- Author: Kathy Keatley Garvey
Corbett will speak on "In Silico Experiments with the Effect of Natural Habitats on Biological Control in Agricultural Landscapes" at the next department seminar, set for 4:10 p.m., Monday, Oct. 21 in Room 122 of Briggs Hall. The seminar also will be on Zoom. The link:
https://ucdavis.zoom.us/j/95882849672.
The recording will be archived and posted at https://entomology.ucdavis.edu/seminars.
"Field studies and recent meta-analyses have found conflicting effects of habitat diversity on biological control in agricultural landscapes," Corbett says in his abstract. "To explore the reasons behind these variable responses, a detailed mechanistic model of pest/predator dynamics has been developed to enable in silico experimentation. The model structure allows for varying landscape factors such as coverage and distribution of natural habitats, varying resources provided by both natural habitats and crops, as well as varying predator traits such as overwintering densities, dispersal distances and predator search area."
"Overall, crop pest loads are highly variable across simulation scenarios, mimicking the conflicting results from field research," he continues. "Simulation results suggest that while natural enemy response to landscape structure is moderated to some extent by dispersal behavior, variation in resource availability to early colonizers is pivotal to understanding the highly variable responses of natural enemies to landscape heterogeneity. In silico experimentation that informs, and is informed by, field research has the potential to yield predictions regarding when conservation biological control efforts are likely to be most successful."
Corbett will be presenting results of some simulation studies. The simulations are intended to approximate lygus and Geocoris (bigeyed bugs) on cotton, but they also apply to "really any annual crop/plant bug/predatory bug combination."
"I've had an eclectic career path that includes ecological research, teaching, mathematical modelling, computer programming, instructional design, project management and team leadership," Corbett writes on LinkedIn. "I am currently engaged in ecological research, using simulation modeling to explore how the structure of agricultural landscapes impacts crop pest insects and their natural enemies. Although I recently retired from full-time employment, I remain active in the design and creation of simulation-based learning experiences. I'm currently consulting for SimInsights, creators of HyperSkill, a no-code authoring and deployment platform for VR learning experiences."
Corbett, formerly with the lab of UC Davis distinguished professor Jay Rosenheim (now emeritus), focuses his research on landscape ecology of natural enemies in agricultural systems. His current work involves landscape-scale simulation of how natural enemies respond to resources provided by natural habitats and the subsequent effects on crop pest loads.
Corbett received his doctorate in ecology in June 1991, in a joint UC Davis/San Diego State University doctoral program. His career includes serving as an instructional innovative specialist with the Betty Irene Moore School of Nursing, UC Davis Health System, and as a senior instructional designer with the UC Davis Continuing and Professional Education.
Nematologist Amanda Hodson, assistant professor, is coordinating the ENT seminars. The full list is here. For more information or for technical issues, contact Hodson at akhodson@ucdavis.edu.
- Author: Kathy Keatley Garvey
It's Arachtober and that means celebrating arachnids for the entire month of October.
Well, we ought to celebrate them year around, but October is THEIR month.
Let's especially applaud crab spiders when they prey on such agricultural pests as the lygus bug, also known as the "western tarnished plant bug." It's a member of the genus Lygus in the family Miridae and feeds on plants by piercing the plant tissues.
The lygus bug is easily distinguished by the triangular mark on its back.
The western tarnished plant bug (Lygus hesperus) is known as a very serious pest of cotton, strawberries and seed crops such as alfalfa, entomologists tell us. In California alone, the bug causes $30 million in damage to cotton plants each year, "and at least $40 million in losses to the state's strawberry industry," according to Wikipedia.
"Lygus bugs are one of the causes of irregularly shaped, cat-faced strawberries; another cause may be poor pollination, which results in small undeveloped seeds," says UC Statewide Integrated Pest Management Program (UC IPM) in its Pest Management Guidelines. "Lygus bugs damage fruit by puncturing individual seeds; this, in turn, stops development of the berry in the area surrounding the feeding site. Straw-colored seeds that are large and hollow are a good indication of lygus bug damage. Lygus bug damage is more of a problem in strawberry-growing areas where continuous fruit production occurs.
"Adults are about 0.25 inch (6 mm) long, oval, and rather flattened," UC IPM points out. "They are greenish or brownish and have reddish-brown markings on their wings."
So what happens when a crab spider nails a lygus bug?
The cheering section is loud.
- Author: Kathy Keatley Garvey
At a recent visit to the UC Davis Ecological Garden at the Student Farm, we watched a honey bee, Apis mellifera, and a lygus bug nymph, Lygus hesperus, foraging on a batchelor button, Centaurea cyanus.
The bee: the beneficial insect.
The lygus bug or Western tarnished plant bug: a pest.
The lygus bug, which punctures plant tissues with its piercing mouthparts, was there first, but no matter. The bee joined in, edging closer and closer until they touched.
In photography insect circles, that's a "two-for"--two insects in one image.
The bee finally buzzed off, leaving the lygus bug to "dine" alone.
The lygus bug, distinguished by a conspicuous triangle on its back, is a very serious pest of cotton, strawberries and seed crops, including alfalfa. Scientists estimate that in California alone, the pest causes $30 million in damage to cotton plants each year, and at least $40 million in losses to the state's strawberry industry. The insect is also a pest of numerous fruits and vegetables, including apples, pears, peaches, eggplant, tomato, potato, artichoke, lettuce, sugarbeet, and beans. See what the UC Statewide Integrated Pest Management Program (UC IPM), says about the pest.
