Guanacaste Dry Forest Conservation Fund

"After 55 years, the world’s most ambitious caterpillar inventory will come to a close. This monumental project in ACG has reared 870,000 caterpillars, of 8,000 species of butterflies and moths, and 18,000 species of wasp parasites—all documented by a team that grew to 30 local parataxonomists."

Happy to share our latest newsletter! The latest GDFCF and Area de Conservación Guanacaste news is here: mailchi.mp/54601d57a15d...

Figure of the decline of caterpillars collected in ACG over time since the standardisation of the paratxonomist workforce in 2005 (black line). The red line tracks the proportion of the collected caterpillars that were parasitised - also declining. Lepidopteran abundance in ACG is declining (Janzen and Hallwachs 2021). While the trajectory of species within individual families may differ in the specifics from the overall trend (Figure X, Janzen and Hallwachs 2021) it is clear that in most cases, once the parataxonomist workforce stablised in ~2005 (that is – the individuals in the forests of ACG collecting caterpillars and leaves), there has been a marked decline collections of lepidoptera and their fly and wasp parasitoids. Over this same time-period, the seasonal rains in the dry forest and low-elevation rain forest have become more erratic and the temperatures of air and soil are creeping upwards in all forest ecosystems – especially the high elevation rain forest and cloud forest (Janzen and Hallwachs 2021, Smith 2023). Thus, although the evident declines documented here may not solely due to climate change – the rapidity and force of the abiotic changes to these forests are involved in these declines. Some taxa may be capable of moving upslope or towards the wetter forests of the Caribbean (Warne et al 2020), but many will, or can, not. These observations parallel other observations of reductions in the diversity and abundance of caterpillars and their parasitoids within a protected area that are at least partially due to changing climate (Salcido et al 2020).

Bipartite figure of relationships between Erebidae caterpillars and their host plants in ACG. The bipartite network of Erebidae species and host plants had a high network-wide estimate of specialisation (H2' = 0.894 Blüthgen et al., 2006) where values close to 0 indicate extreme generalization and those closer to 1 indicate specialization (Blüthgen et al., 2006). Specialisation can be visualized in Figure y by the broad blue links that connect some of the most common species of caterpillar to their host plant. For example, two species of Phaeoblemma (P. apicata and P. dares) were found only on two species of the Fabaceae, Senna (S. obtusifolia and S. papillosa). Smaller links flow out of these Senna to indicate that these species have also been, much more infrequently, food for 17 other species of Erebidae in this matrix. In another example, two Dysschema species (D. jansonis and D. leucophaea) both consume the Asteraceae Lepidaploa tortuosa – but this host plant has been found associated with 32 other species in the reduced matrix.

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Very honored/excited to take part in this paper analysing & releasing 🐛 caterpillar rearing info from #ACG #CostaRica collected by #DanJanzen and #WinnieHallwachs and the #parataxonomists of @gdfcf.bsky.social

doi.org/10.3389/fevo...

Figures from data available at doi.org/10.5683/SP3/...

Figure 1. Four representative tachinid species from ACG. (A) Patelloa ‘xanthuraDHJ01’ voucher DHJPAR0034758; (B) Chorotegamyia sp.; (C) Spathidexia atripalpus; (D) Phosocephala alexanderi female voucher DHJPAR0048468. Photo credits - AJ Fleming CNC

bipartite diagram showing the host-specificity of ACG tachinids in the genus Belvosia. Species in red were formerly known as one species that is now known to be three by host-use and genetics. Where formalised names exist, they are largely honoring ACG paraxonomists.

Venn diagram of the overlap between the diversity of ACG tachinids known from rearing larval lepidoptera versus those that are collected in Malaise traps. Only 18.5% overlap.

Evident decline in the abundance of tachinid parasaitoids (here counts/year for the two most abundant subfamilies) in ACG after the stabalisation of the parataxonomist collection workforce in ~2005

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Happy to see this large data release and analysis of decades of #tachinidae collected by #DanJanzen, #WinnieHallwachs and the #parataxonomists of #ACG @gdfcf.bsky.social in #CostaRica. So much diversity!

Paper here:
doi.org/10.3390/d170...

Data here:
doi.org/10.5683/SP3/...

