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Bacillus thuringiensis var. kurstaki (Bt.) is a bioinsecticide that is often used as an alternative for controlling tobacco cutworm, Spodoptera litura Fab. (Lepidoptera: Noctuidae). However, this bioinsecticide might easily degraded by ultraviolet (UV) from the sun light. This study aimed to determine the effectiveness of eri, Samia ricini Drury (Lepidoptera: Saturniidae) and atlas moth, Attacus atlas L. (Lepidoptera: Saturniidae) cocoon extracts as UV B protectants for Bt. against the larval stage of tobacco cutworm. Cocoon extracts of 0, 0.5, 1, 2, and 2.5% of eri and atlas sericin was added respectively to make Bt. suspensions at 10LC95 (2 × 108 spores/ml). After that, the suspensions then exposed under UV B lights at laboratory conditions for 1, 2, 3, and 4 weeks. Then, the pathogenicity was tested against 25 individuals of 1st larval instar of tobacco cutworm using three replicates. The results showed that the mortality percentage of tobacco cutworm treated with cocoon added Bt. were significant difference compared to Bt. alone. At the 1st week of UV B exposure, the mortality of tobacco cutworm in Bt. alone, Bt. + eri, and Bt. + atlas was 31.67, > 90, and > 75% respectively. Whereas, at the 4th week, the mortality of each treatment was 46.67, > 81, and > 75% respectively. The pathogenicity results implied that the addition of eri and atlas silk moths cocoon extracts significantly improved the Bt. toxicity by 1.75 – 1.86 and 1.6 – 2.1 fold, respectively, even after four weeks of UV B exposure. Based on this research, it can be concluded that the addition of eri and atlas silk moths sericin extracts show high potential for the UV B protectants for Bt. to enhance its persistence for future formulations.

Green peach aphid (GPA), Myzus persicae, is a major pest of most horticulture crops. Chitosan-based pest management emerges as an alternative to pesticides due to its biocompatibility and biodegradability properties. Population growth and electrical penetration graph (EPG)-based feeding behavior studies were conducted to assess the effect of chitosan application on caisim against GPA at three concentrations (0.1%, 0.5%, and 1%) including two controls of water and acetic acid. Evident GPA population growth reduction was observed in the chitosan-treated caisim. The effect of chitosan was further monitored by 10 h of EPG recording, which revealed a significant increase in probing activities due to frequent stylet withdrawal that generated high levels of short probing activities. Additionally, inter- and intracellular stylet punctures (waveform C and potential drop-Pd, respectively) displayed a significant increase. However, once the stylet reached the phloem tissue, GPA under chitosan treatment and water control can access the phloem tissue equally, either in terms of the number and duration. Therefore, we suggest that the reduced population growth due to chitosan treatment was related to extra energy consumption during frequent stylet withdrawal and intracellular puncture. This finding indicates the role of chitosan as a plant defense elicitor. However, further investigation regarding this topic is required.

The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier), is the most deleterious pests of palms worldwide, including date palms in the Kingdom of Saudi Arabia (KSA). An understanding of RPW diversity is crucial for designing management strategies of this pest. In this study, collections of RPW from date palm plantations were made in six known RPW-infected regions of KSA. The main objectives of the study were to characterize the RPW diversity in KSA using pronotal markings and cytochrome oxidase subunit I (COI) gene. The results showed that based on pronotal markings, 18 different color morphs of RPWs were found, while based on the COI gene, it could be separated into three main haplotypes. Pronotal marking and COI gene diversity revealed that the Riyadh and Eastern Regions were the major RPW diversity hotspots and the primary sources for subsequent RPW introductions into other regions of KSA.

The pathogenicity of various local entomopathogenic fungal isolates from the kingdom of Saudi Arabia has been tested in the laboratory against the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae). Fungi were coded, isolated, and purified. Beauveria bassiana (Balsamo-Crivelli) Vuillemin, coded as: BbSA-1 PDA-15 and Metarhizium anisopliae (Metsch.) Sorokin, coded as: MaSA-1 PDA-15, isolates demonstrated significant potential against R. ferrugineus larvae. A 1 × 1010 conidia/mL concentration of positive fungal isolates along with natural B. bassiana was used against different stages of R. ferrugineus. Rhynchophorus ferrugineus larvae were supplied with synthetic diets that contain preservatives and non-preservatives. The fungal isolates BbSA-1 PDA-15 and MaSA-1 PDA-15 affected the egg hatchability and caused significant larval mortality of red palm weevil. It was shown that MaSA-1 PDA-15 is one of the most pathogenic fungi against R. ferrugineus larvae followed by BbSA-1 PDA-15 and Natural B. bassiana isolates. Therefore, these local fungal isolates have the potential to be used against R. ferrugineus. Further development in the research could facilitate the farmers to save their valuable palm trees from the notorious pest.