Thursday, July 15, 2010

Bat Visitors Offer Insect Opportunity

batsWe occasionally noticed a bat flying around our lab space but didn’t pay too much attention to it. On our last night however, when it was unseasonably cold, several bats decided to use our lab as shelter. Often when the door opened one would fly in and around and then perch underneath one of our lab benches; five in fact were roosting together there at one point. I didn’t think too much of it until I recalled that bats have some pretty bizarre fly parasites that wander about through their fur. Suddenly this became an opportunity to make a novel entomological find. So eventually we got one in a butterfly net, and, while Choru held it down, I picked off the small flies with forceps. We let the bat go outside, but I suspect it may have flown right back in again.

—Dan Bennett

Thursday, July 15, 2010

Hymenoptera Impressions, part II

collectingwaspsOther obvious hymenopterans at our field site include the eusocial wasps of the family Vespidae. Sure, in the temperate regions we have our hornet nests and paper-wasp nests, but these types of wasps really become conspicuous in the tropics. There are just so many more elaborate mud and paper domiciles hanging about trees, bushes, and buildings built by a number of interesting genera that are sadly missing from higher latitudes. In fact on one cool day, when few insects were flying about, I took the opportunity to collect these nests and their occupants. The lower activity levels due to the cooler temperature made the whole endeavor a bit less risky. Indeed, 12 nests and about 2500 wasps later I was only attacked once!

—Dan Bennett

Monday, July 12, 2010

Looking for Damage


Since the traps were established on Day 2, we have developed into an efficient 5-person vacuum of arthropods. This morning, we return to the plot to service each trap. We remove the insects and spiders that have been caught, replenish the ethanol, clean out leaves and twigs that have fallen on them, and make sure the traps are not collapsed or overturned. By lunch time, we are having a generous hot meal with our dynamic assortment of field station researchers, swapping stories about wildlife and research. This is such a select crowd: intrepid biologists with a sprinkling of stand-up comics. I am learning as much as I am laughing!

insect damage

The traps are working 24 hours a day but we go out on routine daytime, evening and nighttime walks. As I am seeking plant-feeding insects, I am searching the plants.  It is slow and intense, scrutinizing for feeding damage — scars, mines, holes — and then moving in closer to turn over leaves, pull down branches.  In this part of Peru, I am particularly interested in chrysomelids that have become specialists of bamboos and bambusiform grasses, palms (the ones a 5 ft tall person can reach!), and a particular chrysomelid species that live in unopened or slightly opened leaves of monocot plants in the Marantaceae and Heliconiaceae families.  This latter group is particular abundant here — nearly every rolled leaf has a few individuals of different species living in this tight semi-aquatic space.  Unrolling a leaf is like opening a Christmas present — which specimens, how many individuals, what is their feeding pattern?


Sunday, July 11, 2010

Monkeys vs. Birds



A very nice colony of oropendola birds was nesting outside our lab. We became accustomed to their comings and goings and admired their long, basket-like nests and gargling calls. They always seemed to come and go together and did so with much fanfare. One afternoon however, while the birds were away, three capuchin monkeys raided their nests, and we were lucky to see it. The capuchins systematically went to each one, inserted their heads and torsos into the long nests, pulled out the oropendola eggs, and ate them right there in front of us. It was quite shocking. Of course we were sad on behalf of the birds, yet at the same time excited to witness such drama. 

—Dan Bennett

Saturday, July 10, 2010

Keeping Up With the Traps

Our days have developed into a pattern of servicing the traps in the mornings: picking up all the arthropods collected by the traps, returning to the lab and processing the specimens (cleaning, sorting, labeling), then each person going off in a different direction to use specialist techniques to collect their favorite group.  I spend the afternoons surveying palms, heliconias and bamboos for their particular fauna of chrysomelid beetles.

Saturday, July 10, 2010

Hymenoptera Impressions

One of the first things one realizes (anyone, really, but particularly an entomologist) as you walk around the field station is the sheer number of ants, not only individuals, but all the different kinds. There might be three species walking around on the windowsill. On the trunk of a tree half-a-dozen kinds are immediately apparent, and who knows how many are up higher. Most are minute, but quite a few are enormous, approaching half the size of your pinky finger. Then there are the army ants; these deserve your utmost respect. They will go wherever they please, and when they decide to use your bedroom floor as a superhighway you can do nothing about it but hope they keep off your mattress until the last one streams by.

—Dan Bennett

Friday, July 9, 2010

Hunting for Tiger Beetles

Typical ground beetles (Carabidae) are predators that actively seek their prey and can be found in every imaginal habitat in a forest, from the ground to the canopy. I am looking particularly for tiger beetles (a particular carabid subfamily, Cicindelinae; ~2100 species).  The colorful  fast-running adults are active diurnal hunters. 

