Abdul Hafiz Ab Majid

Background: Coptotermes gestroi is one of the most destructive subterranean termite species in Southeast Asia, causing structural damage in urban areas such as Penang Island, Malaysia. This study aimed to confirm the species identity of urban tree-associated infestations and to determine whether populations from different locations on Penang Island exhibit genetic differentiation. Methods: Termites were collected from three locations across Penang Island: Teluk Bahang, Queensbay, and Universiti Sains Malaysia (USM). They were identified morphologically using soldier caste features. Molecular identification was performed using the mitochondrial cytochrome oxidase I ( COX1 ) gene. Results: All specimens were confirmed as C. gestroi morphologically and molecularly. Five haplotypes were identified among 23 samples based on their COX1 sequences, showing moderate haplotype diversity (Hd = 0.763) but low nucleotide diversity (Pi = 0.00526). Phylogenetic analysis indicated high similarity among sequences, with no clear clustering by location. Pairwise Fst values suggested limited differentiation between Queensbay and USM (0.1919), as well as between USM and Teluk Bahang (0.1993). In contrast, Queensbay and Teluk Bahang shared haplotypes. Conclusion: All samples from three sites (three populations) in Penang Island were identified as C. gestroi using morphology and COX1 sequences. The populations of C. gestroi across Penang Island were largely similar.

Fire ants (Solenopsis spp. Westwood) pose a major ecological and economic threat, mainly due to the invasive potential of certain species. Current identification methods are highly dependent on taxonomic expertise, which can slow down decision-making. The development of an automated detection system could therefore support the identification process. We present SolenopsisDetector (SolenopD), an automated system for identifying Solenopsis ants using computer vision and deep learning. Following taxonomic practice, which emphasizes diagnostic body segments (head, thorax, abdomen), we evaluated 2 classification strategies: the use of whole-body images or segment-based images. To localize and crop out the target ants/segments, we first trained and compared 3 detection algorithms (YOLOv5, YOLOv8, and YOLOv11) to localize ants and their body segments. We then tested 3 classification models (ResNet, MobileNet, and InceptionV3) to categorize the ants into 4 classes. A total of 8,300 images were used to develop SolenopD. Among the detection models, whole-body detection achieved 0.931 mAP, whereas segment-based detection achieved 0.788 mAP, representing an average improvement of 18.15% using YOLOv8 and YOLOv11. However, for classification, segment-based images—especially thorax and abdomen—provided higher accuracy than head or whole-body images, with InceptionV3 performing best. To further validate our approach, we used Grad-CAM to visualize the features used in the classification. The highlighted regions corresponded to the taxonomically relevant segments and emphasized the biological interpretability of the system. In summary, SolenopD integrates YOLOv11 for precise localization of ants and body segments, followed by InceptionV3 for accurate classification of Solenopsis spp.

A detailed understanding of the core microbiome in Blattella germanica is essential for clarifying host–symbiont interactions. Although factors such as diet, developmental stage, and environmental conditions influence cockroach gut microbial communities, their combined effects remain poorly understood. Moreover, most studies rely on whole-gut homogenates, leaving the midgut microbiota largely uncharacterized. Hence, 16S rRNA gene amplicon sequencing was used to characterize and compare the midgut bacterial community structure from 28 samples (including 1 negative control), considering the factors of developmental stage, sex, physiological status, and environmental origin. Microbial community profiling revealed 923 unique genera corresponding to 505 families, 306 orders, 137 classes, and 47 phyla. Bacterial communities belonging to the families Lactobacillaceae, Desulfovibrionaceae, Lachnospiraceae, Dysgonomonadaceae, Christensenellaceae, and Rikenellaceae were consistently present across all treatment groups. Alpha diversity analysis showed significant differences in Shannon diversity, while Simpson and Chao1 diversity indices showed no significant variation. Beta diversity analysis based on UniFrac distances revealed significant differences in microbial community composition across experimental conditions, with stronger separation observed when considering taxa abundance. PERMANOVA indicated that both physiological status and environmental origin significantly shaped community structure, while host sex and developmental stage showed significant effects only in weighted UniFrac distance. Family-level and prevalence analyses consistently demonstrated greater similarity between laboratory-fed and starved groups, whereas field-collected samples exhibited a more distinct and less shared taxonomic profile. Overall, these findings advance current understanding of compartment-specific gut microbiota and underscore the ecological stability of microbiome taxa under diverse conditions.

Tribolium castaneum (Herbst, 1979) (Coleoptera: Tenebrionidae), commonly known as the red flour beetle, is one of the most destructive pests of stored grain products worldwide. This study aimed to identify T. castaneum populations collected from Sabah, Penang, and Selangor using both morphological and molecular approaches and to assess their genetic structure and diversity. Morphological identification confirmed all specimens as T. castaneum. Molecular analysis using mitochondrial COX1 and 16S rRNA genes further verified species identity, with all samples showing 98% to 100% similarity to reference sequences in GenBank. Phylogenetic analysis revealed minor regional variation, with Penang and Selangor populations forming a distinct clade, suggesting greater genetic relatedness between these 2 Peninsular Malaysia populations than between them and Sabah. Microsatellite analyses indicated moderate genetic differentiation among populations (FSt = 0.162), accompanied by high within-population variation (FIs = 0.737). Complementary measures of genetic differentiation based on Jost’s D and DEST (G’ST) revealed substantial allelic differentiation among populations (global Jost’s D = 0.709; global DEST = 0.766), consistent with pronounced population structuring. Principal Coordinates Analysis (PCoA) and Bayesian clustering analysis (STRUCTURE, K = 5) further supported moderate substructuring and admixture among regions, suggesting ongoing gene flow. Overall, T. castaneum populations in Malaysia are genetically structured yet interconnected, likely influenced by trade and transportation activities. These findings provide baseline data on the dispersal dynamics of red flour beetles in Malaysia.

