February 2024 - 6

PEST CONTROL
It's all the
Buzz
With wave of cicadas
coming, research looks
at feeding habits
D
o adult periodical cicadas actually feed on
anything? The Entomological Society of America
recently published a USDA-Agricultural Research
Service analysis of DNA in Brood X cicadas' gut contents.
The periodical cicadas in the genus Magicicada come
every 13 or 17 years, though other types may emerge
much more frequently. A long-standing agricultural
query related to the periodical cicadas was recently
answered by a USDA-ARS research team at West
Virginia's Appalachian Fruit Research Station. Simply:
Once periodical cicadas emerge, do they actually
feed on vegetation?
Threat to agriculture
Magicicada pose a threat due to their ability to
damage orchard trees when they lay their eggs on tree
branches. Many growers and nurseries take this into
consideration and refrain from planting new trees in
years when periodical cicadas emerge, as their eggs
can kill young trees.
ARS researchers investigated the best way to solve
this challenge by reviewing the life history, reproductive
biology and evolutionary relationships of cicadas over
the past 150 years. But many have often disagreed about
whether, or how much, the adults feed. This is because
the needle-like mouthparts of cicadas do not leave
much evidence of any feeding, unlike chewing insects,
and their digestive tracts are notoriously difficult to
dissect. USDA-ARS researchers studied adult male and
female Magicicada during the 2021 emergence of Brood
X in Maryland, Virginia and West Virginia as the insect
moved through apple orchards, wooded public parks and
residential properties.
The findings, published in October in the Entomological
Society of America's open-access Journal of Insect
Science, disrupted the age-old popular myth of adult
6 | FEBRUARY 2024
USDA researchers recently studied cicadas that emerge
every 13 or 17 years, answering the question: Once
they emerge, do they actually feed on vegetation?
Photo by Peggy Greb, USDA-ARS.
periodical cicadas not feeding. Scientists found mainly
woody plant and Malus, or apple tree DNA, in adult cicada
guts and found that 54% of those cicadas contained DNA
from multiple plant species.
While this strongly implies that adult Magicicada feed
on plant sap, it was necessary to show that the recovered
plant DNA was not just leftovers from meals eaten during
the nymph stage.
USDA-ARS research
" We tested teneral adults, or brand new adult
Magicicada that had not had a chance to feed yet, to
check for any leftover plant DNA, " James Hepler, USDAARS
research team leader, said in a news release. " We
couldn't find any plant DNA in the guts of teneral adults,
so we can be reasonably sure that the DNA found in
mature adult Magicicada was eaten during the adult
stage, since no DNA carries over from the nymph stage. "
Cicadas appear to have highly permeable exoskeletons
that permit considerable water loss and allow water
to evaporate out of the insect a little easier than many
other insects. Also, the presence of essential amino
acid-producing endosymbionts in the gut tissues of adult
Magicicada imply that, despite the water loss, some
nutrition is being derived as they feed on plant species.
USDA-ARS will continue to examine the life cycle of
Brood X and solve agricultural challenges directly related
to their life span above ground. More studies will also be
conducted to look at the impact that adult Magicicada
contribute to tree physiology.
Additionally, growers should be aware of reports from
late January that indicate two broods of cicadas are
expected to emerge from the ground from April through
June. Affected states include Virginia to Illinois. With the
prevalence of the insects, it is important for growers to
be watchful of effects to crops.
February 2024

Table of Contents for the Digital Edition of February 2024
