Postmortem Evaluation of Rabbit Carcasses Using Insect Populations in Keffi Nasarawa State, Nigeria

Untimely, forceful, and unexpected death is inevitable and common worldwide. Evidence for causes of death may be obtained through the knowledge of insects’ successional pattern and postmortem interval on dead carcasses. Two rabbits (Lepus cuniculus) weighing 2.5 kg each were used as the experimental animals. The rabbits were sacrificed by poisoning and stabbing, postmortem evaluation was achieved by taking record of the insect’s successional pattern. The insects’ successional pattern revealed the following insects’ species in order in which they arrived on the carcasses: Musca domestica, Lucilia sericata, Chrysomya albiceps, Dermestes maculatus, and Armadillidium vulgare (usual sp). The family Formicidae were represented by two unidentified species. M. domestica arrived first on the stabbed carcass while L. sericata on poisoned carcass. A total of 105±50 insects were collected throughout the study period, with stabbed rabbit contributing 61±10 and poisoned 44±60 insects’ species. Variation in the number of forensically important insects’ species encountered in the study site did not show any significant difference (p>0.05) in relation to each decomposition stage. There was however a significant difference (p<0.05) between insects’ relative abundance and mode of killing. Insect evidence was found 3 minutes after death on the stabbed carcass and 3 days after on the poisoned carcass. The study has shown that insects' population can be used to establish postmortem evidence in rabbit carcasses.

Efficacy of fresh crushed leaves and essential oil of Eucalyptus camaldulensis Dehnh on larvae of Dermestes maculatus De Geer insect damage to smoked dried Sardinella aurita "Kétiakh" stored in Senegal

Synthetic pesticides used to protect stored smoked and dried fish often cause enormous damageto human health and the environment. To limit the harms due to the use of these chemicals, it is necessary to find alternative methods. For this purpose, natural substances may constitute a beneficial way. The objective of this work is to study the effect of crushed fresh leaves and essential oil of Eucalyptus camaldulensis on the mortality of the larvae of an insect pest of smoked and dried fish, Sardinella aurita "Kétiakh", Dermestes maculatus (De Geer, 1774). Essential Oil was obtained by steam distillation from Eucalyptus leaves (0.8% w/w) and analyses carried out by GC/FID and GC/MS. For the biological test, fresh crushed leaves and essential oil were tested at different doses at varying treatment times again larvae Dermestes maculates. The results showed that D. maculatus was sensitive for both fresh crushed leaves and the essential oil, the efficacy of which depended on the dose and duration of treatment. The doses of 2 g and 2.5 g of freshly ground leaves showed a high efficiency of 27 to 40%, of mortality respectively. However, for the essential oil, with the increase in the duration of exposure, the highest mortality (33.3%) was recorded after 72 hours of treatment with the 40µl dose and at 120 hours with the 60µl dose. This study showed that fresh crushed leaves and essential oil of Eucalyptus camaldulensis can be considered as an alternative to the use of chemical insecticides in the conservation of smoked and dried Sardinella aurita "Kétiakh" stored in Senegal.

Effect of Intraspecific Larval Aggregation and Diet Type on Life-History Traits of Dermestes maculatus and Dermestes caninus (Coleoptera: Dermestidae): Species of Forensic Importance

Introduction: Numerous studies have examined the effect of abiotic factors on the development and survival of Dermestes and their importance for forensic entomology. Dermestes maculatus is one of the most known beetle species associated with corpses and D. caninus has little biological information available and no case report records. To better understand the life-history traits of those species we evaluated the impact of diet type and intraspecific larval density. Methods: Adult beetles were collected from human remains and colonies were kept under controlled conditions (27.0 ± 1.0 °C, 55.0% RU, and 12:12 L:D) and F1 generation was used to collect eggs. Newly emerged larvae were separated according to the treatments, being the combination of larval density (1, 15, 30 individuals), food (dried dog food or dried pork) and contact (with or without). We used factorial-ANOVA to test the individual and combined effect of both larval densities and diet on dependent variables, followed by post-hoc Tukey test. Pearson correlations were carried out to evaluate the relationship between larval parameters for each species in each treatment. Results: Pork-based diet positively affected species fitness, with larvae being ca. 1.1 (D. caninus) and 1.7 (D. maculatus) times bigger and heavier than in dog food. Diet type also impacted the development time for both species. Conclusions: Data generated through the current study serve as a foundation for potential application of this species as an indicator of time of colonization in relations to a minPMI. However, validation is still needed to determine the accuracy and precision of these calculations.

