Rapid visual estimates of thrips (Thysanoptera: Thripidae) densities on cucumber and rose crops

Scouting techniques combining rapid counting methods must be developed to help growers with immediate decision making in integrated pest management programs. We evaluated a method for estimating densities of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), one of the most damaging insect pests of greenhouse cucumber, Cucumis sativus L., and rose, Rosa X hybrida crops in southeastern France. This method is based on abundance classes of thrips observed on sampling units of flowers and foliage during a period of < 1 min. Classes were calibrated using actual counts, and precision was improved by introducing additional predictive variables into multivariate nonparametric regression models. Regression models using infestation variables with and without climatic variables significantly increased calibration precision and made possible the accurate description of population dynamics. Rapid visual scouting methods could be combined for surveys of different pests and diseases. When calibrated, they provide growers or technicians with accurate tools guiding crop protection decisions.