Influence of Verbesina encelioides (Asterales: Asteraceae) on thrips (Thysanoptera: Terebrantia) populations and tomato spotted wilt virus epidemics in south Texas peanut fields
1996
Mitchell, F.L. | Smith, J.W. Jr
From October 1991 to November 1992, thrips (13,350), adults (12,986) and larvae (364), were collected from the composite weed Verbesina encelioides. Of these, 5,229 adults were mounted on slides and identified to species. Four thrips--Frankliniella minuta Moulton, F. tritici (Fitch), F. occidentalis (Pergande), and Microcephalothrips abdominalis (D. L. Crawford)--predominated in the routine sample counts. Supplemental samples of thrips were collected on 11 dates and 835 thrips were identified to species and assayed for tomato spotted wilt virus contamination by ELISA. Only 3 individual adult thrips (1 F. occidentalis, 1 F. fusca, and 1 F. tritici) were positive for tomato spotted wilt virus contamination by Double Antibody Sandwich (DAS) ELISA. Laboratory life tables demonstrated that both F. fusca and F. occidentalis developed from 1st instar to adult on foliage of V. encelioides. A paired sample test conducted in grower peanut fields infected with tomato spotted wilt virus rejected the hypothesis that peanut plants adjacent to V. encelioides were more likely to be infected with tomato spotted wilt virus than more distant plants. Thus, the hypotheses that V. encelioides was serving as a reservoir for primary spread of tomato spotted wilt virus in peanut and as foci for within field secondary spread of tomato spotted wilt virus by either recruiting competent thrips vectors into the fields or infecting the progeny of recruits with tomato spotted wilt virus was rejected.
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