- Author: Alejandro Del Pozo-Valdivia
There are sex pheromone traps for Diamondback moth set up across the Salinas Valley. This pheromone only attracts males of this pest. These traps were first put out on February 20th, 2019. Traps are located in Castroville, Marina, Buena Vista, Chualar, Gonzales, by the Prison (near Soledad), and Soledad. Thanks to the PCAs who are helping me with this project.
Basically, numbers of moths per day per trap have been zeros, with the exception of the trap located in Castroville. Interestingly, moths were captured in all traps last week. The actual values of those captures are presented in the below figure as yellow dots. The bigger the dot represents a larger moth capture.
It seems like a new flight for the diamondback moth is about to begin across the Salinas Valley. Additionally, there has not been a break on the life cycle of this pest in the Castroville area. Population of this moth are persistent throughout the year in that area. The trap in Castroville has always captured moths since it was set up. Populations of this moth are residents of brassica weeds, as noted in previous scouting trips.
But, what does it mean to have less than one moth per trap per day, compared to 5 moths per trap per day? Is 5 moths a high value? How is that translated to caterpillars in the field? The next step will be to pair moth trap captures with actual scout data for caterpillars found in the surrounding areas of the traps. In the meantime, the information from these traps could help us to potentially predict when caterpillars might be present in the system in larger numbers. It is more likely that we will be able to see an increase of diamondback moth caterpillars in the next two weeks. It may be good to pay attention to cole crop fields, with the goal to early detect potential damaging populations of this pest in scouted fields.
I will be updating this map with moth captures at least every other week. Stay tune!
If you would like to learn more about this project, do not hesitate in contacting Alejandro Del-Pozo at adelpozo@ucanr.edu or 831-759-7359.
- Author: Alejandro Del Pozo-Valdivia
- Posted by: Gale Perez
Diamondback moth (DBM) is a persistent pest in the Salinas-Castroville area. We were able to find late instar caterpillars in several spots along Blackie road on Tuesday, January 22nd. Basically, these caterpillars were feeding on brassica weeds, located along the side of the road (Fig. 1). This is an example of how insects exploit weeds as alternative hosts when there is a lack of a preferred and abundant host plant in the landscape. DBM will continue feeding on these weeds, while increasing their numbers. These DBM adults, originated from weeds, have the potential to infest any commercial cole crop during the upcoming weeks and months. Based on our observations, most of these caterpillars were close to pupate. Within the next two weeks, we might see an influx of DBM adults flying around fields and weed patches. A new generation of caterpillars may be present around mid-February in our system, depending on temperature fluctuations.
It seems like not all of these caterpillars will become adults. Approximately, 10% of the caterpillars collected from Blackie road were parasitized by Diadegma wasp. We took these caterpillars to the UCCE Entomology lab to refresh and re-introduce DBM into our colony; and we were able to spot the parasitic wasp pupae inside our rearing containers (Fig. 2).
Ideally, controlling weeds outside our fields and along the roads could be part of our strategies to manage resident pest populations. Control of these weeds will allow to reduce population of these pests cycling through the winter here in the Salinas-Castroville area. Managing these weeds could be challenging too, due to accessibility and other issues. Please keep in mind that cole crop fields surrounded by weedy patches will have a higher chance to be infested with DBM. You could prioritize the scouting of those fields to timely detect any economically damaging DBM population in your crop.
If you would like to learn more about DBM and the research conducted by the University of California Cooperative Extension (UCCE) Entomology team, please contact Alejandro Del-Pozo at adelpozo@ucanr.edu or (831) 759-7359.
- Author: Alejandro Del Pozo-Valdivia
It has been a couple of “rough” weeks managing the diamondback moth (DBM), Plutella xylostella (Lepidoptera: Plutellidae), in the Central Coast. Based on my conversations with some PCAs, we are managing large populations of this moth, resulting in high infestations in cole crops like broccoli and Brussel sprouts. Larvae of this insect will typically feed on the underside of the leaves, rasping the epidermis and generating this characteristic “window panning” that results on perforations later on (Fig. 1). Diamondback larvae will also feed on the plant's growing points, floral stalks, and even on flower buds.
It seems like populations have been building up during early summer in our area, resulting in enough individuals, at this point, generating significant injury in cole crops. PCAs have been recommending spraying several different insecticides to reduce the infesting populations in affected fields, since damage has been beyond tolerable. For instance, after one of my field visits, I was able to spot affected larvae in treated fields (Fig. 2). Treatments are working, I believe we need to continue being ahead of future DMB infestations.
Some information to consider:
- Scout early. If you have transplants or direct seeded seedlings, pay a visit more often. We are dealing with a large DBM population right now. There will be a high chance that those fields may ended having DMB earlier than expected during this time of the year.
