Presence of cover crops for the conservation of overwintering natural enemies in citrus orchards: friends or foes for spring and summer pest control?

Wintertime in subtropical areas such as the Mediterranean citrus growing regions has always been considered a critical period for natural enemies. During winter, the major part of citrus pests are not present, and furthermore, citrus trees do not offer any nutritional sustenance for natural enemies. Under this situation, natural enemies either, abandon citrus orchards or suffer severe undernourishment, letting citrus orchards unprotected in early spring, a key period due to the arrival of many citrus pests. Cover crops can offer food resources and shelter to natural enemies and, through well-managed, may represent a sustainable tool to avoid this undesirable biocontrol imbalance.