Archive for May, 2011

Live fast, die young

It is finally starting to feel like summer.  The sun is shining, the weather is heating up, and the humidity is not that bad yet.  It’s a glorious Sunday for a graduation BBQ and a good way to celebrate Memorial Day Weekend.  I’ve been sleeping with the windows open the past few days, and while I’ve been waking up to the birds singing, I haven’t heard many of the crickets.  Soon though, they will come.  The evening chorus will ring on and on in celebration of summer.

Like summer, crickets can’t go on forever.  But new research indicates that crickets who live fast, die young.  The resting metabolism of crickets determined their longevity.  Calling crickets expend energy, which perhaps takes away from their overall energy budget for other activities.  The research team suggests this may have an impact on their overall lifespan.

The results found that crickets with a higher resting metabolic rate have lower life expectancy.  However, the link between mating calls and resting metabolic rate was not fully distinguished.  While links between physiology and behavior have not been thoroughly explored, they are likely to be very important.

Read more about the article on Wired or for the full article, click here.

Who’s Who #2

That cute little critter from Wednesday is a pest of the plant below!

If you’ve never seen asparagus growing in a field, this is what it looks like (picture was taken about a week ago in western New York).  It’s asparagus season, and in fact I had some deliciously prepared asparagus at a tapas restaurant in town last night.  My favorite preparation of asparagus is quite simple.  I arrange the stalks on a baking sheet, drizzle with some olive oil, squeeze some lemon juice over them, sprinkle a bit of garlic powder and pepper, then bake for about 30 minutes at 375º until tender but crisp.

Wednesday’s bug is the spotted asparagus beetle, Criocercis duodecimpunctata.  Here’s our spotlight pest on the crop itself.

Photo courtesy of Insect Images

The beetles are quite small, about 6-8mm in length.  Spotted asparagus beetles are in the family Chrysomelidae and may resemble ladybugs to the untrained eye.  It is distinguished from ladybugs by the six spots on each wing with longer antennae and an almost rectangular shape.  (Ladybugs tend to be more oval or almost totally round with similar but varying coloration.)  This particular species of asparagus beetle is often considered a secondary pest of asparagus, with the asparagus beetle Criocercis asparagi the most common pest (below).

Photo courtesy of Flickr

Both these pests directly damage the asparagus crop by feeding on tips and spears.  Furthermore, C. duodecimpunctata feed on the asparagus berries of the male plant.  Cutting stalks close to the ground is a good way to manage for asparagus beetle, not allowing larvae to establish in the crop.  Removing dead stalks over winter can also help reduce success of overwintering populations.  Particularly for the spotted asparagus beetle, removing asparagus berries can help reduce pest populations in home gardens.

Now that the weather has finally warmed up, it’s time to get working on the summer garden.  As soon as these thunderstorms let the soil dry up.  Happy gardening!

Guess Who Wednesday #2

Who is this little critter?  Hint: it’s a crop pest.

TEDx

I love TED.  Someday, I would love to attend the conference, even an independent TEDx event.  Until then, I will just be satisfied by watching TED talks.  Like this one about biological control!  He even talks about thrips 🙂

One ray of sunshine

We’ve gotten a lot of wet weather the past few weeks which has greatly affected the vegetable growers in the region.  Soil preparations and field plantings have been delayed, putting everything a couple weeks behind schedule.  With the delays in crop host establishment, it seems like pests may also be delayed in the colonizing of crop fields.  One way of determining whether this is the case is to use degree day models.

In pest management, degree days are a measure of heat which can be used to track development or manage insect pests.  Organisms have development temperature thresholds, below and above which development is arrested.  For example, with San Jose scales Quadraspidiotus perniciosus the lower threshold is 51ºF and the upper threshold is 90º.  As long as the ambient temperature is between these two thresholds, San Jose scales continue to develop.  For onion thrips, the lower threshold is 52.7ºF.

Degree days are the accumulated product of time and temperature between temperature thresholds.  One degree days is one 24 hour period in which the temperature is one degree above the lower development threshold.  Of course, temperature varies throughout a 24 hour period in field situations. This is taken into account when constructing a degree day model.  Degree days can also be accumulated throughout a growing season, which is how emergence predictions are calculated.

In the simplest model, the equation for a degree day calculation for one 24 hour period looks something like this:

(min temp +max temp)/2 – (min threshold)

Summing the above term for the number of days would give you the degree day accumulation.  Other calculations model temperature fluctuation in more complicated ways, which may provide closer estimates of actual degree days accumulated.

So let’s check on onion thrips in Elba, NY.  Cornell has degree day information here, with 147.6 degree days accumulated since Jan 1.  This calculation is based on 50ºF as the minimum threshold.  The UC IPM site states 140.4 degree day accumulations are necessary for egg development.  Given that onion thrips have a slightly higher threshold than the Cornell model, they’re not hatching.  In Penn Yan, degree day accumulation is 182.0.  Slightly higher, which is better for onion thrips.  But on account of the rain, which demolishes thrips populations, I still didn’t see any thrips out and about when I was in the field yesterday.  So until we get some sun and it warms up, I may just be sitting pretty.