Insecticidal Effect of Diatomaceous Earth Formulations for the Control of a Wide Range of Stored-Product Beetle Species.

Diatomaceous earth (DE) formulations are promising alternatives over the use of traditional insecticides. In the present study, a series of laboratory bioassays was carried out to assess the efficacy of three diatomaceous earth formulations, i.e., Silicid, Celatom® MN-23, and SilicoSec®, for the control of a wide range of stored-product insect species in soft wheat. The species tested were Tribolium confusum, Tribolium castaneum, Sitophilus oryzae, Sitophilus granarius, Rhyzopertha dominica, Oryzaephilus surinamensis, and Alphitobious diaperinus. Different dose rates, i.e., 0 (control), 100, 300, 500, and 1000 ppm, were used for each of the aforementioned dust formulations. Mortality levels of the exposed individuals were assessed after 3, 7, 14, and 21 days of exposure. Moreover, progeny were counted 65 days later. Based on our results, dust formulations were effective for the control of most of the stored-product beetle species tested. Among the DE formulations tested, Silicid could adequately control the stored-product insect species. Complete suppression of offspring was observed only for secondary species (T. confusum, T. castaneum, O. surinamensis, and A. diaperinus). For primary species (S. oryzae, S. granarius, and R. dominica), the lowest number of progeny was observed in wheat treated with Silicid. For instance, in the case of R. dominica, significantly fewer individuals were produced in Silicid-treated wheat at the highest dose rate. The results of the present study aim to encourage the utilization of DE in stored-product protection as an integrated pest management tool. Additional experimentation is required to apply the tested DE formulations in the field and on different surfaces.

Evaluation of the susceptibility of Alphitobius diaperinus meal to infestations by major stored-product beetle species.

The projections for the production of insects as food and feed show an enormous increase for insect production in the near future, which will subsequently lead to the increase of the stored quantities of insect meals and related products. However, information on the susceptibility of insect meals to infestations by stored-product insects is rather limited. To this end, the objective of the present study was to evaluate the potential of major storage insect species to grow and reproduce on insect meals that are based on larvae of the lesser mealworm, Alphitobius diaperinus. The progeny production of thirteen stored-product insects on A. diaperinus meal, as well as their instantaneous rate of increase, as a measure of population growth, was recorded for each species. Based on the results, six out of the thirteen examined insect species (A. diaperinus, Tenebrio molitor, Trogoderma granarium, Lasioderma serricorne, Tribolium confusum, and Tribolium castaneum) were able to infest pure A. diaperinus meal, as they grew well and developed progeny on the insect meal substrate. Tribolium confusum, T. castaneum, and especially T. granarium gave the highest progeny production numbers in the A. diaperinus meal with the latter giving an instantaneous rate of increase of 0.067. Expecting the upcoming increase in the production of insect-based products globally, further research in this field is needed for improved production and storage facilities, detection and estimation methods, and technologies to minimize insect infestations without causing negative effects to farmed insects.