Search Results (59)

The tomato leafminer (Tuta absoluta) is a globally invasive pest that causes severe yield losses in tomato crops. Nanotechnology-based strategies offer promising alternatives to conventional insecticides. This study examines the physiological, biochemical, and demographic responses of T. absoluta following exposure to mesoporous silica nanoparticles (MSNs) applied to tomato leaves at concentrations of 0, 3, 30, and 300 mg L⁻¹. Comprehensive assessments were conducted, including digestive and detoxifying enzyme activities in the insect, neurotoxicity indicators, life table parameters, and antioxidant responses in the host plant. At 30 mg L⁻¹, MSNs significantly impaired larval development, fecundity, and survival of T. absoluta without inducing phytotoxicity. Tomato plants treated at this concentration exhibited enhanced antioxidant enzyme activity (SOD, CAT, POD) and a reduced malondialdehyde (MDA) content, indicating an active oxidative defense. These plant responses were significantly correlated with changes in insect fitness traits, suggesting a plant-mediated effect on pest physiology. Digestive enzyme disruption, decreased acetylcholinesterase activity, and extended developmental periods contributed to suppressed population growth, as evidenced by reductions in the intrinsic rate of increase (r), net reproductive rate (R₀), and fecundity. At 300 mg L⁻¹, however, severe phytotoxicity and enzymatic collapse were observed in both plant and insect systems. These findings highlight moderate concentration of MSNs (30 mg L⁻¹) as a promising dose for sustainable and host-safe pest management, offering multi-targeted suppression of T. absoluta through combined plant and insect biochemical pathways. Full article

The Tuta absoluta species represents a significant threat to solanaceous crops globally and has developed resistance to conventional synthetic insecticides. This study investigated the insecticidal properties of essential oils (EOs) from Melaleuca alternifolia and Eucalyptus staigeriana against T. absoluta using the age-stage, two-sex life table methodology. Initially, the EOs of M. alternifolia and E. staigeriana were chemically characterized by gas chromatography (GC) techniques. In this analysis, we identified 19 compounds in M. alternifolia essential oil, with terpinen-4-ol, γ-terpinene, and α-terpinene as the predominant constituents. Eucalyptus staigeriana essential oil contained 25 identified compounds, predominantly limonene, terpinolene, geranial, and neral. Essential oils were dissolved in acetone and applied topically to larval stages. Both treatments significantly reduced pest longevity and adversely affected key demographic parameters. Melaleuca alternifolia treatment resulted in a substantial decrease in the intrinsic rate of population increase, indicating potential for population suppression. These findings support the potential application of M. alternifolia and E. staigeriana EOs as biological control agents against T. absoluta in integrated pest management programs. Full article

Carbon nanotubes are promising in agriculture for improving crop resilience and delivering agrochemicals. However, their effects on insect pests, especially chewing pests such as the fall armyworm (Spodoptera frugiperda), remain underexplored. In this study, we investigated how two types of functionalized multi-walled carbon nanotubes—hydroxylated (MWCNTs-OH) and carboxylated (MWCNTs-COOH), both obtained from Jiangsu Xianfeng Nano (Nanjing, China)—affect the pest’s development and reproduction. Using an age-stage two-sex life table approach, we fed larvae diets containing 0.04, 0.4, or 4 mg/g of these nanomaterials. Both types of MWCNTs exhibited concentration-dependent inhibitory effects. At the highest dose (4 mg/g), larval development was significantly prolonged, adult pre-oviposition periods increased, and fecundity (egg production) sharply declined, especially with MWCNTs-OH. Population growth parameters were also suppressed: net reproductive rate (R₀), intrinsic rate of increase (r), and finite rate of increase (λ) were reduced at 4 mg/g, particularly with MWCNTs-OH, while mean generation time (T) was extended with MWCNTs-COOH. Overall, MWCNTs-OH demonstrated a greater inhibitory impact compared to MWCNTs-COOH. These findings suggest that functionalized MWCNTs could serve as potential novel pest control agents against S. frugiperda by impeding its development and reproduction. Full article

