Monitoramento da praga dos citros Diaphorina citri (Kuwayama, 1908) (Hemiptera: Psyllidae), vetor das bactérias associadas ao HLB, na região metropolitana de Manaus-AM

Abstract

Huanglongbing (HLB) caused by the phloem bacterium Candidatus Liberibacter spp. and transmitted by the Asian citrus psyllid, Diaphorina citri (Kuwayama, 1908), is currently the world's most serious citrus disease. Difficult to control and with no known cure, HLB severely compromises productivity and fruit quality, generating major economic losses. Its phytosanitary importance is such that the disease is classified as a quarantine pest, requiring strict prevention and control measures. The state of Amazonas is the third largest citrus producer in the North, and the activity generates income, supplying the local and regional market. Given the scarcity of studies on the distribution of psyllidin the region and the presence of orchards with intense vegetative flow and favorable conditions for its development, continuous monitoring of the insect is essential for the early detection and effective control of possible outbreaks of the pest and the disease. With this in mind, the aim of this study was to expand our knowledge of the occurrence of the citrus pest D. citri and to carry out research into Huanglongbing (HLB) in four municipalities in the metropolitan region of Manaus-AM: Manaus, Iranduba, Presidente Figueiredo, and Rio Preto da Eva. The survey took place in four orange orchards in Amazonas. To obtain the samples, 40 plants were selected in each orchard, and eight young branches were collected from each plant. To obtain adults, plastic tubes (eppendorf) were used with a collection time of 120 seconds in each quadrant of the plant. Sweeps were also made of the undergrowth, and weeds present in the orchards were subsequently collected. All the samples were identified and sent for analysis. At the same time, investigations were carried out in the urban areas of the municipalities, on the ornamental myrtle plant (Murraya paniculata (L.)) and on lemon trees (Citrus limon (L.)) on public roads. Adults collected were subjected to DNA extraction and conventional PCR to investigate HLB. The presence of D. citri was not detected in any of the samples collected from the orange orchards. The insect was only found on 'myrtle' and 'lemon' plants in the municipality of Manaus. Over the course of the year, 3,872 new branches were assessed, distributed over 42 myrtle plants and two lemon trees, collecting a total of 15.839 eggs, 14.981 nymphs and 1.946 adults. On the myrtle plants, the population density of D. citri averaged 6,57 ± 0,7 eggs∕ramo, 4,0 ± 0,54 nymphs∕ramo and 3,0 ± 0,51 adults∕plant, with the population peaks occurring in october, december and january. In the lemon trees, the insect's population density averaged 5,59 ± 2,49 eggs/plant, 3,1 ± 1,3 nymphs/plant and 1,6 ± 0,46 adults∕plant, with peaks occurring in october, november and december. The parasitoid Tamarixia radiata (Waterston, 1922) (Hymenoptera: Eulophidae) was recorded in all the areas sampled. Analysis of the samples by conventional PCR did not result in amplification of the target fragment corresponding to the DNA of Ca. L. asiaticus, so the results obtained were interpreted as negative for Huanglongbing.