Macrotermes carbonarius is a fungus-growing termite widely distributed in Southeast Asia and is ecologically important in both natural and urban environments. In Malaysia, this species may act as a secondary pests following the suppression of primary termite infestations, making an understanding of colony structure and spatial connectivity particularly relevant. Microsatellite markers are widely used for such population-level studies; however, the performance and informativeness of loci developed for related taxa remain uncertain for M. carbonarius. In this study, genome-derived microsatellite markers were developed using Illumina-based next-generation sequencing. Seven loci showing strong amplification and high polymorphism were validated across 60 individuals from 6 locations in Penang, Malaysia. The number of alleles per locus ranged from 9 to 13, with expected heterozygosity (HE) values ranging from 0.751 to 0.888. All loci exhibited high polymorphic information content (PIC = 0.707 to 0.869), indicating their suitability for genetic studies. Population genetic analyses revealed high population differentiation (FST = 0.282 to 0.424), suggesting limited gene flow and substantial genetic structuring among colonies. The consistently high inbreeding coefficient (FIS = 1) reflects the species’ eusocial reproductive system, where colony members are closely related. These developed markers provide valuable molecular tools for examining genetic diversity, colony organization, and population connectivity in M. carbonarius.

The red flour beetle, Tribolium castaneum (Herbst), is a major pest of stored products. Microsatellite markers offer valuable tools for population genetic studies; however, existing markers often exhibit limited polymorphism or lack validation in field-collected populations. In this study, microsatellite loci were identified from whole-genome sequencing data of T. castaneum and tested for their utility in Malaysian populations. A total of 13.8 million sequence reads yielded 108,318 primer pairs, from which 20 markers were selected for screening. Of these, 7 loci consistently amplified and exhibited high levels of polymorphism, producing 14 to 28 alleles per locus. Expected heterozygosity values ranged from 0.798 to 0.962, and polymorphic information content exceeded 0.750 for all loci, indicating their high informativeness. Population differentiation analysis revealed moderate genetic structuring among populations (mean FSt = 0.162), suggesting restricted gene flow across sampled regions. These results demonstrate that the newly developed microsatellite markers are robust and highly polymorphic, providing a valuable resource for population genetic studies of T. castaneum and supporting efforts to understand pest dispersal and management in Malaysia.

This study compared insect diversity in Allium cepa var. aggregatum G. Don, Solanum lycopersicum L., and Capsicum annuum L. agroecosystems Parhaboan District, North Tapanuli, and Juhar District, Karo, North Sumatra, Indonesia, aiming to assess species composition, abundance, and ecological roles. Using pitfall, yellow sticky, and blue ball traps, hand picking, and direct observation, we identified pest and beneficial insects. In A. cepa var. aggregatum fields, Spodoptera litura (Fabricius) and Liriomyza chinensis (Kato) were dominant pests, with L. chinensis populations peaking during specific crop growth stages, highlighting the impact of crop phenology and pesticide use. S. lycopersicum plantations showed moderate diversity, dominated by Bactrocera spp. and Formicidae, with blue ball traps capturing high densities of Bactrocera spp., suggesting strong visual attraction. C. annuum crops had abundant natural enemies, including Paratrechina longicornis (Latreille) and Scelio spp., alongside pests like S. litura and Aphis spp., demonstrating a complex ecological balance. Despite moderate diversity, high evenness of natural enemies indicated a stable predator community. Intercropping C. annuum with A. cepa var. aggregatum or S. lycopersicum revealed varied insect compositions. A critical imbalance between herbivores and natural enemies was observed across all agroecosystems, emphasizing the need for integrated pest management (IPM). This research highlights the importance of insect diversity for sustainable agriculture in North Sumatra, advocating for habitat diversification, biological control, and strategic pesticide use. Future studies should examine seasonal dynamics, crop-specific variations, and long-term agricultural impacts to refine IPM and promote biodiversity conservation.

Symbiotic bacteria are closely associated with insect adaptability and survival, particularly in species with nutritionally limited diets. In the tropical bed bug Cimex hemipterus, these microbial partners synthesize essential nutrients such as B vitamins and amino acids that are absent from blood meals. The global resurgence of bed bug infestations, fueled by increased international travel and insecticide resistance, has challenged conventional control methods. Microbial symbionts are increasingly suspected to contribute to resistance mechanisms, but their role remains poorly defined. This study investigated the impact of four insecticides—chlorfluazuron, tebufenozide, pyriproxyfen, and a combination of β-cyfluthrin and imidacloprid—on the culturable bacterial symbionts of C. hemipterus using surface contact bioassays at concentrations of 100, 500, 1000, and 10,000 parts per million (ppm). Results showed a statistically significant reduction in colony-forming units (CFUs) in treated groups (p = 0.01), with the greatest suppression observed at 10,000 ppm. A significant negative correlation was observed between CFU abundance and mortality in pyriproxyfen-treated groups (p = 0.005), suggesting a potential link between bacterial suppression and sublethal physiological effects. DNA sequencing identified Bacillus species—particularly B. cereus and B. thuringiensis—as predominant symbionts across all treatments, indicating core microbiota stability despite insecticidal stress. These findings highlight that while bacterial abundance can be reduced by insecticides, core symbionts persist, which may contribute to host resilience. This study provides foundational evidence for integrating symbiont-targeted strategies with existing chemical controls to improve bed bug management.

GENETIC DIVERSITY AND PHYLOGENETIC RELATIONSHIP OF GERMAN COCKROACHES, Blattella germanica (L.) (BLATTODEA: ECTOBIIDAE) FROM URBAN COMMERCIAL SPACES