Chelisoches morio (Fabricius) (Dermaptera:Chelisochidae) is an important predator of Tirathaba rufivena (Walker) (Lepidoptera:Pyralidae). For better use of the natural enemy, a biological study on C. morio was conducted, particularly its developmental duration, survival, fecundity and sex ratio. And the feeding capacity of C. morio against T. rufivena was also studied under laboratory conditions. The biological study on C. morio was revealed that female adults usually lay eggs in egg masses. The number of eggs per female averaged 140.17 eggs, and the incubation period was 7.50 days. The duration of nymphal development included four instars. The immature period was 83.95 days. The longevity of males and females was 58.60 and 93.55 days, respectively. The results from the study on the feeding capacity of C. morio using T. rufivena as food revealed that C. morio adults could consume 11.08, 7.87, 7.09, 6.82 and 5.89 first-to-fifth-instar T. rufivena larvae, respectively. C. morio showed a huge amount of predation on this pest at all larval stages, implying a significant potential for the use of C. morio in controlling T. rufivena.

In this study, the changes in the conventional nutrient and mineral compositions as well as the metabolomics characteristics of the red palm weevil (RPW) Rhynchophus ferrugineus Olivier (Curculionidae: Coleoptera) larvae at early (EL), middle (ML) and old (OL) developmental stages were investigated. Results showed that the EL and ML had the highest content of protein (53.87 g/100 g dw) and fat (67.95 g/100 g), respectively, and three kinds of RPW larvae were all found to be rich in unsaturated fatty acids (52.17–53.12%), potassium (5707.12–15,865.04 mg/kg) and phosphorus (2123.87–7728.31 mg/kg). In addition, their protein contained 17 amino acids with the largest proportion of glutamate. A total of 424 metabolites mainly including lipids and lipid-like molecules, organic acids and their derivatives, organic heterocycle compounds, alkaloids and their derivatives, etc. were identified in the RPW larvae. There was a significant enrichment in the ABC transport, citrate cycle (TCA cycle), aminoacyl-tRNA biosynthesis, and mTOR signaling pathways as the larvae grow according to the analysis results of the metabolic pathways of differential metabolites. The water extract of EL exhibited relatively higher hydroxyl, 2,2-diphenyl-1-pyrroline hydrochloride (DPPH) and 2,2’-azobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging ability with the EC₅₀ values of 1.12 mg/mL, 11.23 mg/mL, and 2.52 mg/mL, respectively. These results contribute to a better understanding of the compositional changes of the RPW larvae during its life cycle and provide a theoretical grounding for its deep processing and high-value utilization.

Background: The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier), is an important quarantine pest, which has caused serious economic losses in various palm species, such as coconut, oil palm and date palm. Finding effective biocontrol resources is important for the control of this pest and the protection of palm crops. Methods: A pathogenic strain HJ-01 was isolated from infected and dead pupa of Tenebrio molitor using tissue separation method. The HJ-01 strain was streak cultured and purified, and its morphological, physiological, biochemical characteristics, and 16S rDNA homology were identified after conducting a pathogenicity test on RPW larvae. Results: Strain HJ-01 exhibited remarkable pathogenicity against RPW larvae. Under the concentration of HJ-01 suspension was 1.0 × 10⁸ cfu/mL, the mortality rate of RPW reached 82.22%, and the half-lethal time (LT₅₀) was 4.72 days. RPW larvae infected with strain HJ-01 showed reduced movement, decreased appetite, and eventual death. As the treatment progresses, the larvae’s bodies turned red, became soft, and started to rot, resulting in the discharge of liquid. HJ-01 demonstrated the ability to produce scarlet pigment after 24 h of culture on a basic medium. Colonies of HJ-01 appeared convex, bright red, moist, and viscous, opaque in the center, irregular at the edges, and emitted an unpleasant odor. Under microscopic observation, the cells of HJ-01 appeared as short rod-shaped and flagellate, with a size ranging from (1.2–1.8) μm × (1.0–1.2) μm. Genomic DNA extraction was performed on the strain, and the 16S rDNA sequence was amplified, yielding a sequence length of 1445 bp. The sequence of strain HJ-01 displayed a 99.72% similarity to that of Serratia marcescens. Phylogenetic tree analysis further confirmed that strain HJ-01 belonged to S. marcescens. Therefore, the strain HJ-01 has a very good lethal effect on RPW larvae, and it may be used as an effective bacterium for the control of RPW.

Insect-specific pathogens present a sustainable alternative to pesticides for managing the red palm weevil (RPW). This study assessed the efficacy of Steinernema carpocapsae ALL nematodes and their symbiotic bacteria against the third-instar larvae and adults of RPW under laboratory conditions. The symbiotic bacteria were isolated, morphologically characterized, and genetically identified. The results indicated that the mortality rates of RPW larvae treated with S. carpocapsae exceeded 50% in all treatments at 120 h, reaching 93.33% at a concentration of 250 IJs/mL. The morphology of isolated symbiotic bacterium from S. carpocapsae on NBTA medium exhibited a light green color with a glossy surface, a raised center, and a mucilaginous texture. A novel strain of symbiotic bacterium was identified and named as LZ-G7. The bacteria toxicity on RPW adults showed a notable mortality rate of 66.67% at 48 h after feeding with concentration of 10 × 10⁷ CFU/mL. The mortality rate of the third-instar larvae of RPW reached 83.33% after feeding with 0.30 × 10⁸ CFU/g at 96 h and 93.33% after injection into blood cavity with 8 × 10⁶ CFU at 48 h. These results suggest that S. carpocapsae and a novel symbiotic bacterium strain exhibit strong virulence against RPW and have the potential to serve as effective biological control agents in integrated pest management strategies.