Texas A&M Entomology Research Network

Research

Zero waste: Maggots as recyclers and protein sources

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Texas A&M professor invents technology to harness black soldier flies for waste removal, protein for animals

by Laura Muntean, Texas A&M AgriLife Communications

Adult black soldier flies look similar to wasps, but without the stinger. (Photo courtesy of Dr. Jeff Tomberlin.)
Adult black soldier flies look similar to wasps, but without the stinger. (Photo courtesy of Dr. Jeff Tomberlin.)

COLLEGE STATION — Black soldier fly maggots provide a zero waste option for organic recycling, according to Jeff Tomberlin, Ph.D., professor in the department of entomology at Texas A&M University and director of EVO Conversion Systems, LLC.

Despite the “ick-factor,” maggots can be helpful for the environment by reducing waste and serving as an animal feed source, he said.

The larval form of the black soldier fly eats profusely during this stage of development. The maggots essentially climb on top of each other, wriggling and writhing in an effort to get to the food source or waste material. The larvae eat until they are full, and as they take a breather from their snack, other larvae push in to snag a bite to eat, shifting the others up and out of the way, creating a tower of maggots.

It may sound gross, but it reduces decomposition time for compost by months, Tomberlin explained.

At the end of the 14-day cycle, the tower of larvae is dried. These dried larvae become feed for animals that humans then consume. The most common example is as a protein source for chickens.

The larvae can also be processed to isolate the protein, which can then become part of a feed for livestock, poultry and fish. The maggot waste can also be used as compost for landscaping. Essentially, it’s the natural life-cycle power of the black soldier fly but harnessed by humans.

It’s been very successful in China, Europe and other parts of the world, and the process is now being utilized for profit here in Texas.

BULLET TECHNOLOGY

Tomberlin and his team have come up with a more efficient way to harness the process of waste reduction with a new technology he calls the Black Soldier Fly Bullet. The Bullet provides storage of the larvae for an extended period of time, giving the human users the ability to “wake them up” whenever the need arises by opening the container and placing them on the waste material.

“Drs. Tomberlin, Cammack and Mr. Yang, all from Texas A&M AgriLife Research, invented a new technology to greatly increase the efficiency of black soldier fly, or BSF, conversion of waste material,” said Robert Brummett, AgriLife Research licensing manager, College Station. “This technology, called the Black Soldier Fly Bullet, also facilitates storage and shipment of BSF, thus creating more stability and assurances in processes utilizing BSF larvae.”

Texas A&M AgriLife Intellectual Property and Commercialization worked with Dr. Tomberlin to exclusively license this AgriLife technology created by Tomberlin to his company, EVO Conversion Systems, LLC.

“Through EVO, he and his co-inventors can take the results of their research from the lab to real-world application and use,” Brummett said.

Tomberlin said this gave the company, which manages organic waste with black soldier fly larvae then uses the insect biomass as a sustainable animal feed ingredient and crop fertilizer, an opportunity to create zero waste on a larger scale.

“We were able to develop a system to put them in a state of stasis,” said Dr. Jonathan Cammack, chief operating officer of EVO Conversion Systems and former AgriLife Research postdoctoral research associate. “We are taking newly hatched larvae and putting them in an optimal environment to develop to a certain point, then sit and hang out until ready to be used.”

Tomberlin explained data supports that they can hold the larvae at an optimal temperature, potentially up to five months.

“The larval development time is 14 days, and we can do it in 6-7 days,” he said.

The larvae can then be placed on to the material, regardless of what the waste is, and in six to seven days, they have matured, Cammack explained. The larvae can then be harvested and dried, and the biomass has been converted from waste to insect protein in half the time.

“Basically, this technology puts them into hibernation for long-term storage, and when ready to use them, you wake them up and put them to work,” Tomberlin said.

RESPECT FOR SUSTAINABILITY

Growing up in Georgia, Tomberlin was taught the importance of family, agriculture and sustainability at a very young age. His grandmother, the matriarch of the family, shared with him the importance of taking care of the things you own and the resources available. This life lesson has stayed with Tomberlin and is reflected in his work with the black soldier fly and his dedication to finding ways to most effectively utilize food waste.

