1a. Objectives (from AD-416)
Develop and evaluate multidisciplinary biologically-based pest management technologies to reduce the impact of newly discovered or existing invasive plant viruses in Hawaii. Conduct research and outreach activities to minimize the impact of invasive viruses on Hawaii’s agriculture.
1b. Approach (from AD-416)
A well-equipped laboratory at the University of Hawaii (UH) will be charged with the responsibility for detecting new invasive plant viruses and develop integrated management strategies to minimize the impact of the new or existing plant viruses on crops produced in Hawaii. A research team will be organized to maximize the expertise of the University of Hawaii at Manoa (UH) and the Pacific Basin Agricultural Research Center (PBARC) in virus diagnosis, management strategy development and conducting outreach activities to assist farmers in gaining knowledge on newly discovered viruses and then transferring the knowledge to farmers for use in their crop production practices.
3. Progress Report
This project supported 4 subprojects covered under this progress report. The findings of this project refuted the commonly held belief that there is no population-based differentiation of aphids in Hawaii due to asexual reproduction. Multiple introductions may have contributed to the current aphid population structures in Hawaii. Since there are two distinct taxa of Pentalonia in Hawaii; Pentalonia nigronervosa and P. caladii, pest management strategies against these two species have to be tailored accordingly to each population. In addition, findings on the diversity of the Pentalonia in Hawaii brought up a new question as to how efficient are these different genotypes in transmitting Banana bunchy top virus (BBTV). The development of BBTV-resistant banana plants through the use of the genetic engineering offered a quickest way to develop banana plants with long-lasting, broad-spectrum resistance to BBTV. A total of 20 independently transformed lines of ‘Dwarf Brazilian’ that had been exposed to BBTV but had shown no BBTV symptoms were produced. This is the first time that a BBTV resistant banana had been developed using transgenic methods. Five of these lines were multiplied in vitro and planted in field trials. In the near future, a field test for resistance to BBTV on 14 other transgenic lines will be conducted in the field. All necessary permits for this testing have been obtained from the USDA-APHIS-BRS, HDOA, and the UH Institutional Biosafety Committee. Successful development of such cultivars will directly benefit the commercial banana growers of Hawaii and the world. The banana growers have become more familiar with judicious use of Provado ® and glyphosate as part of an integrated practice to manage BBTV and its aphid vector. Growers responded positively towards the knowledge gained from this project on the distribution of banana aphids on the banana mats. Based on a statewide banana aphid distribution survey, it was found that only 7.6% of the plants had aphids higher than 2.5 m above the base of a plant. Farmers decided that, based on this finding, a risk was worth taking by focusing their chemical spray on the lower canopy of the banana; thus minimizing insecticide spray significantly. Results of the same survey also showed that it was not worth the effort to control the ants in order to control the banana aphids. More growers have become more interested in growing ‘Pisang Awak’, but recognized its susceptibility to BBTV. Growers were reminded that the proper sanitation practices in conjunction with the use of disease-free tissue culture plantlets is the key to reduce the spread of BBTV within a field or between farms. This project also completed an online booklet on the banana varieties available at the College of Tropical Agriculture & Human Resources (CTAHR) Seed Program. The project is monitored through meetings, site visits, and telephone and email communications.