Population Growth Changes in Major Stored Product Insects on Rice Fortified with Spearmint and Basil

Abstract

Rice is the most important durable food product for more than half of the world’s population, as it is very nutritious food in terms of carbohydrate containment and can meet a large part of human caloric needs on a daily basis. The sensitivity of a rice product fortified with spearmint or basil was evaluated for three stored product insect species: Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Five different containments of fortified rice were used (0, 25, 50, 75 and 100% of the total rice quantity), and the population growth of the above species was examined after 65 days. We found that fortification generally reduced the infestation level of the species tested and reduced their population growth, as compared with the control rice. In some of the treatments, there were some differences between the application of spearmint and basil. There was higher frass production in the rice that had been fortified with basil than that with spearmint, indicating different infestation patterns. For S. oryzae, with the gradual increase in fortification, the number of insect-damaged kernels and weight of damaged kernels reduced, and significant differences were recorded between the fortification with spearmint and that with basil. The results of the present study are certainly encouraging for further utilization of the characteristics of fortified rice for stored product insect control.