The red spider mite, Tetranychus macfarlanei, is a significant pest of various crops, and silicon (Si), a beneficial micronutrient, serves as a physical defense against herbivores when accumulated in plant tissues. This study examined the effects of silicon on the biology of T. macfarlanei on Lablab purpureus plants treated with 0 ppm (control), 28, and 56 ppm silicon concentrations. The results showed that silicon treatments notably affected mite development. At the highest concentration of 56 ppm Si, females exhibited the longest immature period, shortest lifespan, and shortest oviposition period. Egg production per female was highest at the 0 ppm Si level (94.62) and lowest at the 56 ppm Si concentration (42.29). Life table parameters, including the intrinsic rate of increase (r), net reproductive rate (R₀), finite rate of increase (λ), and gross reproductive rate (GRR), declined progressively with increasing silicon concentrations. Compared to the control (0 ppm Si), the highest silicon level resulted in reductions of approximately 24% in r, 55% in R₀, 4% in λ, and 27% in GRR, indicating a substantial negative impact of silicon on the reproductive potential of T. macfarlanei. These findings suggest that higher silicon levels effectively suppress T. macfarlanei populations and may be useful in integrated mite management strategies. Full article

Phthorimaea absoluta, an important pest of tomato crops, has reportedly developed high levels of resistance to the insecticide chlorantraniliprole, which has a unique mode of action and high efficacy. This study evaluated the sustained multigenerational effects of chlorantraniliprole on P. absoluta, focusing on resistance development, growth, development, reproductive capacity, population parameters, and nutritional indicators. After continuous selection with sublethal chlorantraniliprole for eight generations (CX-Sub₈), bioassays showed that CX-Sub₈ had 225.37-fold higher resistance than the susceptible strain. The age-stage, two-sex life table analysis revealed that the preadult development time and mean generation time were significantly prolonged, while population reproduction and pupal weight were reduced. Moreover, the relative fitness of CX-Sub₈ was 0.62, and changes in the life table parameters correlated with an increase in the serial number of selection cycles. The second-instar larvae of CX-Sub₈ presented lower triglyceride, glycerol, trehalose, free fatty acid, and protein contents than the unselected strain (CX-S₈). Transcriptome analysis identified 2517 differentially expressed genes, with most being enriched in nutrient metabolism-related pathways, such as amino acid biosynthesis and fatty acid degradation metabolism. These results indicate that multigenerational sublethal chlorantraniliprole treatment disrupts the nutritional metabolism, and inhibits the growth, development, and reproduction of P. absoluta. Full article

The brown marmorated stink bug, Halyomorpha halys, has become a severe threat to agriculture worldwide with continuous invasion and spread. Sulfoxaflor is the pioneering sulfoximine insecticide and has been widely employed for managing sap-feeding insect pests across diverse crops. However, the sublethal effects of sulfoxaflor on the growth and reproduction of H. halys remain unexplored. This study employed age-stage life tables and physiological parameters to evaluate the sublethal effects of sulfoxaflor on H. halys. The bioassay results indicated that the LC₂₀ and LC₅₀ values of sulfoxaflor against second-instar nymphs of H. halys were 7.75 and 20.97 mg/L, respectively. Treatment with the LC₂₀ concentration of sulfoxaflor reduced the lifespan of female adults by 11.74 days. Importantly, the oviposition period of females was shortened by 9.47 days, and the fecundity was decreased by 1.4-fold. Additionally, the activities of cytochrome P450 (P450s) and glutathione S-transferase (GSTs) enzymes in H. halys were enhanced 1.40 and 1.54 times after treatment with sublethal concentrations of sulfoxaflor. These findings demonstrate that sublethal concentrations of sulfoxaflor significantly inhibit the population development of H. halys. Moreover, the detoxification enzymes P450s and GSTs may be associated with the potential resistance to sulfoxaflor in H. halys. This information provides valuable insights into the application of sulfoxaflor in the management of this pest. Full article

