Assessing the cascading effects of management and landscape on the arthropod guilds occurring in papaya plantations

Arthropods can provide ecosystem services or disservices to agricultural systems. Whereas herbivores can cause substantial crop losses, natural enemies can offer pest regulation services that otherwise would be difficult to obtain. Two major factors affecting arthropod communities within plantations are farming practices and surrounding landscape. Previous studies have shown that natural enemies are less abundant in plantations within simplified landscapes and intense management practices, while herbivores do not always respond to these factors. Given the different roles of arthropods in plantations, we assessed the cascading effects that the surrounding landscape and different management practices can have on different arthropod guilds in papaya plantations, ultimately affecting plant damage and fruit production. A piecewise structural equation model was used to assess the direct and indirect effects of management practices and landscape upon herbivores and their natural enemies, and their cascading effects on papaya leaf damage and fruit production. We studied 11 papaya plantations in the surroundings of a tropical dry forest (TDF) in Jalisco, Mexico. The model indicated that there is a decrease of natural enemies with intensive conventional management, which had no effect on pest abundance. Furthermore, surrounding landscape had an effect on pest abundance and not on predators, but this effect was different between seasons. Even when pest abundance explained crop damage, this was not reflected on fruit production. Crop yield was explained by management practices, available phosphorus in soil and by the abundance of natural enemies.