Pineapple cultivation is of economic importance for farmers; however, pineapple production can be affected by pests and diseases. Recently, the presence of mealybugs and pineapple mealybug wilt-associated viruses (PMWaV)-1, -2, and -3 has been reported in the provinces of Satipo and Chanchamayo, in Peru’s central jungle. This study aimed to molecularly identify mealybugs collected from the Hawaiiana cultivar and the MD-2 hybrid in those provinces to determine if they are indeed hosts of the PMWaV-1, -2, and -3. Through amplification and sequencing of the internal transcribed spacer ribosomal genes, the mealybugs were identified as Dysmicoccus brevipes. In the phylogenetic analysis of these D. brevipes, Peruvian isolates were associated with isolates from India, China, Taiwan, and Japan. In addition, our results confirmed the presence of PMWaV-1, -2, and -3 in all mealybug specimens collected from both the Hawaiiana cultivar and the MD-2 hybrid tested, with these PMWaVs showing a 99% sequence identity with others recently reported in Peru. Therefore, D. brevipes is a host and probable vector of PMWaV-1, -2, and -3 for the cultivar Hawaiiana and the hybrid pineapple MD-2 in Satipo and Chanchamayo, Peru. Based on these findings and observations of crop management strategies in these provinces, we recommend integrated management practices to control this pest.

The predator Chrysoperla externa (Neuroptera: Chrysopidae) has great potential for its use in biological pest control programs. In order to assist future biological control programs that use Chrysopidae as a control agent, this research aims to study the behaviour of the green lacewing, C. externa, consuming two-spotted spider mites, Tetranychus urticae (Acari: Tetranychidae). In the laboratory, experiments were carried out to determine the predation behaviour of C. externa on different densities of adults of the two-spotted spider mite, T. urticae (1, 2, 4, 8, 16, 32, and 64 prey). For comparison purposes, the behaviour of C. externa was also studied using eggs from the alternative prey Ephestia kuehniella (Lepidoptera: Pyralidae). The functional response was determined by logistic regression of the number of mites consumed as a function of the initial number of prey using polynomial logistic regression. The random equation was used to describe the parameters of the functional response. The predator C. externa showed a type II functional response consuming both E. kuehniella eggs and T. urticae adults. The results obtained will allow to define the best strategy for the use of green lacewings in the biological control of the two-spotted spider mite, T. urticae.

Ostrinia furnacalis Guenée (Lepidoptera: Crambidae) is a key lepidopteran pest affecting maize production across Asia. While its general biology has been well studied, the phenomenon of pupal ring formation remains poorly understood. This study examined the factors influencing pupal ring formation under controlled laboratory conditions. Results showed that pupal rings were formed exclusively when larvae were reared on an artificial diet, with no ring formation observed on corn-stalks. Females exhibited a significantly higher tendency to participate in ring formation than males. Additionally, male participation increased proportionally with the number of rings formed, a pattern not observed in females. The size of the rearing arena significantly influenced ring formation, with smaller arenas (6 cm diameter) promoting more frequent pairing, particularly among females. Temperature also played a significant role: lower participation rates were recorded at 22 °C compared to 25 °C and 28 °C, although the number of rings formed did not differ significantly across temperatures. Developmental stage and sex composition further influenced pairing behaviour; pupal rings formed only among individuals of similar maturity, and male participation was significantly reduced in all-male groups compared to mixed-sex groups. These findings suggest that pupal ring formation in O. furnacalis is modulated by dietary substrate, larval sex, environmental conditions, and developmental synchrony, offering new insights into the behavioural ecology of this pest.