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These Bats Like to Give Hugs and Play With Bugs

Fascinating new research on spectral #bats conducted in Área de Conservación Guanacaste #hugs #murcielago #batconservation #science #costarica @plosone.org

These Bats Like to Give Hugs and Play With Bugs www.nytimes.com/2025/08/20/s...

How do Rufous-and-white Wrens respond when this 3D-printed owl is presented near versus far from their nest? Find out in Dr. Natalie Sanchez' talk "Singing in the face of danger" today at 16:00 in Grand Ballroom A at #AOS2025. 🦉🇨🇷🎶 @natingui.bsky.social @gdfcf.bsky.social @lincolnsavi.bsky.social

Frontiers | Caterpillar diet breadth in Area de Conservación Guanacaste (ACG), a large and diverse Neotropical wildland in northwestern Costa Rica: toxins, silica, aluminium and sclerophylly Caterpillar-food plant records collected over approximately 38 years in the Area de Conservación Guanacaste (ACG) in northwestern Costa Rica are described an...

New paper out in Frontiers in Ecology & Evolution on #caterpillar diet in Área de Conservación Guanacaste. Authors include GDFCF's taxonomists in Costa Rica, Dan Janzen and Winnie Hallwachs, @alexsmithants.bsky.social, and Scott Miller. #science #Lepidoptera

www.frontiersin.org/journals/eco...

We are studying adult trees, saplings, and seedling composition in tropical dry forests, rainforests and the dry-wet ecotone in ACG Costa Rica to understand the future of these hyper diverse forests. #CostaRica @gdfcf.bsky.social

Will tropical dry forests survive the next 50 years? In 1978, renowned ecologist Dan Janzen jumped into a ravine in Costa Rica, broke three ribs, and spent the first month of the rainy season watching the tropical dry forest from inside a shack. At nigh...

New article in Mongabay featuring Dan and Winnie and the future of the tropical dry forest.

Their survival, Dan says, is “...going to depend on how much land is given back to it, as well as climate change.”

news.mongabay.com/2025/06/will...

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“There’s just no moths on that sheet.” @tessairini.bsky.social writes in the @theguardian.com about #InsectDecline with #DanJanzen, #WinnieHallwachs and the caterpillars of the Area de Conservacion Guanacaste #ACG in #CostaRica @gdfcf.bsky.social

www.theguardian.com/environment/...

‘Half the tree of life’: ecologists’ horror as nature reserves are emptied of insects A new point in history has been reached, entomologists say, as climate-led species’ collapse moves up the food chain even in supposedly protected regions free of pesticides

Featured prominently in this heartbreaking article are our very own Dan and Winnie. #insects #costarica #insectos #biodiversityloss #climatechange #cambioclimatico

www.theguardian.com/environment/...

‘Half the tree of life’: ecologists’ horror as nature reserves are emptied of insects A new point in history has been reached, entomologists say, as climate-led species’ collapse moves up the food chain even in supposedly protected regions free of pesticides

Half the tree of life’: ecologists’ horror as nature reserves are emptied of insects

- A new point in history has been reached, entomologists say, as climate-led species’ collapse moves up the food chain even in supposedly protected regions free of pesticides

www.theguardian.com/environment/...

Last April, we nano-tagged Swainson's Thrush in Monteverde, 🇨🇷 to contribute to understand their migration pathways.

This is part of GDFCF @gdfcf.bsky.social BioAve project

We detected them by our Motus stations at Área de Conservación Guanacaste and in their way North. @birdscanada.bsky.social

image from Volcan Cacao in ACG around 1000m elevation

image of Smith with Manuel and Dunia - two of the parataxonomists who work on Volcan Cacao

image of parataxonomists Manuel and Dunia walking up to the Estacion Cacao

Image of Volcan Cacao from ~1400m entering the cloud forest

On #BiologicalDiversityDay I reflect on the privilege and responsibility I feel to work with the passionate people of ACG and @gdfcf.bsky.social to help to share stories of the tens upon tens of thousands of little things that run the world.

Costa Rica’s May Beetles Vanish, Signaling Ecological Crisis Costa Rica’s iconic May beetles are disappearing due to urbanization, pesticides, and climate change, threatening ecosystems.