During his undergraduate career at the University of Georgia, Tomberlin was introduced to the black soldier fly through his Ph.D. advisor. The insect was not being widely studied at the time, but through Tomberlin’s research, has been widely adopted and is now being used around the world.

FROM MAGGOTS TO PROTEIN SOURCE

Black soldier flies typically lay one batch of eggs. (Photo courtesy of Dr. Jeff Tomberlin.)
Black soldier flies typically lay one batch of eggs. (Photo courtesy of Dr. Jeff Tomberlin.)

Tomberlin explained the adult black soldier fly, which looks similar to a wasp but without the stinger, will live for about two weeks. In general, the female will mate once and lay one batch of eggs. Those eggs hatch in about four days, and the larvae will feed for two weeks. This leaves about 18 days in the development aspect and about another two weeks in the pupal stage before the adult emerges.

“The lab at Texas A&M is a leading lab in the world on this topic,” Tomberlin said. “The first thing we did was develop a method to mass produce this insect in a colony. That method is now being employed in every major black soldier fly production facility in the world.”

As other countries employ these systems, they often first come to Tomberlin’s lab at Texas A&M to learn about the research, then go to the factory to learn about the industrial side of things.

“Most groups around the world are focused on that 14-day development that they can feed waste to it, recycle it and produce protein,” he said. “Through our research at Texas A&M, we have been able to enhance that system.

Cammack explained that they wanted to put some stability into the system, so the team looked at how much waste material a colony needed in order to flourish without having too much material for the colony, or too little. This balance would help to maximize the number of eggs that the colony would produce.

“If they lay a whole bunch of eggs and you don’t have enough material for them to digest or process, then you are losing eggs, and if you don’t have enough eggs and you have a whole bunch of waste available, then you have waste that rots,” Cammack said. “One is driving the other.”

PARTNERING UP FOR ZERO WASTE

With zero waste being the ultimate goal, the team has implemented a circular economy by working with Blackwater Draw Brewing Company, Rio Brazos Distillery and Cosmic Landscapes of Texas.

“We get the byproducts from the distillery and brewery and convert them to protein, and the compost that we then produce, or digestate, goes to the landscape company, and they use it for landscaping,” Tomberlin said. “So it is zero waste. That is what we are developing here in College Station and Bryan. There should be no food waste going into the landfill. It should be recycled to products of value.”

ZERO WASTE FACILITIES

“Our goal is to build a facility here and make College Station and Bryan a zero waste area,” he said. “If we can build a facility like that, it is not just a facility for recycling waste, it is a teaching facility. If we can build it in conjunction with A&M, we are talking about a facility where research can take place and students can be trained, and at the same time we are taking care of the community. We are creating jobs. That’s what we would like to see happen.”

Tomberlin sees success in this industry through the building of small to mid-sized industry sites, producing a facility with as little as $250,000. Creating these smaller facilities and placing them throughout rural America is the goal and will create jobs, protect the environment and produce a valued resource.

“We are looking to expand who we get our material from here in Bryan-College Station, but at the same time we want to talk with our local waste management companies,” Tomberlin said. “We don’t want to encroach on them, we want to help them. If there are things that we can divert from that waste that can go into our compost facility, we will work with them. We don’t see that as competition; we see it as collaboration.”

New research helps hay producers manage Bermuda grass stem maggot

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by Adam Russell, Texas A&M AgriLife Communications

A clump of Bermuda grass shows damage by stem maggots. (Texas A&M AgriLife Extension Service photo by Shane McLellen)
A clump of Bermuda grass shows damage by stem maggots. (Texas A&M AgriLife Extension Service photo by Shane McLellen)

OVERTON – A relatively new pest – the Bermuda grass stem maggot – is plaguing Texas hay producers this season, according to Texas A&M AgriLife Extension Service experts.

However, new research from Texas A&M AgriLife is helping growers better manage this pest.

“Previously, there was no information on how damaging this insect was to hay production and thus no guidelines on when an insecticide was needed to protect yields,” said Dr. Allen Knutson, AgriLife Extension entomologist, Dallas. “Our field research documented that for each percentage of stems with stem maggot damage, there is a potential loss of 8.9 pounds of hay per acre.”

Using data from fields in North Texas, Knutson and Dr. Forrest Mitchell, Texas A&M AgriLife Research entomologist, Stephenville, developed guidelines as to when an insecticide treatment is justified based on the cost of treatment and value of hay.

