- Author: Kathy Keatley Garvey
No wall can separate a Gulf Fritillary from its host plant, the passionflower vine (Passiflora).
The Gulf Frit Agraulis vanillae), an orangish-reddish butterfly of the family Nymphalidae, fluttered over our six-foot fence, heading straight for the passionflower vine. What's a little height when there are eggs to lay?
The showy butterfly's silver-spangled underwings glowed in the sunlight.
Its history glows, too. It first appeared in the vicinity of San Diego in the 1870s, according to noted butterfly researcher Art Shapiro, professor of evolution and ecology at the University of California, Davis. He's been monitoring the butterflies of central California for four decades and maintains this website.
From San Diego, “it spread through Southern California in urban settings and was first recorded in the Bay Area about 1908," says Shapiro. "It became a persistent breeding resident in the East and South Bay in the 1950s and has been there since.”
We remember hearing about the butterfly in the Sacramento/Davis area in the 1960s. Shapiro says it “apparently bred in the Sacramento area and possibly in Davis in the 1960s, becoming extinct in the early 1970s, then recolonizing again throughout the area since 2000.”
Last year, at our home in Vacaville, the caterpillars were so thick on the vine that they skeletonized it. Killed it, they did. Deader than the proverbial doornail or a nail hammered into the fence. But not to worry--we have more plants this year for them.
Watching them flutter over the wall and lay their eggs on the Passiflora is a good thing. Soon we'll see males chasing them like winged ballet dancers, eventually providing us with even more Gulf Frits. You can never have too much of a good thing. Not ever.
- Author: Kathy Keatley Garvey
The black-tailed bumble bee wasn't flying very well.
You wouldn't, either, if you were trying to fly with a backpack on your back.
Except this wasn't a backpack but sticky pollen.
The bumble bee, Bombus melanopygus, was foraging in our Spanish lavender last weekend when we noticed something unusual: a sort of hump on the back, a reddish coloration.
"That mass on the rear of the Bombus melanopygus thorax is a load of pollen," said Robbin Thorp, distinguished emeritus professor of entomology at the University of California, Davis. "A larger lump than most that I have seen before. Deposited from several visits to some 'nototribic' flower. Nototribic flowers are those that deposit pollen on the upper side of visitors. Like salvias with their anthers at the top of the tube."
Biologist Africa Gomez of the UK writes about it in her abugblog: "Some bees...specialize on collecting pollen from flowers with raised anthers, which touch over the bee's head or thorax when bees land on them. These are called nototribic flowers and include species from the Lamiaceae (the mint family) and Scrophulariaceae (the figwort family)."
"Although bee-pollinated plants benefit from bees taking nectar--exchanging nectar for inadvertent pollination- they do not benefit when potential pollinators efficiently gather the pollen for their offspring consumptions instead," Gomez points out in her blog. "Nototribic plants in response to specialised pollen gathering by bees, have flowers that make pollen hard to collect, even when they have plentiful nectar. Only bees equipped with either specialised behaviour or morphological modifications, or both can effectively make use of their pollen."
As for the bumble bee foraging on our Spanish lavender, it eventually bumbled off with that heavy load, taking flight like a weighted Spruce Goose.
- Author: Kathy Keatley Garvey
What's better than a yellow-faced bumble bee (Bombus vosnesenskii) on yellow mustard?
Not much. Both are signs of early spring.
Mustard is popping up all over, along with oxalyis and wild radish. The earth is warming. Spring is here. Get ready.
In the University of California book, California Bees and Blooms: Guide for Gardeners and Naturalists, the authors write that B. vosnesenskii and B. melanopygus "are considered spring bees because that is when their population is highest, tailing off in numbers the rest of the year."
The book is the work of Gordon Frankie, UC Berkeley entomology professor; Robbin Thorp, distinguished emeritus professor of entomology at UC Davis; photographer and entomologist Rollin Coville (he received his doctorate from UC Berkeley), and botanist Barbara Ertter, also affiliated with UC Berkeley.
Be sure to check out their companion pocket guide on the UC ANR website. It's titled Common Bees in California Gardens. It will help you identify 24 of the most common bees found in urban gardens and landscapes. That's 24 out of nearly 1600 species of native bees found in the Golden State.
Yellow-faced bumble bee, yellow mustard, Golden State....Life is good...
- Author: Kathy Keatley Garvey
In his paper, titled “Edge-Biased Distributions of Insects: A Review,” Nguyen reviewed how many species of insects show a definite preference for living on the edges of fields and orchards.
This phenomenon can lead to more accurate monitoring and better pest management tactics, said Nguyen and co-author Nansen.
