The best part about an online magazine, is that they send you emails only if you want them. And in the case of Saveur, I get tasty recipes to try on a regular basis. Last week, a number of recipes for a Summer Vegetarian Feast filled my email inbox. One was a delicious leek and zucchini galette, combining great flavor and seasonality.
There are leeks growing alongside my onions in some fields. Some of the growers I work with have a few different Allium species growing including garlic and leek. These crops could be subject to leek moth infestation, but leek moth is currently only known in certain areas of New York and Canada (in North America). An invasive species from Europe, leek moth, Acrolepiopsis assectella, is a small, brown to black moth with yellow-green caterpillars. The pupae are small cocoons with a distinct lacy casing.
Adult Leek Moth courtesy of AgroAtlas
Leek moth pupal casing
Leek moth damage include mining and perforations in the leaf, with window-paning damage where the caterpillar has not eaten all the way through all layers of the leaf tissue.
Leek moth damage
While there are no chemical treatments yet in New York, cultural treatments such as crop rotation, row covers, and removing vegetative debris at the end of the season are recommended. In Canada, a parasitoid wasp Diadromus pulchellus was released as a biological control agent as part of an integrated pest management approach to control leek moth. Perhaps that may be an option for leek moth control here as well.
When you take time to smell the flowers, or rather peer at the onions, you find some pretty cool stuff. This week, Simon shared with me another little gem of nature: parasitized natural enemies. Just a reminder, parasitoids develop internally on their host, usually killing it. This particular case of parasitism, however, is atypical in that the host does not die
Image courtesy of Maure et al. 2011
The victim of the story is the common Pink Lady Beetle, Coleomegilla maculata, affectionately called C-mac in some circles. C. maculata is a generalist predator, feeding on aphid species and other small soft bodied insects. I’m not surprised to see many of them in the onion fields. In this case, a parasitic wasp, Dinocampus coccinellae, lays a single egg inside its beetle host. Rather than killing the host, the wasp larva emerges and spins its pupal casing around the legs of the ladybug, keeping it in place. Thereby, providing its own bodyguard to protect it from predation and hyperparasitism (parasitoids that parasitize other parasitoids…that’s a lot of parasitism). This article was just published online about the system. Pretty cool!
Image courtesy of Stippen.nl
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 🙂
As many of you may know, not all insects are bad. In fact, some are actually quite beneficial. The groups I’m referring to are predators and parasitoids. These kinds of insects help maintain population balance in natural ecosystems. In agricultural systems, they can help suppress and manage pest populations and prevent outbreaks.
Predatory insects are the carnivores of the insect world, feeding on other insects and animals. Common predators include ladybugs, hover flies, and mantises. Arachnids, like spiders, are also great predators. My current favorite are predacious diving beetles in the family Dytiscidae. Specifically, the pair of sunburst diving beetles Thermonectus marmoratus (order Coleoptera) I have swimming around in the tank on my desk.
Photo from Arthropoda
In explaining parasitoids, I must also differentiate between parasites. So I’ll start with the latter. Parasites are organisms, in this case insects, that feed on other organisms and depend on them for survival. They complete their reproductive cycle on the host without killing it. Lice are parasites for example. Their host specificity can vary from humans, cows, or birds in some cases. In contrast, parasitoids feed on other organisms and complete their reproductive cycle while killing their host. Many parasitoids include wasps or flies. A majority of parasitoids have specific hosts but some are generalist parasitoids and can use different host species. Parasitoids lay their egg(s) in their host, and the immature parasitoids develop within the live host. As parasitoids continues to develop, it slowly kills the host. For the record, it’s one of my pet peeves when the terms “parasite” and “parasitoid” are used interchangeably. They’re similar, but really not the same.
Photo courtesy of University of Florida Entomology
This video was shown in one of my classes. From National Geographic, it’s a clip about parasitic wasps called “Body Invaders.” Fascinating, and a little gruesome.