Differentiation, distribution, and elimination of two different pineapple mealybug wilt-associated viruses found in pineapple

Surveys for Pineapple mealybug wilt-associated virus-1 (PMWaV-1) and PMWaV- 2 were conducted on pineapple samples from Hawaii and around the world. Tis sue blot immunoassays (TBIAs) with two different monoclonal antibodies (MAb ) specific to either PMWaV-1 or PMWaV-2 indicated that both closteroviruses are widely distributed throughout the pineapple-growing areas of the world . In the worldwide survey, PMWaV-1 was found in 801 of the mealybug wilt of pineapple (MWP)-symptomatic and 78% of the asymptomatic pineapple plants t ested. A subset of plants was tested for PMWaV-2; 100% of the symptomatic p lants and 1246 of the asymptomatic plants were positive for this virus. A r everse transcription-polymerase chain reaction (RT-PCR) assay was developed to differentiate between PMWaV-1 and PMWaV-2. Oligonucleotide primers were designed using distinct regions of the HSP 70 homolog genes of the two vir uses. PMWaV-specific RT-PCR assays and TBIAs were used to screen the pineap ple accessions maintained at the United States Department of Agriculture-Ag ricultural Research Service National Clonal Germplasm Repository for PMWaV infection; 73% of the accessions were found infected with at least one PMWa V. Pineapple accessions found PMWaV-free were challenged with viruliferous mealybugs to test for immunity to PMWaV-1. No immune germ plasm was identif ied. Potential alternative virus hosts were screened for infection with vir us-specific RT-PCR assays and TBIAs and were also challenged with virulifer ous mealybugs. No alternate hosts of PMWaV-1 or PMWaV-2 were identified. PM WaV-1 infection was eliminated through axillary and apical bud propagation from infected crowns. Strategies to manage MWP are discussed.