Search

An insecticidal efficacy of two newly developed grain protectant formulations were assessed against lesser grain borer Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) on wheat and corn after 6 months period of. Tested formulations, marked as F1H and F2H, based on inert dust, laurel leaves, lavender essential oil, corn oil, silica gel (both F1H and F2H) and pyrethrin (only F2H) were tested at six doses (from 100 ppm to 600 ppm) depending on formulation and type of grain. The appropriate weights of each formulation, were added seperately to plastic containers containing 10 kg of wheat or corn. An initial population of 200 adults of R. dominica were added into each container and left under natural environmental conditions for up to 6 months. A commercial diatomaceous earth (DE) insecticide, Celatom® Mn 51, was used for the comparison of the results, in addition to the untreated control. After six months, both formulations showed higher insecticidal effect than DE Mn 51 in corn and in wheat. Furthermore, the initial population of R. dominica, introduced in wheat was suppressed almost completely, with only 0.7%-5.3% live adults found, depending on formulations and dose. The order of efficacy was F1H>F2H>DE Mn 51. Similar suppression of the initial population was recorded in corn, where F2H was slightly more effective than F1H with 2.0%-10.6% and 4.1%-9.5% live adults found, respectively. At the same time, in the treatments with DE Mn 51 there were 4.7%-74.7% and 33.4%-56.1% live adults in wheat and corn, respectively

The red flour beetle, Tribolium castaneum (Herbst), holds a significant place in Croatia by causing considerably damages on stored products. This study was initiated in order to test contact and fumigant activity of three essential oil compounds (1, 8-cineole, camphor and eugenol) for the control of adults of this stored-pest species. Contact toxicity of compounds was tested at four doses (0.2, 1.0, 5.0 and 10.0 μL/adult) and mortality was recorded every 2, 4 and 24 h after the application. The most effective compound was 1, 8-cineole by its fastest action (2 h after application), with maximum mortality at the lowest dose (0.2 μL/adult). With its prolonged effect of 4 h, eugenol resulted in mortality of 87.5% at the dose of 0.2 μL/adult, while camphor obtained the highest mortality (78.5%) just after 24 h, and at the highest tested dose (10.0 μL/adult). Fumigant toxicity of compounds was tested at three doses (30, 60 and 120 μL/350 mL vol.) and after 48-h of exposure time ; mortality was recorded every 24 h until the “end point mortality” (when no time-dependent changes in mortality occurred). The highest mortality (98.5%) had 1, 8-cineole at the lowest dose (30 μL/350 mL vol.), followed by camphor (93.5%) at the highest dose (120 μL/350 mL vol.), while eugenol had no statistical significance in the control of T. castaneum adult by application of this fumigation method. Such investigations make positive contribution to new possible alternatives to conventional insecticides and fumigants used in protection of stored cereals.

A mixture of diatomaceous earth (DE) and deltamethrin (DM) was developed to control stored-grain insect pests. The formulation contains a low quantity of DE and small amounts of insecticide deltamethrin technical powder dissolved in solvent and soap. This study was initiated in order to determine how long the mixture DE/DM will provide acceptable protection against infestation by the rice weevil, Sitophilus oryzae (L.), the lesser grain borer Rhyzopertha dominica (F.) and the red flour beetle, Tribolium castaneum (Herbst), when applied to hard red spring wheat (HRSW) and stored under normal storage conditions. Immediately after treatment, all three species were controlled at 100 milligram per kg or parts per million (ppm) of DE/DM mixture. At 100 ppm, DE/DM mixture provided 100% population reduction of all three species for up to 12 months with little or no progeny produced.

In order to mitigate the negative effect of diatomaceous earth (DE) on bulk density and grain flowability, DE was mixed with other insecticides. This paper investigates the efficacy of a mixture of DE and deltamethrin against Sitophilus zeamais, the maize weevil, Rhyzopertha dominica, the lesser grain borer, and Tribolium castaneum, the red flour beetle. Five mixtures of DE and deltamethrin were prepared in the laboratory containing the same quantity of DE and different concentrations of the active ingredient of deltamethrin. The ratio of DE and deltamethrin in formulations were: DE 1 part: deltamethrin 0.00025, 0.00050, 0.00075, 0.0010 and 0.00125 parts. Co-toxicity and Co-efficient values higher than 100 (S.zeamais 170–386, R. dominica 188–601, and T. castaneum 157–285) indicated synergism between DE and deltamethrin.