Piper guineense: A potent ethnobotanical preservative against Dermestes maculatus in smoke-dried African catfish, Clarias gariepinus

Piper guineense fruits were purchased, sun-dried (30±2oC) for 10 days and ground into fine powder. Fifteen (15) pieces of Clarias gariepinus (300 ± 5.0 g) were procured and smoke-dried in the laboratory using a charcoal-powered smoking kiln at 65oC for 10 hours. Each smoke-dried fish sample was placed in a plastic container with perforated lids covered with muslin cloth and Piper guineense fruit meal was sprinkled at varying quantities (0.0 g, 2.5 g, 5.0 g, 7.5 g and 10.0 g). Ten (10) adults of Dermestes maculatus bred from highly infested smoke-dried fish samples were introduced into each container and covered air-tight for seven (7) days. Mortality of D. maculatus was significantly different (p = .05) in all treatments and increased with an increase in the quantity of P. guineense and number of days. Mortality ranged between 73.33 and 100 % in treated groups while none was recorded in the control. Chemical compositions in treatments showed an increase in crude protein, lipids and lower moisture content at higher inclusion levels. This study showed that P. guineense can prolong the shelf-life of smoke-dried C. gariepinus against D. maculatus while retaining its nutritional composition. Key words: Dermestes maculatus, Piper guineense, smoke-dried, Clarias gariepinus

Responses of two plant-derived bioinsecticides as protectants of smoke-dried catfish, Clarias gariepinus [Pisces: Clariidae] against hide beetle, Dermestes maculatus (De Geer) [Coleoptera: Dermestidae]

Background Toxicities of Vernonia amygdalina and Tithonia diversifolia leaf powders and extracts on larva and adult mortality of Dermestes maculatus on smoke-dried catfish were evaluated in the laboratory. The leaf powders were admixed at 1, 3, 6, 9 and 12 g/100 g of smoked catfish in 500 ml plastic container while plant extracts were tested at 1, 3, 6, 9 and 12% concentrations. Results The toxicities of the plant products were concentrations and exposure time dependent. Significant difference (P < 0.05) existed between the toxicity of V. amygdalina and T. diversifolia leaf powders and control. Tithonia diversifolia powder evoked 27.5, 40, 52.7, 60 and 82.5% larval mortalities at the various concentrations after 24 h of exposure of the catfishes to the plant powder. Similarly, V. amygdalina leaf powders caused 20, 30, 42.5, 52.5 and 77.5% larval mortalities at varying concentrations of 24 h intervals of exposure to the plant powder. Tithonia diversifolia powder achieved 100% mortality at 9 g dosage after 96 h of treatment. Similar trend was achieved on the response of both plant leaf extracts as protectants of smoke-dried catfish against hide beetle. Conclusion Tithonia diversifolia powder and extract were more lethal than bitter leaf (V. amygdalina) and could be integrated as smoked fish protectant against hide beetle (D. maculatus).

Effect of Mating Disruption in Leather Beetle, Dermestes maculatus on Biological Activities and Nutritional Quality of Infested Smoked Catfish, Clarias gariepinus

Mating between male and female leather beetle, Dermestes maculatus infesting smoked catfish, Clarias gariepinus was disrupted in this study. The effects of disruption on pest biological activities and nutritional quality of fish after pest infestation were determined using standard methods. Mating disruption technique of 2:1 (♂: ♀); where the males were removed after 24 h of mating had the highest number of survived adults. Number of developed larvae (156.80 and 167.50) was significantly higher on treatments 1:2 and 2:1 (♂: ♀) in which males were removed after 48 h and 24 h, respectively. Frass weight generated by the beetle was higher in the mating disruption treatment 2:1 (♂: ♀) in which the male insects were removed at 24 h. Mating disruption technique 1:1 (♂ : ♀) in which male was removed after 144 h of mating, had higher ash content (5.307%) whereas, the least ash content (3.622%) was recorded in mating disruption treatment 1:1 (♂ : ♀) and the male was removed after 120 h. Moisture content (29.05%) was significantly higher on mating disruption technique 1:1 (♂: ♀) where the male was removed after 144 h. Mating disruption resulted into different number of offspring of D. maculatus and different degree of loss of minerals. These give unequivocal signal that mating disruption can affect biological activities and nutrient quality. Therefore, the use of physical mating disruption technique can be applied to D. maculatus control to reduce their (adults and larvae) biological impact on smoked fish and ensure quality and sufficient fish for human use.