El-Sayed H. Shaurub

Background: Snake envenomation represents a significant health concern in some regions of the world, with fatal cases occasionally requiring forensic investigation to estimate the postmortem interval (PMI). However, the influence of venom on carrion decomposition dynamics and arthropod succession patterns remains poorly understood, potentially compromising postmortem interval (PMI) estimations in such cases. Objectives: This study investigated the effects of Naja haje and Cerastes cerastes venoms on decomposition progression and necrophagous arthropod succession. Methods: Fifteen rabbits were allocated into three experimental groups. Two groups received median lethal intravenous doses (LD₅₀) of N. haje or C. cerastes venom, whereas the control group received a saline injection followed by CO₂ euthanasia. The carcasses were subsequently placed under natural field conditions and monitored daily for 15 days. Results: The presence of venom significantly altered decomposition dynamics. C. cerastes venom accelerated early decomposition, shortening both the fresh stage (1 ± 0.22 days vs. 2 ± 0.31 days in controls,) and bloating stage (3 ± 0.35 days vs. 5 ± 0.35 days), while extending both the decay stage (6 ± 0.3 days vs. 6 ± 0.17 days) and the dried stage (5.0 ± 0.44 days vs. 2 ± 0.039 days). N. haje venom showed intermediate effects. Overall arthropod abundance peaked on day 5 and declined thereafter. Control carcasses exhibited significantly higher arthropod abundance than carcasses envenomed with C. cerastes or N. haje. Conclusions: Snake envenomation significantly influenced decomposition kinetics and arthropod colonization patterns. Envenomation with C. cerastes venom produced more pronounced alterations than envenomation with N. haje venom.

Background: Coleoptera is the second-most significant insect group associated with decomposing carcasses, yet its role in the decomposition process and postmortem colonization following envenomation is poorly understood. Purpose of the Study: This study aimed to investigate the effects of the venoms from Cerastes cerastes and Naja haje on the decomposition of rabbit carcasses while evaluating the main beetle taxa attracted to these decaying remains. Methods: Three groups of rabbits, each with five individuals, were utilized. The first group was injected with the venom of Cerastes cerastes, the second with Naja haje venom, and the control group received 0.85% physiological saline before euthanasia with CO₂. Results: Four decomposition stages (fresh, bloating, decay, and dry) with durations varying based on venom type and carcass condition were observed. A total of 647 individual beetles of six species (Necrobia rufipes, Attagenus sp., Dermestes frischii, D. maculatus, Bledius sp., and Apentanodes sp.) belonging to four families (Cleridae, Dermestidae, Staphylinidae, and Tenebrionidae) were collected and identified. D. maculatus was the most abundant species. Fewer beetles were attracted to carcasses envenomed with N. haje compared to the other groups. Conclusions: Envenomation by snake venom influences the attraction and succession rate of necrophilous coleopterans to carcasses, which is important for forensic investigations.

The present work aimed to identify camel ticks Hyalomma dromedarii and Hyalomma marginatum using direct sequence of the mitochondrial 16S rRNA gene and the detection of their natural infection rate with Rickettsia and Borrelia using the PCR/hybridization method for amplification of the citrate synthase (gltA) gene. The phylogenetic analysis showed 99% similarity between Hyalomma dromedarii and its reference with accession #L34306.1, as well as between Hyalomma marginatum and its reference with accession #KT391060.1 obtained from GenBank data base. The prevalence of H. dromedarii and H. marginatum was about 99% and 1%, respectively. The intraspecific variation among H. dromedarii ranged between 0.2-6.6%. The interspecific variation between H. dromedarii and H. marginatum was 18.3%. PCR/hybridization of the sampled H. dromedarii detected about 31%, 37% and 18% natural infection with Rickettsia, Borrelia and co-infection with both pathogens, respectively. In contrast, none of Rickettsia or Borrelia was detected in H. marginatum. The present study emphasizes the accuracy of the identification of camel ticks based on molecular techniques. The ability of H. dromedarii to spread more than one disease is an important issue from the epidemiological standpoint. Future epidemiological research should be carried out in Saudi Arabia to monitor the distribution of tick species and suggest effective control strategies.

