Tag Archives: Semiochemicals

Beetle Trapping Expedition

It was a beautiful, hot, Spring morning, and 3 out of shape committed scientists set out to bait and trap beetles in a mountainous and rugged sub-Mediterranean area of Romania.  Enthusiastic, we were carrying 50 traps, anxious to see what surprises will wait for us in those 50 cups over the next several weeks. We wanted to survey threatened and endangered longicorn beetles that live in the unique habitats that make up the Iron Gates Natural Park (IGNP) but we would have been excited to find even the most common of them all!  This was a brand new territory for us and one that has never been systematically surveyed. We were looking for one beetle in particular, the endangered European Maple Longicorn Beetle (Ropalopus ungaricus), but found more then we ever expected!

Pheromone Factory Line

The “Pheromone Factory Line”, here Gabriel Vanau, Viorel Popescu and I are tying multiple generic pheromone lures together in preparation for deployment in the field. The pheromone lures were provided by David Wakarchuck at Synergy Semiochemicals.  (Yes, we are wearing socks!  The lab is inside someones home… so, no shoes allowed! Next time I will be prepared and bring/wear slippers.) .

Hanging flight intercept traps and recording habitat data.

The pheromone lures are used in combination with flight intercept traps (above) provided by Joseph A. Francese at USDA APHIS.  …Here’s how it works, the pheromones are chemical compounds that transmit a seductive message to the beetles (i.e. “happy hour” or “ladies night”) and attracts members of the same species (often the opposite sex) to the trap location.  The responding beetle flies toward the pheromone message in search of a mate, bumps into the panel, and slides into the white cup below (trapped!).

The pheromones we are using are generic (many species of longicorn beetle produce the same or very similar pheromones) and we hope that they will attract a variety of beetle species (Hanks and Miller 2013, Wickham 2014). The pheromones and traps will help shed light on the diversity and community of beetle species, which is critical since the deciduous forests in Romania are among the last remaining habitat in the European Union suitable for the survival and persistence of a variety of endangered species and because knowledge about them is relatively scarce.  Additionally, the pheromones we are using have yet to be tested in Europe. So, what we find in the trap cups will be a great big surprise (like Christmas morning… but for insect nerds)!

We walked over 3 kilometres setting up traps, up steep mountains and through open fields. The elevation in Eselnita Valley increased from just under 200 meters above sea level to almost 500 meters in less than 1 km!  Within this landscape, there is a temperature inversion causing the Beech trees (which prefer a colder climate and usually grow at higher altitudes) to grow near the valley bottom (200-300 meters), where the river maintains a cooler microclimate.  The higher we climbed, the warmer it got, the Beech trees disappeared and were replaced by Oak trees.  In the open fields (Mala Valley) it is sunny, hot, and full of wildlife, including wild boar, deer, snakes (vipers!), and insects (lots of ticks!).

Vipera_ammodytes ammodytes_VGavril

Baby corn viper posing for the camera, Vipera ammodytes, IGNP, RO [Photo: Viorel Gavril]

While setting up our traps in Mala Valley, we just about walked into a barbed wire… and looked like we trespassed on someone’s land!  We had to be careful about setting up our traps because we didn’t know if our presence would be welcome, and didn’t know how serious people are about trespassing.  Carefully, we proceeded onto the property in hopes that we would be permitted access to continue our work… And we were greeted with kindness!  We met an old couple, Ion and Veta Jianu, who not only welcomed us, but they gave us coffee and homemade cheese (which became my staple food for the next several weeks), and also gave us permission to trap beetles on their land.  (In fact, Ion greeted me by hand-kissing without making eye contact, which I learned is a traditional way for a gentleman to greet a lady in Eastern Europe!)  Throughout the field season, I would continue to meet Ion every day (no hand-kissing since). Ion spoke no English, but he patiently waited while I strung together a few Romanian words (thanks iPhone data and Google translate!), and we made conversation for hours at a time.  We chatted about the beetles captured, the trees and plants I came across in the woods, our families, and the weather (always up to date with weather conditions in the area, as well as in the town where my in-laws were babysitting my son, at the other end of the country).  I would often bring leaves from trees where I was catching beetles and Ion would teach me the Romanian name of the tree and its traditional use (scythe handle, cane, etc.).  …So, as it turned out, on the other side of that barbed wire was a very good friend!

