harvest. Unfortunately,
there is more and more evidence showing that thiamethoxam and similar agro-chemicals have negative consequences for other beneficial insects, including ants and honey bees.

"With our study we show that ants, which play a very important roles
in our ecosystems and provide valuable ecosystem services such as
natural pest control, are negatively affected by neonicotinoids too,"
says Schla"ppi.

In the present work, colonies of black garden ants were chronically
exposed to field realistic concentrations of thiamethoxam over 64
weeks. Colonies were raised in the laboratory from queens that were
captured in the field. Before the first overwintering of the colonies no
effect of neonicotinoid exposure on colony strength was visible. However,
until the second overwintering it became apparent that colonies exposed to thiamethoxam were significantly smaller than control colonies. Because
the number of workers is a very important factor for the success of
an ant colony, the observed effects are most likely to compromise
colony survivorship. Considering the important role of ants in natural ecosystems, our results indicate that neonicotinoids impose a threat to ecosystem functioning.

The call for sustainable solutions "Accumulating long-term impact of neonicotinoids on ants is alarming," says Prof. Peter Neumann of the
Institute of Bee Health at the University of Bern.

"This is an exemplary study showing how negative effects of an
environmental contaminant only become visible after long monitoring,
but with potentially far reaching consequences." Therefore, the authors
stress the importance to include ants as model organisms and to fully incorporate long-term effects in future risk assessment schemes for more sustainable agriculture.


========================================================================== Story Source: Materials provided by University_of_Bern. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Daniel Schla"ppi, Nina Kettler, Lars Straub, Gae'tan Glauser, Peter
Neumann. Long-term effects of neonicotinoid insecticides on ants.

Communications Biology, 2020; 3 (1) DOI: 10.1038/s42003-020-1066-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200701125502.htm

--- up 23 weeks, 1 day, 2 hours, 40 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)