Susceptibility of Capsicum varieties to Thaumatotibia leucotreta (Lepidoptera: Tortricidae) infestation for production optimization.

Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae) is a major threat to the production and marketing of pepper (Capsicum spp.) in Ghana. To reduce the damage of the pest on pepper farming, it is important to find appropriate control methods, which may include the use of resistant host plants. This study investigated the relative susceptibility of 6 pepper varieties commonly cultivated in Ghana: Legon 18, Bird's eye, Scotch bonnet, Cayenne, KA2, and sweet pepper (Yolo wonder+ variety). Choice and no-choice ovipositional preference tests were conducted and the population growth rate of T. leucotreta was determined by establishing life table parameters including the net reproductive rates (R0), the mean generation time (G), intrinsic rate of natural increase (rm), the population doubling time (T), and the finite rate of increase (λ). In the no-choice test, females exhibited oviposition preference for sweet pepper (12.08 eggs/fruit), while Bird's eye was the least preferred (5.00 eggs/fruit). The same results were observed in the choice test. However, the population growth rate of T. leucotreta was highest on the Scotch bonnet and Cayenne, with rm of 0.124 and 0.127, respectively, while the Bird's eye and sweet pepper recorded the least rm of 0.116. Thus, the tested varieties had varying levels of susceptibility to T. leucotreta infestation. Bird's eye was the least susceptible variety, while Cayenne and Scotch bonnet were the most susceptible varieties. These findings could direct farmers on the choices of pepper varieties for cultivation and proffer potential opportunities to breed new varieties resistant to T. leucotreta infestation.

Evaluating the effects of short-term low temperature on the growth and development of Trichopria drosophilae based on the age-stage two-sex life table.

BACKGROUND: The effects of low temperatures on parasitic wasps are crucial for maintaining farmland biodiversity and enhancing biological control, especially given the implications of global warming and frequent extreme cold events. METHODS: We studied the effects of different low temperatures (-8 ± 1 °C, -4 ± 1 °C, 0 ± 1 °C, 4 ± 1 °C, and 8 ± 1 °C) on the mating frequency and duration of male adults of Trichopria drosophilae and the number of pupae beaten by female adults, and constructed the age-stage two-sex life table of T. drosophilae. RESULTS: This study found that male T. drosophilae adults exposed to low temperatures for 12 h significantly altered their mating behavior, peaking between 15:00 and 17:00. As the temperature dropped during the exposure, both the mating frequency of T. drosophilae and the duration of pupal beating were affected. The survival rate of female adults dropped from 39.55% at 8 °C to just 21.17% at -8 °C. Low-temperature treatment shortened the development period and lifespan for T. drosophilae adults. They developed 4.71 days faster and had a total lifespan that was 10.66 days shorter than those in the control group after being exposed to -8 °C. Furthermore, the average number of eggs laid by females at -8 °C was 4.46 less than that at 8 °C and 6.16 less than that in the control group, which laid an average of 21.55 eggs. The net reproductive rate (R0) of T. drosophilae decreased with lower temperatures, reaching a low of 23.64 at -8 °C. Conversely, the intrinsic growth rate (rm) actually increased as temperatures dropped, with the lowest value being 0.21 at -8 °C. CONCLUSIONS: The findings indicate that short-term exposure to low temperatures hampers the growth and population increase of T. drosophilae, thereby reducing their effectiveness as biological control agents.

How does Neoseiulus californicus McGregor respond to sublethal doses of entomopathogenic fungus Beauveria bassiana (Hyp.: Cordycipitaceae)?

Two-spotted spider mite, Tetranychus urticae Koch (Acari: Prostigmata), is one of the most economically important mite species, mainly controlled by chemical acaricides. Natural enemies have been assessed as reliable alternatives for management of this phytophagous mite. In the current project, demographic characteristics of Neoseiulus californicus McGregor (Acari: Phytoseiidae) to sublethal concentrations (LC10 = 6.76 × 102, LC20 = 8.74 × 103 and LC30 = 55.38 × 103 conidia ml-1) of entomopathogenic fungus, Beauveria bassiana (Bals.) Vuill. TV strain were investigated under laboratory conditions at 25 ± 2°C, 70 ± 5% RH and a photoperiod of 16:8 (L:D) h. Our results indicated that when adult predators were exposed to LC20 and LC30 of B. bassiana, the oviposition period was significantly reduced compared with other treatments. Neoseiulus californicus fecundity was significantly greater in the control (37 eggs) than in LC30 (24 eggs). Life table analysis revealed that the net reproductive rate (R0) declined as the sublethal concentrations of B. bassiana increased. The most striking result to emerge from the data is that not only intrinsic (r); but also, finite rate of increase (λ) was not significantly affected by different concentrations of B. bassiana. Our findings revealed some potential interactions of B. bassiana and N. californicus during their combinations for managing T. urticae that may be helpful for optimising control of this important pest.