The extracellular matrices, such as the haemolymph, in insects are at the centre of most physiological processes and are protected from oxidative stress by the extracellular antioxidant enzymes. In this study, we identified two secreted superoxide dismutase genes (PxSOD3 and PxSOD5) and investigated the oxidative stress induced by chlorpyrifos (CPF) in the aquatic insect Protohermes xanthodes (Megaloptera: Corydalidae). PxSOD3 and PxSOD5 contain the signal peptides at the N-terminus. Structure analysis revealed that PxSOD3 and PxSOD5 contain the conserved CuZn-SOD domain, which is mainly composed of β-sheets and has conserved copper and zinc binding sites. Both PxSOD3 and PxSOD5 are predicted to be soluble proteins located in the extracellular space. After exposure to different concentrations of sublethal CPF, MDA content in P. xanthodes larvae were increased in a dose-dependent manner; SOD and CAT activities were also higher in CPF-treated groups than that in the no CPF control, indicating that sublethal CPF induces oxidative stress in P. xanthodes larvae. Furthermore, PxSOD3 and PxSOD5 expression levels and haemolymph SOD activity in the larvae were downregulated by sublethal CPF at different concentrations. Our results suggest that the PxSOD3 and PxSOD5 are putative extracellular antioxidant enzymes that may play a role in maintaining the oxidative balance in the extracellular space. Sublethal CPF may induce oxidative stress in the extracellular space of P. xanthodes by reducing the gene expression and catalytic activity of extracellular SODs.

The use of sodium channel blocker insecticides (SCBIs) has been one of the tools for managing the resistance of fall armyworm Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) to insecticides. In this study, we selected resistant strains of S. frugiperda to the SCBIs indoxacarb (Indoxacarb-R) and metaflumizone (Metaflumizone-R), under laboratory conditions, to evaluate the inheritance of resistance, cross-resistance to insecticides targeting voltage-gated sodium channels, and verify the absence of the F1845Y and V1848I mutations. The LC50 values of the susceptible (SUS) and the Indoxacarb-R strains to indoxacarb were 3.72 and 114.43 µg mL−1 respectively, and for the SUS and the Metaflumizone-R strains to metaflumizone were 4.57 and 3,141.96 µg mL−1, respectively, with resistance ratios of approximately 30-fold to indoxacarb and >600-fold to metaflumizone. The resistance of S. frugiperda to both insecticides was characterised as autosomal, incompletely recessive, and polygenic. Cross-resistance between indoxacarb and metaflumizone was detected. Moreover, Indoxacarb-R and Metaflumizone-R strains showed lower susceptibility to the pyrethroid insecticide lambda-cyhalothrin, possibly due to multiple resistance. The partial sequencing of the S. frugiperda sodium channel gene did not confirm the association of F1845Y and V1848I mutations with S. frugiperda resistance to indoxacarb and metaflumizone. These results will be important for implementing proactive insect resistance management programmes to preserve the lifetime of SCBIs in controlling S. frugiperda.

Pieris brassicae (Linnaeus, 1758) (Lepidoptera: Pieridae), commonly known as the cabbage butterfly, is a major herbivorous pest causing significant damage to Brassica crops, which are widely cultivated for edible parts and economic uses such as oilseed production. Conventional chemical-based pest control methods pose risks to environmental and human health, prompting interest in sustainable alternatives like biological control using parasitoids. This study evaluated crop damage by P. brassicae larvae and the potential of the larval parasitoid Cotesia vestalis (Haliday, 1834) (Hymenoptera: Braconidae) in managing pest populations. Larvae and fertilized eggs of P. brassicae were collected and reared on four host diets (cabbage, cauliflower, turnip, and generic brassica) under controlled laboratory conditions. Larval growth, feeding behavior, and development were assessed, along with a feeding index for dietary efficiency. Parasitisation was introduced by exposing larvae to adult C. vestalis, and host-parasitoid interactions were statistically analyzed using one-way ANOVA and regression models. Results revealed that larvae had the highest feeding preference and weight gain on brassica, while turnip-fed larvae consumed the least. Parasitisation by C. vestalis significantly suppressed larval development, with a strong correlation between parasitisation rates and reduced host fitness. These findings highlight C. vestalis as a promising biological control agent for P. brassicae, offering an effective and eco-friendly alternative to chemical pesticides. Further research should focus on optimizing C. vestalis mass-rearing protocols and release strategies tailored to diverse Brassica cropping systems to promote sustainable pest management.

