Section I: UNEP- WCMC Weblink Information
Principal Investigator: Lee Dyer
E-mail address: email@example.com
Research Sites and Local Management Status:
Scientific names of primary species being studied (if appropriate):
Lepidoptera, Hymenoptera, Diptera, Angiosperms, Nemata
Key Research Objectives (5-8 brief bullet points):
· What affects diversity and abundance of caterpillars and parasitoids in natural forests and adjacent agriculture (banana and alfalfa)?
· What parasitoids might be good candidates for biological control in banana plantations and alfalfa fields?
· How do variation in precipitation and temperature affect levels of parasitism (and subsequently affect caterpillar densities)?
Date this report was completed: January 29, 2006
Data Collection and Results
One objective of our Earthwatch caterpillar
research was to determine the effects of plant-herbivore-predator interactions
on biodiversity. We measured grassland plant and insect diversity at our
Figure 1. Path diagrams based on analyses of Earthwatch plot data, as well as experimental data from managed and unmanaged grasslands. Arrows indicate positive effects, lines with a circle-head indicate negative effects. Numbers next to effects are values of significant path coefficients and indicate the size of the effect. H’ = arthropod diversity, ni = arthropod abundance.
Earthwatch teams quantified parasitism at our research sites in
Figure 2. A linear regression of total parasitism levels of caterpillars from fifteen extensive rearing programs against year-to-year variability in precipitation (CV; R2 = 0.33). Letter codes correspond to sites of rearing studies; AZ = Arizona, USA; ACGd = Guanacaste Conservation Area, Costa Rica, dry forest; ACGr = rain forest; LS = La Selva Biological Station, Costa Rica; YBS = Yanayacu Biological Station, Ecuador; NO = Southeast Louisiana, USA; Braz = Reserva Ecológica do IBGE, Brazil; BCI = Barro Coloardo Island, Panama; PNM = Parque Nacional Metropolitana, Panama; FS = Fort Sherman, Panama; Can = Southern Ontario, Canada; MD = Maryland, USA; MO = Southern Missouri, USA; VA = Virginia and West Virginia, USA.
Leaf damage caused by Lepidoptera as they are
responsible for the majority of the herbivory suffered by rainforest plants as
well as many agricultural systems, including banana plantations. We used Earthwatch parasitism data
to link ecological theory to the biological control of insect pests in banana
plantations. Through our established predictive approach, ecological data on
plant-caterpillar-parasitoid interactions from natural systems were used to
formulate simple recommendations for biological control in banana plantations.
The specific goals were (1) to determine the most effective parasitoid enemies for
biological control of caterpillars in banana plantations and (2) to examine the
impact of nematicides on enemy populations. To assess percent parasitism,we
reared 1,121 caterpillars collected from six plantations managed under two
nematicide regimens. Attack by parasitoids in the families Tachinidae
(Diptera), Braconidae, Eulophidae, and Chalcididae (Hymenoptera) closely
paralleled rates reported for species with similar characteristics at our
Earthwatch site at La Selva, and statistical models predicted the relative
importance of these parasitoids as sources of mortality. We found that tachinid
flies were the most important source of early instar larval parasitism in
banana plantations, and their importance increased with more intensive
nematicide applications. The statistical models that we derived from data at La
Selva were useful in predicting which parasitoids would be important in banana
and which larval characteristics they would preferentially attack. We provided
predictions for caterpillars that can occur in other banana plantations (Table
1), especially those that shift from insecticide use to biological control.
This approach could be used in other managed ecosystems (e.g., near our sites
Table 1. Percent parasitism predictions (with SE in parentheses) for common species of Lepidoptera found in Costa Rican banana plantations based on logit models from Earthwatch data collected over the past 10 years. Parasitism levels over 30% are likely to result in successful biological control.
Significance/Benefits of Research
Diversity and natural history
Our most significant accomplishment is the compilation of natural history data related to approximately 2800 species of caterpillars, plants, and parasitoids. We share this natural history information with locals and scientists alike (refer to the list of talks and publications), including talks in Spanish to Costa Rican and Ecuadorian students, naturalists, and local workers; the local talks have increased awareness and respect for insect diversity. Many of the naturalist guides at our research sites now point out caterpillars in their tourist walks and discuss the role they play in the forest. We also share these data with anyone who has internet access by publishing it on caterpillar web pages at www.caterpillars.org. The web pages are currently undergoing major improvements and should be a very useful tool for managing and studying biodiversity for many years to come. In addition, our basic research on diversity relationships between trophic levels will contribute to a growing understanding of how parasitoids and other natural enemies affect entire biotic communities.
Managers of banana plantations, alfalfa fields, and other agricultural systems who are attempting to control pests without using pesticides will benefit from increased knowledge of the parasitoid community. First, we discovered at least 12 new species of parasitoids (that are still being treated by taxonomists) in the families Braconidae and Tachinidae, all of which are potentially important biological control agents. Second, our modeling approach identified the most important biological control agents in banana plantations under different pesticide management, which allows plantation owners to manage for caterpillar pests without resorting to harmful insecticides.
Sustainable employment in the rainforest
Although it is not a direct benefit from the research, our
Earthwatch project benefits the local communities by supporting the research
stations and by continuing collaborations with local naturalists and
scientists. Field stations generally benefit the local community by providing
excellent employment opportunities that are not destructive to the forest and
by boosting the local economy. At the
Finally, our work has directly benefited the educational community because many volunteers have been school teachers and have incorporated ideas learned from this project into their classes. It has indirectly benefited the educational community because the research addresses basic theoretical questions in ecology. One of the most important issues to which our Earthwatch project has contributed is the idea of “trophic cascades.” Theory predicts that the effects of predators and parasitoids on plant biomass and diversity should not be great in complex systems such as rainforests, but we have demonstrated that the enemies of caterpillars significantly enhance plant biomass and diversity by killing caterpillars. This means that the consequences of tropical predator extinctions are more severe than previously thought, and predators of all sizes and all predatory guilds (i.e. including parasitoids) should be a major focus for conservation efforts.
