The prothorax (the body region behind the head) is strongly pitted and the elytra have rows of pits within lon… Proctor, D.L. from Sitophilus oryzae (L.) (Coleoptera: Cuculionidae). The pupa does not feed. Sitophilus Oryzae is also called as Rice weevils. It can be found in numerous tropical areas around the world, and in the United States, and is a major pest of maize. [7], A close relative of the rice weevil,[6] the maize weevil has a length of 2.3 mm to 4.9 mm. The impact of grain quantity on the biology of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae): oviposition, distribution of eggs, adult emergence, body weight and sex ratio. Maceljski, M., Korunić, Z. [9][10][11][7], S. zeamais occurs throughout warm, humid regions around the world, especially in locations where maize is Sometimes, they are also found infesting beans, sunflower seeds and dried corn. The efficacy of insecticides for the control of Sitophilus oryzae and Rhyzopertha dominica on stored rice was evaluated. We have loaded Previous years questions with explanations...for all competitive exams. Environmental Entomology, 28(5): 836–844. Inside the grain kernel, the egg hatches into a young larva which migrates toward the centre of the grain kernel. 2009b. [1], "Greater Rice Weevil (Sitophilus zeamais)",, Control of Sitophilus zeamais Mots., 1958 and Sitophilus oryzae (L., 1763) weevils (Coleoptera, Curculionidae) in stored rice grain (Oryza sativa l.) with insecticide pirimiphos methyl (Actellic 500 CE). Development of Sitophilus zeamais and Tribolium castaneum in whole, cracked, and ground pearl millet. The most significant identification feature of weevils is their snout, which is pretty long. Mason, L.J. The emerged adults are ready to mate and begin their generation. Larva: They feed inside the grain kernel for 18 days. The combination of mechanical and biological methods was evaluated in the laboratory to assess their impact on the rice weevil Sitophilus oryzae in rice. 2003. DNA identification of two laboratory colonies of the weevils, Sitophilus oryzae (L.) and S. zeamais Motschulsky (Coleoptera: Curculionidae) in Taiwan. }); Merri Lynn Casem BA, PhD, in Case Studies in Cell Biology, 2016. Contribution to the morphology and ecology of Sitophilus zeamais Motsch. This was repeated every 30 days. These insects are cosmopolitan in distribution and have originated in Far East region. Explain the stages in the life cycle of rice weevil. The larva is the only stage during which the insect grows. Males are then attracted to this pheromone. [2] Breeding conditions require temperatures between 15 and 34 °C and[vague]40% relative humidity. They infest wheat, oats, rye, barley, rice, and corn. // ]]>, Pest of rice (Sitophilus oryzae): Distribution, Life cycle, Nature of damage and Control measures, Feeding habit and development of rice weevil. When the adults emerge, the females move to a high surface and release sex pheromones. Adults move and penetrate deeply into bulk of grains and get widely distributed. Rice weevils in all stages of development can be killed by freezing infested food below -18 °C (0 °F) for a period of three days, or heating to 60 °C (140 °F) for a period of 15 minutes. [CDATA[ Sitophilus oryzae L. (Rice weevil)—one of the major insect pests of stored food grains especially of cereals and their products contribute significantly to the physical, nutritional and quality deterioration of food grains. Females drill a tiny hole in the grain kernel through whic it deposits its egg and then plugs the hole with a gelatinous substance. Identification. The complete development time for the life cycle of this species averages 36 days. The snout is long (1 mm), almost 1/3 of the total length. Fifteen days after treatment, 200 g of rice was infested with 40 adults of each species. [6] In large stores of grain, an increase in temperature may be detected. 1982. [6] Sitophilus zeamais appears similar to the rice weevil (Sitophilus oryzae), but has more clearly marked spots on the wing covers, and is usually somewhat larger. [8] This small, brown weevil has four reddish-brown spots on the wing covers (elytra). However, the only reliable features to distinguish adults of both species are on the genitalia (see table below).