Plant Extracts and Essential Oils Against Major Pests of Citrus and Red Fruits: Trends, Limitations and Knowledge...

Citrus and red fruit crops are exposed to constant pest pressure, leading growers to rely heavily on synthetic insecticides. This dependence raises problems related to resistance, impacts on non-target organisms, and chemical residues. This review synthesizes data from 411 peer-reviewed articles to evaluate the effectiveness of plant-based extracts as pest control tools in the context of these crops. Research activity on plant-based products and their applications in this sector grew sharply after 2011, with most studies conducted in Brazil, China, Egypt, Iran, and the USA. The focus was predominantly on mite species, like Tetranychus urticae, while other pests are underrepresented. Essential oils are the most tested products, particularly those containing α-pinene, carvacrol, thymol, and 1,8-cineole. Laboratory studies dominate while field-based testing is still rare. Most trials target adult pests, and immature stages, including eggs and/or larvae, are often ignored. Plant extracts trigger multiple negative effects in targeted pests, encompassing high mortality, reduced fertility, longer development times, enzyme disruption, and altered behavior. Yet, some extracts also produce unexpected results, such as increased reproduction, attraction to treated areas, or no effect. Only 11% of the studies included non-target species, and 6% reported harmful side effects with some compounds reported to cause mortality in natural enemies or pollinators. While current research is uneven and often disconnected from practical farming needs, future research priorities should include testing under real conditions, evaluating more pest species and extract types, and addressing non-target safety. Plant extracts hold strong potential, but their real value depends on how they can be applied and validated in the field.