Dissemination of Results (all publications below are available in pdf format at: http://caterpillars.unr.edu/papers.htm)
Stireman III, J.O., L.A.
Dyer, D.H. Janzen, M.S. Singer, J.T. Lill, R.J. Marquis, R.E. Ricklefs, G.L.
Gentry, W. Hallwachs, P.D. Coley, J.A. Barone, H.F. Greeney, H. Connahs, P.
Barbosa, H.C. Morais, and I.R. Diniz. 2005. Climatic unpredictability and
caterpillar parasitism: implications of global warming. Proceedings of the
J.O. III, Dyer,
Organization for Tropical Studies,
Ecological Society of
Bodega Marine Laboratory, 2005
Section II: Volunteers
February 3, 2006
While I write this letter from a FEMA trailer (without
electricity), I am reflecting on a year that was filled with ups and downs. The
last 5 months have been difficult for everyone in
I have been impressed with the amount of high quality data that Earthwatch volunteers have collected with us over the past 9 years. I am sure that I will continue leading this research for at least 20 more years, and I hope to keep discovering new species and new associations. Perhaps the most important paper that we published from these data was our paper in the Proceedings of the National Academy of Sciences in November (2005 – the paper is available here: http://www.pnas.org/cgi/reprint/0508839102v1). We discuss how extreme weather events (like hurricanes) cause a decrease in parasitism – this means that increases in extreme weather events as a result of climate change may cause parasitoid extinctions and increases in caterpillar outbreaks in forests and agricultural systems. We hope that this paper helps land managers plan for future conservation of natural enemy communities.
If you are wondering about the rest of the team of
plant/caterpillar/enemy investigators, feel free to send an email asking for
their addresses. Unfortunately, Marco and
I would like to thank all of you for your hard work. As an extended team, we have a strong database and positive memories of great people. My collaborators and I have enjoyed working with all of you, and our project could not have been done without your help. We also want to thank all of you for sending us great emails, cards, pictures, slides, and other thoughtful items. We definitely appreciate all this correspondence. Please feel free to keep in touch and we will do our best to respond. Hopefully we'll see you again in the field.
Lee Dyer, gusanero, firstname.lastname@example.org
Volunteer Tasks and Accomplishments
In our 9th year of funding by Earthwatch, we were fortunate to have the help of 30 volunteers. These volunteers helped us bring our rearing total up to approximately 1800 species of butterflies and moths (26,000 individuals) and over 350 species of parasitoids. The four teams participated in all aspects of our Forest Caterpillars project. Team members searched for and collected caterpillars, noted possible morphological or behavioral characters, and took care of the larvae. At La Selva and Tirimbina, they also assisted with experiments on the understory pepper plants, Piper spp. and helped with encapsulation experiments.
The four teams logged over 1400 total person hours in the field, searching for and recording data on caterpillars and working on related experiments. At La Selva and Tirimbina, they found over 1900 caterpillars belonging to 55 butterfly and moth species in 21 families; at least 9 of those were new species. From these caterpillars they reared over 20 species of parasitoid wasps and flies. At the Southwest Research Station, volunteers collected 210 individual caterpillars for a total of 45 species in 16 families. At least 8 species of parasitoids were reared. The teams in Ecuador contributed to our new NSF funded biotic survey and inventory of the eastern slope of the Andes, collecting 1400 caterpillars, including 75 species and 18 families, and a couple dozen new species. The site will continue to yield many new species of caterpillars and parasitoids (Figure 3). The levels of parasitism at our 3 Earthwatch sites were used in our important new finding that climatic unpredictability is associated with lower levels of parasitism.
Figure 3a. A new species in the family Geometridae.
It will be years before this caterpillar receives a name (the genus may be
undescribed). Tirimbina Biological
Figure 3b. A cryptic lycaenid caterpillar from
the Southwest Research Station,
The data we have collected thus far at all sites support our hypotheses that the dynamics in these strikingly different habitats (Arizona, Ecuador, Costa Rica, Louisiana) are very similar, but the actors are different — species composition of the caterpillars and their parasitoids show almost zero overlap. The larvae that we studied exhibited a wide array of defenses, and we continued a focus on two specific defenses: frass-throwing and encapsulation. Several more years of data will allow us to make conclusions about how these defenses function against different types of parasitoids. For all sites, we will continue to focus on collecting new species (Figure 4), but we will also focus more on altitudinal gradients in parasitism, similar to the precipitation gradient that we’ve tested.
Figure 4. This Notodontid caterpillar, Nebulosa elicioi, was parasitized by an ichneumonid wasp, which has pupated in the old skin of the caterpillar (which is now dead). Both the moth and the specialized parasitoid were new species. You can find more information on the web page for this species:
Educational opportunities were provided to:
Earthwatch project has united workers from
Costa Rican paraecologists: Gerardo Vega, Humberto Garcia, Maylin Paniagua
paraecologists: Rafael Maitio, Wilmer Simbana, Maria de
Graduate students: Angela Smilanich, Malia Fincher, Michael Olson, Clark Pearson, Tara Massad, Genoveva Rodriguez, Kathleen Burke
Harold Greeney, Yanayacu Biological Station
Organization for Tropical Studies
Grants from additional funding sources:
National Science Foundation – Ecology
National Science Foundation – Biotic Surveys and Inventories
United States Department of Energy