LB 34-284 - Thrips mediate the predator-mutualist arthropod network in T. cacao host flowers

Theobroma cacao L. is pollination limited. However, cacao pollination ecology remains poorly understood, especially the functional roles of the diverse cacao flower visitors. Understanding the diversity and ecology of cacao flower visitors is essential to developing production systems that optimize pollination and therefore yield. Such systems are also likely to have positive knock-on effects for other ecosystem services. Dipterans have long been associated with cacao pollination services. However, recent surveys show that other taxa also visit cacao flowers, may provide pollination services, and in some cases are more frequent visitors than the Dipterans. Of 4320 flowers sampled from eight cacao plantations in South-western Ghana, we identified nine insect and two arachnid orders across the dry and wet seasons. Insect visitors of the Thysanoptera (thrips) were the most abundant, followed by the Dipterans (flies, midges). Using network topology, both Diptera and thrips show strong centrality metrics and highest degree of co-occurrence in the arthropod network. A third-degree K-core decomposition reveals a predator-mutualist network core in which Aranea and Hemiptera taxa are strongly associated with Dipterans and thrips as predators and likely moderate the population of the network components. Further, the thrips-Dipteran co-occurrence forms the primary core structure of the flower-visitor assemblage and implicates their influence on the network stability. Nevertheless, thrips emerge as the most influential taxa of the cacao flower-visitor network likely involved directly and or indirectly with pollination services.