A new UC Riverside study shows that a type of insecticide made for commercial plant nurseries is harmful to a typical bee even when applied well below the label rate.

The study was published today in the journal Proceedings of the Royal Society B: Biological Sciences.

Chemically similar to nicotine, neonicotinoids are insecticides that protect against plant-consuming insects like aphids, but seriously harm beneficial insects, like bees. They are widely used by commercial growers.

Much research has focused on their use in food crops like canola, in which they are typically applied at low doses. However, this study is one of the few to examine neonicotinoid application in potted ornamental plants, which can represent more potent, acute sources of exposure to the toxin for bees.

“Neonicotinoids are often used on food crops as a seed treatment,” explained UCR entomologist and lead study author Jacob Cecala. “But they’re usually applied in higher amounts to ornamental plants for aesthetic reasons. The effects are deadly no matter how much the plants are watered.”

Cecala said he was surprised by this result, given that neonicotinoids are water soluble. Going into the study, he assumed that more water would dilute the amount of harm they caused the bees. The researchers were also curious whether increased watering could benefit bees despite insecticide exposure by increasing the quantity or quality of nectar offered by the plants.

To test these assumptions, the researchers raised bees on flowering native plants in pots that either received a lot of watering, or a little. Plants were selected based on their popularity at nurseries, drought tolerance to ensure blooming even without much water, and their attractiveness to bees. In addition, half the plants were treated with the insecticide.

Though increased water decreased the pesticide’s potency in the nectar of the flowers, the negative effects on bees were still observed.

“Unfortunately, we observed a 90% decrease in the bees’ reproduction with both high and low levels of irrigation,” Cecala said.

This study is also one of the few to examine neonicotinoid effects via ornamental plants on solitary bees, which make up more than 90% of native bee species in North America, and an even higher percentage in California.

Solitary bees are not bees who have left the hive and are now alone. This is a type of bee that lives alone, does not produce honey, and does not have a queen or live in a hive. Because they do not have a store of honey to protect, they are also not aggressive.

“Solitary bees are more representative of the ecosystem here, and they are potentially more vulnerable to pesticides,” said UCR entomologist and study co-author Erin Rankin.

If a worker bee that is social—like the honeybee—gets exposed to insecticide and dies, it won’t necessarily affect the longevity of the hive. However, if a solitary bee dies, its lineage is cut short.

In this study, the researchers used alfalfa leafcutter bees, which make their nests in tunnels and lay eggs one at a time. They are very similar to California’s solitary native bees and are part of a genus that can be found worldwide.

The first time Cecala and Rankin tried this experiment, they used the concentration of insecticide recommended on the product label. All the bees died in a matter of days.

The next time they ran the experiment, they used a third of the recommended dose and still found negative effects on reproduction, the ability of the bees to feed themselves, and overall fitness. “It almost completely wiped them out,” Cecala said.

Though this study used a neonicotinoid product formulated for nurseries, formulations of similar products for home gardeners also tend to be highly concentrated.

Plants in nurseries or residential backyards represent a smaller total area than food plant fields like corn or soy. However, high-potency neonicotinoid products can have a big effect even in small areas. In 2013, neonicotinoids applied to flowering trees in a retail parking lot in Oregon caused a massive bumblebee die off, with more than 25,000 found dead.

The researchers recommend that nurseries quantify the amount of pesticides that are making their way into flowers given their watering and pesticide regimes, and consider alternative management practices that reduce harm to bees and the ecosystems dependent on them.

“It’s not as simple as ‘don’t use pesticides’—sometimes they’re necessary,” Cecala said. “However, people can look for a different class of insecticide, try to apply them on plants that aren’t attractive to bees, or find biological methods of pest control.”

It’s estimated that an average-sized wastewater treatment plant serving roughly 400,000 residents will discharge up to 2,000,000 microplastic particles into the environment each day. Yet, researchers are still learning the environmental and human health impact of these ultra-fine plastic particles, less than 5 millimeters in length, found in everything from cosmetics, toothpaste and clothing microfibers, to our food, air and drinking water.