The present study was carried out to evaluate the nutritional indices, histological (light microscopy) and ultrastructural (transmission electron microscopy) changes in the midgut of the 4th larval instar of Spodoptera littoralis treated with the LC30 of the essential oil of garlic (Allium sativum) (16.60×104 mg/l) and lemon (Citrus limon) (20.09×104 mg/l) based on leaf–dip method compared to untreated larvae (control). The results of the nutritional metabolism revealed a significant reduction in food consumption index (CI), relative growth rate (RGR), and approximate digestibility (AD) of treated larvae. On the contrary, the efficiency of conversion of ingested food to body mass (ECI) and the efficiency of conversion of digested food to body mass (ECD) increased significantly in treated larvae. The most prominent symptoms revealed by light microscopy on the midgut of the treated larvae were vacuolization of the epithelial layer, clumping of the nuclear chromatin material and degeneration of the peritrophic membrane and microvilli. On the other hand, transmission electron microscopy showed vacuolization and degeneration of the columnar cells, clumping of the nuclear chromatin, breaking of microvilli, loss of the cytoplasmic projections of the goblet cells, appearance of residual bodies, and disintegration of mitochondria. In particular, treatment with lemon oil resulted in the appearance of numerous lysosomes and electron-dense mitochondrial matrices. In conclusion, the reduction of the RGR would result in undersized females in the next generations; in turn this would lead to a reduction of the reproductive potential. Also, the present investigation indicates that the microvilli and/or mitochondria are the probable target site(s) of action of garlic and lemon essential oils.

Background: The present study was undertaken to study the larvicidal activity of different extracts of Nerium oleander leaves, and post-treatment temperature-toxicity relationship of these extracts against Culex pipiens. Further, the most potent extract was used to evaluate its biological and genotoxic activities. Methods: Crude extracts of N. oleander leaves were prepared using water, chloroform, acetone and diethyl ether as solvents. Extraction was carried out using soxhlet apparatus. Bioassay test was carried out on the larvae, and the LC50 of each extract was determined. Thus, newly hatched first instar larvae were treated, and the mortality count was recorded daily till pupation (accumulated mortality). The LC50 of diethyl ether extract, as the most potent extract, was used for the further biological and genotoxic studies. Results: The results obtained indicated that diethyl ether extract of N. oleander leaves was the most potent extract, with LC50 of 10500 mg/l. The toxicity of the four extracts, using the LC50, at 10 degrees C was higher than that at 35 degrees C. The LC50 of diethyl ether extract significantly decreased the larval duration, pupal duration, percentage of pupation, percentage of adult emergence, longevity of females, fecundity, and oviposition activity index, whereas the growth index and the percentage of development per day of larvae and pupae were significantly increased compared to non-treated insects. Moreover, treatment with this extract induced significant dominant lethality in both male and female adults. Conclusion: It appears that diethyl ether extract of N. oleander leaves is potential control agent to Cx. pipiens.

Late third instars of the medfly, Ceratitis capitata (Wied.), migrate from the host fruit into the soil and leaf litter beneath host trees, where they may become a target for entomopathogenic nematodes (EPNs). The effects of ultraviolet (UV) light, temperature, soil type (texture), and soil moisture level on infectivity of the four tested EPNs Heterorhabditis bacteriophora AS1, H. bacteriophora HP88, Steinernema carpocapsae ALL, and Steinernema riobrave ML29 to late third instars of C. capitata were evaluated. Biochemical alterations induced by the most virulent nematodes were quantified. The nematode infectivity decreased with increase in exposure time to UV light, whereas it increased with increase in temperature. Infectivity increased in sandy soil, whereas it decreased in silt and clay soils. Soils with high moisture levels decreased infectivity. Based on the 50% lethal concentration (LC₅₀), H. bacteriophora AS1 and S. carpocapsae ALL were the most virulent heterorhabditid and steinernematid nematodes, respectively, with the highest virulence for H. bacteriophora AS1. The nematodes caused significant decline in total protein and cholesterol content of larvae and caused reduced activity of transaminases and phosphatases. In contrast, they significantly enhanced total glucose content. It can be concluded that the most optimum environmental conditions of the tested nematodes to elicit their infectivity against late third instars of C. capitata were sandy soil with 10% moisture level, ambient temperature of 25°C, and no exposure to UV. The EPNs tested can affect late third instars of C. capitata by targeting different biochemical molecules in different metabolic pathways. The interaction between them and the host larvae appears to be primarily nutritional.

The effects of different abiotic agents that may modulate the activity of an insect's immune system are reviewed. These agents include insecticides, chitin synthesis inhibitors, juvenile hormone analogues, inert particles, antibiotics, heavy metals, radiation and miscellaneous substances. The significance of studying immunomodulation in insects treated with abiotic agents in relation to both insect control and insect-borne parasitic diseases and the link between immunomodulation in insects post-treatment with both abiotic and biotic agents are discussed.