World Aquaculture December 2019

58 DECEMBER 2019 • WORLD AQUACULTURE • WWW.WA S.ORG door to limit entry of insects. A 50-m 3 HDPE-lined circular tank (8 m diameter × 1 m deep) with a central drain was built in the greenhouse. The tank was stocked with 740 Nile tilapia Oreochromis niloticus juveniles (24 g, 11 cm) two weeks prior to planting cucumber seedlings. Fish were fed a 45 percent protein and 5 percent lipid commercial feed (Rangen Inc., Buhl, Idaho) at 4 percent body weight daily divided into two daily feedings. A sample of fish was captured and weighed weekly, mortalities removed and counted daily, and feeding regimen adjusted accordingly. Dissolved oxygen concentration, pH and temperature of tank water and greenhouse air temperature were measured daily and ammonia and nitrite concentration of tank water were assessed weekly. Twice during the experiment, ammonia levels increased beyond 1.5 mg/L and half the water in the tank was used to irrigate a nearby apple orchard and replaced with groundwater. A 320-m 2 area of the greenhouse was divided into four plots (A, B, C and D) and planted with 800 Alfrid RZ powdery mildew resistant hybrid cucumber seedlings (Fig. 1). A drip irrigation systemwas established, dividing the area into two equal sections, one section irrigated with groundwater and the other irrigated with fish tank effluent. Water used for irrigation was replaced with groundwater after each irrigation event. Each of the two irrigation treatments was further subdivided so that half the area of each treatment received a fertilization regime typical of commercial greenhouse cucumber production (weekly fertigation with 90 g of NPK (13-46-36), increasing to 110 g by the end of the season) and the other half not fertilized. Accordingly, there were four irrigation treatments in the experiment: A – fish tank effluent; B – fish tank effluent with fertilizer; C – groundwater with fertilizer; D – groundwater. On eight occasions between 16 August and 2 F reshwater resources are a limiting factor in the production of more food for a growing global population (Saoud 2017). As the availability of freshwater cannot be increased, the problem can be partially mitigated by increasing freshwater productivity. One way to do this is to integrate aquaculture with terrestrial crop irrigation in an Integrated Agriculture/Aquaculture (IAA) system (Abdul-Rahman et al . 2011). This approach allows farmers to produce at least two types of crops (fish and vegetables) using the same water, thus increasing profit, food security and water productivity. If IAA projects are conducted in controlled production facilities such as greenhouses, insecticide use could be limited or eliminated to avoid toxicity to the fish (Mahmood et. al . 2016) as well as farmworkers and consumers. A large pool of water in a greenhouse provides thermal mass that has the potential of modulating daily temperature variation in temperate zones, thus extending the planting season. However, the water also increases humidity in the greenhouse thus making the environment more conducive to insect pests. In addition, irrigation with aquaculture water provides fish ni- trogenous wastes to plants with each irrigation event. Although nitro- gen is a desirable nutrient, excessive nitrogen fertilization can make plants more susceptible to insect pests (Ali et al . 2006, Draz et al . 2013). Accordingly, we investigated the effect of irrigating cucumber plants with fish aquaculture tank effluent on insect pest infestation and the efficacy of biological agents in controlling those infestations. Study Methods The study was conducted in a 16 m × 40 m greenhouse at the Agriculture Experiment Station of the American University of Beirut in Beqaa, Lebanon. The greenhouse was equipped with a double Integrating Agriculture with Aquaculture and Biological Pest Management – Does it Work? Sara Daher, Youssef Abou Jawdeh, Mustafa Haidar, Andre Abou Haidar, Bruce Parker, Margaret Skinner and I. Patrick Saoud FIGURE 1. Greenhouse with a 50-m3 fish tank and newly planted cucumber plants. Freshwater resources are a limiting factor in the production of more food for a growing global population. As the availability of freshwater cannot be increased, the problem can be partially mitigated by increasing freshwater productivity. One way to do this is to integrate aquaculture with terrestrial crop irrigation in an Integrated Agriculture/Aquaculture (IAA) system. This approach allows farmers to produce at least two types of crops (fish and vegetables) using the same water, thus increasing profit, food security and water productivity.