Effect of environmental factors on the flight activity ofTrialeurodes vaporariorum(Westwood) under greenhouse conditions

Abstract

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.

Environmental factors affecting the behavior of Coenosia attenuata, a predator of Trialeurodes vaporariorum in tomato greenhouses

“…This species can become established for long periods of time inside greenhouses (Pohl et al, 2012); still, future investigations are needed to estimate C. attenuata movements between habitats (in and out of greenhouse). Flights appeared to be largely unaffected by air humidity, but the positive relationship between temperature and C. attenuata flights matches results for whitefly flights (Liu et al, 1994;Bonsignore, 2015). Temperature variation and deviation from optimal temperature affect predation efficiency (Logan & Wolesensky, 2007).…”

“…attenuata have addressed the environmental effects on predation, and the current study will thus help improve our understanding of the dynamics of the C. attenuata -T. vaporariorum relationship. Flights appeared to be largely unaffected by air humidity, but the positive relationship between temperature and C. attenuata flights matches results for whitefly flights (Liu et al, 1994;Bonsignore, 2015). Whitefly density in the greenhouse varied as a result of the entry of whiteflies from the outside (Gabarra et al, 2004); however, this may have relatively little effect on polyphagous C. attenuata populations, making the presence of alternative hosts in greenhouses important.…”

“…In general, the flight activity of whiteflies is affected by temperature (Ekbom, 1982;Noldus et al, 1985;Bonsignore, 2015) and T. vaporariorum is more active during the last 3 h of daylight. In general, the flight activity of whiteflies is affected by temperature (Ekbom, 1982;Noldus et al, 1985;Bonsignore, 2015) and T. vaporariorum is more active during the last 3 h of daylight.…”

“…The daily flight patterns of C. attenuata and T. vaporariorum were similar, but their distributions did not overlap during the day. In general, the flight activity of whiteflies is affected by temperature (Ekbom, 1982;Noldus et al, 1985;Bonsignore, 2015) and T. vaporariorum is more active during the last 3 h of daylight. The temperature during this period is lower than in the early afternoon (14:15-16:00 hours) when the predators are more active; the predators display the fewest flights in the first and last hours of the day.…”

“…All whitefly adults were counted on a random terminal leaflet of a subapical compound leaf of a tomato plant in each area of observation, given that whitefly adults were usually present on this part of the plant (Arn o et al, 2006). The length of the central axis of the leaflet was measured and used to calculate the leaf area, as described previously (Bonsignore, 2015). Greenhouse temperature and r.h. were recorded every 20 min throughout the entire season, using a HOBO U12-013 data logger (Onset Computer Corporation, Bourne, MA, USA) positioned in the center of the greenhouse.…”