Z. Ahmadzadeh, B. Hatami,
Volume 7, Issue 3 (10-2003)
Abstract
Greenhouse whitefly, Trialeurodes vaporariorum West. is one of the most important pests of the field crops and ornamental plants in greenhouses. Pest control is based on using chemical insecticides and biological control agents. In this study, the efficiency of the green lacewing, Chrysoperla carnea ( Steph.) with release ratios of 1:1, 1:5, 1:10, 1:15, and 1:20 (predator:prey) using eggs in chrysobag and the effect of three insecticides including Confidor (35% Sc), Permethrin (25% Ec) and Dimilin (25% Wp) at concentrations of 0.3 ml/l, 0.3 ml/l and 0.15 g/l in water, respectively, were investigated. In one experiment, the eggs of the green lacewing were released on tomato plants that were infested with 150 different nymphal instars of the pest. Control treatment included chrysobag whithout any egg. After 11 days, nymphal mortality was calculated. In insecticidal experiments, in control treatment, only water was sprayed. Both experiments were conducted in a randomized complete block design with four replications in a greenhouse with 25±5 °C, 50-60% RH and 14:10 LD period light conditions. The means of data were compared using Duncan Multiple Range Test. The results showed that the maximum nymphal mortality of 52.42% was due to the release ratio of 1:1 (predator:prey) however, this was not sufficient and did not control the pest population. The results of the chemical control also revealed that one application of Confidor caused the highest mortality about 88% that was more effective in reducing pest population compared with the release of predator eggs. Neither method had absolute control. In general, results indicated that to be more effective the two methods need to be applied more than once, and they must be combined into one or with other control methods.
Z. Ahmadzadeh, B. Hatami,
Volume 9, Issue 4 (1-2006)
Abstract
Greenhouse whitefly, Trialeurodes vaporariorum West., is one of the most important pests of field crops and ornamental plants in greenhouses which usually controlled by chemical insecticide and/or by biologic control factors. In this study the effect of singular and integrated use of Confidor and predator, Chrysoperla carnea (Steph.) against different nymphal instars of the pest on tomato plant was investigated. This experiment was carried out in 7 treatments, each in 3 replicates. Treatments included predator alone, the use of insecticide alone, and 4 integrated treatments of both the predator and insecticide. The predator was released at 5, 10, 15 and 20 day intervals after insecticide application. The control (water), insecticide spray and release of the predator were repeated each 10 days. In integrated treatments, insecticide was applied only once at the beginning of the experiment. The results showed that there was a significant difference between treatments. Pest control was not achieved with one or two attempts of release of predator or spray of insecticide. Pest elimination was only observed after third spray in insecticide treatment and 3 releases of predator beginning 20 days after spray in integrated treatment. These two treatments were shown to be of equal effectiveness in pest control. Also pest population was controlled after 5 releases which began 5 days after insecticide application. The use of the alone predator was statistically found to be less effective than treatment with the insecticide alone. Generally, integrated treatment is a promising alternative approach to pest control in longterm. It has clear advantages over chemical control in terms of pest resistance, environmental and general pest control issues. .
