GREENHOUSE CLIMATE: AN IMPORTANT CONSIDERATION WHEN DEVELOPING PEST MANAGEMENT PROGRAMS FOR GREENHOUSE CROPS

Greenhouse climate not only has a major impact on plant growth and productivity, but also influences the development, behaviour and interactions among pest and beneficial arthropods present in the greenhouse production system. Studies have demonstrated how temperature and humidity affect the flight activity of pests and their biological control agents. Increased flight activity can increase the dispersal of biocontrol agents and improve the efficacy of pesticide applications. Recent research has shown how seasonal climatic conditions (i.e., temperature, light intensity and photoperiod) affect the parasitism and predation levels of whitefly parasitoids and predatory mites on thrips. In addition, elevated temperatures and low humidity can be used as a control strategy at crop clean up. With the trend to continuous year round production of greenhouse crops, growers in northern temperate climates have started to use supplemental lighting. The effect of continuous or extended lighting on arthropods is not well understood. Also, dynamic temperature regime models are being investigated as an energy conservation method for greenhouse vegetable production. This paper will discuss the current status of our knowledge on how pest dynamics and integrated pest management practices, especially biological control, are influenced by the greenhouse climate. In addition, we will discuss how all year round greenhouse vegetable production under supplemental lighting and how continuous or extended artificial lighting can affect integrated pest management in floriculture and vegetable crops. INTRODUCTION Greenhouse climate (the general spatial above canopy climate and the more specific microclimate within the canopy and around the plant) is a major driving force influencing plant productivity and fruit/flower quality of greenhouse crops (Papadopoulos et al., 1997; van Henten et al., 2006). With the high cost of energy, global warming and the need to protect our environment, energy conservation and energy use efficiency are top priorities of greenhouse growers. Different strategies have been investigated and developed to increase energy conversion, minimize heat loss, and improve energy efficient cooling (Bakker et al., 2008). Growers have also been expanding the production season to essentially year round production where possible to maintain continuity of product supply and increase their competitiveness in the global market share. As a result, this has led to the development of semiand closed-greenhouse systems to improve control of greenhouse climate variables. However, this technology requires substantial a les.shipp@agr.gc.ca Proc. IS on High Technology for Greenhouse Systems GreenSys2009