Treatment with topical application showed that the pyrethroids group, (Cypermethrin) was the highest toxic against the subterranean termites Psammotermes hypostoma (Desn.) after 12 hr. where recorded (LD50 value = 0.056001 and LD90 reached to 0.59557 μg/worker), followed by chlorpyrifos, recorded (LD50 value = 0.08066 and LD90 reached to 0.42698 μg/worker), and fipronil was in the last rank where recorded (LD50 value = 0.089141 and LD90 reached to 1.33442 μg/worker). Data after 24 hr. indicated again that, cypermethrin in the first rank in the acute toxicity, while fipronil come in the next rank followed by chlorpyrifos (LD50 value recorded 0.02265, 0.026085 and 0.0393 μg/worker respectively), and the values of LD90 reached 0.10035, 0.1054 and 0.15748 μg/worker, respectively. At all times control recorded 2, 2 and 4 % for chlorpyrifos, fipronil and cypermethrin, respectively.
Present work was conducted for studying biological control of the termite psammotermes hypostoma (sand termite) This study includes the following results: Toxicity results of Bacillus thuringiensis var. kurstaki against the termite psammotermes hypostoma revealed higher mortality values at the highest concentrations used 6gm/L, while the lowest concentrations gave moderate mortality values 53%. Use of Beauveria bassiana, indicated negligible mortality values ranged between from (3.6-16.2%) at the three tested concentration. Application of nematodes (Steinernema carpocapsae) against subterranean termites, mortality has begun 24 hours post-treatment. The first concentration represented (40.2%) mortality, the second concentration represented (78.2%), and the highest used concentration gave complete mortality values (100%). The LT 50 for Dipel 2X was 2.6, 3.01 and 4.9 days and 2.2, 3.2 and 7.3 days for Bacillus thuringiensis approximately.
The catched termites of untreated areas at first year 2009 showed highly population of subterranean termites Psammotermes hypostoma (Desn.), when compared with population catched at second year 2010 in soil treated with insecticides in the location A and B of all tested insecticides. In 2 nd year data showed in location A (insecticides treated with water solvent), the insecticides were more toxic than insecticides in case location B (insecticides treated with kerosene solvent). Chlorpyrifos was the best for decreased of termite individuals followed by cypermethrin and fipronil in location A, while the insecticide cypermethrin was in the first rank followed by fipronil and chlorpyrifos in location B. The Chlorpyriphos found amount residues highly stability and more going deeply into depth layers in the treated soil followed by cypermethrin and fipronil, also the leachibility of insecticides treated with water solvent were more going deeply into depth layers than the insecticides treated with kerosene solvent, and vice versa in surface layers, whereas the insecticides treated with kerosene solvent more toxic and counted highly content of treated chemicals.
The obtained results of soil treatments against Psammotermes hypostoms (Desn.), indicated that, the three tested insecticides in different groups; chlorpyrifos, fipronil and cypermethrin were highly toxic in sub-surface layers of treated soil contains particle size of >850µm more than other particle sizes 425 and 250µm, respectively, and the fine soil was more safety to the ground water. Fipronil showed the highly toxic effect, followed by cypermethrin and chlorpyrifos, respectively. In coarse soil cypermethrin showed more toxic than other tested insecticides. The results of chemical determination of insecticides residues, data indicated that chlorpyrifos was more save for water table at all particle sizes followed by cypermethrin, while fipronil was the lower safety one, especially in soil particle sizes of 850 and 425µm, respectively. Generally the data of statistical analysis showed significant variations between all tested factors, (insecticides, particle sizes and depths of soil). with the variable, (mortality%).
The results of washing on treated soil with insecticides against subterranean termites Psammotermes hypostoma (Desnuax),indicated that, the first washed of treated soil were the highly efficacy and quicker in the killed against termites of all tested particle sizes than second and third, respectively, and the small particle size were the quicker and more toxic than others in the first washed of treated soil, while was the lower of toxic than others in third, second and first washed of soil, respectively. Also cypermethrin showed the highly toxic, followed by fipronil and chlorpyrifos, respectively. The treated coarse soil showed more toxic in the second and third than the fine, and to consider the lower safety to the water table, also the washed samples analysis indicated that, the chlorpyrifos showed the higher safety followed by fipronil and cypermethrin. Statistics analysis showed highly significantly between the factors treatments, number of washing and times, with the variable, (mortality %), while low significant recorded for particle sizes.
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