Assessing potential for biological control of Japanese giant silkworm Caligula japonica using Anastatus gansuensis, a thelytokous parasitoid firstly reported in Eupelmidae.

BACKGROUND: Caligula japonica, commonly known as Japanese giant silkworm (JGS), is a serious defoliating pest of fruit and forest trees in East Asia. To develop eco-friendly and cost-effective control methods for this pest, we evaluated the potential for biological control of JGS using its egg parasitoid Anastatus gansuensis reared on the Chinese oak silkworm (COS) Antheraea pernyi. We compared the reproductive traits and population increase potential of the parasitoid on JGS and COS eggs, as well as its functional response to host egg densities and mutual interference at different parasitoid densities. RESULTS: Anastatus gansuensis was confirmed to be strictly synovigenic, with most eggs maturing post-emergence, and produced <1% male offspring on both host eggs. Although A. gansuensis females reared from COS eggs had longer longevity and oviposition period, and higher fecundity and net reproductive rate compared to those reared from JGS eggs, the parasitoid had a higher intrinsic rate of increase on JGS than COS eggs. The parasitoid exhibited a type II functional response to increasing host densities, with mutual interference among foraging female wasps occurred at higher parasitoid densities. CONCLUSION: Our results indicate a high potential for biological control of JGS using A. gansuensis. The parasitoid can be efficiently reared on COS eggs and used against JGS. It may be essential to provide food for emerging adult parasitoids allowing time for egg maturation prior to the rearing or augmentative release of the parasitoid. Some mutual interference at high parasitoid rearing densities likely reduces per capita parasitization efficiency of A. gansuensis. © 2024 Society of Chemical Industry.

Effects of Dietary Zinc Chloride and Zinc Sulfate on Life History Performance and Hemolymph Metabolism of Spodoptera litura (Lepidoptera: Noctuidae).

Zinc is an essential micronutrient crucial in various biological processes of an organism. However, the effects of zinc vary depending on its chemical form. Therefore, the aim of this study was to conduct a comparative analysis of the life history performances and hemolymph metabolism of Spodoptera litura exposed to different concentrations of dietary zinc chloride (ZnCl2) and zinc sulfate (ZnSO4), utilizing two-sex life tables and untargeted metabolomics. The preadult survival rate of S. litura significantly decreased, while the preadult developmental period of S. litura was prolonged as the dietary ZnCl2 concentration increased. However, the fecundity of S. litura at 50 mg/kg dietary ZnCl2 was significantly increased. The intrinsic rate of increase (r) and the finite rate of increase (λ) in S. litura in the control group (CK, no exogenous ZnCl2 or ZnSO4 added) and with 50 mg/kg dietary ZnCl2 were significantly higher than those at 100 mg/kg, 200 mg/kg, and 300 mg/kg. Dietary ZnSO4 exerts a devastating effect on the survival of S. litura. Even at the lowest concentration of 50 mg/kg dietary ZnSO4, only 1% of S. litura could complete the entire life cycle. Furthermore, as the dietary ZnSO4 concentration increased, the developmental stage achievable by the S. litura larvae declined. High-throughput untargeted metabolomics demonstrated that both 100 mg/kg dietary ZnCl2 and ZnSO4 decreased the hemolymph vitamins levels and increased the vitamin C content, thereby helping S. litura larvae to counteract the stress induced by ZnCl2 and ZnSO4. Simultaneously, dietary ZnCl2 obstructed the chitin synthesis pathway in the hemolymph of S. litura, thus extending the developmental period of S. litura larvae. These results indicate that low concentrations of Zn2+ positively impact populations of S. litura, but the effectiveness and toxicity of Zn depend on its chemical form and concentration.

Fitness implications of low-temperature storage for Eocanthecona furcellata (Hemiptera: Pentatomidae).