Ion Jianu

Ion Jianu waiting for us to finish our work for the day (Mala Valley, Eselnita, RO)

There are many vulnerable, threatened, and poorly understood beetles in the IGNF.  (I will post stories about many of them in the future.)  However, there is one beetle in particular that we were interested in finding, the endangered European Maple Longicorn Beetle, Ropalopus ungaricus.  This beetle has an endangered IUCN status due to severe destruction Ropalopus_ungaricus_copyright_Petr_Zabranskyof mixed forest habitat for intensive agriculture and urbanization, and because of deficient forest management, and most importantly, the abandonment of traditional land uses (fewer people like Ion and Veta). The Maple Longicorn develops in living and dying Maple trees (Acer spp.) with a preference for pollarded or open trees. Pollarding is a form of traditional forest management in Central and Eastern Europe used to produce more branches and foliage for use as animal feed or firewood. Pollarding also has a side effect of increasing the amount of light that enters the tree canopy, as well as its undergrowth, allowing for optimal conditions Maple Longicorn.

A "wolf beetle" overpowering a longicorn beetle, Hungary, Gerence Highlands. [Photo: Sig]

A “wolf beetle” overpowering a longicorn beetle, Hungary, Gerence Highlands. [Photo: Sig]

Over the next month and a half we checked the traps daily.  We wanted to ensure that none of the beetles were harmed… especially the Maple Longicorn beetle.  We were worried about them getting harmed because we caught more then just beetles responding to pheromones for romance (a mate), we also caught beetles looking for a meal!  We caught hundreds of checker beetles (Clerus mutillarius) daily (about 10-20 per trap)!  The Romanian people I spoke to called these beetles ‘gândacul lup’, or wolf beetles, because they’re amazing hunters and eat everything!    So, we had to check the traps daily to reduce the number of Longicorn beetles that would have been on the “wolves” menu.

After an entire month and a half of hiking 1.5 kilometers of rugged terrain daily, we decided to wrap up the project and take down the traps.  The pheromones were quickly depleting from the heat and we hadn’t caught any new beetles species in a week.  And, although we hadn’t found our target beetle, the endangered Maple Longicorn Beetle (Ropalopus ungaricus), we still had plenty of data for a great story!  (As it turns out it’s so elusive that even the Grigori Antipa Natural History Museum in Bucharest, RO, does not have one in their vast collections).  However, (and quite ironically) on the very last day we captured a similar species of Maple Longicorn beetle (Ropalopus insubricus), a cousin of our target beetle (and featured on the header this post).  So, we are getting closer!  We will be back in August to scope out better habitat to trap for the elusive Maple Longicorn Beetle.

Overall, we managed to collect 40 different species of Longicorn beetles and of those approximately 10 are rare, vulnerable, and threatened beetles.  One species of beetle was unidentified, possibly a new species or invasive species??  Many beetles were captured in specific habitats within our trapping areas or at different times of the day.  I will write more detail about the beetles, their identification, habitat, and behaviour in future posts… So, please stay tuned or “follow” this blog.

In the mean time, for more details on the project, please visit my new page “RO Beetle Project“!

Removing traps from the Eselnita Valley with Akis and Laurentiu Rozylowicz.

Removing traps from the Eselnita Valley with Alexandru Gavrilidis Athanasios (AKA “Akis”) and Laurentiu Rozylowicz [Photo: Laurentiu Rozylowicz).

The spot where the Maple Longicorn Beetle "should be" in the collection at the Antipa...

The blue arrow shows the empty location for the Maple Longicorn Beetle in the collection at the Grigori Antipa Natural History Museum, Bucharest, RO

Citations:

Hanks LM and Millar JG (2013) Field bioassays of cerambycid pheromones reveal widespread parsimony of pheromone structures, enhancement by host plant volatiles, and antagonism by components from heterospecifics. Chemoecology 23:21-44.