Water hyacinth is an invasive aquatic plant that has been associated with major negative economic and ecological impacts in water systems worldwide, including Rwanda, since its establishment in the country in the 1960s. While biological control is considered the most sustainable management method, the success of biocontrol agents depends on various abiotic factors, with temperature being critical. This study assessed the suitability of potential water hyacinth biocontrol agents such as: Neochetina weevils, Megamelus scutellaris Berg (Hemiptera: Delphacidae), and Cornops aquaticum Bruner (Orthoptera: Acrididae) for regions with a temperate climate by testing their thermal boundaries. Using thermal physiology limits and CLIMEX modelling, we found that Neochetina eichhorniae Warner and N. bruchi Hustache (Coleoptera: Curculionidae) had lower thermal minimums (CTmin) of 2.4°C and 2.6°C, respectively, compared to Megamelus scutellaris (4.7°C) and Cornops aquaticum (6.2°C). CLIMEX modelling predicted the suitability of Neochetina weevils and C. aquaticum across Rwanda, while M. scutellaris appeared unsuitable for the colder northern regions of the country but appropriate for the central and eastern regions. These findings suggests that the historical failure of Neochetina weevils introduced to Rwandan water bodies in 2000 was not due to temperature extremes. Rather, other factors such as release numbers or water quality may have played a role. This study provides crucial information for future biocontrol efforts in Rwanda and similar temperate regions, highlighting the importance of pre-release thermal tolerance assessments and climate modelling to predict biocontrol agent establishment and efficacy.

The whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is economically one of the most threatening pests in tomato cultivation, which not only causes direct damage but also transmits many viruses. Breeding whitefly-resistant tomato varieties is a promising and environmentally friendly method to control whitefly populations in the field. Accumulating evidence from tomato and other model systems demonstrates that flavonoids contribute to plant resistance to herbivorous insects. Previously, we found that high flavonoid-producing tomato line deterred whitefly oviposition and settling behaviours, and was more resistant to whiteflies compared to the near-isogenic low flavonoid-producing tomato line. The objective of the current work is to describe in detail different aspects of the interaction between the whitefly and two tomato lines, including biochemical processes involved. Electrical penetration graph recordings showed that high flavonoid-producing tomato reduced whitefly probing and phloem-feeding efficiency. We also studied constitutive and induced plant defence responses and found that whitefly induced stronger reactive oxygen species accumulation through NADPH oxidase in high flavonoid-producing tomato than in low flavonoid-producing tomato. Moreover, whitefly feeding induced the expression of callose synthase genes and resulted in callose deposition in the sieve elements in high flavonoid-producing tomato but not in low flavonoid-producing tomato. As a consequence, whitefly feeding on high flavonoid-producing tomato significantly decreased uptake of phloem and reduced its performance when compared to low flavonoid-producing tomato. These results indicate that high flavonoid-producing tomato provides phloem-based resistance against whitefly infestation and that the breeding of such resistance in new varieties could enhance whitefly management.

