Feb. 3, 2025
Studies by the Agrimip Group have found that controlling the Candidatus Liberibacter bacteria during the Asian citrus psyllid nymph stage is key to managing greening.
Researcher Regiane Oliveira, an entomology professor and coordinator of this integrated pest management study initiative at Unesp (São Paulo State University Júlio de Mesquita Filho), reported this conclusion to AgroPages.
According to Oliveira, significant advances are being made in knowledge related to controlling the Asian citrus psyllid (Diaphorina citri), the insect vector of greening. Oliveira noted that the disease, currently the main challenge for Brazilian citrus farming, tends to be more effectively contained by breaking the pest cycle.
"Controlling the 'nymph' stage of the Asian citrus psyllid is key to managing greening. While the adult insect transmits the disease, the insect stage with time to acquire the disease-causing bacteria (Candidatus Liberibacter) is the 'nymph.' This management approach has opened a new chapter in knowledge related to effective psyllid containment," Oliveira emphasized.
According to her, "Today it is clear that the vector insect has a 'relationship' with the Candidatus Liberibacter bacteria, acquired during the nymph's feeding process. If we properly manage the nymph, we break both the pest cycle and the disease development cycle."
The researcher explained that until recently, most treatments primarily focused on the adult form of the insect. "Targeting adults isn't among the most difficult missions because they remain exposed. But reaching the nymph is more complex: after hatching from the egg, it settles inside the plant canopy, staying 'hidden'. Therefore, in citrus, proper application technology is crucial to ensure spraying reaches inside the tree canopy, where the nymph is generally found," Oliveira added.
Oliveira stated that successful nymph management with appropriate insecticide treatment also prevented the emergence of 'infective' adult insects that would potentially disperse healthy plants and, in this process, transmit the greening-causing bacteria. "This is the key point, a result of academic evolution in disease knowledge and, especially, its transmission method," Oliveira said.
Through Agrimip, the researcher conducted studies emphasizing the use of the insecticide active ingredient buprofezin, described as a growth regulator, in Asian citrus psyllid management. "It works by inhibiting chitin formation, that is, in the insect's growth hormone, in the endocrine system, blocking pest development and breaking its cycle through nymph control. The number of infective adults decreases," Oliveira continued.
"This is a tool that arrives for citrus farming as an innovation with supporting academic evaluation, linking knowledge of the pest with that of the bacteria. Buprofezin allows us to add control at another pest stage. In experimental areas where this concept has been used, results have shown promise," the researcher reinforced.
According to her, citrus producers should consider employing good agricultural practices besides insecticide selection. "Orchard monitoring is essential, as is managing pest eggs and adults."
Furthermore, the researcher emphasized that citrus farmers' concerns should not be limited to reducing the pest only on their property. "They must look at the production region as a whole. If we lower the psyllid population, we lower disease intensity overall," Oliveira said in conclusion.
(Editing by Leonardo Gottems, reporter for AgroPages)
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