Posts Tagged ‘specialists’

On Guard

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

Cycle of life

The last few posts have been a little heavy on the policy side so I thought it would be good to write more about bugs. That is part of the reason I’m here anyway.  Today’s post will be a bit more technical, but hopefully not more boring.

Most insects exhibit one of two kinds of life cycle: hemimetaboly or holometaboly.

Hemimetabolous insects include true bugs, grasshoppers and crickets, mantises, dragonflies and damselflies, cockroaches, and termites to name a few.  The “hemi” refers to the simple type of development or metamorphosis.  In this case, the immature insects look very similar to the adults.  Most often, immature insects are called nymphs. Below, we have nymphal (L) and adult (R) bugs (Order: Hemiptera).  They look like milkweed bugs, perhaps Lygaeus kalmii.

Photo courtesy of Wikipedia

Holometabolous insects include beetles, flies, bees, wasps, ants, butterflies, and moths (and several others).  Theirs is a complete metamorphosis with the following stages: egg, larva, pupa, adult.  There can be several laraval stages as the insects grow.  Typically, the immature larva look nothing like the adult stage.  Likewise, the pupal stage varies in appearance and similarity to larva or adult.  Larval moths and butterflies are most often known as caterpillars.  Below is the life stage cycle of monarch butterflies, Danaus plexippus  (Order: Lepidoptera), who also feed on milkweed.  More on these specialist feeders to come.

Photo courtesy of Laurie Williams

Understanding the development of insects is imperative to appropriate management and control by biologically based strategies, as well as chemical or cultural strategies.  Happy Earth Day everyone!