Feeding behaviour and mortality of Philaenus spumarius exposed to insecticides and their impact on Xylella fastidiosa transmission

• Published in: Pest management science Vol. 78; no. 11; pp. 4841 - 4849
• Main Authors: Lago, Clara, Cornara, Daniele, Minutillo, Serena Anna, Moreno, Aránzazu, Fereres, Alberto
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-11-2022; Wiley Subscription Services, Inc
• Subjects: Acute toxicity; Animals; Deltamethrin; electrical penetration graph (EPG); Feeding Behavior; Hemiptera - microbiology; Inoculation; Insecticides; Insecticides - pharmacology; integrated pest management (IPM); Kaolin; Mortality; Nitriles; Pest control; pesticide; Pests; Philaenus spumarius; Plant Diseases - microbiology; Plant Diseases - prevention & control; Pyrethrins; Pyridines; Spinosad; spittlebugs; Sulfur Compounds; Survival; Toxicity; transmission; vector‐borne disease; Xylella; Xylella fastidiosa; integrated pest management (IPM); transmission; pesticide; vector-borne disease; electrical penetration graph (EPG); spittlebugs
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.7105

BACKGROUND
Insecticides are essential, though controversial tools in modern pest management. Insecticides can slow the spread of key vector‐borne plant pathogens, but often lead to inconsistent results given that insecticide use is generally focused on acute toxicity under no‐choice conditions. Here, we analysed the lethal (survival) and sublethal (feeding behaviour) effects of six commercial products (acetamiprid, deltamethrin, spinosad, sulfoxaflor, pyrethrin and kaolin) on Philaenus spumarius, vector of the bacterium Xylella fastidiosa. Furthermore, we assessed the impact of insecticides displaying different degrees of acute toxicity against spittlebugs (highest to lowest: acetamiprid, pyrethrin and kaolin) on the transmission of X. fastidiosa by P. spumarius under both free‐choice and no‐choice conditions.
RESULTS
Deltamethrin, acetamiprid and to a limited extent pyrethrin significantly altered the feeding behaviour of P. spumarius. Deltamethrin and acetamiprid were highly toxic against P. spumarius, but the mortality induced by exposure to pyrethrin was limited overall. By contrast, spinosad, sulfoxaflor and kaolin did not significantly impact P. spumarius feeding behaviour or survival. Under no‐choice conditions, both pyrethrin and acetamiprid reduced the X. fastidiosa inoculation rate compared with kaolin and the control. On the other hand, pyrethrin reduced transmission, but acetamiprid failed to significantly affect bacterial inoculation under free‐choice conditions.
CONCLUSION
Pyrethrin was the only compound able to reduce X. fastidiosa transmission under both free‐choice and no‐choice conditions. Xylella fastidiosa management strategy based exclusively on the evaluation of insecticide acute toxicity under no‐choice conditions would most likely fail to prevent, or slow, bacterial spread. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Acetamiprid was toxic against spittlebugs, whereas pyrethrin was not. Both compounds altered their feeding and reduced bacterium transmission under no‐choice conditions, but acetamiprid failed to affect transmission under free‐choice conditions.