Frankliniella intonsa (Thysanoptera: Thripidae) is a polyphagous pest that causes significant economic agricultural losses by damaging flowers, vegetables, and fruit trees. We performed an age-stage two-sex life table analysis to evaluate the performance and adaptability of F. intonsa against nine common vegetable crops cultivated in Guangxi: cowpea (Vigna unguiculata) (Fabales: Leguminosae), green beans (Phaseolus vulgaris) (Fabales: Leguminosae), soybean (Glycine max) (Fabales: Leguminosae), catjang cowpea (Vigna cylindrica) (Fabales: Leguminosae), courgette (Cucurbita pepo) (Cucurbitales: Cucurbitaceae), wax gourd (Benincasa hispida) (Cucurbitales: Cucurbitaceae), bitter gourd (Momordica charantia) (Cucurbitales: Cucurbitaceae), cucumber (Cucumis sativus) (Cucurbitales: Cucurbitaceae), and chieh-qua (Benincasa hispida) (Cucurbitales: Cucurbitaceae). Among the tested host crops, green beans, cowpea, and courgette significantly accelerated the growth rate and favored the reproductive success of F. intonsa. Green beans, cowpea, and courgette facilitated rapid growth and reproductive success. The mean generation times (T) and net reproductive rates (R₀) were as follows: 14.90 d, 17.09 d, 21.03 d, and 104.04, 45.51, 32.61. Bitter gourd and chieh-qua significantly suppressed population growth (T: 49.49 d, 0 d; R₀: 0.73, 0). Wax gourd, catjang cowpea, cucumber, and soybean exhibited moderate effects characterized by delayed development and lower reproductive output (T: 22.30 d, 20.30 d, 19.51 d, 32.73 d; R₀: 7.17, 25.22, 13.74, and 12.54). These findings highlight the critical role of crop type in F. intonsa population dynamics. Therefore, the agricultural production of green beans, cowpea, and courgette crops necessitates improved control measures and monitoring. Similar measures are needed for cucumber, catjang cowpea, soybeans, and wax gourds because they pose risks as potential hosts. Full article

Bactrocera latifrons (Hendel) is a serious pest requiring quarantine in many countries worldwide. It has caused huge economic losses to the cultivation of solanaceous plants, such as peppers and eggplants. In this study, we constructed an age-stage, two-sex life table using eggplant as the host to clarify the occurrence and damage patterns of B. latifrons on this crop for better field prevention and control in the laboratory. The results showed that the egg, larval, and pupal stages lasted 4.3, 11.3, and 9.3 days, respectively. The average lifespan of adult females and males was 101 and 102 days, respectively. The egg hatching rate, larval survival rate, and pupal emergence rate were 96%, 88%, and 84%, respectively. The average generation time was 43.96 days, with an intrinsic rate of increase of 0.097 d⁻¹ and a net reproductive rate of 73.4. We established the life table based on group rearing. The research findings provide essential data for rearing B. latifrons in the laboratory, offer a reference for the dynamic prediction of field population dynamics, and offer a theoretical foundation for developing pest control strategies for B. latifrons. Full article

The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), is an invasive polyphagous pest that has been reported in several tomato-producing Mediterranean countries. However, information regarding the impact of temperature variations on its potential damage and population dynamics on this crop is limited. The effect of four temperatures (20 ± 1 °C, 25 ± 1 °C, 30 ± 1 °C and 35 ± 1 °C) on the development, reproduction, and population growth parameters of P. solenopsis on tomatoes under controlled laboratory conditions was investigated using age-stage two-sex life tables. The increase in temperature caused a significant decrease in the developmental periods of all instars except eggs. The shortest durations of the life cycle (29.58 ± 0.28 days for females and 13.91 ± 0.25 days for males), the adult preoviposition period (APOP), and the total preoviposition period (TPOP) (APOP: 7.78 ± 0.09 days and TPOP: 18.33 ± 0.13 days) were obtained at 35 ± 1 °C. Fecundity varied with temperature, and the highest value was recorded at 30 ± 1 °C (183.29 ± 7.13 eggs/female). The highest average net reproduction rate (R₀) (154.24 ± 14.681 offspring/female), intrinsic rate of increase (r) (0.222 ± 0.0036 d⁻¹), and finite rate of increase (λ) (1.248 ± 0.00495 d⁻¹) were observed at 35 ± 1 °C. A simulation of population increase and structure under different temperatures over a period of 90 days revealed that the greatest expected population size was at 35 ± 1 °C, with the completion of four overlapping generations. The data from this study provide valuable information for adapted pest management approaches against P. solenopsis on tomato crops. Full article