Dr. Vanessa Corriher-Olson, AgriLife Extension forage specialist, Overton, said she has received numerous phone calls and emails from producers and reports from AgriLife Extension agents in the region regarding the pest. She has also found them in hay and forage pastures at the Texas A&M AgriLife Research and Extension Center at Overton.

There was very little Bermuda grass stem maggot activity reported in the state last season, she said, but this appears to be a banner year for the pest.

“They’re definitely out there,” she said. “A few weeks ago, we had reports from Central Texas, but it’s not just there anymore. We can assume that if you have Bermuda grass in the state of Texas, you should be watching for signs of stem maggots.”

Feeding by the stem maggot causes the death of the top two to three leaves while the rest of the plant remains green. This gives a stand of Bermuda grass the appearance of frost damage. Also, the discolored top leaves are easily pulled from the leaf sheath, and plant growth is stunted.  

“They’re typically not a major problem in grazing pastures because cattle are grazing those top leaves,” she said. “But they can cause serious damage in a hay meadow. The field will look like it’s been burned by frost, and stem maggot damage is often confused with a chemical burn.”

To use the new guidelines, it is necessary to estimate the level of stem maggot damage. To do this, Knutson advises cutting a handful of grass at the base of the stems and carefully examining 50 stems at random for stem maggot damage. Set aside those with the top two leaves dead and easily pulled from the sheath. Once 50 stems are examined, calculate the percent of damaged stems in the sample. Repeat this at five to 10 locations across the field and calculate the average percent of damaged stems for the field.

The new guidelines consider the cost of insecticide and the value of hay in determining when insecticide treatment is economically justified, Knutson said.

“For example, if the insecticide application cost is $12 per acre and the hay value is $140 per ton, the treatment threshold is 16% of the stems with stem maggot damage,” he said. “If the average field infestation is 16% or greater, an insecticide treatment should result in a positive economic return. If the control cost is $12 an acre, and hay value is $100 per ton, then the treatment threshold is 22% or more of the stems with stem maggot damage.”

In fields where stem maggot damage is already extensive, an insecticide treatment may not be sufficient to get the crop growing again, Knutson said, because damaged stems shade the lower nodes, preventing regrowth of new shoots. In this situation, the hay should be cut and removed as soon as possible to allow sunlight to stimulate regrowth.

A pyrethroid insecticide should be applied seven to 10 days after cutting to protect the regrowth from another stem maggot infestation.

“Weekly field inspection to determine the percent of stems with maggot damage can reduce the risk of significant yield loss and determine if and when insecticide treatment is justified,” Knutson said.

The Bermuda grass stem maggot is an invasive pest native to southern Asia and was first reported in Georgia in 2010. The pest has been found in Texas since 2012.

This pest only infests Bermuda grass and stargrass, Corriher-Olson said. The fly, which is yellow with a black head, lays its eggs inside the Bermuda grass stem. After the egg hatches, the larva, or maggot, which is white with a black head and 1/8th to 3/16ths inch long, moves to the last plant node and begins consuming the plant material within the stem.

Guidelines on managing Bermuda grass stem maggot and the table of treatment thresholds for a range of control costs and hay values are available online at https://foragefax.tamu.edu/.

AgriLife Research looks at gene expressions in sugarcane aphid-resistant sorghum

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by Kay Ledbetter, Texas A&M AgriLife Communications

Sugarcane aphids cover a sorghum leaf. Photo by Ada Szczepaniec.
Sugarcane aphids cover a sorghum leaf. Photo by Ada Szczepaniec.

AMARILLO – Gene expression in sugarcane aphid-resistant sorghum varieties at times when they are most prevalent in the Texas Panhandle were the focus of a recent Texas A&M AgriLife Research study.

Sugarcane aphids remain the most significant threat to sorghum production, and their outbreaks can arise quickly and unexpectedly, especially in the Southern High Plains where infestations commonly coincide with sorghum bloom, said Dr. Ada Szczepaniec, AgriLife Research entomologist in Amarillo.

Sugarcane aphid outbreaks in sorghum were first reported in 2013. Previous research has illustrated that the outcomes of interactions between sugarcane aphid and sorghum — and thus the severity of the outbreaks — depend on the sorghum hybrid and potentially the phenology of the sorghum, Szczepaniec said.