Exploring the impact of low-temperature storage on the fitness of natural enemy insects is crucial for practical field applications because this parameter directly influences their potential for population growth and effective pest control. Eocanthecona furcellata (Wolff) (Hemiptera: Pentatomidae) is widely used in biological pest control. This study aimed to identify optimal storage stages, temperatures, and durations for E. furcellata to produce high-quality individuals for practical use. The quality of E. furcellata after storage was evaluated by assessing parameters such as predatory capacity and fecundity, along with age-stage, two-sex life table. The findings revealed that the adult stage was the optimal storage form for E. furcellata, and the most favorable temperature for storage was 12 °C. Adult females had the highest predatory ability after 15 days of storage at 12 °C. Although survival rates declined with prolonged storage, they remained above 50% after 30 days, and longevity, fecundity, and predatory capacity of surviving individuals remained comparable to those of individuals in the control group (rearing at a constant temperature of 26 °C without low-temperature storage). The effects of low-temperature storage extended to the F1 generation of E. furcellata, which exhibited maximum mean longevity, fecundity, net reproductive rate, and mean generation time as well as fastest population growth after 30 days of storage at 12 °C. These results can be used to achieve optimal low-temperature storage conditions for E. furcellata production, particularly for extending its shelf life.

Sublethal effect of emamectin benzoate on age-stage, two-sex life table and population projection of red palm weevil, Rhynchophorus ferrugineus.

The red palm weevil (RPW), Rhynchophorus ferrugineus Olivier, is a devastating insect-pest of 29 plants including date palm. It feeds inside the tree bark thus it is difficult to manage using insecticides. Only a few insecticides have been found effective against RPW. Among these insecticide, emamectin benzoate (EMB) is widely used. This insecticide can pose threat human and environmental health as it is used in the form of tree injection. Thus, keeping in view its possible, its sublethal effect on RPW was studied using Age-stage, two sex life table. Life table parameters of the progeny of exposed larvae to LC10, LC25, and LC50 of EMB were computed. Statistically higher fecundity (161.12 per female) was observed in control treatment, while less fecundity was observed in LC50 treatment. Significantly higher values for intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (Ro) (0.0376, 1.0383, and 67.13 per day, respectively) were recorded for the control treatment. Contrarily, lower values for r, Ro, and λ i.e. 0.0318, 23.82, and 1.0324 per day, respectively were recorded in the LC50 treatment. Decreased population parameters suggest that EMB can be successfully used in for the management of RPW.

Ecotoxicological insights into the effects of triflumezopyrim on P. fuscipes fitness, detoxification pathways, and gene expression.

The primary objective was to evaluate the toxicity of triflumezopyrim (TFP) on P. fuscipes larvae and adults at lethal and sublethal levels through topical application. Sublethal effects were assessed by examining developmental period, fecundity, life-table parameters, and fitness parameters. Enzymatic and transcriptional analyses were conducted to determine the impact of TFP on P. fuscipes physiology and gene expression. The LC50, LC30, and LC10 of TFP against P. fuscipes larvae and adults were lower than the field-recommended dose (48.75 mg a.i. L-1), indicating direct toxicity and sublethal effects during immature stages. Exposure to LC30 of TFP extended developmental periods for 2nd-instar larvae and pupae, reduced oviposition, larval predation efficiency, and body weight in both sexes. Sublethal concentrations affected antioxidant, detoxification, and energy reservoir enzymes significantly. Transcriptional analysis revealed impacts on insecticide detoxification, resistance, and stress-related genes. KEGG analysis showed glycerolipid metabolism is the most regulated pathway, and UGT2B10 regulated several detoxification-related pathways under TFP stress. These findings prompt reconsideration of the role of TFP in paddy field IPM due to its adverse effects on P. fuscipes, emphasizing the importance of assessing its ecological impacts before widespread application in agricultural practices.

Effect of microplastics on the demography of Brachionus calyciflorus Pallas (Rotifera) over successive generations.

Microplastics (MPs) are becoming increasingly common in freshwater ecosystems. Rotifers may involuntarily ingest MPs through non-selective filtration, thus causing non-real satiety, leading to adverse effects on their demography. Here, we evaluated the acute and chronic effects of MPs (30 µm) on two successive generations of Brachionus calyciflorus s.s. at 20 and 25 °C. Demographic variables and ingestion rates were compared in the absence and presence of microplastics (550 spheres mL-1). For the life table experiments, cohorts of twenty neonates were introduced into 20 mL medium with four replicates per treatment. Ingestion rates of the rotifer were tested at both test temperatures in the absence and presence of the microplastics in 20 mL containers with 1 ind. mL-1 per container. The rotifer population growth rates ranged from 0.55 to 1.05 d-1 depending on the treatment. MPs decreased the fecundity by 20-24 %. The average lifespan of rotifers exposed to MPs in the F0 generation was lower than that in the F1 generation at both temperatures, indicating that pre-exposure of mothers may offer some protection to the offspring. The population growth rate was higher at 25 °C. The ingestion rates were significantly lower in the presence of the microplastics. Our observations indicated that this strain of B. calyciflorus was better adapted to 20 °C; microplastics and higher test temperature resulted in a pronounced changes in the demographic variables of the rotifer.

