Breaking news and a well-deserved honor: Insect chemical ecologist Walter Leal, a distinguished professor at the University of California Davis, has just been selected to deliver the Founders' Memorial Award Lecture at the Entomological Society...
Walter Leal, UC Davis distinguished professor, has been selected to deliver the ESA Founders' Memorial Award Lecture on Nov. 19 in St. Louis, Mo. (Photo by Kathy Keatley Garvey)
Insect chemical ecologist Thomas Eiser(1929-2011), is widely known as "the father of chemical ecology."
UC Cooperative Extension is hosting a sudden oak death bioblitz April 25-28 in Northern California, in which a corps of volunteers will fan out across the wildland areas to track the progression of the devastating disease, reported Derek Moore in the Santa Rosa Press Democrat.
Sudden oak death is caused by the pathogen Phytophthora ramorum, which was inadvertently introduced to California forests on nursery stock in the 1990s. The disease has killed up to 50 million trees (primarily tanoak, coast live oak, California black oak, Shreve's oak and canyon live oak) from Big Sur to southwest Oregon.
Kerry Winiger, the UCCE sudden oak death outreach coordinator, is organizing this weekend's bioblitz in Sonoma and Mendocino counties.
Wininger said one of the highlights of this year's surveys is the unveiling of a new test for the European strain of Phytophthora ramorum in time to possibly thwart its spread. The new strain has been detected in Oregon.
“We want to nip it in the bud, if it's here,” Wininger said.
Sonoma County is still reeling from deadly wildfires, making the spread of SOD infection seem to some like a lower priority.
But Winiger said that oaks, as a keystone species, are crucial to the overall health of an ecosystem.
“It's like an arch,” she said. “If you lose a stone in the arch, everything else in the ecosystem is affected.”
Across the globe, scientists have shown that birds can be farmer allies. Insectivorous birds feed on damaging insect pests in many crops including coffee, cacao, oil palm, corn, cabbage and apples. Raptors, including hawks and barn owls, feed on rodents, including gophers, voles and mice (see blog, Barn owls help clean up rodents naturally).
Despite this deep historic knowledge that birds are important predators of crop pests, over time the perception of birds as natural enemies of pests has been generally replaced with the idea that birds are often major crop pests themselves. Indeed, some bird species — like some types of insects — can cause trouble for farmers, but many others — especially those that eat insects and rodents — can be beneficial.
Do birds control insect pests on farms in California's Central Valley?
They do! Recent studies by Dr. Sacha Heath, UC Davis, and Rachael Long, field crops and pest management advisor, UC Cooperative Extension, showed that birds help control insect pests in walnut orchards. Dr. Sara Kross (UC Davis postdoctoral alumnus, now with Columbia University) showed that birds help control alfalfa insect pests.
Birds are voracious predators of codling moth pests in walnuts
Codling moth is a major worm-like pest that infests walnuts, apples and pears. The larvae go dormant during winter, living in cocoons in crevices in trees. Adult moths emerge in the spring, lay eggs and infest crops.
We evaluated bird predation of codling moth using “sentinel prey” and exclosure cages. We glued codling moth cocoons to walnut trunks and covered them with cages, allowing insects and spiders to access the cocoons, but not bird predators. This allowed us to count how many larvae were eaten inside and outside of the cages to estimate pest reduction by birds.
What did we find?
Natural enemies, like parasitic wasps and lacewings, alone reduced codling moth larval numbers by 11%; adding birds into the pest control system reduced them by 46%! Nuttall's woodpeckers and white-breasted nuthatches did a lot of the work; these birds travel up and down the trunks of trees, searching for insects.
Above, a white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. Video by Sacha Heath.
Alfalfa weevils are no match for insectivorous birds
Alfalfa weevils are key pests of alfalfa, reducing yields and hay quality if left uncontrolled. Dr. Sara Kross looked at bird predation of this pest by excluding birds from alfalfa plants via cages, and counting the number of weevils inside and outside the cages. She found that birds reduced the number of weevils by more than 30%, showing their importance in helping to protect alfalfa from this serious pest.
Does field edge habitat, like hedgerows, help attract beneficial birds?
Yes! Hedgerows are important habitat for beneficial birds, serving as nesting, foraging and roosting sites. In a study in the Sacramento Valley, crop margins with hedgerows, tree lines and riparian buffers harbored up to six times more birds and up to three times more bird species than bare or weedy margins.