As two major pests of cowpea in South China, bean flower thrips [Megalurothrips usitatus (Bagnall)] and flower thrips [Frankliniella intonsa (Trybom)] always occur on the same plant. In this study, the two-sex life table parameters of these two species were investigated on three bean pods: cowpea (Vigna unguiculata L. var. Chunqiu Wujiadou), snap bean (Phaseolus vulgaris L. var. Yonglong 3), and green bean (Phaseolus vulgaris L. var. Linghangzhe) using standard cut bean protocols. Longevity of female adult M. usitatus showed no significant difference on cowpea and snap bean, but was shortest on green bean, with the highest fecundity on snap bean, followed by cowpea and green bean. Longevity and fecundity of female adult F. intonsa were both highest on cowpea, followed by snap bean and green bean. On snap bean, the population parameters (R₀, GRR, T) of M. usitatus were higher than F. intonsa, whereas r and λ were not different, suggesting that M. usitatus were more competitive on snap bean. On cowpea, the population parameters (R₀, GRR, r, λ) of F. intonsa were higher than M. usitatus, suggesting a competitive advantage of F. intonsa on cowpea. To better mimic field conditions, we investigated the survival and fecundity of adult M. usitatus under two distinct scenarios: when they could feed directly on cut surfaces of cowpeas (standard lab protocol), and when they could not. Adult survival of M. usitatus is not significantly influenced by whether or not they fed directly on cut surfaces of cowpeas. However, a notable decrease in fecundity was observed in M. usitatus that fed on surface-covered cut pods. This suggested that direct feeding on cut surfaces of cowpea did have an impact on thrips’ fecundity, offering fresh perspectives for future research into the growth and development of thrips in a laboratory. Our study suggests that experiments involving cut surfaces may be misleading, and further investigations are ongoing to address these concerns. Full article

The fall armyworm (FAW) is an invasive pest that has been rapidly spreading across China since its detection in Yunnan province in January 2019. Although sugarcane and sorghum have been reported as hosts, their effects on FAW’s population growth and life table parameters have not been examined in China. Our research shows that FAW’s development and life table metrics vary significantly when reared on sorghum, sugarcane, and maize. Notably, the preadult stage, adult preoviposition period, and total preoviposition period of FAW were markedly longer on sugarcane and sorghum compared to maize. FAW reared on these two crops also exhibited reduced survival rates, pupal weight, fecundity, and lower female-to-male ratios. The study highlights that FAW had lower population growth rates, reproductive rates, and longer generation times on sugarcane and sorghum compared to maize. The consumption index and digestibility index were higher on maize, while conversion efficiency and growth rate were greater on sorghum. Although maize is the most favorable host, FAW can still survive and reproduce on sugarcane and sorghum during the nongrowing season, posing a risk to economically important crops in China. Despite being less favorable for population growth, sugarcane and sorghum still support FAW development and spread. Therefore, enhanced surveillance and early warning measures for sugarcane and sorghum are recommended to monitor FAW population dynamics and mitigate its potential impact on primary host plants. Full article

The diamondback moth (DBM), Plutella xylostella, is the main pest of Brassicas crops worldwide, and its recorded resistance to 101 active ingredients indicates it is difficult to control. The purpose of this study was to investigate the hypothesis that P. xylostella has fitness costs associated with its resistance to lufenuron, a chitin-synthesis inhibitor insecticide. Thus, concentration–mortality bioassays were performed for susceptible (REC-S), resistant (BZR-R) populations, their progenies F1 and F1′, and one established population without selection pressure (BZR-Rns) after four generations. A fertility life table was used to assess the biological performance of the REC-S and BZR-R. BZR-Rns of P. xylostella. The larval stage, longevity, and survival differed between populations. The reproductive rate (R₀) was significantly lower in the F1 (♀R × ♂S) (28.19) and F1′ (♀S × ♂R) (34.06) progenies compared with their parents, but not with the relaxed BZR-Rns (39.39). The mean generation time (T), intrinsic rate of population growth (r_m), and doubling time (DT) differed between REC-S and progenies, with fitness of 0.52 and 0.64 for F1 and F1′, respectively. Overall, the results suggest that the resistance of P. xylostella to lufenuron is stable and that low fitness costs appear to be associated with resistance to lufenuron, although heterozygotes showed lower fitness than their parents. Strategies such as preserving refuge areas, rotation of modes of action, etc., are essential for resistance management and prolonging the efficacy of control agents; this highlights the importance of integrated insecticide resistance management. Full article

