Understanding and managing avocado pollination in Chile

Insect pollinators provide a critical ecosystem service by increasing the yield and quality of many globally important crops, with both managed and wild pollinators playing an important role. The protection of pollinators has gained increasing attention in recent years due to threats to pollination services such as climate change, pesticide usage, and natural habitat loss. However, implementing effective protective measures is challenging, as the level of crop dependency on insect pollination and the specific pollinator species important for different crops are often unknown. Moreover, the adoption of pollinator-friendly land management practices by growers frequently requires external support, which is often not available in many regions. The private sector has a vested interest in safeguarding pollinators given that numerous companies rely on insect-pollinated products within their supply chain and, thus, they have the potential to play a key role in supporting growers. However, at present, only a limited number of companies take action on pollinator protection, largely due to a lack of understanding regarding the risks faced by pollinators and the most effective support mechanisms. To investigate some of these knowledge gaps, this thesis used avocado (Persea americana) as a study crop. Avocado is a globally important insect-pollinated fruit, for which little is known regarding pollination dependency, the contribution of wild pollination services and effective tools for sustainable management of avocado pollination. The first objective was to determine the extent of the contribution of insect pollinators to avocado production, and which insect taxa are the most important pollinators in different growing regions. The second objective was to investigate the impact of proximity to natural habitats on pollinators in avocado orchards, with a focus on the important avocado-growing region of Chile. The final objective was to develop a tool that private sector companies can employ to develop effective strategies for safeguarding pollinators, using an avocado supplier company as a case study. Chapter 2 involved a literature review and meta-analysis of existing avocado pollination studies and showed that insects contributed greatly to pollination, fruit set, and yield. Honeybees (Apis mellifera) were important pollinators in many regions due to their efficiency and high abundance, however, many wild pollinators also visited avocado flowers and were the most frequent visitors in over 50% of studies. Stingless bees (Meliponini spp) and blow flies (Calliphoridae spp) were identified as effective avocado pollinators, although for the majority of flower visitors’ data on pollinator efficiency was lacking. Chapter 3 reports findings from pollinator surveys and controlled pollination experiments in three avocado orchards in central Chile. The result showed that over 70 different insect species visited avocado flowers and that wild pollinator abundance, visitation rate, diversity, and richness were significantly higher in areas directly adjacent to a natural habitat border. The pollinator exclusion experiments showed that insect pollinators contributed significantly to avocado production, with almost no fruit set when pollinators were excluded. Hoverflies and flies were identified as effective avocado pollinators due to their high flower visitation rate, with fruit set positively correlated with the abundances of these taxa. Finally, Chapter 4 developed a tool to assist companies in formulating and implementing effective pollinator protection strategies. The tool comprises of seven activities, including new and existing desk-based methodologies, grower surveys, and informant interviews. The activities will help companies to 1) understand the threats to pollinators in different supply regions, 2) recognize the significance of pollinators to their business 3) assess the current implementation of pollinator actions, and 4) identify additional measures to better support pollinators. Application of this tool to an international company sourcing and supplying avocado indicated that increasing knowledge transfer to growers and supporting their participation in environmental certification schemes could serve as effective strategies for pollination protection. The overall results from this thesis underscore the importance of insect pollinators in avocado production, with wild pollinators and the natural habitats which support them playing significant roles. To optimise yields, growers should implement land management practices that protect and restore natural areas within and around their orchards. Furthermore, the industry tool developed in this thesis provides private sector companies with a means to enhance pollinator protection by providing a mechanism to develop effective safeguarding strategies. Its potential implementation could greatly benefit growers and pollination services worldwide.