Walnut orchards adjacent to hedgerows and riparian areas had higher numbers of beneficial birds along with more species. In alfalfa, there were more beneficial birds in fields when at least two tall trees were present along the field edges. More beneficial birds were associated with better pest control, that is, fewer codling moth cocoons and alfalfa weevils.
Birds have large territories, fly long distances, and are influenced by what happens on the farm as well as by what happens in the landscape around the farm. For example, we found that codling moth predation by birds greatly increased in walnut orchards as the amount of habitat in the landscape around the orchards increased (including hedgerows, tree lines, riparian and oak woodlands, and grasslands).
Will hedgerows increase the numbers of pest birds?
Pest birds are present on farms regardless of field edge habitat (such as weedy vegetation or hedgerows). Cases will be different, depending on the crop, but in the fields and orchards of Yolo County, researcher Hillary White (formerly with UCCE and now with U.S. Fish and Wildlife) found that three of the most common avian crop pests (American crow, red-winged blackbird and Brewer's blackbird), were up to 10 times more abundant in agricultural fields with bare or weedy margins than in fields with hedgerows.
What can I do to attract beneficial birds to my farm?
Our avian research team has been quantifying the conditions under which birds are helpful or harmful to growers. We are looking for ways to help farmers create bird habitat on their farms to harness the beneficial pest control services birds can provide, while also protecting crops from the damaging effects of some bird species. This information is available in the new publication “Supporting Beneficial Birds and Managing Pest Birds,” co-authored by the Wild Farm Alliance and Drs. Kross and Heath, and technically advised by UC Cooperative Extension and several farmers. This is a user-friendly guide for farmers and conservation practitioners, with the goal of co-managing farmlands for biodiversity and farming.
A white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. (Video still: Sacha Heath)
Why are we in this situation? Multiple factors are involved. We suppressed wildfires in our forests for 100 years, and stopped using prescribed fire as a tool for ecosystem benefits and fuel reduction. Further, we have been experiencing hotter summers (so the window for burning is wider) and we've continued to build into wildfire-prone areas with home construction, lot layout and community planning that often are not up to the fire challenge.
Is there hope? I present these as my take always, noting there is more detail to be seen at the UC ANR fire and other websites (e.g., CFSC). I was impressed by the three relatively clear battle grounds we need to attend to:
- Our homes: how we build, layout and landscape our homes
- Our communities: how we structure our neighborhoods and communities
- Our forests and beyond: how we manage (what I'll call) the forests and wildlands. Each has particular needs and opportunities
While the above focuses on prevention and management of fires, the Summit had good representation of the health sector, reminding us of the need to help humans, domestic animals and wildlife affected and traumatized by fire events.
The Summit was deemed by the participants themselves as very successful. Kudos to the many organizations who participated. There is momentum building with a genuine desire to work together to help the people of California.
Want to learn more? Contact some of our experts, who served as the chairs of the Summit coordinating committee:
David Lile, Leader, Sustainable Natural Ecosystems Strategic Initiative, UC ANR
Lenya Quinn-Davidson, fire advisor, Cooperative Extension, Humboldt County, UC ANR
Yana Valachovic, forest advisor, Cooperative Extension, Humboldt and Del Norte County, UC ANR
Want more? See UC ANR fire
Little Logan Loss of Rocklin is only 6 but already he knows more about scorpions than many, if not most, adults do. Logan, a visitor at the Bohart Museum of Entomology's recent open house on spiders and other arachnids, wowed the crowd with his...
Logan Loss, 6, of Rocklin talks about scorpions to Bohart associate and scorpion scientist Wade Spencer. The kindergarten student is an avid scorpion enthusiast. Also pictured are members of the Vacaville Brownie Girl Scout Troop (from left) Jayda Navarette, Keira Yu and Kendl Macklin, front. (Photo by Kathy Keatley Garvey)
Bohart associates and entomology students Lohit Garikipati show scorpions to the crowd. (Photo by Kathy Keatley Garvey)
This is Wade Spencer's desert hairy scorpion named Barthlomew. (Photo by Kathy Keatley Garvey)
Wade Spencer's desert hairy scorpion named Barthlomew glows under UV light. (Photo by Kathy Keatley Garvey)
Wade Spencer holds his African burrowing scorpion (left) and desert hairy scorpion under UV light. (Photo by Kathy Keatley Garvey)