- Use of adjuvants. The waxy nature of cole crop leaves represents a challenge for insecticide deposition in the canopy. Make sure that you are using a spreader/sticker adjuvant to potentially reduce any pesticide “sliding off” from the waxy leaves.
- Rotate pesticides. Consider using different classes of insecticides, before using different active ingredients within the same class. For instance, using an avermectin and then a diamide, instead of using chlorantraniliprole and cyantraniliprole (two different active ingredients within the diamide class) back to back. Using different modes of actions will help to delay potential issues of developing insecticide resistance in our DBM populations.
- Author: Alejandro Del Pozo-Valdivia
We have been scouting for Bagrada bug on wild host plants at two sites in the San Ardo area since middle of May. We selected San Ardo as our most southern scouting point for the Salinas Valley. Every other week, we have performed plant visual counts and collected yellow sticky cards to document the presence of these bugs. So far, we have not found any Bagrada bug in the San Ardo area.
Four additional sites, along Highway 101, were added today to the Bagrada bug scouting route. These sites, from south to north, are located: 1) near King City, 2) south of Greenfield, 3) south of Soledad, and 4) north of Soledad. Today, we were able to document the presence of Bagrada bug adults (Fig. 1), on shortpod mustard (Fig. 2), in two of the four additional scouting sites. Bagrada bug adults are currently located north of Soledad and near King City. From our observations, there are no nymphs nor eggs on the shortpod mustard. Adults were observed mostly mating. Early instar nymphs will be expected in the next couple of weeks.
We will be increasing the frequency of the scouting for this bug to weekly visits, and we will be adding two additional sites near Gonzales, one in Chualar, and another one south of Salinas. Adding more sites will help to document if Bagrada bugs are present in other places besides Soledad and King City. Are these bugs isolated and resident Bagrada populations? We plan to answer this question setting up more scouting sites across the Salinas Valley.
Today, we also noticed that the most of the shortpod mustard plants are senescing. It would be expected that Bagrada bug females might disperse from unsuitable wild host plants to recently planted cole crops in the surrounding areas. Dispersing and mated females may lay their eggs on these crops. I would suggest to PCAs to check recently planted or young cole crops in the surrounding areas of Soledad and King City during this week. Early detection of potentially migrating females will help everybody to successfully manage this pest.
We will continue to visit our scouting sites for Bagrada bug in the Salinas Valley. If you have any further question about the situation of this pest in your area, please call or email Alejandro Del-Pozo at 831-759-7359 or adelpozo@ucanr.edu.
- Author: Kathy Keatley Garvey
So here's this praying mantis perched on top of a prickly pear cactus.
It's early morning and she's hungry.
A cabbage white butterfly, looking like a white-gowned princess in a medieval palace, flutters by and pauses on the prickly pear to seek some sunshine.
Oops! Fatal mistake. When you're seeking sun, do not do that in front of a predator.
Breakfast? Yes, that's what happened.
Before you feel sorry for the cabbage white butterfly, consider this: farmers who grow cole crops, such as cabbage, cauliflower and broccoli, would probably let out a shout of approval. That's because the cabbage white is considered a major pest of commercial cole crops. The butterfly lays her eggs--which are pale yellow to orange--in cole crops. The larvae, known as "green worms" or "green caterpillars," can cause major economic losses.
The cabbageworms have voracious appetites. They chew "large, irregular holes in leaves, born into heads, and drop greenish brown fecal pellets onto edible portions of the leaf," according to the UC Statewide Integrated Pest Management Program's Pest Management Guidelines on "Imported Cabbageworm" (Pieris rapae).
In home gardens, the cabbage white is considered a minor pest, although gardeners aren't fond of cutting open a broccoli head only to see that cabbageworms got there first.
At UC Davis, the common cabbage white butterfly assumes a more scientific role. Butterfly guru Art Shapiro, distinguished professor of evolution and ecology, hosts an annual "Butterfly for a Beer" contest. The first person in the three-county area of Sacramento, Yolo and Solano who brings in the first cabbage white of the year wins a pitcher of beer. It's all in the interest of science.
Shapiro, who does long-term studies of butterfly life cycles and climate, says the cabbage white is “typically one of the first butterflies to emerge in late winter. “Since 1972, the first flight has varied from Jan. 1 to Feb. 22, averaging about Jan. 20.”
The 2016 winner was UC Davis graduate student Jacob Montgomery, who caught the cabbage white outside his home in West Davis.
Shapiro, who has monitored the Central California population of butterflies for more than four decades, says the cabbage white is now emerging a week or so earlier on average than it did 30 years ago here.
As for the praying mantis, the cabbage white butterfly was just...breakfast.