The effect of environmental factors on the flight activity of Trialeurodes vaporariorum (Westwood) under greenhouse conditions

The flight activity of the greenhouse whitefly Trialeurodes vaporariorum (Westwood) was monitored over a 3-year period in greenhouses containing tomato and zucchini crops. The environmental factors affecting its flight activity and dispersal were analyzed. Among the climatic variables, temperature had a positive impact on T. vaporariorum flight, whereas relative humidity had only a weak effect. More flights were made during the morning and afternoon, with fewer flights occurring when the temperature was above 25°C in greenhouses containing zucchini or above 30°C in those containing tomato; no flights were recorded when the temperature was 12.30°C in either setting. Flight typology, classified as short, long or dispersal, and covering a few centimeters to more than 2–3 m, was influenced by the vegetative condition of the plants. As the plants aged and declined in condition, the number of short flights decreased, whereas the number of long and dispersal flights increased. Based on these results, we can conclude that the dispersal of T. vaporariorum in greenhouses containing either tomato or zucchini crops is generally influenced by environmental factors, which also affect the type of flight, with a trade-off between short and long dispersal flights. However, adult dispersal is driven not only by temperature, but also by other factors, such as conspecific density and time of the day. Therefore, producers must consider such factors when aiming to reduce the dispersal of pest insects within greenhouses and, thus, to maintain the productivity of their crops.