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.

The lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), has emerged as a promising nutrient source for food and feed applications. Efficient rearing of this species requires a wet feed as a moisture source, apart from the dry feed. Currently, vegetables and other plant materials are commonly used, but their inconsistent nutritional profiles may affect the larval development of A. diaperinus . Artificial, nutrient-enriched wet feeds may offer a more reliable way to deliver both moisture and essential nutrients. In this context, the objective of this study was to investigate the potential of agar as a carrier medium for the targeted delivery of water and nutrients to A. diaperinus larvae. Agar supplemented with three different concentrations, i.e. 2.5, 5 and 10% of baker’s yeast, brewer’s yeast or sugar was provided to larvae as wet feed three times per week, while wheat bran served as dry feed. Larval survival and growth, as well as feed utilization parameters were assessed. Our results clearly show that larval growth and other fitness-related traits are positively affected by the provision of agar supplemented with 5% brewer’s or baker’s yeast, while doubling the yeast concentration to 10% did not have any additional effect. In contrast, the provision of agar supplemented with sugar did not significantly affect the growth of A. diaperinus larvae. From a practical point of view, the utilization of agar as nutrient carrier may be a solution that can ensure water availability together with the targeted provision of nutrients for A. diaperinus larvae.

Insecticide resistance is a continuing global problem in the management of multiple stored product insect pests due to overuse of single chemistries and lack of alternative active ingredients. Therefore, there is a need to diversify IPM programs, by incorporating alternative chemistries. While pyrethroids are the most commonly applied grain protectants in stored product protection, organophosphates are another older class of insecticides that have been used as grain protectants, but fallen into disuse. Recently, the European Union approved the organophosphate azamethiphos (10% w/v), which has been labeled for use against cockroaches, bedbugs, ants, mosquitoes, flies, and wasps. Thus, the goals of this study were to (1) assess the direct mortality of Prostephanus truncatus (Horn) and Sitophilus oryzae (L.) after exposure to azamethiphos on concrete surfaces and (2) investigate its efficacy as a grain protectant on maize against P. truncatus and wheat against S. oryzae. To this end, for concrete surface bioassays, adults were exposed to azamethiphos at different concentrations for periods of 24, 48, and 168 h. For grain bioassays, azamethiphos was applied at 0.01, 1 and 10 ppm (mg of active ingredient per kg of grain) and adults were exposed for 72 h, 7, and 14 d on maize or wheat. At the tested surface doses, azamethiphos was not effective on concrete for either species. However, after 72 h exposure or grains, the percentage of dead and affected S. oryzae reached 52% and 48%, respectively at the 10 ppm., For P. truncatus, 74% and 100% of adults were affected at the 1 and 10 ppm, respectively. We found that azamethiphos holds promise for further evaluation in stored product protection against major insect pests.

The insecticidal efficacy of a commercial silicon dioxide (SiO₂) formulation (ChinCheX^®) was evaluated as a grain protectant and surface treatment against adults of Oryzaephilus surinamensis (L.) and Tribolium confusum Jacquelin du Val. In grain-treatment bioassays, wheat and barley kernels were treated with 0, 100, 200, 500 and 1000 ppm of the SiO₂ formulation and adult mortality was assessed after 3, 7, 14 and 21 d of exposure. Mortality increased with both concentration and exposure interval. Complete mortality of O. surinamensis was achieved at all concentrations, including 100 ppm after 21 d, whereas T. confusum was less susceptible at the lowest concentration but reached complete mortality at concentrations of 200 ppm or higher. Progeny production of both species was almost completely suppressed in all treated groups. In surface-treatment bioassays on concrete and plastic surfaces, high mortality (>85%) was recorded within 3 d of exposure at all application rates, while complete mortality was generally achieved within 7 d regardless of surface type. Overall, the SiO₂ formulation tested exhibited strong insecticidal activity both as a grain protectant and as a surface treatment, indicating considerable potential for the management of storage beetles in stored-product protection programs.

The present study evaluated the insecticidal efficacy of a commercial formulation containing azamethiphos (Teenox^® EC) against adults of the saw-toothed grain beetle, Oryzaephilus surinamensis, the lesser grain borer, Rhyzopertha dominica (F.), and the granary weevil, Sitophilus granarius (L.), under laboratory conditions. The azamethiphos formulation was assessed both as grain treatment on wheat and barley at 0, 2.5, 5, 10 and 20 ppm for all species, and as surface treatment on concrete and plastic surfaces at 0, 0.125, 0.25, 0.5 and 1 μg a.i./cm² for O. surinamensis and R. dominica. In grain treatments, adult mortality increased significantly with concentration and exposure interval for all species. Mortality was generally higher in barley than in wheat, particularly after longer exposure periods. Sitophilus granarius was the most susceptible species, reaching high mortality at the highest concentration, whereas R. dominica exhibited lower mortality responses, especially at lower concentration. Progeny production was significantly reduced with increasing concentration for all species, although the effect was more pronounced in barley than in wheat, particularly for O. surinamensis. In surface treatments, mortality was strongly influenced by surface type, with significantly higher efficacy on concrete compared to plastic. Mortality increased with both concentrations and exposure time for all species, while interspecific differences were less pronounced than in grain treatments. These responses indicate that both substrate characteristics and exposure time are important parameters of azamethiphos efficacy. Overall, the results indicate that the azamethiphos formulation tested can provide effective control of key stored-product beetle species when applied either on grains or different surfaces, although its performance is influenced by commodity and surface type. These findings highlight the potential of azamethiphos as a versatile tool in integrated stored-product pest management programs.