In tropical ecosystems, ants are among the most abundant and biodiverse taxonomic groups in the tropics, and play important ecological roles such as predation, herbivory and seed dispersal. Canopy connections are important structural resources for arboreal ant communities because they facilitate resource discovery. In agroforestry systems, ants provide predation services, but especially in more intensive systems, with fewer trees, a lack of canopy connectivity between shade trees, or between shade trees and crop plants may hinder ant abilities to provide ecosystem services. We examined whether increasing canopy connectivity in coffee plantations increases ant activity and enhances biological control of the coffee berry borer (CBB), the most devastating insect pest of coffee. The present study was conducted in 20 sites within a 300 ha shaded coffee plantation in the Soconusco region in Chiapas, Mexico. The coffee plantation is located at 1100 m a.s.l. in the Sierra Madre Mountains. We used jute strings to create canopy connections between Inga micheliana shade trees containing Azteca sericeasur ant nests and coffee plants and then compared ant activity and CBB removal before and after placement of the strings, and on coffee plants with and without strings.
Results/Conclusions
Our results show that ant activity increases after the placement of strings in both treatment and control plants, as well as ant activity on trees. However, connected coffee plants had a significantly higher ant activity than treatment plants. This result could be explained by the relatively easy access to these linear and narrow pathways and higher recruitment rates, as has been shown in previous studies. The increase in ant activity could explain a higher rate of prey capture observed in connected coffee plants. We demonstrate that favoring connectivity and structural complexity at the local scale, by artificially adding canopy connections in the arboreal substrate, promotes ant activity on coffee plants, favors resource discovery and therefore increases CBB removal.