- (Focus Area) Pest Management
- Author: Thomas J Getts
I have gotten quite a few calls about blister beetles this year. There was a newspaper article up in Modoc that caused some stir, and was picked up by a lot of social media pages. So, what are blister beetles and why do we care?
Blister beetles get their name for a reason. They contain the toxin cantharidin, which can be excreted when they are threatened, or crushed which causes bad blisters on the skin. While this is problematic they typically are not drawn to humans, and blisters can be avoided by not handling them. Where they pose a larger problem is as a contaminant of hay, where they can be crushed/killed and incorporated into a bale posing as a potential toxin to be consumed by livestock.
Photo One: Blister Beetle on Musk Thistle next to a Roadway
Let's take a step back. What are blister beetles and why are they a subject of conversation now? There are numerous native blister beetles in California. Some are striped, some are brightly colored, but most of the ones I have been seeing are black or grey. The immature larvae of blister beetles feed on the eggs of grasshoppers or ground dwelling bees. I don't have to tell anyone in the Intermountain region, we have had quite a few bad grasshopper years which has led to an increase in blister beetle populations. Typically, the adults lay eggs right on top of the egg beds of grasshoppers. I'd be on the lookout for blister beetles the rest of this year, and definitely next year as they feast on the eggs underground. (So, they are not all bad as they kill some hoppers!).
Photo Two: Grasshoppers flying away from an ATV in a pasture up in Modoc County
As adults, they can consume forage, but typically they are drawn to flowers and consume pollen. (Different species have different preferences.) I have mainly seen them on roadsides, trail sides, and rangelands where there are flowering plants. In hay fields I have only seen them in “native hay pastures” that have wildflowers. However I have gotten reports of them being on the edges of some alfalfa fields that have started to go to bloom.
For livestock generally they are only problematic when they get caught up in a bale. How many is too many? This is a good question. Numerous extension publications cite research done back in the 80's looking at how many blister beetles it would take to kill a horse (horses are more susceptible to the toxin than cattle of sheep). As with all toxin's it often depends on numerous factors, and there is not a single number of beetles that will kill a horse every time. The amount of toxin per beetle can vary by species of beetle as well as within species of beetle. From the research done in the 80's the cantharidin content per beetle ranges from 0.5mg to 5mg, and is toxic to horses at the tune of 1mg/kg. This means that there can be a huge range of how many beetles it will take to kill a horse (see table one). With that being said while it may take a significant number of beetles to kill a horse, as few as five beetles can start to cause colic.
Table one: Adapted from Capinera et al. 1985. J. Econ. Entomol. 78:1052-55.
So, what do you do about the beetles? One of the best things to do is scout fields before they are cut to make sure you do not have them in the field. While it might be counter your management objectives to maximize yield during the mid-season cuttings, cutting alfalfa or clover before bloom can reduce the incentive of beetles to move into hay fields. It is also important the keep a clean hay field, and reduce the number of weeds that may flower in the field drawing the beetles in. There are insecticides like (Sevin- carbaryl, or Warrior- lambda-cyhalothrin) which are effective at killing blister beetles in forages, but may pose their own drawbacks. While most of the beetles should die and fall down to the ground after an insecticide application, there is still some potential for them to be incorporated into the hay during the cutting and raking process. Likewise, the pre harvest intervals for these materials can delay cutting and could require driving over a lot of hay, if an aerial applicator is not available. Cutting around infested patches or isolating/discarding hay that may be contaminated, could be a prudent strategy. Likewise waiting until the beetles move out of the field could be an option.
Photo Three: Blister beetles on clover in a "native" hay meadow in the Intermountian region
There are over 300 species of blister beetles in North America, and not all have been tested for their Cantharidin content. When haying especially using modern equipment with conditioners, I urge you to be cautious, and take time to scout fields before cutting, especially if that hay is going to the horse market.
For more information there are some excellent extension publications online from UCIPM, Colorado State University and North Dakota State.
Photo Five: Blister Beetle on Feral Rye next to the Susan River in Lassen County
Nobody wants cockroaches in their home, especially since these pests can cause and worsen allergies in children, transmit diseases and bacteria, and contaminate foods.
If you find cockroaches in or around your home, do you reach for a do-it-yourself spray product? Well, you might not want to waste your money!
New research shows that some common consumer-grade insecticide sprays don't work to get rid of cockroach infestations. The study focused on products containing pyrethroids, which is a group of pesticides commonly found in many household insecticide products. Examples of pyrethroids include the active ingredients bifenthrin, cypermethrin, and permethrin.
In the study, both liquid and aerosol pyrethroid products killed less than 20% of German cockroaches on sprayed surfaces. Even when cockroaches were confined to the sprayed surfaces, most products took 8 to 24 hours to kill them, with some taking up to 5 days.
Research has also shown that frequent use of pyrethroid insecticides for cockroach management had caused the insects to develop resistance to these products.
So, what can you do to effectively control cockroaches?