“Even protected areas aren’t spared,” says Daniel Janzen, a biologist studying ACG’s ecosystems. #abejones #beetles #pesticides #insects #areadeconservactionguanacaste #ACG

ticotimes.net/2025/05/11/c...

Do beetle families show a common pattern of taxon or phylogenetic diversity across elevation? - Journal Highlight - Royal Entomological Society Do beetle families show a common pattern of taxon or phylogenetic diversity across elevation?  First published: 16 April 2025 A recent review article by Alexandre M. M. C. Loureiro and M. Alex Smith i...

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📢 a neat news piece from @respublications.bsky.social
#RESEcolEnt about the @alexandreloureiro.bsky.social led global #meta-analysis of #elevation & #biodiversity for #beetle #Coleoptera families.

www.royensoc.co.uk/news/do-beet...

Read the paper here: doi.org/10.1111/een....

Figure 111. Dolichogenidea puschendorfi Fernandez-Triana & Boudreault holotype female DHJPAR0031864 A habitus, lateral B head, frontal C wings D head, dorsal E metasoma, lateral F mesosoma, dorsal G metasoma, dorsal H propodeum, dorsal.

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New paper led by Jose Fernandez-Triana of #CNC, builds on decades of Janzen & Hallwachs #ACG @gdfcf.bsky.social collections;

A description of 102 new species of the #parasitoid #wasp genus #Dolichogenidea in @zookeys.pensoft.net including this 1 for @rpuschen.bsky.social

doi.org/10.3897/zook...

World’s Largest DNA Library Collects 15 Millionth Specimen A beetle from Costa Rica has become the 15 millionth specimen to enter a genetic reference library at the Centre for Biodiversity Genomics (CBG) at the University of Guelph

And the 15 millionth insect was a Placosternus guttatus long-horned beetle from Área de Conservación Guanacaste! #DNAbarcoding #insects #DNA #beetle #species
news.uoguelph.ca/2025/04/worl...

Our Late Dry Season newsletter is out today! Please read and share widely!

mailchi.mp/cdb7585b1111...

Earth Day. Every Day. Celebrating Área de Conservación Guanacaste on this #earthday and everyone working to support our planet 🌎. #earthactionday @earthdayorg.bsky.social #earthdayeveryday

A new publication by GDFCF Science Advisor Roberto Fernández regarding a novel case of spider-snake predation in Costa Rica. #snake #spider #CostaRica #predation #reptiles #serpientes #arañas #behavior

herpetologia.fciencias.unam.mx/index.php/re...

#tbt to 1986. Dan and Winnie in the field in Área de Conservación Guanacaste processing Lepidoptera specimens. Photo by Bill Fasth. #history #lepidoptera #biodiversity #mariposa #butterflies #moths #science

Screen grab of article in Irish Times that reads A shocking collapse: forests that once showed traces of insect life on every leaf often now appear ‘fumigated’ ‘The house is burning. We don’t need a more sophisticated thermometer, we need a fire hose,‘ says a resident expert at a unique conservation area in Costa Rica Resident Expert is Dan Janzen and Winnie Hallwachs Underneath is the image of a larval stage of the lepidoptera Calydna sturmula

"The house is burning. We don’t need a more sophisticated thermometer, we need a fire hose" Dan Janzen & Winnie Hallwachs

@paddywoodworth.bsky.social #IrishTimes re. #ACG and the crisis in #Insect #Biodiversity

@gdfcf.bsky.social @irishrainforest.bsky.social

www.irishtimes.com/environment/...

A shocking collapse: forests that once showed traces of insect life on every leaf often now appear ‘fumigated’ ‘The house is burning. We don’t need a more sophisticated thermometer, we need a fire hose,‘ says a resident expert at a unique conservation area in Costa Rica

New article in the Irish Times highlighting the work of Dan and Winnie #biodiversity #biodiversityconservation #climatecrisis #insects #AreadeConservacionGuanacaste

www.irishtimes.com/environment/...

Thank you, @alexsmithants.bsky.social! Glad to be here. Please give us a follow!

Yesterday, I returned from 3 weeks in Costa Rica, where I went to find out what can be learned from their spectacular success rewilding a country.

I cannot overstate how awe-inspiring the trip was: nature loss CAN be reversed on a huge scale, benefiting *everyone*.