To dig further into the mechanisms that drive the severity of aphid attacks and the role planting timing has in management protocols, she designed a study to understand the physiological changes in a commercially available resistant variety and a susceptible variety of sorghum. The varieties were studied at two weeks and six weeks post-emergence and were exposed to sugarcane aphid infections.

“In prior years, we demonstrated that using resistant sorghum varieties is the most effective way to manage these pests,” Szczepaniec said. “We also documented that when sugarcane aphids colonize flowering sorghum or just prior to bloom, their numbers increase extremely fast. This can pose a challenge to timely insecticide applications.”

The effects of sorghum age and genotype on the daily change in aphid densities were also evaluated in separate greenhouse experiments in her study.

“We found that the seedling sorghum expressed significantly more genes involved in natural plant resistance to pests than sorghum at the cusp of panicle emergence. This was true across varieties,” Szczepaniec said.

“More importantly, we found a suite of transcriptional changes in the resistant variety that were weak or absent in the susceptible sorghum. Specifically, the aphid-resistant variety exposed to sugarcane aphids bolstered several genes involved in natural plant resistance to pests, and this response was particularly robust in the two-week plants.”

She said her new research links the sugarcane aphid population dynamics noted in the field studies with gene expression data, which provide strong support for previous management recommendations.

“We found specific pathways in the plants that explain how resistant sorghum can mount powerful natural defenses against the aphids, and we discovered mechanisms responsible for greater susceptibility of sorghum in reproductive stages,” Szczepaniec said.

“These findings further support our recommendations for planting early, using resistant sorghum varieties, and intensifying scouting and sampling, particularly when sorghum is flowering.”

Szczepaniec said outcomes of this research were also of interest to other scientists as research on sugarcane aphid association with sorghum is still fairly new. Prior to this publication, she said, not much had been known about the molecular mechanisms that drive their interactions and result in sugarcane aphid outbreaks.

The gene expression changes in the younger resistant sorghum included induction of powerful plant hormones that govern how sorghum responds to pests, and more effective deployment of genes that help sorghum alleviate the harmful effects of oxidative stress following sugarcane aphid herbivory.

“The suite of physiological changes we quantified in sorghum was mirrored in the aphid population growth, which was significantly faster in the susceptible and older sorghum than in the resistant and younger plants,” Szczepaniec said.

“We believe this research is providing the first insights into molecular mechanisms underlying lower population growth of sugarcane aphids on the resistant sorghum variety,” she said. “It also appears that the younger resistant sorghum was able to mount a robust defense response following aphid infection, which was much weaker in the older sorghum.”

She said there are several pathways and specific genes that provide specific clues into the mechanisms underlying host-plant resistance to this invasive insect, and that will be a part of her continued study.

“We believe this knowledge will inform future sorghum breeding programs and contribute to the development of more varieties that can combat sugarcane aphid infestations,” Szczepaniec said. “It also helps us understand the mechanisms responsible for sugarcane aphid outbreaks and provides further support for specific integrated management tactics producers can take to help reduce the economic costs of these pests.”

This research was published in BMC Genomics and presented at several national and international conferences.

Funding came in part from the U.S. Department of Agriculture’s National Institute of Food and Agriculture, USDA-Agricultural Research Service, Areawide Pest Management of the Invasive Sugarcane Aphid in Grain Sorghum and Texas A&M AgriLife Genomics and Bioinformatics Center.

New research gives insight into warding off insect pests by way of nematode odors

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by Laura Muntean, Texas A&M AgriLife Communications

The above image shows the findings from the study. Helms found that chemical cues from certain entomopathogenic (insect-killing) nematodes enhance plant defenses and can help deter insect herbivores. (Image courtesy of Anjel Helms et al 2019.)

COLLEGE STATION — A recent study revealed insect-killing nematodes also produce distinctive chemical cues that enhance plant defenses and deter Colorado potato beetles.

Entomologists from Texas A&M University, including Dr. Anjel Helms, who led the study, and Penn State University took a look at whether Colorado potato beetles and potato plants responded to the presence of entomopathogenic nematodes, EPNs, or insect-killing nematodes.