An Internal Marking Method for Adult Spodoptera frugiperda Smith Using an Artificial Diet Containing Calco Oil Red N-1700.

As a migratory invasive pest, Spodoptera frugiperda (fall armyworm, FAW) has recently posed a serious threat to food security in newly invaded areas (especially in Africa and Asia). Understanding its migration (or dispersal) patterns in newly invaded areas is crucial for regional forecasting and management efforts. By screening an appropriate marking technique to conduct mark-release-recapture (MRR) experiments, the migration patterns of the FAW can be effectively studied. In this study, we added different concentrations of Calco Oil Red N-1700 (an oil-soluble marker) to a self-made artificial diet and assessed the rearing and marking efficacy. The results indicated that a concentration of 0.2% of Calco Oil Red N-1700 in the diet was optimal for marking adult FAWs. The biological indicators (e.g., developmental duration, reproductive parameters, and flight ability) of FAWs fed this diet were basically consistent with those of FAWs fed a normal diet, with a larval stage of 15.46 days, a pupal stage of 9.81 days, a pupal mass of 278.18 mg, an adult longevity of 15.41 days, and an egg deposition count of 1503.51. Meanwhile, the flight distance, duration, and velocity were 24.91 km, 7.16 h, and 3.40 km/h, respectively (12 h tethered-flight tests), without difference with the control. Females and males exhibited distinctive marking colors (red or pink) that persisted for at least 5 and 9 days, respectively. This study developed an economically effective internal marking method for the adult FAW, laying the foundation for conducting MRR experiments. This will help clarify the migration behavior and routes of the FAW, providing a scientific basis for formulating effective pest management strategies.

Insufficient and excessive Ca2+ intake negatively impact the life history performance and disrupt the hemolymph metabolism of Spodoptera litura.

Calcium ions (Ca2+), essential as second messengers in all cells, play a pivotal role as micronutrients in insects. However, few studies have explored the effects of both insufficient and excessive Ca2+ intake on life history performance and population parameters. This study examines the impact of varying Ca2+ intake levels-insufficient (0 mg/kg), appropriate (100 mg/kg), and excessive (250 mg/kg)-on the life history performance and population parameters of Spodoptera litura using two-sex life tables. Insufficient and excessive Ca2+ intakes significantly extended the preadult development period and decreased the preadult survival rates of S. litura, compared to those on an appropriate Ca2+ intake. The population parameters (Intrinsic rate of increase (r), Finite rate of increase (λ), and Net reproductive rate (R0)) of S. litura on a 100 mg/kg diet (r = 0.1364, λ = 1.1462, R0 = 390) were significantly higher than those on a 0 mg/kg diet (r = 0.1091, λ = 1.1153, R0 = 130.52). Additionally, untargeted metabolomics analysis revealed that inappropriate Ca2+ levels (either insufficient or excessive) triggered significant up-regulation of 71.1 % and 92.8 % of the metabolites in the hemolymph, respectively, compared to the appropriate Ca2+ intake. Notably, disruptions in metabolite balance affected critical components such as melatonin and melanin within the tryptophan and tyrosine metabolism pathways. These findings underscore that both insufficient and excessive Ca2+ intakes adversely affect the life history performance and disrupt hemolymph metabolic balance in S. litura.

The impact of different photoperiod regimes on vital life traits of Amblyseius swirskii and Neoseiulus cucumeris (Acari: Phytoseiidae).

