lunes, 13 de julio de 2009

Ongoing projects

Geographical expansion of Acromyrmex lobicornis (finished project)

After defending my PhD at the Autonomous University of Barcelona we (my husband and I) returned to Argentina on 2007. Here, I got involved in the research project of Dr Alejandro Farji-Brener who investigates which factors favour the increase of the geographic range of Acromyrmex lobicornis. This leaf cutting ant is moving toward the south of Argentina and had already been found in the east limit of the National Park Nahuel Huapi, 15 km from the city of Bariloche (41º S, 72º W). In order to investigate if plasticity of nest arquitecture, diet choice and foraging activity allow this ant species to colonize new areas, I compared two populations, one located in the north of Argentina (Cafayate, Salta, 26º S, 65º W) and the other in the center of Argentina (San Cristóbal, Santa Fe, 30º S, 61º W).

Very happy after finding the first nest of Acromyrmex lobicornis at El Moyar an area 12km close to Cafayate a very nice village from the north of Argentina. I should follow the activity of the same ten nests for one year.
As part of my curiosity I excaveted an Acromyrmex lobicornis nest. I reached the first fungi chamber and here you can see a piece of fungi garden with some larvae in gaps and a A. lobicornis big worker at the left. If you enlarge the photo you can see the lobule at the base of the antenna (this is a taxonomic trait for Acromyrmex sp)

I love filming ant activities. When you see on a large TV screen what you had filmed you discover nice details of ant behaviour.

A. lobicornis nest are really different depending on the site. At Santa Fe this ant species built domes. Here I was sampling damp material.

It is really nice to share the field with the ants. Here I was at my camp where I lived for 12 days to invest less time in travelling from the village to the field. In my opinion organization is very important to do your field work properlly.

As part of my postdoctoral training, I was encouraged by Dr Farji-Brener to develop my own research projects. So, I did. One of them concerns the control of the invasive ant Linepithema humile in vineyards from north of Argentina and their effect on leaf cutting ants. The aim of the other project is to estimate the biodiversity of ground dwelling ants in the National Park of Iguazú (Misiones, Argentina).

Leaf cutting ants vs. Linepithema humile

In vineyards, leaf cutting ants are a serious problem, not only through direct economic loss but also because their control implies the use of pesticides which are not always desirable, particularly for organic wines. Some years ago (apparently 18 years ago), an ant species of Linephitema arrived in a timber load from the northeast of Argentina to San Pedro de Yacochuya an area 8km away from Cafayate, Salta, north of Argentina. At the beginning nobody noticed its presence. But, as time goes on, this ant species spread and it was noticed that tends insects in vineyards and it was seen actively attacking leaf cutting ants (see the video at: Now, in the area there is a supercolony that covers 293 ha. Local workers said “she took out from the nest some tiny-white things, like little worms”. This species of Linepithema seems able to steal larvae from leaf cutting ants in spite of their smaller size. As a consequence, the attacked leaf cutting ant species are apparently declining in the area. The owners of the vineyards, though that may be this ant species can be used as a biological control of leaf cutting ants. However, I think that other outcomes may arise due to aphid and coccid attention by ants. See research interest for a detalied explanation of this point. 
First of all it was necessary to confirm the species identification. So, I sent some workers to Dr Alex Wild from Illinois University who has reviewed this genus recently. He confirmed it is Linepithema humile. “Ups! we have a problem”, I though. The native distribution of this ant specie is the Paraná River drainage basin area of subtropical Argentina, Brazil, Paraguay, and Uruguay not the north of Argentina. At San Pedro de Yacochuya area, L. humile tends the mealybug Planococcus ficus, a pest of vineyards. So, the situation in this area matches with that showed in the right part of figure 2. Our aim in this project is to stop L. humile spread, to control it by combining poisoned baits and the modification of cuticular hydrocarbons (ants use them to recognize individuals belonging to the same colony) and finally to evaluate the net outcome for the vines.  The results of our first sampling are in the poster (only in Spanish) presented in the last meeting of the Ecological Society of Agentina in Buenos Aires.

Diversity of ground dwelling antsMore and more, ant taxonomy is becoming a great tool to evaluate the stage of conservation or restoration of an area. Ants seem to be good bioindicators because their taxonomy is described quite well; they are ubiquitous and relatively easy to sample.

      I chose the National Park of Iguazú for our research project because this area has been identified as a biodiversity hotspot at global scale. We are applying the ALL protocol to sample ants (pitfall, winklers and subterranean baited probes). In this way our data will be comparable to the information of other rainforest areas. This will be the first step of a bigger project trying to sample the ant community along the green corridor of Misiones Province. This corridor links some natural areas, protected areas and private areas in a good stage of conservation. Our big goal is to relate the composition of the ground-dwelling ant community to historical land use. We also hope to add some new records for myrmecology and to encourage students to become enthusiast ant taxonomists.

The red line shows the limit of the areas included in the green corridor of Misiones province. Light green represent protected areas occupying 412.259 ha.
    In this project it is involved Priscila Hanish, one of my undergraduate student, who is also working at the Museum of Natural Science of Buenos Aires at the Department of Entomology. Now, she is identifying ants at morphospecies and species level when possible. Go ahead Priscila! Other person that was involved in this project was my husband Pablo. He always participates in the logistic of the field travels i.e. making some equipment we need (he made very nice Berlesse extractors), transporting the heavy stuff, opening trails in the rain forest with the machete, doing the shopping, etc.

From the left to right. Pablo, my husband, me and Priscila an undergraduate student. We were going to work at the rain forest. January 2009

That me, shifting litter at rain forest

Having luch and doing a break. Mosquitos, bees and butterfly were really interested in our blood and sweatHanging winklers at the laboratory in the CIES, the research tropical center at the National Park of Iguazú

No hay comentarios:

Publicar un comentario