Pollinators make a big impact on edamame marketability
UMD study provides evidence to guide emerging edible soybean market
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A BEE VISITS AN EDAMAME FLOWER
view moreCREDIT: KATHLEEN C. EVANS/ UNIVERSITY OF MARYLAND
Soybeans can pollinate themselves, but a new study by UMD researchers shows that pollen from multiple plants can greatly increase their yields. What’s more, the addition of a strip of wildflowers near rows of soybeans amplifies the effect. The information could help farmers of one of Maryland’s top commodities increase production and marketability of their crop.
The research was published December 15, 2023, in the Journal of Pollination Ecology.
Soybeans represent an important crop in the U.S., but scientists don’t completely understand their pollination and reproduction strategies.
“Our study has shown that cross pollination is important for improving soybean production, and suggests that increases of biodiversity near edamame fields can affect production in market-relevant ways,” said Kathleen Evans, lead author on the paper and a graduate student in the Department of Entomology at the University of Maryland.
The researchers focused their study on edamame, which is the same species of soybean grown in the U.S. for animal feed, but harvested earlier for human consumption. That means the study’s findings are applicable to both edamame and feed soy, but understanding how pollination strategies affect the size and quality of soybeans is especially important for the growing edamame market, where consumer acceptance and number of seeds per pod are important for sales.
Although soybeans are globally cultivated, no formal tests had previously been evaluated whether flowers receiving their own pollen (self-pollination) or a different soybean flower (cross-pollination) affects beanpod quality.
To answer that question, Evans and her colleagues used three different methods to pollinate soy plants in a 16 x 16-meter experimental plot at the University of Maryland Central Maryland Research and Education Center (CMREC) at Beltsville, MD. They also planted a strip of wildflowers native to the Mid-Atlantic region along one end of the plot.
The researchers covered the flowers of some plants with a fine mesh that prevented pollinators from visiting. Those flowers would be self-pollinated. They also carefully pollinated a secondgroup of flowers by hand with pollen from a separate donor plant. A third group of flowers was left open and untreated to be pollinated naturally, which means they were likely cross-pollinated by insects.
The researchers found that, compared to self-pollination, hand cross-pollination and open pollination led to more market grade-A quality pods, but open-pollinated flowers had more grade-A beans than either of the other two treatments. In addition, the harvest from plants that had been left open was 17% heavier than self-pollinated and hand-pollinated plants.
They also found that open-pollinated soybean plants grown closer to flower strips had greater yield. The researchers believe more pollinators, and/or predators of pests may have visited those soybean plants on their way to or from the wild flowers, suggesting that a greater biodiversity near and in the fields could increase yields in this crop.
Other co-authors from the University of Maryland Department of Entomology include Assistant Professor Anahí Espíndola, Professor Cerruti Hooks, and Master’s student Jenan El-Hifnawi.
A japanese beetle eating an edamame flower. Research suggests a strip of wildflowers near edamame rows may increase bean pod yield by attracting predators of such edamame pests.
Lead author Kathleen Evans, a researcher at University of Maryland stands in the experimental soybean plot at CMREC in Beltsville, MD.
CREDIT
Courtesy Kathleen Evans / University of Maryland
JOURNAL
Journal of Pollination Ecology
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
BENEFITS OF CROSS-POLLINATION IN VEGETABLE SOYBEAN EDAMAME
ARTICLE PUBLICATION DATE
15-Dec-2023
ICYMI
Pesticides and adjuvants disrupt honey bee’s sense of smell
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GRADUATE STUDENT WEN-YEN WU CONDUCTS AN ELECTROANTENNOGRAPHY (EAG) ASSAY—A METHOD TO MEASURE HOW INSECTS RESPOND TO DIFFERENT ODORS BY RECORDING ELECTRICAL ACTIVITY IN THEIR ANTENNAE.
view moreCREDIT: LING-HSIU LIAO
It has long been known that exposure to pesticide sprays is harmful to honey bees. In a new study, researchers have uncovered the effect of such sprays on the sense of smell in bees, which could disrupt their social signals.
Honey bees live in dynamic communities and constantly communicate with each other using chemicals that serve as social cues. For example, nurse bees—that are responsible for taking care of larvae that ultimately become queens and worker bees—constantly monitor the larvae using in the dark using pheromones. The larvae emit brood pheromones to indicate that they need food. There are also alarm pheromones that workers produce to warn the other bees of danger. If these cues are dampened or not perceived properly, the colony may fail to thrive.
Since 2007, scientists have known that honey bees have been in trouble. One of the stressors that have raised concerns are insecticides, which affect honey bee health. Because these are usually used in combination with other chemicals, the resulting mixture can become unexpectedly toxic to bees.
“For many years, it was assumed that fungicides do not have an adverse impact on insects because they are designed for fungal targets,” said May Berenbaum (GEGC/IGOH), a professor of entomology. “Surprisingly, in addition to insecticides, fungicides also have an adverse effect on bees and combining the two can disrupt colony function.”
For more than a decade, reports originating from almond orchards, where two-thirds of the U.S. honey bees are transported every year when the flowers are in bloom, implicated pesticide spray mixtures. In particular, the problem lies in the use of supposedly inactive chemicals called adjuvants, which increases the “stickiness” of the insecticide so it stays on the plants.
Because adjuvants have long been considered to be biologically benign, they are not subject to the same level of safety testing as other insecticidal agents. “Recently, researchers have shown that adjuvants alone or when used in combination with fungicides and insecticides are toxic to bees,” Berenbaum said.
Nurse bees are especially vulnerable to these combinations. “The health of the queens is paramount,” Berenbaum said. “If healthy queens are not produced, the colony can suffer.”
To understand how combinations affect nurse bees, the researchers tested their effect on the olfactory system of honey bees using the adjuvant Dyne-Amic, the fungicide Tilt, and the insecticide Altacor.
The researchers divided bees into four groups of ten bees and for a week exposed them to either untreated commercial pollen or to pollen that had been treated with either Dyne-Amic, or Tilt and Altacor, or all three together. The bees were then anesthetized on ice and one antenna was carefully removed from each bee. The researchers then exposed the antenna to chemical mimics of brood and alarm pheromones and recorded the antenna’s response using a technique called electroantennography.
With this method, Ling-Hsiu Liao, a research scientist, and Wen-Yen Wu, a graduate student, in the Berenbaum lab, found that when nurse bees had consumed pollen contaminated by the three chemicals, their antennal responses to some brood pheromones and alarm pheromones were altered. Their finding suggests that these commonly-used pesticides can interfere with honey bee communication.
How these chemicals interact and influence the bees is still unclear. “There are many possible explanations for how consuming these chemicals can affect the sensory responses of bees,” Liao said. “The antenna detects and triggers the response to olfactory signals. In this study we did not look at what other changes are triggered, particularly changes in behavior.”
In addition to parsing out the underlying molecular pathways that are affected, the researchers are also interested in testing other mixtures of commonly used pesticides as well as looking at the response of bees in other populations. They hope that their work can help beekeepers rethink how they manage and protect their colonies.
The study “Effects of pesticide-adjuvant combinations used in almond orchards on olfactory responses to social signals in honey bees (Apis mellifera)” was published in Scientific Reports and can be found at https://doi.org/10.1038/s41598-023-41818-7. The work was supported by the Almond Board of California, the USDA-AFRI National Institute of Food and Agriculture, Ohio State University, and the University of Illinois Urbana-Champaign.
JOURNAL
Scientific Reports
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Effects of pesticide-adjuvant combinations used in almond orchards on olfactory responses to social signals in honey bees (Apis mellifera).
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