Desenvolvimento biológico de Lasioderma serricorne (Coleoptera: Anobiidae) em substratos de armazenamento submetido a diferentes condições térmicas

Abstract

Grain storage is a highly important stage in the agricultural production chain, constantly challenged by infestations of insect pests that result in significant economic and sanitary losses. Lasioderma serricorne (Fabricius, 1792) (Coleoptera: Anobiidae), commonly known as the cigarette beetle, stands out as a cosmopolitan pest of high economic importance due to its broad ecological plasticity and polyphagous feeding behavior. The traditional management of this species has relied on phosphine fumigation; however, repeated and improper use has led to the emergence of resistant populations, limiting its effectiveness and highlighting the need for alternative strategies. Among these alternatives, thermal control arises as a promising option, though the use of extreme temperatures presents both technical and economic limitations. Despite advances in understanding the biology of L. serricorne, little is still known about the combined physicochemical effects of economically significant food substrates and moderate temperatures on its biological development. The objective of this study was to evaluate the combined effects of different food substrates (flours and whole grains) and moderate thermal conditions (15 °C, 20 °C, and 30 °C) on the biological development of L. serricorne, in order to provide technical support for sustainable strategies of integrated pest management in storage environments. The experiments were conducted under laboratory conditions in a completely randomized design with a 4×3 factorial arrangement (four substrates × three temperatures) and three replications per treatment. For each experimental unit, 100 g of the respective substrate were placed in 300 mL plastic containers, maintained at the three specific temperatures under a relative humidity of 70 ± 2% and a 12-hour photoperiod. Each container was infested with 100 four-day-old adults of L. serricorne, kept closed for 15 days to allow oviposition. After this period, adults were removed, and daily evaluations were carried out until larval viability was detected; pupal development, adult emergence, and longevity were then assessed every other day. For longevity tests, five emerged adults were individualized in Eppendorf tubes without substrate and monitored until death. Data were subjected to ANOVA, and means were compared using Tukey’s test (p ≤ 0.05). The results showed that temperatures of 15 °C and 20 °C were effective in controlling the pest, whereas 30 °C significantly favored insect development. Rice and corn flours yielded the highest number of hatched larvae (6.02 ± 96.37 and 5.66 ± 95.85, respectively), pupal development (30.06 ± 0.54 and 15.00 ± 2.89), and adult emergence (4.84 ± 0.73 and 13.67 ± 3.48) at 30 °C across all assessments. Soy flour exhibited the lowest larval viability (2.82 ± 15.85) and no pupal development or adult emergence at any tested temperature. Whole grains showed drastically reduced development compared to their corresponding flours, with maximum larval viability values of only 0.36 ± 0.58 for soybean grain at 30 °C. Adult longevity was highest in rice and wheat flours (18 days) at 30 °C, whereas in corn grain at 20 °C, it reached 48 ± 12 days. These findings suggest that grain physical integrity and the choice of less favorable substrates are complementary strategies for integrated management of L. serricorne. Thus, maintaining grain integrity represents an accessible control measure when combined with temperature management. Flours, particularly rice flour, pose a significantly higher infestation risk than the original grains, as milling transforms a resistant product into a highly susceptible one. Soybeans and soybean flour proved to be resistant substrates, offering a low-risk storage option. Temperature control must be applied cautiously, since moderate temperatures (20 °C) may extend adult longevity. For small producers and units with limited infrastructure, preventive and low-cost measures such as maintaining grain integrity and avoiding the joint storage of grains and flours are recommended, representing an effective approach to reduce post-harvest losses and strengthen food security.