Tropical forests exhibit the greatest richness of tiger beetles in the world; Peru has 79 species recorded and about 35 species are known in our present site. Tiger beetles can be good indicators of the quality of a habitat, and their presence or absence and diversity are being used to measure the environmental impacts of different human activities in terrestrial ecosystems. 

It is easy to locate tiger beetle adults as they search for prey or wait in quiet environments where human traffic is limited. A great place to locate them is the edges of rivers or running water where they often construct small dimple shelters or burrows for their larvae.  

—Malena Vilchez

Friday, July 9, 2010

Setting Traps on the Forest Floor

Today is a big day: reviewing the available established plant plots in the area, relocating their markers (boundaries of edges and internal sub-quadrats), selecting a plot we will follow in the next few years, and setting up several kinds of traps to capture insects.  One of the reasons arthropods are so diverse is because they divide any habitat into 1000s of microhabitats, with many insects specializing on particular aspects — flower feeders, seed drillers, stem and leaf miners, soil arthropods, root feeders, parasites, parasitoids, predators….an insect specialist must have an array of tools if they want to sample that ecological diversity.

Selecting the first one-half plot was a piece of cake but locating the internal markers was not so easy.  There had been several fallen trees in recent years, and these gaps in the canopy create particular kinds of habitat for sun-loving plants and their arthropod associates.  Walking around on foot is not so easy.  We kept losing sight of each other, even though I was using florescent orange tape to mark our path.

After a sweaty but productive few hours, we had laid down malaise traps, flight intercept traps, colorful pan traps, and pitfall traps.  Each one would sub-sample a slightly different group of forest arthropods.  As all these traps were on the forest floor, we would not be sampling the canopy fauna so well this time but next year we will have canopy foggers and other canopy traps.

For some insects, you have to look for them during their most active part of the day. Arthropods may be most active during the day, at dawn and dusk (crepuscular) or at nights. So night walks are necessary for some species.


Friday, July 9, 2010

Night Walks for Spiders

Daddy Long Legs

At night, armed with head lamps and UV torches (and a lot of bug spray), you can actually see tons of spiders and other nocturnal arthropods doing what they live for, i.e., eating, preying, mating, etc. without much search effort. During the daytime, you have to look harder for the various microhabitats; of course, it is easy see the orb weaver spiders as well as some other weavers and a few cursorial spiders but this is only a small portion of the total spider fauna.

On the other hand, at night, your headlamp lets you view the activity all around you: spiders on aerial vegetation, on tree bark, running on the ground, and if you play with the leaf litter, you’ll easily see critters moving around. That’s on 'normal' nights in any Neotropical rain forest but it looks like something is different tonight: None or very little activity the first night after the heavy rain this morning (at other times, an early rain should have promoted higher activity at night!). Surprisingly, we have not found any scorpions or adult tarantulas tonight. - Diana Silva, a curator of spiders at the Museo de Historia Natural

Thursday, July 8, 2010

In View of the Madre de Dios River

We awoke to rain....heavy rain..…that kind of Amazon rain where you can’t keep your eyelids open and that promises to last all day. And we are in the middle of the dry season!  Well, this is time to recover from hectic preparations in Kansas, the long journey here, and to orient to our new home. This field station’s set meal schedule (6 am, 12 noon, 6.30 pm) allows all the current station residents to meet. It is a great opportunity to learn about other exciting research going on here. We meet a University of Toronto group studying ant behavioral ecology, a Washington University anthropology team following Saguinus fuscicollis weddelli tamarin monkeys, an Ecuadorean student enrolled at University of Utah and examining effects of insect herbivory on plant growth, a University of Costa Rica professor studying palms…..indeed, the diversity of investigators and research questions here gives a deeper appreciation of the rich ecosystem around us.

Our team passes the morning in unpacking, cleaning, and organizing our assigned lab space – the wet area near the sink where the alcohol and other chemicals will sit, and dry preparation areas for spider sorting, a small table for beetle work, and a long bench for Hymenoptera study. Diana and Malena establish a line of six mini-Winklers where arthropods that live in soil and leaf litter samples will be extracted in the coming days (some believe that this microhabitat houses a more speciose tropical arthropod fauna that the sexy forest canopy). After dinner, Dan, Choru and I set up the first ultraviolet (UV) light trap in front of my cabin, overlooking the Madre de Dios River  Across the river, the forest canopy stretches in all directions to the horizon. After yesterday’s eye-opening view of the many changes of land use occurring in Peru, I cannot take for granted that this spectacular forest cover will stay continuous.

Entomologists don’t understand why insects are drawn to light, but UV traps are a neat system for attracting many insects from miles away. We don’t get a lot of biological data (e.g., no host plant associations) but we get many species that are otherwise difficult to get with other trapping methods. The insect fauna also seems to come in waves, with some crepuscular flying insects arriving early, then hairy moths coming very late. Predatory spiders also arrive to feast on easy catch.