Honeybee lives shortened after exposure to two widely used pesticides


Date:
June 16, 2020
Source:
Oregon State University
Summary:
The lives of honeybees are shortened -- with evidence of
physiological stress -- when they are exposed to the suggested
application rates of two commercially available and widely used
pesticides.



FULL STORY ==========================================================================
The lives of honeybees are shortened -- with evidence of physiological
stress - - when they are exposed to the suggested application rates of
two commercially available and widely used pesticides, according to new
Oregon State University research.


==========================================================================
In a study published in the journal PLOS ONE, honeybee researchers in
OSU's College of Agricultural Sciences found detrimental effects in bees exposed to Transform and Sivanto, which are both registered for use in the United States and were developed to be more compatible with bee health.

The western honeybee is the major pollinator of fruit, nut, vegetable
and seed crops that depend on bee pollination for high quality and yield.

Coupled with other stressors such as varroa mites, viruses and poor
nutrition, effects from these pesticides can render honeybees incapable
of performing their tasks smoothly. Beekeepers and some environmental
groups have raised concerns in recent years about these insecticides
and potential negative effects on bees.

According to the researchers, this is the first study to investigate
"sub- lethal" effects of sulfoxaflor, the active ingredient in Transform,
and flupyradifurone, the active ingredient in Sivanto. Sub-lethal effects
mean that the bees don't die immediately, but experience physiological
stress resulting in shortened lifespan.

In the case of Transform, the bees' lives were severely shortened. A
majority of the honeybees exposed to Transform died within six hours of
being exposed, confirming the severe toxicity of the pesticide to bees
when exposed directly to field application rates recommended on the label,
the researchers said.



========================================================================== Study lead author Priyadarshini Chakrabarti Basu, a postdoctoral research associate in the Honey Bee Lab in OSU's College of Agricultural Sciences, emphasized that the researchers aren't calling for Sivanto or Transform
to be taken off the market.

"We are suggesting that more information be put on the labels of these products, and that more studies need to be conducted to understand
sublethal effects of chronic exposure," Basu said.

Sivanto and Transform are used on crops to kill aphids, leaf hoppers
and whiteflies, among other pests. Many of these same crops attract bees
for pollination. There are some restrictions on their use. For example, Transform can't be applied to crops in bloom, for example.

Honeybees might be exposed indirectly through pesticide drift, said
study co- author Ramesh Sagili, associate professor of apiculture and
honeybee Extension specialist in OSU's College of Agricultural Sciences.

"The average life span of a worker honeybee is five to six weeks in
spring and summer, so if you are reducing its life span by five to 10
days, that's a huge problem," Sagili said. "Reduced longevity resulting
from oxidative stress could negatively affect colony population and
ultimately compromise colony fitness." For the study, the researchers conducted two contact exposure experiments: a six-hour study and a 10-day
study in May 2019. The honeybees were obtained from six healthy colonies
at the OSU apiaries. In each experiment, groups of 150 bees were placed
in three cages. One group was exposed to Transform, a second to Sivanto
and the third was a control group that wasn't exposed to either pesticide.

Honeybee mortality, sugar syrup and water consumption, and physiological responses were assessed in bees exposed to Sivanto and Transform
and compared to bees in a control group. Mortality in each cage was
recorded every hour for the six-hour experiment and daily for the 10-day experiment.

While Sivanto was not directly lethal to honeybees following contact
exposure, the 10-day survival results revealed that field-application
rates of Sivanto reduced adult survival and caused increased oxidative
stress and apoptosis in the honey bee tissues. This suggests that even
though Sivanto is apparently less toxic than Transform, it might also
reduce honeybee longevity and impart physiological stress, according to
the study authors.

Co-authors on the study included graduate student Emily Carlson and
faculty research assistant Hannah Lucas, who both conduct research in
the Honey Bee Lab; and Andony Melathopoulos, assistant professor and
pollinator health Extension specialist.


========================================================================== Story Source: Materials provided by Oregon_State_University. Original
written by Chris Branam. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Priyadarshini Chakrabarti, Emily A. Carlson, Hannah M. Lucas,
Andony P.

Melathopoulos, Ramesh R. Sagili. Field rates of Sivanto[TM]
(flupyradifurone) and Transform(R) (sulfoxaflor) increase oxidative
stress and induce apoptosis in honey bees (Apis mellifera L.). PLOS
ONE, 2020; 15 (5): e0233033 DOI: 10.1371/journal.pone.0233033 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200616155951.htm

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