Now, researchers at New Jersey Institute of Technology have shown that ubiquitous microplastics can become ‘hubs’ for antibiotic-resistant bacteria and pathogens to grow once they wash down household drains and enter wastewater treatment plants—forming a slimy layer of buildup, or biofilm, on their surface that allows pathogenic microorganisms and antibiotic waste to attach and comingle.

In findings published in the Journal of Hazardous Materials Letters, researchers found certain strains of bacteria elevated antibiotic resistance by up to 30 times while living on microplastic biofilms that can form inside activated sludge units at municipal wastewater treatment plants.

“A number of recent studies have focused on the negative impacts that millions of tons of microplastic waste a year is having on our freshwater and ocean environments, but until now the role of microplastics in our towns’ and cities’ wastewater treatment processes has largely been unknown,” said Mengyan Li, associate professor of chemistry and environmental science at NJIT and the study’s corresponding author. “These wastewater treatment plants can be hotspots where various chemicals, antibiotic-resistant bacteria and pathogens converge and what our study shows is that microplastics can serve as their carriers, posing imminent risks to aquatic biota and human health if they bypass the water treatment process.”

“Most wastewater treatment plants are not designed for the removal of microplastics, so they are constantly being released into the receiving environment,” added Dung Ngoc Pham, NJIT Ph.D. candidate and first author of the study. “Our goal was to investigate whether or not microplastics are enriching antibiotic-resistant bacteria from activated sludge at municipal wastewater treatment plants, and if so, learn more about the microbial communities involved.”

In their study, the team collected batches of sludge samples from three domestic wastewater treatment plants in northern New Jersey, inoculating the samples in the lab with two widespread commercial microplastics—polyethylene (PE) and polystyrene (PS). The team used a combination of quantitative PCR and next-generation sequencing techniques to identify the species of bacteria that tend to grow on the microplastics, tracking genetic changes of the bacteria along the way.

The analysis revealed that three genes in particular—sul1, sul2 and intI1— known to aid resistance to common antibiotics, sulfonamides, were found to be up to 30 times greater on the microplastic biofilms than in the lab’s control tests using sand biofilms after just three days.

When the team spiked the samples with the antibiotic, sulfamethoxazole (SMX), they found it further amplified the antibiotic resistance genes by up to 4.5-fold.

“Previously, we thought the presence of antibiotics would be necessary to enhance antibiotic-resistance genes in these microplastic-associated bacteria, but it seems microplastics can naturally allow for uptake of these resistance genes on their own.” said Pham. “The presence of antibiotics does have a significant multiplier effect however.”

Eight different species of bacteria were found highly enriched on the microplastics. Among these species, the team observed two emerging human pathogens typically linked with respiratory infection, Raoultella ornithinolytica and Stenotrophomonas maltophilia, frequently hitchhiking on the microplastic biofilms.

The team say the most common strain found on the microplastics by far, Novosphingobium pokkalii, is likely a key initiator in forming the sticky biofilm that attracts such pathogens—as it proliferates it may contribute to the deterioration of the plastic and expand the biofilm. At the same time, the team’s study highlighted the role of the gene, intI1, a mobile genetic element chiefly responsible for enabling the exchange of antibiotic resistance genes among the microplastic-bound microbes.

“We might think of microplastics as tiny beads, but they provide an enormous surface area for microbes to reside,” explained Li. “When these microplastics enter the wastewater treatment plant and mix in with sludge, bacteria like Novosphingobium can accidentally attach to the surface and secrete glue-like extracellular substances. As other bacteria attach to the surface and grow, they can even swap DNA with each other. This is how the antibiotic resistance genes are being spread among the community.”

“We have evidence that the bacteria developed resistance to other antibiotics this way as well, such as aminoglycoside, beta-lactam and trimethoprim,” added Pham.

