عنوان مقاله [English]
Introduction: Termites are the common destructive pests of wood and cellulosic products in world-wide structures. In Iran, several Microcerotermes species regularly cause economic damages to wooden structures and building components in non-residential and residential areas. Microcerotermes diversus is a serious wood-destroying termite that exists in Khuzestan Province. This species has a broad scope of food foraging and also has the ability to create secondary communities within building walls and ceilings, as well as on trees. Eradication and control of this species by common methods such as the operation of drilling and injection of insecticides into the ground is faced with problems and in some cases is not always effectiveness. According to these problems, one of the effective methods of control is the use of baiting systems in which application of poisoned bait is an effectiveness control method for subterranean termites’ control. A variety of materials and toxicants have been tested to build suitable and attractive bait matrices against termites. The current research was carried out to produce a suitable formulation of toxic bait for control of subterranean termite M. diversus in Iran.
Materials and Methods: In this research, feeding responses of tested termite were evaluated to different cellulosic matrix substrates (filter papers) treated with different concentrations of molasses (ranging from 1 to 6%), urea (ranging from 0.01 to 1%), yeast (ranging from 0.01 to 1%) and soybean oil (ranging from 0.01 to 10%) additives. Non-treated filter papers were considered as control. Choice and no-choice laboratory tests were conducted. In no-choice tests, each matrix was treated with its assigned additive and allowed to be stabilized for 24hours before recording pre-trial weight. Each test matrix was separately placed in a Petri dish (9 cm in diameter) and wetted with distilled water prior to adding the termites. Then fifty termite workers were added to the Petri dishes. Experimental units were kept in a dark incubator (90±5%RH; 28±2°C) for two weeks, and termite mortality was periodically determined. The choice tests were performed following the same no-choice laboratory tests. Each experimental unit consisted of a 9cm plastic container connected to two other 9 cm plastic containers by a T-shaped tube. The central container included a mixture of soil and vermiculite (in the ratio of 2:1) moistened with distilled water, and a filter paper disc measuring 9 cm in diameter was plased in each two other plastic containers, one treated with selected concentrations of molasses, urea, yeast and soybean oil of no-choice tests and another with distilled water. Groups of foragers comprising 100 workers were placed in the central container. Experimental units were kept in a dark incubator (90±5%RH; 28±2°C) for two weeks. All experiments were conducted with four replicates. At the end of the trials, each test matrix (filter papers) was individually dried and weighed to determine feeding losses. Data analysis was done by SPSS software (version 16.0). Means were compared by Tukey̕̕ s test (no-choice test), and t-tests for two-sample paired (choice tests) (α=0.05).
Results and Discussion: The mean comparison of treatments with control through survival (after transformation the percentages to Arcsin ) showed that different concentrations of molasses and yeast did not had significant differences with compared to control. Also, there were not significant differences between soybean oil and urea and control, however 10% concentration of soybean oil and1% concentration of urea was significantly different compared with control and these two concentrations had lower survival compared with control. The mean comparison of treatments with control through feeding in no-choice test indicated that different concentrations of molasses and yeast had significant differences with control. By increasing the concentration of sugar in the molasses feeding rate is increased. Also with increasing concentration of yeast, the rate of feeding increased. The mean comparison of treatments with control through feeding showed that different concentrations of soybean oil and urea did not have significant differences with control, whereas 10% concentration of soybean oil was significantly different compared with control. With increasing concentration of soybean oil, the rate of feeding and survival of termites were greatly decreased. The mean comparison of treatments with control through feeding in choice test showed that selective concentrations of molasses (4%) and yeast (1%) had significant differences with control, but selective concentrations of urea (0.01%) and soybean oil (0.01%) did not had significant differences with control. These results confirmed the results of the no-choice test. Overall, matrices with 4% and 6% molasses concentrations and 1% yeast sustained the greatest feeding weight losses. Termite survival and matrix weight losses for different concentrations of urea and soybean oil were not significantly different with controls.
Conclusions: Adding of 4% molasses (w:w) and 1% yeast (w:w) to bait matrix is proposed to be used in a commercial production to increase consumption of toxic bait.