The study, “Chemical cues linked to risk: cues from below-ground natural enemies enhance plant defenses and influence herbivore behavior and performance,” focused on how organisms communicate using signals and cues, specifically how organisms eavesdrop on each other as part of their survival strategies, said Helms.

“For this study, we wanted to flip things around and determine whether plants and insect herbivores can eavesdrop on chemical cues produced by a predator,” she said.

Throughout the study, Helms found that these insect-killing nematodes do produce distinctive chemical cues that both the plant and insect herbivores respond to. While the female Colorado potato beetles laid fewer eggs when the cues were present, the potato plant also increased its defenses.

This was especially important since the Colorado potato beetle is notorious for developing insecticide resistance, making them an especially devastating pest, she said.

“Although Colorado potato beetles feed above ground on plant leaves, they are susceptible to EPNs at all life stages,” she said.

While a beetle is not likely to come in contact with EPNs during most stages of life, it is most susceptible to EPNs while on the ground moving from plant to plant, or when entering the soil to pupate and emerge as an adult beetle.

The study also found that growers can experience additional benefits from using EPNs for biological control of insect pests.

“Not only are the EPNs directly killing insect pests in the soil, they also produce chemical cues that provide additional protection to plants,” Helms said. “They deter herbivores and enhance plant resistance to pests.”

For more information, view the study in the journal “Functional Ecology” here.

Professor Speaks on Fire Ant Research at International Conference

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Dr. Patricia Pietrantonio speaking
Dr. Patricia Pietrantonio speaking to the group at the conference about her research. Submitted photo.

Dr. Patricia Pietrantonio, professor of Entomology at Texas A&M University, was the State-of-the-Art Speaker at the 29th Conference of European Comparative Endocrinologists (CECE), in August in Glasgow, Scotland.

Held every two years, the purpose of the CECE meeting is to share new ideas and network with other researchers interested in the field of endocrinology. Pietrantonio’s presentation was during the “Omics and the Physiology of Insect Neuropeptides” section.

Pietrantonio was invited by Professor Shireen Davis (University of Glasgow), the coordinator for nEUROSTRESSPEP. This Horizon 2020 Research and Innovation Programme is funded by the European Commission and aims to discover novel control molecules for insect pests.

Her presentation was titled “Omics and the Physiology of a Superorganism: GPCR Signaling and Brain Transcriptomes of the Fire Ant (Solenopsis Invicta Buren): Toward Linking Nutrition and Reproduction”.

Pietrantonio discussed her ongoing research investigating the hormonal signaling in fire ants. Her lab uses various methodologies in physiology, cell biology, biochemistry, molecular biology and reverse genetics to address fundamental research questions on the physiology of the neuropeptide signaling in the invasive polygyne (multiple queen colonies) ants.

By finding differentially expressed genes in brains of virgin versus mated queens the Pietrantonio lab, in collaboration with Dr. Cecilia Tamborindeguy lab, aims to find candidate signaling genes controlling reproduction.

The research included in the presentation was published in the journal Ecology and Evolution. A second publication that will appear soon in the journal General and Comparative Endocrinology follows the comparative theme by identifying G protein-coupled receptors expressed in brains of fire ant queens versus those expressed in the brains of worker ants.

Pietrantonio said her research would help control the ants by targeting the genes that control and link reproduction and feeding status in queens.

“Fire ants are a pest in the lands they invade partially due to their high reproductive ability and their capacity to exploit numerous nutritional resources, so our research strives to find critical genes involved in signaling for both nutritional status and key aspects of reproduction that may be potential targets to disrupt the reproductive process in queens,” she said. “Colonies are complex organisms so understanding the gene networks in queens and workers is important to understand colony organization at the endocrine and molecular level. Selective insect hormone mimetics, synthetic molecules as receptor agonists or antagonists could disrupt these processes in these ants to our benefit”.

The research can also impact the understanding of the physiology of other hymenopteran insects in addition to fire ants, as the endocrinology of reproduction in honey bee queens is poorly understood.

“With respect to broader impacts, our research my also inform these processes in other hymenopterans, such as pollinators, and the neurobiology of insects in general,” Pietrantonio said.

Pietrantonio was honored by the invitation, and said the conference was a great networking experience as the presentation was well-received by the audience.