Marcelo P Miranda1, Pedro T Yamamoto2, Rafael B Garcia1, João Pa Lopes1, João Rs Lopes2. 1. Fundo de Defesa da Citricultura, Fundecitrus, Departamento Pesquisa e Desenvolvimento, Araraquara, SP, Brazil. 2. Escola Superior de Agricultura 'Luiz de Queiroz'/Universidade de São Paulo, Departamento de Entomologia e Acarologia, Piracicaba, SP, Brazil.
Abstract
BACKGROUND: Chemical control is the method most used for management of Diaphorina citri, the vector of the phloem-limited bacteria associated with citrus huanglongbing (HLB) disease. The objectives of this study were to determine the influence of soil-drench applications of neonicotinoids (thiamethoxam and imidacloprid) on the probing behaviour of D. citri on citrus nursery trees, using the electrical penetration graph (EPG) technique, and to measure the D. citri settling behaviour after probing on citrus nursery trees that had received these neonicotinoid treatments. RESULTS: The drench applications of neonicotinoids on citrus nursery trees disrupt D. citri probing, mainly for EPG variables related to phloem sap ingestion, with a significant reduction (≈90%) in the duration of this activity compared with untreated plants in all assessment periods (15, 35 and 90 days after application). Moreover, both insecticides have a repellent effect on D. citri, resulting in significant dispersal of psyllids from treated plants. CONCLUSIONS: This study clearly demonstrates the interference of soil-applied neonicotinoids on the feeding and settling behaviour of D. citri on citrus nursery trees, mainly during the phloem ingestion phase. These findings reinforce the recommendation of drench application of neonicotinoids before planting nursery trees as a useful strategy for HLB management.
BACKGROUND: Chemical control is the method most used for management of Diaphorina citri, the vector of the phloem-limited bacteria associated with citrus huanglongbing (HLB) disease. The objectives of this study were to determine the influence of soil-drench applications of neonicotinoids (thiamethoxam and imidacloprid) on the probing behaviour of D. citri on citrus nursery trees, using the electrical penetration graph (EPG) technique, and to measure the D. citri settling behaviour after probing on citrus nursery trees that had received these neonicotinoid treatments. RESULTS: The drench applications of neonicotinoids on citrus nursery trees disrupt D. citri probing, mainly for EPG variables related to phloem sap ingestion, with a significant reduction (≈90%) in the duration of this activity compared with untreated plants in all assessment periods (15, 35 and 90 days after application). Moreover, both insecticides have a repellent effect on D. citri, resulting in significant dispersal of psyllids from treated plants. CONCLUSIONS: This study clearly demonstrates the interference of soil-applied neonicotinoids on the feeding and settling behaviour of D. citri on citrus nursery trees, mainly during the phloem ingestion phase. These findings reinforce the recommendation of drench application of neonicotinoids before planting nursery trees as a useful strategy for HLB management.
Authors: Michele Carmo-Sousa; Rafael Brandão Garcia; Nelson Arno Wulff; Alberto Fereres; Marcelo Pedreira Miranda Journal: Insects Date: 2020-05-16 Impact factor: 2.769