Tage der Biodiversität 2027

Cacao has many varieties and genotypes that differ greatly in taste and yield. Hybrid varieties are frequently favoured due to higher yield, but it is not clear yet to what extent the productivity differs from native varieties. Additionally, there is ongoing uncertainty about whether the ecology of varieties differs from each other. It is important to conserve the genetic diversity of cacao in order to promote resilience and ensure productivity in the eye of biodiversity loss and climate change. Although cacao is one of the most widespread cash crops around the globe, surprisingly little is known about its pollinators.

In my master thesis, I investigated the abundance and diversity of cacao flower visitors of hybrid and native cacao varieties in San Martín, Northern Peru. The study was conducted throughout 12 cacao agroforests. I examined the diversity and abundance of flower visitors on cacao flowers using sticky glue on open flowers. I assessed how arthropod diversity varied according to agroforest management variables (shade cover, understory vegetation cover, leaf litter cover and leaf litter depth).

The analysis showed that the most abundant flower visitor group differed between varieties: aphids on hybrid and ants on native trees. This might indicate that they are either pollinated by different insects or exposed to different pests. Furthermore, I found significantly higher abundance and taxa richness of flower visitors on the native varieties, possibly indicating that insects are more adapted to native trees due to long-lasting co-evolution. I found that flower visitor abundance and richness increased with understory vegetation cover. Higher richness enables the cacao agroforest to be more resilient and robust to changing environmental factors.

I conclude that more research on potential pollinators of native and hybrid cacao varieties is required to establish management practices that promote higher biodiversity in a sustainable way. My findings suggest that focussing on understory vegetation might be crucial.