Comportamento de Diaphorina citri (Hemiptera: Liviidae) em mudas de citros tratadas com moléculas de dsRNA homologas e não-homologas

Abstract

Brazil is the largest producer and exporter of orange juice, generating annual revenues of US $ 2 billion. Although well established, citrus cultivation faces the main phytosanitary problem that limits production; Huanglongbing (HLB) or citrus greening. HLB is caused by bacteria belonging to the genus Candidatus Liberibacter (Ca L.). In Brazil, transmission of the causative agent of HLB is done by Diaphorina citri (Hemiptera; Liviidae). The control of D. citri is based on the use of pesticides, which have a negative impact on the environment. Thus, there is a need to develop new control strategies that are efficient and environmentally sustainable. Strategies based on the mechanism called interference RNA (RNAi) are being tested, and are very promising. Thus, the present study aims to evaluate the host selection behavior of D. citri in citrus treated with homologous and non-homologous double stranded RNA (dsRNA) molecules to the psyllid. The work was carried out in the Embrapa Mandioca e Fruticultura (CNPMF), Cruz das Almas – Bahia. Citrus flush were collected from plants kept in a greenhouse. The flushes were placed in 1,5 mL microtubes containing water or water solution with the dsRNA molecules. After uptake of the dsRNA, the microtubes with the flushes were transferred to supports. In entomological cages, four supports were arranged equidistantly, each support with two flushes treated with dsRNA and two with water. Then, 80 adults of D. citri were released in the center of the cage. The experiment was conducted in a growth chamber under controlled environmental conditions. Daily, for a period of 10 days, the number of psilids in each flush was accounted for. The data were submitted to analysis of variance and the comparison of means was done by the Scott-knott test at 5% probability. In four of the six bioassays performed, there was no significant difference between insect numbers in treated or untreated flushes; for the other bioassays, there was a higher insect mean in the flushes treated with dsRNA. There is no evidence that indicates plant repellency to D. citri because of the presence of the dsRNA molecule.