Larval competition in the khapra beetle, Trogoderma granarium everts (Coleoptera: Dermestidae)

High population density, or crowding, represents a significant stressor for insects, influencing various life history traits in adults, including survival, body weight, and reproduction. This study investigates the response of the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), to crowding, potentially manifesting as a form of scramble competition. The effects of crowding on key life history traits were systematically evaluated, encompassing survival, body weight, and reproductive parameters. The experiment involved monitoring insect development at different larval densities (4, 12, 20, 28, 32, 44, 52, and 60 larvae per container) under controlled laboratory conditions. Additionally, intraspecific competition, gauged by gain in insect biomass produced per grain, was examined after one day of starvation followed by three days of feeding. Results revealed that initial larval density significantly impacted insect development, particularly during the larval stage. Notably, the egg incubation period and pupa development remained largely unaffected or exhibited minimal sensitivity to larval density. The female fecundity curve peaked at approximately 15 larvae per container, while fertility per container displayed a linear increase with larval density. Gain of insect biomass per container also exhibited a linear correlation with larval density, consequently influencing a parallel pattern of grain loss. In summary, larval crowding emerged as a pivotal factor influencing T. granarium, underscoring the substantial impact of intraspecific competition. These findings affirm the presence of a scramble-type competition among khapra beetles, highlighting their high tolerance to elevated larval density and competition levels. The implications of these results reinforce management concerns associated with this species, emphasizing the importance of addressing intraspecific competition in the context of khapra beetle population dynamics and its management.