Wickham JD, Harrison RD, Lu W, Guo Z, Millar J, Hanks LM, and Chen Y (2014) Generic lures attract cerambycid beetles in a tropical montane rain forest in southern China. Journal of Economic Entomology 107(1):259-267.

Featured imageRopalopus insubricus 

The Beginning of the End: How Blow Flies find Corpses

In the spirit of Halloween…

“I see dead people”, whispers  Haley Joel Osment in M. Night Shyamalan movie “The Sixth Sense”… and he is very convincing. That’s just a movie, but for blow flies, seeing and smelling dead people, or any decomposing corpse for that matter, is what adult life is all about. Unlike Osment, blow flies want and need to see and smell dead things! They have to be able to find decomposing corpses quickly in order to lay their eggs and propagate their kind. In fact, they are so good at finding dead things that we use their progeny (read maggots and pupae) in forensic sciences for determining time of death (TOD), and ultimately putting criminals behind bars.

Haley Joel Osment in M. Night Shyamalan movie “The Sixth Sense” (Photo: Huffington Post) and blow fly (Photo: Mike Hrabar)

In a recent article published in Entomologia Experimentalis et Applicata, my collegues and I explain how fertile blow flies rapidly locate a recently deceased corpse.  Reproductively mature female blow flies use very low concentrations of dimethyl trisulfide (DMTS) in combination with dark animal pelt mimicking colours (black and reddish brown) to rapidly locate the corpse.

Blow flies lay their eggs on recently deceased animal corpses.  The eggs quickly hatch into maggots which consume and break down the corpse. After approximately 1 week of consuming the rotting flesh, they will leave the corpse and pupate in the soil nearby.  But blow flies aren’t the only organism scavenging the corpse; they face a lot of competition with other insects, bacteria, fungi, and vertebrates.  In order to reduce competition with these organisms, blow flies need to get there first, and they do!  Often, they get there within the first few hours after death!  This means that they can smell a corpse long before our noses can; very intriguing!

Working with one of the first species of blow fly to arrive on the scene, Lucilia sericata, we show that blow flies can detect ‘death’ volatiles, and respond faster to a recently dead and wounded rat carcass than they do to an intact rat carcass.    Our next step was to identify the odour using a variety of lab equipment including a gas chromatograph electro-antennal detector (GC-EAD) which is a fancy name for a process with a easy explanation… the antenna acts as a filter for all the smells and we only identify the odours that excite the antenna.  Using this process we identified 9 compounds that excited the antenna.

Using a series of laboratory and field experiments, we concluded that DMTS was the key compound that attracted flies, but not just any flies… female flies laden with eggs!

Like most insects blow flies use antenna to smell odours and locate resources, like the corpse, but unlike many insects blow flies have huge eyes that take up 70% of their head.  So we paired visual cues with DMTS and found that dark animal pelt mimicking colours accentuate the response of blow flies.

Ultimately these findings will be developed into a lure for trapping blow flies, both industrially and residentially.  But more importantly, the lure can be used to monitor blow flies for the impending Zombie Apocalypse.  Due to the fact that the rotting flesh of zombies is likely similar to the rotting flesh of a recently deceased corpse (although, arguably, my dead experimental rats were far from being undead), Metro Vancouver (one of the safest Canadian cities in case zombies decide to finally take down us humans) will be able to use our lure in a trapping and monitoring system, part of their “Zombie Preparedness Campaign“.

…No, but really, BC really does have an emergency zombie preparedness Campaign!  Deal is: If you are ready for zombies, you are ready for the inevitable Megathrust Earthquake, which is due every 70 years or so in the Pacific Rim. Anyway, zombie preparedness is probably one of the things that makes Vancouver one of the best places to live in the Solar System.  I swear I didn’t make any of this stuff up!

Read the full article:

Brodie, B.S., R. Gries, A. Martins, S. Vanlaerhoven, and G. Gries. 2014. Bimodal cue complex signifies suitable oviposition sites to gravid females of the common green bottle fly. Entomologia Experimentalis et applicata. 153(2) 114-127

Citations:

McCann, S. feeding and ovipositing blow flies. [Cover Photo] 2012. Vancouver, BC, Canada.