Seasonal Occurrence and Biodiversity of Insects in an Arid Ecosystem: An Ecological Study of the King Abdulaziz Royal Reserve, Saudi Arabia

Each living organism thrives best in a habitat that provides optimal conditions for flourishing, reproduction, and distribution within a certain area. This study aims to investigate the seasonal variation in insect biodiversity across different sites of the King Abdulaziz Royal Reserve (KARR), located between E 45.19-46.57 and N 25.15-27.41, with a focus on assessing biodiversity, density and seasonal variation using active and passive methods, over the period from January to November 2023. A total of 68 sites within the study area were randomly selected for trap placement. The trapped specimens were labeled and transferred to plastic bottles half filled with 70% ethanol and then taken to the laboratory for counting and identification. Identification was based on morphological characteristics and appropriate identification keys, with the assistance of entomological expertise, and a list of local species. Simpson's diversity index (D) was also calculated. The results revealed that, out of 6320 trapped insects, species were identified across six orders: Blattodea (termites), represented by 2 families and 2 species; Coleoptera, comprising 12 families and 38 species, of which 11 belonged to the family Tenebrionidae; Hemiptera, comprising 7 families and 9 species, 3 of which belonged to the family Lygaeidae; Hymenoptera, comprising 5 families and 15 species, 9 of which were from Formicidae; Lepidoptera, comprising 2 families and 3 species; and Orthoptera, comprising 3 families and 7 species, 4 of which were from family Acrididae. Insect biodiversity and abundance were observed to be relatively low during the winter (January-March) and autumn (October-November) seasons, while relatively higher densities were recorded during spring (May) and summer (August-September).