The paper indicates that “the prevalence of such edge-biased distributions has considerable implications for how to sample and monitor insects, and it also suggests that in many cases pest management tactics, such as, releases of natural enemies or insecticide applications can be spatially targeted to field edges.”
Nguyen traced the history of edge-based distribution of insects in agricultural systems to a study on black bean aphids led by British entomologist C. G. Johnson and published in 1950 in the Annual of Applied Biology. The aphids, major pests of sugar beet, bean and celery crops, spread from the field edges to within, but the edges remained the areas of highest aphid density.
Nguyen also called attention to scientific studies that found that wild bees in high bush blueberry were more prevalent along the edges of orchards, and that the density of the pest, Asian citrus psyllid, prevailed more at the edges of citrus groves than within.
Nansen praised Nguyen's work as outstanding. “Sometimes we professors are fortunate enough to interact with undergraduate students who – even with English not being their first language – possess keen abilities to describe a scientific problem or phenomenon in clearly articulated scientific writing, and Derrick is a great example of that!”
“He started writing drafts of this review article about six months before he started as a graduate student,” Nansen said. "This review article is an example of how we can use writing of review papers as a tool to engage with undergraduate students before they start their thesis projects.” Professor Jay Rosenheim of the UC Davis Department of Entomology and Nematology also helped with the drafts.
“We are supposed to focus more and more on ‘diversity' and here we have an undergraduate from Singapore publishing in a very prestigious journal,” Nansen added.
The UC Davis scientists suggest that mathematical modeling approaches can partially explain edge-biased distributions but “that abiotic factors, crop vegetation traits, and environmental parameters are factors that are likely responsible for this phenomenon.”
They advocate more research, especially experimental research, “to increase the current understanding of how and why edge-biased distributions of insects are so widespread.”
“In my opinion, discussions about edge-biased distribution of insects tend to be entomocentric; much emphasis is often put on the insects themselves,” Nguyen commented. “However, agricultural insect pests are dependent on their host plants for survival. Interestingly, it has been shown in various systems that agricultural crops also display edge effect as well. Therefore, through my review, I would like to bring attention to this correlation and propose insect-plant interactions as a potential explanation of edge effect and broaden the discussion about this widely observed but insufficiently understood phenomenon.”
Nguyen received a bachelor's degree in plant sciences from UC Davis in December 2017, graduating with highest honors. A high-achieving scholar, he was on the dean's honor list, College of Agricultural and Environmental Sciences, every quarter since the fall of 2015. He enrolled in the UC Davis graduate student program in entomology in January 2018.
“I am interested in IPM, insect behavior and insect ecology, and greenhouse production of leafy vegetables,” he said. “Currently I am working on projects that explore the potentials of hyperspectral imaging technology as early detection tools for pest infestation and insect host selection based on the framework of preference-performance hypothesis. As my research model, I focus on the interactions between vegetables (bok choy and spinach) and their insect pests (leafminers and armyworms).
Nguyen served as an assistant training officer with the Singapore Armed Forces (SAF) from April 2014 to March 2015. For his studies at UC Davis, he received a 2015-2019 undergraduate and graduate scholarship sponsored by Agri-Food and Veterinary Authority of Singapore.
“For my career plan, since I am currently sponsored by AVA, I will be working for them for six years upon my graduation,” Nguyen said. “In the long term, I am interested in doing a Ph.D in imaging technology for pest detection, plant health status analysis and food quality analysis.”
Well done.
- Author: Kathy Keatley Garvey
Think spring. Think ceanothus. Think salvia. Think pollinators.
Despite the rain forecast, the open house and plant sale at the Häagen-Dazs Honey Bee Haven at the University of California, Davis, will take place from 11 a.m. to 2 p.m., Saturday, April 7.
The haven, a half-acre bee friendly garden operated by the UC Davis Department of Entomology and Nematology, will offer a number of plants, including asters, California fuchsia, salvia, ceanothus, manzanita, coffeeberry and currant. Favorites include Salvia "Bee's Bliss" and Ceanothus "Valley Violet." Check out the plant list here. Payment is cash only.
Meanwhile, the plant sale initially scheduled Saturday, April 7 at the UC Davis Arboretum Nursery on Garrod Drive has been postponed until April 14. Hours: 9 a.m. to 1 p.m. The one-acre Arboretum Nursery will be offering Arboretum All-Stars, California natives and thousands of other attractive, low-water plants perfect for creating a landscape alive with environmentally important pollinators." Look for the inventory here. Members receive discounts, and you can join online, at the gate. Credit cards are accepted.
Think spring. Think ceanothus. Think salvia. Think pollinators.