Identifying the species present is important since some cockroaches live and breed indoors, while others live and breed outdoors. Knowing which cockroach species you have will allow you to focus control efforts on the correct location, using methods that are effective for managing that specific type of cockroach.
Pesticides alone will not solve a cockroach problem. Use pesticides indoors only if the cockroach population is reproducing and living in your home, not for the occasional intruder. Use insecticide bait products in combination with other non-chemical control methods, such as exclusion and sanitation.
Hiring a professional pest control service that takes an IPM approach can be helpful in reducing serious indoor cockroach infestations but can be also be expensive. Professionals have the tools, experience, and knowledge to better address serious pest issues. Infestations in multi-unit housing, such as apartment complexes, can be especially difficult to control and often requires a community-wide effort.
For more detailed management information, see the Pest Notes: Cockroaches.
[Adapted from an article published by the Entomological Society of America on August 14, 2024.]
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- Author: Kathy Keatley Garvey
Two UC Davis nematology doctoral students were invited to give research presentations at the international Society of Nematologists' conference in Park City, Utah and they excelled.
Meet the two young women: Alison Blundell, a doctoral candidate who was invited to compete in a 12-minute student oral competition to discuss her research on root-knot nematodes, and doctoral student Veronica Casey, invited to share her research on "Pathogenic Hitchhikers."
Their major professor, Shahid Siddique, encourages his students to participate in the Society of Nematologists (SON), an international organization that advances the science of nematology in both its fundamental and economic aspects.
Blundell, who anticipates receiving her doctorate in 2026, won second place in the international competition with her presentation, “Overcoming Resistance: Unraveling the Mechanisms Behind Root-Knot Nematode Evasion of Tomato Mi-Gene.” She received a $250 prize.
Blundell researches plant-parasitic nematodes specifically root-knot nematodes, and their molecular mechanism to defend against plant immune systems. In her abstract, she wrote: "Root-knot nematodes (RKNs) are among the most devastating pathogens of crops, causing substantial yield and economic losses worldwide. These parasitic organisms can infect over a hundred different plant species and can evade plant defense mechanisms by secreting a concoction of effectors. For decades, the Mi-1 resistance gene has been effective in detecting and inhibiting RKNs in tomatoes. However, the underlying mechanisms by which Mi-1 detects these pathogens remain largely unknown. In recent years, resistance-breaking populations have emerged in both greenhouse and field settings, posing a threat to the potency and effectiveness of the Mi-1 gene and, consequently, the tomato industry. "
"We used two strains of M. javanica, one strain VW4, which is recognized by Mi-1, and another strain, VW5, which was selected from VW4 and can overcome resistance mediated by Mi-1," Blundell explained. "Utilizing the newly constructed reference genome for M. javanica (VW4), we compared genomes of VW4 and VW5 and identified an approximately 50 kb region that is present in VW4 but missing in VW5. This missing region contains seven protein-coding genes, three of which encode putative effectors and are currently being tested as potential avirulence genes for Mi-1."
"In addition, we have conducted a series of infection assays on different host plants lacking Mi-1, and the results revealed a significantly lower egg count in VW5 when compared to VW4. We plan to expand these assays by testing additional M. javanica resistance-breaking strains collected from fields all over California to determine if this trade-off is consistent across other strains. Overall, our results suggest that although VW5 can overcome Mi-1, there is a trade-off in the form of compromised reproduction. This research helps to better understand the mechanism and components of Mi-1 and develop strategies for addressing resistance-breaking populations."
Pathogenic Hitchhikers
Doctoral student Veronica Casey delivered her invited presentation on “Pathogenic Hitchhikers: Investigating the Synergy of Bacteria and Nematodes on Plant Health.”
a"In the vast scope of soil ecology, plant-parasitic nematodes can forge alliances with other microbial adversaries, such as the disease complex formed between nematodes and bacterial wilt-causing Ralstonia spp.," Casey wrote in her abstract. "These disease complexes exacerbate disease symptoms and yield losses. Plant-parasitic nematodes are microscopic roundworms that cause approximately $100 billion in yield loss a year, and most of the damage is attributed to root-knot nematodes (RKNs; Meloidogyne spp.). Bacterial wilt is caused by multiple Ralstonia species, namely Ralstonia pseudosolanacearum, R. solanacearum, and R. sygzii that enter the plant's roots to colonize its vascular system. Prior to Ralstonia infection, RKN infection may facilitate bacterial disease by increasing access to the vascular tissue."
"However, little research has been conducted to elucidate the molecular details of this interaction," Casey pointed out. "Previous reports of RKN and Ralstonia spp. in the field hypothesized that the infection was due to root wounding and physiological changes. In this study, I will determine the nature of the interaction between Ralstonia and nematodes at both ecological and molecular levels. This research project will explore the hypotheses that 1) Ralstonia adheres to the cuticle of nematodes using specialized appendages called pili and 2) de novo xylem formation in the galls increases Ralstonia transport into the plant. A common strategy for preventing nematode infection is by using resistant plant cultivars."