Now, Li says the lab is further studying the role of Novosphingobium in biofilm formation on microplastics. The team is also seeking to better understand the extent to which such pathogen-carrying microplastics may be bypassing water treatment processes, by studying resistance of microplastic biofilms during wastewater treatment with disinfectants such as UV light and chlorine.

“Some states are already considering new regulations on the use of microplastics in consumer products. This study raises calls for further investigation on microplastic biofilms in our wastewater systems and development of effective means for removing microplastics in aquatic environments,” said Li.

More information:
Dung Ngoc Pham et al, Microplastics as hubs enriching antibiotic-resistant bacteria and pathogens in municipal activated sludge, Journal of Hazardous Materials Letters (2021). DOI: 10.1016/j.hazl.2021.100014

Could cactus pear become a major crop like soybeans and corn in the near future, and help provide a biofuel source, as well as a sustainable food and forage crop? According to a recently published study, researchers from the University of Nevada, Reno believe the plant, with its high heat tolerance and low water use, may be able to provide fuel and food in places that previously haven’t been able to grow much in the way of sustainable crops.

Global climate change models predict that long-term drought events will increase in duration and intensity, resulting in both higher temperatures and lower levels of available water. Many crops, such as rice, corn and soybeans, have an upper temperature limit, and other traditional crops, such as alfalfa, require more water than what might be available in the future.

“Dry areas are going to get dryer because of climate change,” Biochemistry & Molecular Biology Professor John Cushman, with the University’s College of Agriculture, Biotechnology & Natural Resources, said. “Ultimately, we’re going to see more and more of these drought issues affecting crops such as corn and soybeans in the future.”

Fueling renewable energy

As part of the College’s Experiment Station unit, Cushman and his team recently published the results of a five-year study on the use of spineless cactus pear as a high-temperature, low-water commercial crop. The study, funded by the Experiment Station and the U.S. Department of Agriculture’s National Institute of Food and Agriculture, was the first long-term field trial of Opuntia species in the U.S. as a scalable bioenergy feedstock to replace fossil fuel.

Results of the study, which took place at the Experiment Station’s Southern Nevada Field Lab in Logandale, Nevada, showed that Opuntia ficus-indica had the highest fruit production while using up to 80% less water than some traditional crops. Co-authors included Carol Bishop, with the College’s Extension unit, postdoctoral research scholar Dhurba Neupane, and graduate students Nicholas Alexander Niechayev and Jesse Mayer.

“Maize and sugar cane are the major bioenergy crops right now, but use three to six times more water than cactus pear,” Cushman said. “This study showed that cactus pear productivity is on par with these important bioenergy crops, but use a fraction of the water and have a higher heat tolerance, which makes them a much more climate-resilient crop.”

Cactus pear works well as a bioenergy crop because it is a versatile perennial crop. When it’s not being harvested for biofuel, then it works as a land-based carbon sink, removing carbon dioxide from the atmosphere and storing it in a sustainable manner.

“Approximately 42% of land area around the world is classified as semi-arid or arid,” Cushman said. “There is enormous potential for planting cactus trees for carbon sequestration. We can start growing cactus pear crops in abandoned areas that are marginal and may not be suitable for other crops, thereby expanding the area being used for bioenergy production.”

Fueling people and animals

The crop can also be used for human consumption and livestock feed. Cactus pear is already used in many semi-arid areas around the world for food and forage due to its low-water needs compared with more traditional crops. The fruit can be used for jams and jellies due to its high sugar content, and the pads are eaten both fresh and as a canned vegetable. Because the plant’s pads are made of 90% water, the crop works great for livestock feed as well.

“That’s the benefit of this perennial crop,” Cushman explained. “You’ve harvested the fruit and the pads for food, then you have this large amount of biomass sitting on the land that is sequestering carbon and can be used for biofuel production.”

