Posts Tagged ‘insect pathogens’

Suspect Spots (Guest post!)

When walking through the woods on a sunlit day, admiring the new flowers and occasional buzzing bee, it’s easy to forget that the organisms surrounding us are at war with one another. The trees are competing for sunlight, nutrients and water, the wasps are trying to paralyze caterpillars to feed the youngsters back home, and somewhere, a fungal spore just landed on an insect and is about to germinate.

My coworker, Ryan, returned from the field last week, carrying a big tree branch full of leaves. Ryan is a fungus guy. Not a guy made of fungus, but a guy who studies it. He’s spent tons of time scanning the ground, trees, and even insects, for different fungi, and with this tree branch, he’d hit the jackpot. The tree had been blowing around in the breeze, which flipped up some leaves, exposing suspect spots underneath.

And on closer inspection of one such spot:

An entomophthoralean fungus (Zygomycota) growing out of a host fly.

It’s was a fly, and although it looked, at a glance, to be in good shape, an even closer look revealed white fungus growing out of its body.

The culprit? An entomophthorales fungus. (Ento-mop-thor-A-lees) Fungi in this group, whose name means “insect-destroyer,” produce spores on the dead insect that are often shot off like missiles. This type of spore is even referred to as “ballistic.” Once the spores are shot into the air, the wind carries them to whatever destiny may have in store for them. With luck, a spore will land on a suitable insect and germinate, starting the life cycle again.

Sometimes, when the weather is perfect and the host insects are around in abundance, you can get an epizootic episode. Then, the fungus is able to reproduce in mass quantities and launch a full scale war at the insects. Such was the battlefield on Ryan’s tree branch:

Dead flies plastered to the underside of leaves, killed by an entomopathogenic fungus.

Such naturally occurring insect diseases can be used to our advantage when we find one that attacks an insect we consider to be a particular nuisance. If the fungus (or nematode or bacteria, for just a few examples) can be cultured and is suitably host-specific, it can be used for the biological control of the pest. Even if the disease in question isn’t cultured for release to control the pest, the pest population can be monitored so that we know when a natural outbreak of the disease  is likely.  This knowledge can help farmers save money by not spraying pesticides for an insect that would probably be killed anyway by an epizootic episode.

Those people that work in the field of insect pathology focus on finding these pathogens in nature, investigating the biology of how they cause disease, and developing practical uses for their findings. But it all starts with an eye for suspect spots.

Good eye, Ryan!

Integrated Pest Management

Integrated pest management, or IPM, relies on biological, cultural, and chemical methods to manage pests in agriculture and in your community.  It is neither conventional pest management, nor organic management.  Instead, it draws on the best of both, and uses many other tools and resources available.

Biological
Biological control focuses on using living organisms to suppress the population of a pest organism in an effort to reduce damage below a threshold. Such control organisms may be other insects which include predatory insects or parasitoids.  Other biological control agents might be bacteria, fungi, or nematodes.

Cultural
These control efforts include physical barriers like mosquito nets or row covers as well as traditional practices such as crop rotation or intercropping. Field sanitation, the removal of diseased plants or pest refuge, is also considered under cultural control.

Chemical
Chemical control includes using pesticides judiciously to manage pest, but also manage for pesticide resistance. Considering the mode of action, or how the pesticide kills the pest, is an important aspect of chemical control.

IPM is an ecological approach to pest prevention, observation, and intervention.  It is a tool that can be tailored to grower needs and resources for practical pest management while reflecting biological, social, and economic understandings of the system.

There was some buzz a while back about the funding and future of the New York State IPM program.  Thanks to public support, the state budget has allocated monies to continue supporting the agricultural and community programs.  The power of people is incredible.

I see a bee!

Bee feeders were recently featured on Good as a response to the onset of Colony Collapse Disorder (CCD).  CCD popped up around 2006, when apiculturists (bee keepers) began noticing a decline in honey bee populations and empty hives.  We haven’t figured out exactly what is going on, but there are speculations of fungal infections, mite infections, other pathogens, pesticide toxicity…the list goes on.  It’s important to recognize the severity of the situation because bees are important pollinators to a wide variety of crops in the United States and world wide.  Some of these include peaches, squash, apples, coffee, and berries.  It’s almost berry season again, so I’m including a berry pavolova recipe.  Berries and meringue? Delicious.  So I’m in favor of keeping the bees around.

How might the bee feeders help out?  The bee station a great idea in theory, but I’m not convinced they would be used in the manner proposed.  I’m no expert so I’ve got some questions about this contraption:
-Is it like a bee motel, housing wayward bees that can’t make it back to their hive?
-Is it like a drive through restaurant where bees can stop in for a quick bite to eat before heading home?
-What do you put in the bee station to make it attractive for the bees?
-How do you prevent other insects, like ants, from annexing the bee station and making use of it themselves?

I would have to do more research on the efficacy of the contraption.  They are pretty cute though.  But maybe that’s also because of the stark white minimalist appearance on which Apple has also capitalized. Shiny.