Environmental factors, such as photoperiod can play an important role in the development and performance of predatory mites. The influence of five photoperiod regimes (0: 24, 8: 16, 12: 12, 16: 8, and 24: 0 h; Light: Dark) on the population parameters of the predatory mites, Amblyseius swirskii Athias-Henriot and Neoseiulus cucumeris (Oudemans) was studied under the laboratory conditions at 25 °C and 25 ± 1 °C, 65 ± 5% RH. Regarding A. swirskii, the longest and shortest total pre-adult and total preoviposition periods (TPOP) were in the photoperiod of 12 L:12D and 16 L:8D, respectively. The oviposition days, adult longevity, total life span, fecundity, gross reproductive rate (GRR), and net reproductive rate (R0) of the predator had no significant difference in all photoperiods tested. The intrinsic rate of increase (r) and the finite rate of increase (λ) in 16 L:8D photoperiod had no significant difference with the other photoperiods tested except 12 L:12D. Regarding N. cucumeris, the shortest total pre-adult and TPOP were in full darkness. The oviposition days and fecundity were significantly higher in 16 L:8D than the others. The value of R0 in 16 L:8D was significantly higher than 8 L:16D. The highest values of the parameters r and λ were observed in full darkness, which had no significant difference with 16 L:8D and 24 L:0D. According to the results, the photoperiod regime had a more significant influence in terms of development and reproduction on N. cucumeris than A. swirskii, and 16:8 (L: D) h photoperiod was recognized as the proper regime for their rearing.

Demographic analysis and biotic potential of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) on pea.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a highly destructive polyphagous pest that primarily damages maize. Maize is considered a most versatile crop for growing intercrops due to the wide row it needs. Maize-pea intercropping is preferred by small and marginal farmers worldwide due to various advantages including higher yield and improved economic benefits. However, the success of this intercropping system may be hampered if pea could sustain the FAW population. Thus, to clarify the fitness and potential effect of S. frugiperda on pea, we analysed the survival and development of S. frugiperda fed on pea leaves in the laboratory and constructed age-stage and two-sex life tables. Results showed that FAW successfully completed its life cycle when fed on pea and produced fertile offspring. The pre-adult duration was significantly higher on pea than maize. The net reproductive rate, intrinsic and finite rate of population increase on pea (135.06 offspring per individual, 0.12 offspring per individual per day and 1.13 times per day) were all significantly different from those on maize (417.64 offspring per individual, 0.19 offspring per individual per day and 1.21 times per day). The probability of survival of S. frugiperda at each stage was lower when fed on pea leaves than that of maize-fed larvae. Due to the overlapping growth periods of the maize and pea, S. frugiperda can easily proliferate throughout the year by shifting between adjacent crops. Thus, this study revealed the adaptability of S. frugiperda for pea and provides the foundation for further assessment of FAW risk to other inter-crops.

The life history consequences of host switching in Ooencyrtus egeria (Hymenoptera: Encyrtidae), a parasitoid of stink bug eggs.

The stink bugs Acrosternum arabicum Wagner and Brachynema germari Kolenati (Hemiptera: Pentatomidae) damage developing pistachio nuts in Iran. Ooencyrtus egeria Huang and Noyes (Hymenoptera: Encyrtidae) parasitizes eggs of both species, alternating between them seasonally. We compared the biological and life history attributes of O. egeria reared for 3 generations on each host species with those that had been transferred to the alternate host for 2 generations. We also tested female responses to host egg density. Eggs of B. germari were parasitized at higher rates and yielded faster wasp development, heavier female progeny with greater fecundity, and a more female-biased sex ratio, than eggs of A. arabicum. Rearing on A. arabicum did not diminish wasp fitness on B. germari, and the F1 progeny of wasps switched to A. arabicum inherited some beneficial parental effects from rearing on B. germari. Regardless of host species, females parasitized fewer eggs in 8 h as density increased from 10 to 30 eggs, but progeny sex ratio (% female) increased. The anomalous response to host density appears to arise from a combination of behavioral and egg load constraints. Females mature only 10-12 eggs per day. Carefully inspect egg clusters before selecting the most suitable eggs for oviposition, a more time-consuming process for large clusters. Our results indicate that rearing O. egeria on eggs of A. arabicum, which are more convenient and cost-effective to produce than those of B. germari, will not diminish its performance on B. germari following augmentative release, beyond a slight reduction in female fecundity.

Evaluation of the temperature adaptation of three rubber tree pest mites based on their two-sex life table.

