ABSTRACT
The cigarette beetle Lasioderma serricorne (Fabricius) is a major pest of stored products worldwide, especially tobacco and foods, causing huge economic losses. This study aimed to experimentally investigate the population dynamics of this pest at different temperatures and provide theoretical input for its control. Populations of L. serricorne were established under laboratory conditions at five temperatures (21 °C, 24 °C, 27 °C, 30 °C, and 33 °C). Results showed that an increasing temperature significantly affected the developmental time, longevity, oviposition period, and fecundity of L. serricorne. Both the longevity and fecundity of adult beetles were significantly reduced as the temperature increased. High temperatures significantly reduced the total duration of the preoviposition period but prolonged the oviposition period of L. serricorne. Increasing the temperatures from 21 °C to 33 °C significantly influenced the life table parameters of L. serricorne. The intrinsic increase rate (r), finite increase rate (λ), and gross reproductive rate (GRR) all increased with a greater rearing temperature, but mean generation time (T) was significantly shortened. To our best knowledge, this is the first report to detail the entire life history of the cigarette beetle in response to different temperatures when reared on tobacco dry leaves. This finding may provide basic information on the occurrence of L. serricorne in a warehouse setting and its mass rearing.
ABSTRACT
Pyemotes spp. are small, toxic, ectoparasitic mites that suppress Coleoptera, Hemiptera, and Lepidoptera plant pests. To explore their potential use as a biocontrol agent, we studied the reproductive development, paralytic process, time to lethality and mortality, and searching ability of Pyemotes zhonghuajia on different developmental stages of the oriental leafworm moth, Spodoptera litura. Pyemotes zhonghuajia gained 14,826 times its body weight during pregnancy. One single P. zhonghuajia female could rapidly kill one S. litura egg and first to third instar larvae, but not fourth to sixth instar larvae, prepupae, or pupae within 720 min. Pyemotes zhonghuajia could develop on eggs, first to sixth larvae, and pupae, but only produced offspring on the eggs and pupae. A single P. zhonghuajia female (an average weight of 23.81 ng) could paralyze and kill one S. litura third instar larvae (an average weight of 16.29 mg)-680,000 times its own weight. Mites significantly affected the hatch rate of S. litura eggs, which reduced with increasing mite densities on S. litura eggs. Releasing 50 or 100 P. zhonghuajia in a 2 cm searching range resulted in significantly higher mortality rates of S. litura first instar larvae within 48 h compared to second and third instar larvae in searching ranges of 4.5 and 7.5 cm within 24 h. To the best of our knowledge, this is the first study to reveal that P. zhonghuajia undergoes the greatest changes in weight during pregnancy of any adult female animal and has the highest lethal weight ratio of any biocontrol agent.