"However, resistance-breaking nematode populations have arisen and we plan to utilize resistance-breaking nematodes, which are most likely to interact with bacterial wilt in the field," Casey noted. "This presentation will report on the attachment and greenhouse experimental results of the RKN-Ralstonia complex. The escalation of climate change is leading to increased instances of pathogenicity; therefore, it is crucial to uncover disease complexes which can have monumental consequences on food security. A meticulous study into the nematode and Ralstonia disease complex will support the management of these damaging pathogens across the world."
Blundell and Siddique also delivered invited presentations in the illustration workshop. Blundell gave her presentation on "Become an Illustrator Mender Simply by Using BioRender," and Siddique, "Doodle Your Data: Adobe Illustrator for Nematodes."
Other lab mates from the Siddique lab also participated in the SON meeting. (See news story). In the ecology session, doctoral candidate Chris Pagan participated from the UC Davis lab of distinguished professor Steve Nadler, former chair of the Department of Entomology and Nematology. Pagan's presentation: "Nematode Community Structure in the Rhizopsheres of Southern California Creosote (Larrea trientata).”
Of note, Blundell and Casey were among the four graduate students from the Siddique lab who received travel awards. Blundell won a Corteva award and Casey, a Certis award. Also receiving travel awards wer Ching-Jung Lin, a Bayer CropScience award and Romnick Latina, a N. A. Cobb Foundation award.
Honorary Member. At the 2024 conference, UC Davis distinguished professor emeritus Howard Ferris was selected a Honorary Member, the highest award that SON offers. (Feature story pending; wait 'til you hear his exciting life story!)
UC Davis nematologists are already looking forward to the next annual meeting: July 13-17 in Victoria, British Columbia, Canada. Meanwhile, you can chat one-on-one with them at the annual UC Davis Biodiversity Museum Day, usually held in February on the UC Davis campus. It traditionally featuring a dozen or so UC Davis museums. Student nematologists are spotlighted on the current website.
![Doctoral candidate Alison Blundell delivering her award-winning presentation in the 12-minute student competition at the international Society of Nematologists. She won second place. (Photo by Veronica Casey) Doctoral candidate Alison Blundell delivering her award-winning presentation in the 12-minute student competition at the international Society of Nematologists. She won second place. (Photo by Veronica Casey)](/blogs/blogcore/blogfiles/108393.jpg)
![Doctoral student Veronica Casey of the Siddique lab delivering an invited presentation on “Pathogenic Hitchhikers: Investigating the Synergy of Bacteria and Nematodes on Plant Health.” Doctoral student Veronica Casey of the Siddique lab delivering an invited presentation on “Pathogenic Hitchhikers: Investigating the Synergy of Bacteria and Nematodes on Plant Health.”](/blogs/blogcore/blogfiles/108394.jpg)
- Author: Kathy Keatley Garvey
So there you are, admiring your Coreopsis and suddenly you notice spots and holes--spots on the backs of two western spotted cucumber beetles, and holes cut in the petals.
Ah, there's two of them.
The beetles, about a fourth of an inch long, are fun to photograph, but they're not your buddies. Nor would they want to be!
"Cucumber beetles are very common pests in vegetable gardens and may also attack ripening stone fruit," says the UC Statewide Integrated Pest Management Program. "The most abundant species in California is the western spotted cucumber beetle, Diabrotica undecimpunctata...The western spotted cucumber beetle is greenish yellow and has twelve black spots on its back."
Ever counted the spots? Yes, 12.
We've seen the beetles feeding on the leaves of flowers and many vegetables. "Cucumber beetles may also spread cucumber mosaic virus or wilts in cucurbits," UC IPM says. "Larvae feed exclusively on roots, but do not generally damage garden plants, although corn may occasionally be damaged."
Spotted cucumber beetles don't move very fast early in the morning, so they're fairly easy to photograph.
And sometimes you get a "two-fer," two in the same image. 24 spots.
![Two Western spotted cucumber beetles, Diabrotica undecimpunctata, on a Coreposis. (Photo by Kathy Keatley Garvey) Two Western spotted cucumber beetles, Diabrotica undecimpunctata, on a Coreposis. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/108338.jpg)
Fleas can be found on pets year-round, but populations tend to increase dramatically in spring and summer when temperatures are warmer. Larvae develop rapidly in areas where temperatures reach 70° to 90°F. Fleas are a major concern for pet owners as they can give dogs and cats tapeworms, but they can also transmit flea-borne typhus to people and spread plague to wild animals like ground squirrels. These blood-sucking pests can be introduced to backyards from feral cats, squirrels, opossums, and other wildlife.
To learn more about fleas, the diseases they can spread, and their management, check out the recording of UC IPM's Urban & Community IPM Webinar from June 2024 at https://www.youtube.com/watch?v=b-w7J6mkTeM. You'll hear from flea expert Dr. Laura Krueger of the Orange County Mosquito and Vector Control District on how you can protect yourself and pets from fleas.