Cushman also hopes to use cactus pear genes to improve the water-use efficiency of other crops. One of the ways cactus pear retains water is by closing its pores during the heat of day to prevent evaporation and opening them at night to breathe. Cushman wants to take the cactus pear genes that allow it to do this, and add them to the genetic makeup of other plants to increase their drought tolerance.

Bishop, Extension educator for Northeast Clark County, and her team, which includes Moapa Valley High School students, continue to help maintain and harvest the more than 250 cactus pear plants still grown at the field lab in Logandale. In addition, during the study, the students gained valuable experience helping to spread awareness about the project, its goals, and the plant’s potential benefits and uses. They produced videos, papers, brochures and recipes; gave tours of the field lab; and held classes, including harvesting and cooking classes.

Fueling further research

In 2019, Cushman began a new research project with cactus pear at the U.S. Department of Agriculture—Agricultural Research Service’ National Arid Land Plant Genetic Resources Unit in Parlier, California. In addition to continuing to take measurements of how much the cactus crop will produce, Cushman’s team, in collaboration with Claire Heinitz, curator at the unit, is looking at which accessions, or unique samples of plant tissue or seeds with different genetic traits, provide the greatest production and optimize the crop’s growing conditions.

“We want a spineless cactus pear that will grow fast and produce a lot of biomass,” Cushman said.

One of the other goals of the project is to learn more about Opuntia stunting disease, which causes cactuses to grow smaller pads and fruit. The team is taking samples from the infected plants to look at the DNA and RNA to find what causes the disease and how it is transferred to other cactuses in the field. The hope is to use the information to create a diagnostic tool and treatment to detect and prevent the disease’s spread and to salvage usable parts from diseased plants.

Here’s a fun fact: Japan has more bat species than any other order of mammal in the country, and a third of these are endemic. But the bad news is that 90% of the endemic species are at risk of extinction.

Bats play crucial ecological roles, including in pollination and pest control. But while they have been a focus of research in many fields of science—including epidemiology—they remain underrepresented in conservation, particularly in Japan.

Publishing in Mammal Review, researchers from Kyoto University’s Graduate School of Informatics describe a systematic survey of the state of Japanese bat research and their analysis of the possible roots of the problem.

The study authors found poor alignment between conservation needs and allocation of research resources. Although research effort has increased gradually since the year 2000, threatened endemic bats remain significantly less studied than their non-threatened counterparts.

“Conservation status alone is not enough to promote research on these threatened species,” explains Jason Preble, doctoral candidate and one of the authors of the study.

“We systematically reviewed the literature of the last fifty years, assessing patterns in research distribution across multiple categories in order to identify gaps and future priorities.”

The team found a marked shortage of both ecological and conservation-motivated studies in international journals on nearly half of the extant species in Japan. Moreover, while many threats to Japanese bats have been identified, such as forest loss or alteration, there was a shortage of data measuring the impacts of these threats.

“All of these factors are immensely concerning,” says corresponding author Christian E. Vincenot. “We were distressed to see threats such as wind turbines and climate change severely understudied.”

Based on their results, the team lists recommendations aimed at strengthening Japanese bat conservation.

“For example, we need to prioritize research efforts that provide the ecological information needed to design and implement concrete conservation plans,” Vincenot explains.

Data disclosure is imperative, he continues. Openness not only helps the research community, but provides valuable resources to government officers, NGOs, and non-professional naturalists who are equally key players in a comprehensive conservation strategy.

The authors also emphasize the importance of communicating research findings to the public, which in turn can facilitate support from funding agencies.

“While hopeful signs of improvement exist, ultimately a stronger spirit of research and collaboration—along with informed conservation practices—will determine if these creatures can reach the road to recovery or ultimately decline into extinction,” says Vincenot.

More information:
“In the Shadow of the Rising Sun: A Systematic Review of Japanese Bat Research and Conservation” Mammal Review, DOI: 10.1111/mam.12226