Bactrocera dorsalis (Diptera: Tephritidae) is a highly invasive and destructive quarantine pests worldwide. To improved biological control efficiency, reduce chemical pesticides use, and optimise the application of Metarhizium anisopliae (Hypocreales: Clavicipitaceae) against B. dorsalis. This study evaluated the combined toxicity of M. anisopliae with deltamethrin and chlorpyrifos. The biocompatibility of M. anisopliae CQMa421 with these pesticides was assessed based on spore germination, mycelial growth, and sporulation. Additionally, the effects of combined treatments on detoxification enzyme and related gene expression in B. dorsalis were investigated. The results indicated that the virulence effect of M. anisopliae CQMa421 against B. dorsalis adults was time-dependent and dose-dependent. Deltamethrin showed good compatibility with M. anisopliae CQMa421, achieving 100% mortality at 1 × 10⁸ CFU/mL by 84 hours. Different concentrations of deltamethrin can promote the mycelial growth and sporulation of M. anisopliae CQMa421. The toxicity effect of deltamethrin and chlorpyrifos combined with M. anisopliae CQMa421 on B. dorsalis adults was better than that of single-agent treatment, and the co-toxicity factor of 5 mg/L deltamethrin and 1 × 108 CFU/mL M. anisopliae CQMa421 was 24.81, which synergistically affected on B. dorsalis control. Enzyme activity assays and qRT-PCR results revealed that the combination treatment differentially activated and enhanced the activities of AChE, CarE, GST, CAT, and SOD. Meanwhile, BdCarE was significantly inhibited and upregulating BdGSTD7, BdGSTS1, BdCYP4ae1, BdPOD, BdPOD1, and BdCAT genes. In conclusion, the combination of deltamethrin and M. anisopliae CQMa421 enhanced the insecticidal efficacy against B. dorsalis, significantly affected the activity of related detoxification enzymes. Provided a robust basis for integrating biological and chemical control strategies to manage B. dorsalis more effectively.

Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is an invasive tropical pest that is currently expanding in its geographical range into temperate regions. This study examined the temporal and spatial dynamics of B. dorsalis along an altitudinal gradient in Mpumalanga Province, South Africa, in its southernmost adventive limit, which experiences a temperate climate with dry winters. Populations were monitored from October 2020 to October 2022 at three sites with altitudes ranging from 452 to 1 741 m above sea level. At each site, clusters of attractant-based traps (methyl eugenol and three-component Biolure) were set up and serviced at least monthly. We analysed the effects of climate, time of the year, altitude, and landscape on B. dorsalis abundance. Single population peaks of B. dorsalis were recorded from mid-summer to autumn in all sites, with higher prevalence at the low-altitude site. In the low- and mid-altitude sites, catches were recorded year-round, while at the high-altitude site, there were no catches for four to six months after onset of winter. Higher B. dorsalis catches were recorded as temperatures increased and precipitation decreased. Catches were higher in commercial orchards and home gardens compared to abandoned orchards. These findings provide valuable information for improving simulation models of B. dorsalis distribution and population growth that can be used to inform the management of this pest.

Spodoptera frugiperda is a notorious pest that has been recorded attacking over 353 crop species worldwide. Excessive insecticide exposure can lead to resistance and has adverse impacts on the environment and beneficial organisms. Long-lasting pest control methods like entomopathogenic fungi may be used to prevent the negative impact of synthetic insecticides. In the current research, effectiveness of Cordyceps fumosorosea was analysed by applying a sub-lethal dose (LC15 = 2.09 × 106 spores mL−1) and a lethal dose (LC50 = 2.17 × 107 spores mL−1) on filial (F0) and first filial (F1) generations of S. frugiperda to estimate both lethal and sub-lethal effects. The LC15 was used to keep a significant proportion of larvae alive to permit determination of sublethal effects on S. frugiperda. After treatment with the LC15 and LC50, S. frugiperda progeny displayed shorter larval duration, lower fecundity, and shorter adult female and male longevities relative to untreated controls. Likewise, the adult pre-oviposition period, total pre-oviposition period, oviposition days (Od), net reproductive rates (Ro), and mean generation times (T) were reduced in fungal-infected groups. Furthermore, activities of key detoxifying enzymes, i.e. acetylcholinesterase (AChE), glutathione S-transferases (GST), and esterases (EST), were also evaluated. Substantial differences of AChE, GST, and EST (24.3, 18.34, and 10.09 µmol/min/mg protein), respectively, were observed at the LC50 in contrast to the LC15 and controls. The current study showed pathogenicity of C. fumosorosea, which negatively affected insect development and changed the activities of detoxifying enzymes, thereby increasing the effectiveness and eco-friendly management of S. frugiperda.