Last week I attended a webinar hosted by the University of California Statewide Integrated Pest Management Program about what’s new in the world of our bees here in California.
60-70% of flowering plants require animal pollination. More than 80 crops require animal pollination. Some agricultural/garden crops require specific types of pollinators. For example, grapefruit require honeybees, while Tomatoes, cherry, cucumber require wild bees. The researchers used “wild bees” to mean non-honeybees, even though some honeybees have become feral. (Honeybees are not native to California; they originated in Europe.) Wild bees are more efficient pollinators for almost all crops, but the ability to manage honeybees make them economically important. For commercial edible production, it is best to have healthy populations of both wild and honeybees. Wild bees cause honeybees to visit monocrops in a more random style which is better for pollination. Some wild bees, like the alfalfa leaf cutting bee are not native to California. For plant species diversity in the wild lands, and for productive vegetable home gardens, the presence of wild bees, not just honeybees, is necessary.
How to tell a bee from a fly?
Bees have branched hairs (can be tiny hairs) and four wings.
Some flies mimic bee coloration and pattern as a defense against bird predation.
How to tell a bee from a wasp?
Wasps have slender waists. Bees are plumper. Bees have pollen on them, wasps do not.
“Bees are wasps that have gone vegetarian.”
Not all wild bees are solitary nesting, but most of them are. There are abut 20,000 known species of bees worldwide. The majority of these are solitary nesting. There are 1600 bees native to California. Best known examples of solitary bees are leaf cutting bees, carpenter bees and mason bees. Other species are mining bees, sweat bees, digger bees and carder bees.
Bumble bees, some species of sweat bees and honeybees are “eusocial.” They live in hives that range in number from 20 (sweat bees) to 90,000 (typical honeybee hive size). Other traits of eusocial bees are: the have overlapping generations, they practice cooperative brood care, and they practice division of labor.
Wild bees have a much smaller range than honeybees, sometimes only about 100 yards. Honeybees can range up to six miles and visit up to 1500 flowers in one trip.
Reasons for decline in bee population:
1) land use changes – urbanization, tilling, monocrop agriculture. This has affected wild bees quite a bit, weather solitary nesting or eusocial.
2) parasites have increased in honeybee populations as they have been increasingly moved great distances where they are exposed to more parasite species.
3) pesticides, especially neonicotinoids. Studies are ongoing but some have shown that neonics don’t kill bees outright but cause stress in the whole hive and weaken their response to parasites, general poor management practices. This is called “sub lethal” effects and affects their communication, navigation and especially weakens Queens.
Studies are being done to find better management practices for commercial honeybees, like developing beneficial bacteria in hives, using more biological controls in crops to replace pesticides, encouraging professional monitoring of bee health within the veterinary medicine profession, using drones to spot treat with pesticides instead of treating entire fields.
Some things known to help:
1) hedgerows and “wild” rows around and in between rows of monocrop production, especially with diverse species of plants.
2) use of native plants to support specialist bees, most of which are solitary-nesting and small.
3) reduce tilling to avoid destroying ground nests.
4) Mustard is a good cover crop, along with low growing native ground covers.
Researchers who presented the webinar:
Dr. Quinn McFrederick, UC Riverside
Dr. Boris Baer, UC Riverside
The full webinar recording should be posted on the UC IPM YouTube channel around April 17, 2020. The title was: From Integrated Pest Management to Integrated Pest and Pollinator Management: An Update on Current Research on Pollinator Healthy.
It wasn’t in the webinar, but there’s a good article with bee identification pictures and plant suggestions here: https://arboretum.ucdavis.edu/blog/beyond-honey-bee-learn-more-about-california-native-bees