Vectors’ infecting ability modulation for Xylella fastidiosa invasions management in Italian olive orchards

Abstract

Recent estimates have revealed that more than 6.5 million olive trees in southern Italy have subdued to the Xylella fastidiosa infection, leading to the devasting Olive Quick Decline Syndrome (OQDS). This epidemic continues to expand, posing a significant threat to global olive oil production. OQDS has already resulted 30-34% reduction in ecosystem services provided by olive orchards and a 28% decline in associated biodiversity. Additionally, OQDS has annihilated productivity and the entire olive oil supply chain, causing considerable economic losses. To counteract the relentless spread of Xylella, Integrated Transmission Management (ITM) strategies are crucial. Reducing one vector per olive tree present in an olive orchard can confine X. fastidiosa within acceptable economic and environmental limits. Thus, monitoring and managing vector populations are crucial to curbing disease transmission. The complex interactions between insects and microorganisms are pivotal in the OQDS scenario. Understanding these interactions can provide insights into novel control strategies, such as disrupting bacterial symbiosis with Aphrophoridae foams, affecting the fitness of vector insects, and potentially reducing X. fastidiosa transmission. To counteract Xylella transmission effectively, biocontrol measures must be incorporated into IPM strategies for olive orchards. However, more than the current arsenal of vector antagonists is required. The entrance into the Europe of Zelus renardii shows promise in biocontrolling Xylella vectors. Furthermore, Z. renardii's ability to manage other olive pests adds to its utility. Zelus renardii's bionomics and its ability to regulate alarm pheromones via Brindley glands is crucial for its effective use in IPM strategies. The formulation of artificial diets for mass-rearing Z. renardii under controlled conditions can pave the way for its inundative release to enhance ITM. These biological and biotechnological control measures have the potential to significantly reduce Philaenus spumarius populations and the infective capacity of Xylella vectors within IPM strategies. This approach can also act preventively and protectively, reducing the risk of future infections and limiting repeated transmissions. Progress has been made in modulating the transmission abilities of Xylella vectors, while the challenge of OQDS and X. fastidiosa remains tricky. The availability of Z. renardii and exploring its capabilities offer a more sustainable and effective approach to managing this disease in olive production.