Insecticidal Effect of Some Inert Dusts Against Three of Stored Grain Insects at Kafr El-Sheikh Governorate

Abstract

Laboratory and field studies were conducted to evaluate the effect of three inert dusts, diatomaceous earth, kaolin and katelsous as wheat grain protectants against some stored grain insects, i.e., Sitophilus oryzae, Rhizopertha domininca and Tribolium confusum. Inert dusts were mixed with wheat grain in the laboratory at different concentrations. Data obtained from the laboratory experiment showed that the LC50, s of diatomaceous earth, kaolin and katelsous were 0.234, 0.071 and 0.235% w/w, 6.033, 6.306 and 8.938% w/w and 0.495, 0.496 and 103.875% w/w against S. oryzae, R. dominica and T. confusum, respectively one day after treatment. Diatomaceous earth was more effective than the other tested materials where it achieved complete mortality for the three tested insects after two days of treatment at the rate of 0.5% w/w. Results also showed that kaolin and katelsous act slowly on the tested insects, where the higher rates of 8% w/w for kaolin and 0.4% w/w for katelsous gave complete mortality after one week post treatment. For the field study (at farmers , storages), the higher concentrations (0.5, 8 and 0.4% w/w) of the three dusts, diatomaceous earth, kaolin and katelsous, respectively obtained from laboratory experiment were admixed with wheat grain and stored for 4 months at the farms. For the field experiment, the results showed that diatomaceous earth gave 100%, 91.6% and 98.2% mortality against the three tested insects, respectively after 4 months of storage at a concentration of 0.5% w/w at 7 th day of exposure. Kaolin at 8% w/w showed that adult mortality decreased from 100% at zero time of storage after 5 days of exposure to 13.7%, 27.1% and 16.9 at 4 months of storage after the same period of exposure against the three tested insects respectively. At zero time of storage, katelsous at a rate of 0.4% w/w showed the percent mortalities of 100%, 100% and 95.7% against the three tested insects, respectively at 5 days of exposure. The residual effect after 4 months of storage decreased to 14.3%, 52.9% and 35.6% mortality against the three insects, respectively at the same time of exposure. In general the results obtained showed that the diatomaceous earth had the most activity followed by katelsous and kaolin against the three tested insects. Also, the degree of effectiveness decreased with the increasing of storage periods.

Efficacy of Two Entomopathogenic Fungi in Combination with Diatomaceous Earth Against Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)

“…Mewis and Ulrichs (2001) observed high mortality in Tribolium confusum, Plodia interpunctella, and Sitophilus granaries treated with low dosages of DE and found that it required a long exposure period to cause higher mortality. The results stand in the same line as El-Sayed et al (2010), who claimed that the treated wheat with diatomaceous earth highly reduced the population of Sitophilus oryzae, Tribolium castaneum, and Rhyzopertha dominica. Because of its low mammalian toxicity, worker safety, the low danger of food residues, and the formation of resistant insect populations linked to the use of chemical pesticides, diatomaceous earth usage has increased during the past decades.…”

Efficiency of Utilizing Citrullus colocynthis (L) Essential Oil Alone and When it Mixed with Diatomaceous Earth Against some Stored Products Insect Pests

“…are among the most DE-tolerant species, as T. castaneum was the least affected in comparison with the other three species as after the longest exposure time achieved 80% mortality at the highest concentration 10%(w/w), while S. oryzae was the most sensitive reached 100% mortality after 7days followed by O. surinamensis with 100% mortality after 7days, then S.paniceum with 94.4% mortality after 10 days at concentration of 10%(w/w)., so S. oryzae considered more susceptible than Tribolium spp. (Arthur, 2002;Athanassiou et al, 2003;Kavallieratos et al,2005;El-Sayed et al, 2010).…”