Influence of Different Stored Grains and Temperature on Developmental Stages and Survival Rates of Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae)

The sawtoothed grain beetle, Oryzaephilus surinamensis (L.), is a secondary pest causes great damage to cereal grains, commodities, and packaged food all over the world. Beyond cereal grains, this species is a concern because it may be differently impacted based on variation in temperature. Therefore, development time, larval and pupal survival, and adult emergence of O. surinamensis were evaluated on various substrates at different temperatures regimes (22, 28, 32, and 38 °C). With highly significant differences, the larval stage duation of O. surinamensis ranged from 19.2 ± 1.26 days on rice grains to 25.6 ± 0.98 days on white maize grains. The insect exhibited the highest rate of larval survival (95%) on rice grain followed by oat (90%) and wheat grain (89%). The shortest larval stage duration was measured at 38°C (12.1± 0.98 d), followed by 32°C (16.4±1.03 d) with highly significant differences. The total immature stage durations ranged from 22.9 days at 38 °C to 54.2 days at 22 °C. The percentage of larvae that survived varied from 62% at 38°C to 91% at 32°C. The average number of adults that emerged at a temperature of less than 38°C was 5.1 ± 1.12 individuals, which was the lowest recorded value. Therefore, the grain type and temperature range plays a significant role in determining sawtoothed grain beetle infestation, which might have future implications for controlling this insect pest.