What do they look like? "Adult lygus bugs are green, straw yellow, or brown with a conspicuous yellow or pale green triangle on their backs," UC IPM says. "Nymphs are light green...Lygus can move into gardens or orchards from weeds, especially when they dry up. They are a particular problem in beans, strawberries, and orchard crops, feeding on developing flower buds and fruit. Fruit may become blemished and discolored, deformed, or twisted and may develop depressions or pustules."
Cotton? "Lygus bugs," says UC IPM, "migrate to cotton from other hosts, so management of this pest begins with assessing its populations outside the field. Check for them on weeds, in nearby alfalfa, and in other crops, and keep in touch with your pest control adviser, Extension agent or Farm Advisor for area-wide information on lygus bug populations. Proper management of alfalfa harvest can reduce damaging migrations to cotton."
Cooperative Extension specialist Ian Grettenberger, UC Davis Department of Entomology and Nematology, works closely with farmers in their lygus bug battles.
- Author: Kathy Keatley Garvey
Agricultural entomologist Emily Bick is targeting you.
Lygus hesperus, a serious pest of strawberries--as well as cotton, and seed crops such as alfalfa--causes an estimated $40 million in annual losses to California's strawberry industry.
Bick, who received her doctorate in entomology last year from UC Davis and is now a postdoctoral fellow at the University of Copenhagen, is a newly selected recipient of an American Association of University Women (AAUW) American Publishing Grant and her subject is the lygus bug immigration and aggregation in California strawberries.
The $6000 grant is designed to support women over a two-month period in the summer as they prepare a solo-authored manuscript.
Bick's application focused on her scientific modeling work that originated from her Ph.D. program. Her application detailed the academic women who supported her career, including one of her mentors, Cornell University entomology professor Laura Harrington. Additionally, women students she mentored while at UC Davis provided letters of support.
“Prior to receiving this good news, my fiancé, Nora Forbes, and I decided to get married in the historic home of the AAUW in St. Paul, Minn.,” Bick said. “We are both aware of AAUW's legacy of supporting women in their academic pursuits since 1881 and wanted to celebrate in a location in line with their pioneering vision.” Forbes is a statistician at the Danish Medtronic office.
Earlier this year, Bick received a $23,000 fellowship from the American Scandinavian Foundation for her proposal, "Designing Pest-Resilient Apple Orchards Using Bespoke Models." The project will start immediately following the AAUW grant.
As a postdoctoral fellow at the University of Copenhagen, the UC Davis alumnus is a member of Professor Lene Sigsgaard's research team. She received a $244,000 postdoctoral grant from the Danish Innovations Fund to estimate insect population dynamics in relation to FaunaPhotonics's LIDAR insect sensor. LIDAR stands for light detection and ranging.
Emily's entomological journey began at Cornell University, where she received her bachelor's degree in entomology in 2013. She then received two degrees in entomology from UC Davis: her master's degree in 2017 and her doctorate in 2019.
Bick, who specializes in integrated pest management, helped anchor the UC Davis Department of Entomology and Nematology's Linnaean Games Team that won the national championship at the Entomological Society of America (ESA) meeting in 2016, and the University of California (UC Davis and UC Berkeley) Linnaean Games Team that won the national championship in 2018. The Linnaean Games, launched in 1983, are lively question-and-answer, college bowl-style competitions on entomological facts and played by winners of the ESA branch competitions. The teams score points by correctly answering random questions. (Watch the championship game on YouTube).
While at UC Davis, Bick served as vice president of the UC Davis Entomology Graduate Student Association (EGSA). ESA honored her as a Board-Certified Entomologist in 2014, and the Student Certification Award in 2018. She served as an emergency medical technician from 2008 to 2017.
- Author: Kathy Keatley Garvey
A crab spider nailed a major pest, a lygus bug, Lygus hesperus. It's something you don't see very often. But you appreciate very much.
A lygus bug made the fatal mistake of feeding on a blanket flower (Gaillardia) where the cunning spider was lurking and waiting for prey...er...dinner.
A venomous bite and it was all over.
The lygus bug is easily distinguishable by its triangle or V shape on its back. The V does not stand for "Victory" when it's attacked and consumed by a crab spider.
Do not feel sorry for lygus bugs. Their piercing mouthparts suck the lifeblood (juices) right out of the plant tissues. You may have seen them feeding on berries, beets and beans. The females lay their eggs in the plant tissues. Their visible path of destruction ranges from discoloration and deformation to leaf-curling and lesions.
"Lygus bug adults are about 0.25 inch long and 0.1 inch (2.5 mm) wide, and flattened on the back," according to the UC Statewide Integrated Pest Management Program (UC IPM). "They vary in color from pale green to yellowish brown with reddish brown to black markings, and have a conspicuous triangle in the center of the back. Nymphs resemble adults, but are uniformly pale green with red-tipped antennae; larger nymphs have five black spots on the upper body surface. Nymphs do not have wings." (Read UC IPM Pest Management Guidelines for more information and how to control them.)
The some 200 host plants of lygus bugs include Russian thistle, wild radish, London rocket, black mustard and goosefoot.
Their enemies are many. "A parasitic wasp, Anaphes iole, which attacks lygus eggs, is available commercially and can be used for inoculative releases," UC IPM says. "It can reduce lygus populations in strawberry fields; but because thresholds for this pest are very low and adults moving into the field from external sources are not controlled, economically acceptable results may not be achieved. Naturally occurring predators that feed on the nymphal stages of lygus bug include bigeyed bugs (Geocoris spp.), damsel bugs (Nabis spp.), minute pirate bugs (Orius tristicolor), and several species of spiders."
Spiders? Yes, indeed.