Megalurothrips usitatus (Bagnall) feeds on the young tissues of plants, causing wilting and deformity of leaves as well as damage to flowers and fruits, thereby seriously affecting plant yield. Due to its small size and difficulty of control, the species is one of the most important pests in the legume family. To clarify the occurrence and damage pattern of M. usitatus on field crops, a study was conducted using eight different crops as experimental materials, and an age-stage, two-sex life table was constructed. The population density of M. usitatus was the highest on cowpeas (Vigna unguiculata L. Walp.), followed by green beans (Phaseolus vulgaris L.) and Vigna cylindrica (Vigna unguiculata subsp. cylindrica (L.) Verdc.) in terms of net reproductive rate and the intrinsic rate of increase. In terms of reproductive capacity, cowpeas and V. cylindrica were more suitable for M. usitatus growth and reproduction, followed by green beans. M. usitatus could develop into adults on courgettes (Cucurbita pepo L.), wax gourds (Benincasa hispida Thunb. Cogn.), Momordica charantia (Momordica charantia L.), and soybeans (Glycine max L. Merr.) but had difficulty reproducing on those plants. Cucumber (Cucumis sativus L.) was the least suitable for the survival of M. usitatus. Population parameter analysis showed that the cowpea was the most suitable host plant for M. usitatus, followed by green beans and V. cylindrica. M. usitatus had difficulty reproducing on courgette, wax gourd, M. charantia, and soybeans, and feeding on cucumbers inhibited M. usitatus development and reproduction. Full article

The red spider mite, Tetranychus macfarlanei, is a serious pest of many cultivated crops in Bangladesh and other East-Asian and South-East Asian countries, in the Afrotropical, Oriental, and Palearctic regions. Sublethal concentration of pesticides, such as LC₁₅ and LC₃₀ (the concentrations that result in 15 and 30 percent lethality, respectively) impact reproduction, behavior, development, and physiology. This study assessed the effects of different concentrations of spirotetramat, an insecticide that disrupts lipid production, on the biological traits of T. macfarlanei. The LC₁₅, LC₃₀, LC₅₀, and LC₉₀ values were 2.16, 6.57, 20.54, and 332.81 mg·L⁻¹, respectively. Sublethal concentrations (LC₁₅ and LC₃₀) slightly reduced female fecundity but did not significantly affect development duration, pre-oviposition, oviposition period, or longevity compared to the untreated control group. Life table parameters differed between the treated and control groups, with significant reductions in the intrinsic rate of increase (r), the net reproductive rate (R₀), and the finite rate of increase (λ) for LC₁₅ and LC₃₀. LC₁₅ and LC₃₀ had negative effects on the intrinsic rate of increase for females. This study demonstrated that lower lethal concentrations of spirotetramat compromised survivability and negatively impacted the life-table parameters of subsequent generations of T. macfarlanei. These findings highlight the importance of sublethal effects in pest control, offering valuable insights for developing more effective and sustainable integrated pest management strategies. Full article

Insecticides based on baculoviruses have become an alternative for pest control in different agricultural crops. The aim of this study was to assess the biological activity of the bioinsecticide Cartugen^™ (SfMNPV: Baculoviridae: Alphabaculovirus) on larvae of Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae) resistant to Bt corn expressing the insecticidal proteins Cry1A.105+Cry2Ab2+Cry1F. In addition, we assessed the efficiency of SfMNPV on S. frugiperda control in the field from natural infestation of the pest during two agricultural seasons. The results showed that no larvae survived 10 days after being inoculated with Bt and non-Bt corn leaves contaminated with 1.50 × 10¹⁰ occlusion bodies (OBs)/L (equivalent to the recommended dose of the product). However, when using doses equivalent to 50% (7.50 × 10⁹ OBs/L) and 25% (3.75 × 10⁹ OBs/L), the larval mortality ranged from 21.12% to 46.55%, respectively. Although larvae resistant to the Cry1A.105+Cry2Ab2+Cry1F proteins, when exposed to 50% of the SfMNPV dose (7.50 × 10⁹ OBs/L), showed reductions in larval weight (52 to 67% reduction), pupal weight (32 to 59% reduction), and total fecundity (67 to 86% reduction) compared to the control. Furthermore, doses above 25% (3.75 × 10⁹ OBs/L⁻¹) caused a population decrease in the growth of the species in both Bt and non-Bt corn according to the fertility life table. In the field, at 7 and 10 DAA (days after application), corn plants sprayed with SfMNPV (1.50 × 10¹⁰ OBs/L) showed reductions in leaf damage according to the Davis scale. However, from 14 to 21 DAA, there was an increase in leaf damage in corn leaves from both treatments, with or without the application of SfMNPV. This shows that SfMNPV may be an important strategy in the integrated management and resistance management of S. frugiperda. Full article