The purpose of this research is two fold. First to improve pest management of the sciarid fly (Diptera: Sciaridae) by better defining its relation to mushroom production. Secondly, to explore some of the factors and aspects of the biology of the fly which may increase room to room dispersal rates of adults. The effects of different generations of production room Lycoriella mali Fitch infestations and seasons on yield were explored. In models regressing densities of different generations to mushroom yield, significant negative slopes (p=.05) existed in all models. However, flies did not account for as much yield variance as hypothesized (16.43%). Yield is greatest during the winter months when insect pressure is lowest and decreases in summer months when more insects are present. Diflubenzuron (Dimilin 25 WP, Uniroyal Co.) was tested for its effects on fly emergence and oviposition. Diflubenzuron was effective in suppressing fly emergence and remained effective when treated compost was exposed to phase II peak heating. In production room experiments all fly generations had significantly fewer flies in rooms treated with diflubenzuron at fill. L. mali showed a slight preference to oviposition in diflubenzuron treated compost, indicating a possible attractant effect. A criterion table was developed to estimate the age of L. mali. Both younger and larger L. mali carried more ovarioles. The number of ovarioles that L. mali carry dropped significantly after 48 h; this is likely the time the fly becomes parous. The effects of ambient temperature and distance between production rooms on dispersal were explored. The greatest number of dispersing flies were caught during the summer months. As the daily median temperature increased, the number of dispersing flies increased exponentially. Production room blocks on the perimeter of the farm generally had fewer dispersing flies than centrally located production room blocks indicating that it was unlikely that a reservoir population existed outside the farm. Measurements of wing area and age of L. mali captured while dispersing and not dispersing were compared. Dispersing flies had significantly smaller wings than non-dispersers (p=.000). Wing area for dispersing flies decreased along a density gradient, while wing area for non-dispersers did not. The mean age of dispersing flies was not significantly different (p=.082) from non-dispersers, and neither changed along a density gradient. / Graduation date: 1996

Polyclonal antisera were raised against isolates of bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV) using conventional serological methods. Infected tissues containing, respectively, 22 recognized BCMV and BCMNV isolates were tested against the two antisera by antigen-coated plate (ACP) ELISA and double antibody sandwich (DAS) ELISA. Results indicated that each immunoglobulin was virus-specific by DAS-ELISA, providing clear distinction between BCMV and BCMNV. A reverse transcription, polymerase chain reaction (RT-PCR)-based assay in combination with restriction endonuclease analyses, was developed for molecular detection of BCMV, BCMNV and their pathogroups. Specific detection of the two viruses was accomplished by constructing two virus-specific primer pairs that amplified a PCR product specific for each virus. Distinction of two BCMNV pathogroups (PG-III and PG-VI) was achieved by restriction enzyme XbaI digestion of BCMNV PCR products. However, none of the tested restriction enzymes clearly differentiated the five recognized BCMV pathogroups. A primer pair Dts/Uny15 specific for BCMV pathogroup V was also developed. By its RT-PCR application, four BCMV-PG-V isolates were differentiated from the other known variants of BCMV pathogroup I, II, IV and VII. Thus, by a combination of RT-PCR and restriction enzyme analyses, it was possible to differentiate both viruses, and two pathogroups of BCMNV, and one pathogroup of BCMV. / Graduation date: 1996

Four sampling techniques were evaluated to estimate clover aphid, Nearctaphis bakeri (Cowen), abundance in red clover fields in the Willamette Valley. The Berlese funnel method detected one to four times more aphids than other sampling techniques. Visual assessment often underestimated the high aphid densities during the flowering and seeding of clover. Sweep net and Schuh shaker techniques had limitations and underrated the numbers of aphids present in the clover fields. Strong correlations (r² = 0. 74 - 0.87) were found between the Berlese funnel technique and visual assessment technique in a 2nd year established field. Numerical differences in the spatial distribution of N. bakeri on clover stems were shown during various stages of plant development over the season. During development of buds and axils, aphid numbers on the lower half of the plant averaged 1.5 times greater than those on the upper half. As the season progressed into the flowering and seeding stage, aphid numbers on the upper stem halves were approximately five times greater than those on the lower half. Winged clover aphids were too few to show definite peaks of flight using water traps, averaging 2.19 aphids per yellow bucket during the June-August period. No significant differences in aphid attractiveness to the different colors were found among water pan traps. Yellow buckets captured approximately five times more alate aphids than did yellow, red, or green pan traps. Traps placed on the south side of the field contained higher numbers of aphids than in other locations in the red clover fields. / Graduation date: 1991

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