This study focused on comparing between dipteran fauna recovered from small mice (Mus musculus Linnaeus, 1758) and albino rat (Rattus norvegicus Berkenhout, 1769) carcasses placed in different habitats (a botanical garden and on a over the roof of 3rd floor of the faculty of science‘s building in the university campus). It was conducted during winter 2018 in Al-Dir'iya, Riyadh, Saudi Arabia. Collected specimens were identified morphologically and by molecular techniques based on the mitochondrial cytochrome oxidase subunit I (COI) gene. The number of flies recovered from the different decomposition stages of rat and mice carcasses at the two study sites was 5244, representing 11 families and 14 species. A tota nol of 4665 flies, comprising 11 families and 14 species, invaded carcasses located in the botanical garden, compared to the carcasses placed on the rooftop, which attracted 579 flies from 6 families and 9 species. The most abundant species recovered from both sites was Chrysomya albiceps (Wiedemann, 1830), followed by Musca domestica (Linnaeus, 1758), suggesting that these species are the most valuable for estimating Post Mortem intervals (PMIs) in this region of the Kingdom of Saudi Arabia. The data collected from this research can serve as the baseline data for homicide investigation as these flies can help determine PMI.

Plant based insecticides are considered among the most economic and ecofriendly chemicals for the protection of plants and stored grains. The cowpea weevil (Callosbruchus maculatus) causes more than 90% damage to sored grains in three to six months. The current study investigates insecticidal potentials of five selected botanicals: Melia azedarach, Nicotiana rustica, Azadirachta indica, Nicotiana tabacum and Thuja orientalis. They are explored at six different concentrations (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0%) against C. maculatus and compared to effects of distilled water which is used as a control. Toxicities of 3%(V/V) extracts of N. tabacum, N. rustica, A. indica and T. orientalis against C. maculatus were 100%, 86.11%, 80.56% and 72.22%, respectively. Maximum mortality was caused by N. tabacum and N. rustica (100%), followed by A. indica (82%), whereas minimum mortality was observed in T. orientalis (64%) at 2.5%. Several phytochemicals, alkaloids, saponins, diterphenes, phytosterol, flavonoids and phenols were identified in N. tabacum and N. rustica, while few were present in A. indica. Phytosterol was present in greatest abundance. Saponins were only detected in aqueous extracts of N. rustica and N. tabacum. Taken together, these results indicate the utility of N. tabacum, N. rustica and A. indica as potential botanicals to control pest beetle and cowpea weevil.

Insect succession on three rabbit carcasses placed 110.49 cm above ground in winter in Riyadh City, Saudi Arabia was examined in three different microhabitats: dry, semi-submerged, and submerged in tap water. The complete decomposition of the carcasses took 20 d and included five stages. In total 715 insects collected from carrion in different microhabitats were identified morphological, followed by the partial sequence confirmation of their 16S rRNA mitochondrial genes. Results showed that the insect species found and species richness differed among microhabitats. Carrion placed in the dry microhabitat showed the highest species richness and colonized by 400 insect specimens belonging to 16 species. Carrion placed in the semi-submerged microhabitat contained 271 insect specimens belonging to 12 species, showing a relatively low species richness. Lastly, the submerged microhabitat showed the lowest species richness, as the carrion placed in it attracted only 44 insects belonging to 9 species.

Chrysomya albiceps (Wiedemann 1819) is one of the most important insects in forensic entomology. Its larval developmental and survival rates are influenced by nutritional resources, temperature, humidity, and geographical regions. The present study investigated the possibility of relying on body size and cuticular hydrocarbon composition as indicators for age estimation of the different larval instars of C. albiceps. Larvae were maintained in standardized laboratory conditions at different experimental temperatures. All larval instars (first, second, and third) were randomly collected for measuring their body sizes and for estimating their cuticular hydrocarbons at different rearing temperatures (30, 35, 40, and 45°C) using gas chromatography–mass spectrometry (GC–MS). Results indicated that the duration of larval stage was temperature dependent as it gradually decreased on increasing the rearing temperature (30, 35, and 40°C) except 45°C at which larval development was ceased. In contrary, larval body size, in terms of length, width, and weight, was temperature dependent as it gradually increased with larval development on increasing rearing temperature except at 45°C at which larval development was ceased. The GC–MS showed a significant difference in the extracted components of cuticular hydrocarbons between different larval instars reared in the same temperature and between the same larval instar that reared at different temperatures. Furthermore, the highest and lowest amounts of cuticular hydrocarbons were detected at 35 and 40°C, respectively. Overall, larval body size and cuticular hydrocarbon components were temperature dependent within the range 30–40°C, which may suggest them as possible reliable age indicators for estimating the postmortem interval in the field of medicolegal entomology.

Necrophagous species of insects provide useful complementary data to estimate the postmortem interval in forensic cases. Here, for the first time, we report on insect specimens collected from human corpses in Riyadh, Kingdom of Saudi Arabia. During the study, 14 beetle larvae were collected from the outdoor corpse (case report one) and five flies and seven beetles were collected from the indoor corpse (case report two). Sequencing was performed to study the mitochondrial DNA (mtDNA) as the prospective basis of an identification technique. The sequencing focused on a section of the cytochrome oxidase I encoding region of mtDNA. Two beetle species, Dermestes frischii (Kugelann) and Dermestes maculatus (De Geer) (Coleoptera: Dermestidae), and one fly species, Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae), were identified. These results will be instrumental in the implementation of a Saudi database of forensically relevant insects.

Heads of sheep (n = 600) and goats (n = 800) slaughtered at Al-Aziziah Abattoir in Riyadh, Saudi Arabia, were inspected for the presence of O. ovis larvae (L). Heads were split along the longitudinal axes, and larvae (L1, L2, and L3) were gathered. The infestation rate was significantly higher in goats (44.5%; 356/800) than that in sheep (22.3%; 134/600). Out of the 151 collected larvae from sheep, 0% were L1, 1.3% were L2, and 98.7% were L3. Out of the total of 468 larvae from goats, 0% were L1, 1.2% were L2, and 98.8% were L3. The infestation rate was significantly higher in males than that in females. Myiasis-causing larvae collected from Riyadh, Saudi Arabia, were authenticated as O. ovis, according to morphological characteristics. Polymerase chain reaction (PCR) amplification of a partial fragment (600 bp) of the mitochondrial cytochrome c oxidase subunit I (mtCOI) gene further confirmed the species. Phylogenetic analysis based on the partial mtCOI gene sequence demonstrated that 23 unique sequences showed high similarity based on nucleotide pairs of O. ovis accessions retrieved from GenBank.