Development of Frankliniella species (Thysanoptera:Thripidae) in relation to microclimatic temperatures in vetch

Abstract

Continuous generations of Frankliniella occidentalis (Pergande) and F. fusca (Hinds) develop through the winter and spring in northern Florida on plant hosts such as hairy vetch, Vicia villosa Roth. Previously reported research compared development under field conditions of these thrips to predictions of temperature-dependent developmental models obtained in laboratory experiments and concluded that accumulated degree-days of ambient temperatures recorded at a nearby national weather station underestimated development of populations developing under field conditions. Thus, the objective of this study was to compare ambient temperatures to microclimate temperatures in V. villosa plots and its effect on thrips development. An electronic data logger was used in this experiment to continuously record over 63 d ambient, upper plant canopy, middle plant height, lower plant height, and soil temperatures in plots of V. villosa. The microclimatic temperatures and their degree-day accumulations, based on daily maximum and minimum records, were significantly greater (P = 0.05) than the ambient temperature and degree-day accumulations obtained from a nearby National Oceanic and Atmospheric Administration (NOAA) weather station. There were no significant differences in mean temperature and degree-day accumulations within the upper, middle and lower portions of V. villosa plants. Based on degree-day accumulations in the upper plant canopy, 3.1 generations were predicted for F. occidentalis and 2.4 generations for F. fusca during the study. However, using the NOAA degree-day accumulations, only 2.5 and 1.9 generations were predicted, respectively. During this study, an accumulated discrepancy of 3/4 of a generation was calculated for F. occidentalis and more than half of a generation for F. fusca between the NOAA weather data and the microclimate data. Thus, ambient temperatures obtained from the NOAA weather station would underestimate development, as was observed and reported previously. The results demonstrated the importance of using microclimatic measurements, rather than ambient records, for best estimating developmental potential of thrips.