04689naa a2200277 a 450000100080000000500110000800800410001910000170006024501540007726000090023152037410024065000200398165000320400165000160403365000270404970000170407670000190409370000170411270000190412970000230414870000190417170000260419070000190421670000140423577301620424911324792022-10-04       2022    bl uuuu     u00u1 u    #d1 aSILVA, F. N.  aDalbulus maidis and corn stunt pathogens monitoring program in Santa Catarina, BrazilbScientific advancements and challenges.h[electronic resource]  c2022  aDalbulus maidis (DeLong & Wolcott, 1923) (Hemiptera, Cicadellidae) is an insect vector of the pathogens that cause corn stunt diseases (maize bushy stunt phytoplasma, corn stunt spiroplasma, and maize rayado fino virus). In recent years, a considerable increase in the incidence of maize leafhopper and corn stunt complex was observed in Santa Catarina (SC). Therefore, several actions have been undertaken by the action committee against maize leafhopper and associated pathogens, including the program for monitoring the progression of maize leafhopper and its infectivity (?Programa Monitora Milho SC?). This program aimed to monitor D. maidis populations in different regions of SC and its infectivity with the corn stunt?associated pathogens, providing subsidies for the postemergence integrated management of maize in a regionalized context. In 2021/2022 (first and second crops), 22 and 14 representative production areas from different regions of SC were monitored, respectively. In each selected area, four yellow sticky traps were placed and inspected weekly to evaluate the insect-vector population and subsequent extraction of nucleic acids from insects collected to detect pathogens associated with the corn stunt complex. To support these activities and the integrated management of this pathosystem, the following experiments were performed: (1) determination of the time for collecting the traps that would allow the adequate diagnosis of pathogens from the insect tissues, (2) determination of the prevalence of the three pathogens in symptomatic corn plants collected in production areas, (3) development of a tool to detect three pathogens simultaneously, and (4) evaluation of the genetic variability of D. maidis using the mtCOI gene. In experiment (1), 15 insects were collected at different exposure times (1, 3, 7, and 14 days) from the traps in the field; the quality of the genetic material was monitored via spectrophotometry and agarose gel electrophoresis. In experiment (2), 28 samples of symptomatic corn plants were collected in four production areas in SC. The presence of mollicutes and viruses was determined by PCR and RT-PCR, respectively. In experiment (3), the nucleic acid extraction procedure was optimized using tissues isolated from insects and plants. The multiplex reaction was developed using specific primers to detect the three pathogens in the same reaction. In experiment (4), the insects were collected from different production areas in Brazil, including SC, which were characterized for variability and phylogenetic relationship using the nucleotide sequence of the mtCOI gene. The time established for the traps to remain in the fields was 7 days, providing high-quality genetic material and adequate time for the logistics of the established monitoring program. The three pathogens were detected in the plants in the production areas in SC, with the virus and spiroplasm being the prevalent pathogens. However, phytoplasma was also detected in some samples. This result indicates that the virus should also be evaluated in the second cycle of the monitoring program. For this, the multiplex technique proved to be sensitive, cheaper, and faster in detecting the three pathogens in insect and plant tissues. The low genetic variability of D. maidis was observed using the mtCOI gene. During the 40 weeks of monitoring, which included first and second crops, 2,848 traps were monitored, with the exponential growth of D. maidis populations over the weeks and a population peak at the end of the monitored period (second half of April). In addition, total infectivity was variable, reaching 80% within a few weeks. These data were periodically made available to the productive sector.  acorn leafhopper  acorn stunt complex diseases  ainfectivity  apathogens transmission1 aFERREIRA, J.1 aGORAYEB, E. S.1 aSOUZA, V. B.1 aSAVARIS, D. M.1 aSILVA, M. C. C. R.1 aRIBEIRO, L. P.1 aALBUQUERQUE, M. R. M.1 aCAMARGO, M. P.1 aSTOCK, V.  tIn: WORKSHOP BRASILEIRO DE EPIDEMIOLOGIA DE DOENÇAS DE PLANTAS, 6., 2022, Chapecó. Resumos... Brasília: Sociedade Brasileira de Fitopatologia, 2022. p. 14