Posts Tagged ‘biocontrol’

Leek Moth

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.

 

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!

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 🙂

Funions

As a graduate student writing about entomology and agriculture, it’s inevitable that my own research will come up.  So I would like to share a little bit about what I do, especially as I begin my first field season.

My research interests are focused on sustainable pest management of agricultural systems, specifically biological control of insect pests.  Currently I’m working on management of onion thrips in onion production systems of New York.  Onions are one of the most valuable vegetable crops in the state, grossing $45 million in 2009.  Most of the crop is grown for fresh market or storage, indicating a low tolerance for insect damage that reduce bulb size, quality, or both.

Onion thrips (Thrips tabaci) are a major pest in New York onion production.  They hide in leaf folds and feed on green leaves, reducing photosynthetic capacity of the plant and overall yield. Furthermore, onion thrips can can transmit Iris yellow spot vitus (IYSV) a Tospovirus which can further damage plants and cause complete yield loss.

Photo courtesy of Thrips of California

Current management practices rely heavily on foliar broad spectrum insecticide sprays with multiple sprays per season to control onion thrips.  However, efficiency may not be adequate as thrips often hide between leaves, protecting themselves from spray droplets.  Furthermore, the possibility of insecticide resistance development is high due to the nature of thrips reproduction.  Newer selective insecticides have shown to be effective in thrips management and fortunately may be compatible with biological control agents such as predators and parasitoids.

I’m interested in natural enemies that may potentially impact thrips populations.  This season, I am lucky to have multiple research sites with a mix of growers to complete my research.  I’m so excited to be doing field work out in the sunshine!

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.