To determine the optimal temperature range for the development and reproduction of three spider mites (Eotetranychus sexmaculatus, Eotetranychus orientalis, and Oligonychus biharensis), this study investigated their developmental period, survival rate, lifespan, and reproduction under five temperatures, 21, 24, 27, 30, and 33°C, to predict and control in the field. With the gathered data, a two-sex life table was constructed for each of them. The results revealed that as the temperature increased, both O. biharensis and E. orientalis displayed a gradual reduction in their generation period. Furthermore, an inverse relationship was observed between lifespan and temperature for all three spider mite species. When examining the survival rates at varying temperatures, E. sexmaculatus exhibited the highest rate (98%) at 33°C, while E. orientalis and O. biharensis demonstrated their highest survival rates at 24°C, reaching 90% and 100% respectively. Regarding reproduction, O. biharensis displayed the highest oviposition rates at 30°C with an average of 17.45 eggs per individual. Conversely, E. sexmaculatus and E. orientalis exhibited the highest oviposition rates at 33°C, averaging at 15.22 and 21.38 eggs per individual respectively. Significantly higher intrinsic growth rates were observed for O. biharensis and E. orientalis at 33°C, with rates of 0.22 and 0.26 respectively. In contrast, E. sexmaculatus demonstrated the highest intrinsic growth rate at 27°C. The temperature of 27°C was more suitable for the growth of the E. sexmaculatus, while 33°C was the optimal temperature for the E. orientalis and O. biharensis. The current findings provide valuable guidance for the control and prevention of these three spider mites.

Life history parameters of Ectropis grisescens (Lepidoptera: Geometridae) in different Wolbachia infection states.

Wolbachia, a prevalent intracellular symbiotic bacterium in insects, plays a significant role in insect biology. Ectropis grisescens (Warren; Lepidoptera: Geometridae) is a devastating chewing pest distributed in tea plantations throughout China. However, it is unclear how Wolbachia titers affect the fitness and reproduction of E. grisescens. In this study, the impacts of 3 different infection lines, naturally Wolbachia-infected, Wolbachia-uninfected, and Wolbachia transinfected, regarding the life history traits of E. grisescens, were evaluated using the age-stage, 2-sex life table. Wolbachia infection significantly shortened preadult duration and preoviposition periods and notably increased the fecundity, net reproductive rate, and finite rate of increase. Meanwhile, population projection indicated that E. grisescens population size with Wolbachia infection can increase faster than without. These results indicate that Wolbachia plays a regulatory role in the fitness of E. grisescens. It is also noted that the life history parameters of E. grisescens may positively correlate with Wolbachia titers. These findings could aid in pest management in tea gardens.

A comparative approach for life history and functional response demonstrates similar survival strategies for Trichogramma evanescens and T. pintoi.

BACKGROUND: Egg parasitoids are important biological control agents of lepidopteran pests of agricultural crops. Trichogramma evanescens Westwood and T. pintoi Voegele (Hymenoptera: Trichogrammatidae) are egg parasitoids with worldwide importance. The parasitoid selection necessitates comparative assessment of the life table traits and functional response analysis to provide insights into their effectiveness in pest control. In this study, we examined their life table traits including survivorship and reproductivity, and functional response and associated parameters i.e., attack coefficient and handling time. RESULTS: Life table parameters, using age-stage, two-sex theory, revealed similar survival and reproductive strategies for both species. For example, the female longevity, oviposition days and fecundity did not differ between both species. Exceptionally, the male longevity of T. evanescens was shorter than that of T. pintoi. The population growth parameters such as gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ), and mean generation time (T) did not differ between species. The polynomial logistic regression yielded a type III functional response and a non-linear least square analysis revealed different attack coefficient and similar handling time. However, their parasitism rate differed between the lowest (five eggs) and highest (80 eggs) initial host egg densities such that T. evanescens had a lower parasitism rate at the lowest density and higher parasitism rate at the highest density. CONCLUSION: The similarity in survival strategies and minor differences in host handling of both parasitoids are discussed in terms of relevance to applied biological control applications and evolutionary traits. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Cross-sectional Average Length of Life Entropy ( H CAL ): International Comparisons and Decompositions.

Keyfitz and Leser's life table entropy was proposed to serve as a relative inequality in mortality measure. Entropy considers the variation around the age at death relative to the length of lifespan in a population, allowing comparisons across time and populations. It is used widely in period and cohort applications. Here, we propose extending this measure and present an index that incorporates the history of survival of all cohorts present at a given time, namely the cross-sectional average length of life entropy, or CAL-entropy ( H CAL ). We decompose cross-population differences of CAL-entropy into the contribution of longevity and lifespan variation, and the change of those differences across time. Our illustrations show that populations are converging regarding lifespan inequality. Lifespan variation holds a noticeable share in the CAL-entropy gap among selected European populations. Longevity held once a pronounced share in CAL-entropy differences and their change, but its influence has receded over the years. The US demonstrates a unique trend where it performs worse across time compared to the selected European populations, and lifespan variation has played a major role in this process. This study signals the importance of lifespan variation in reducing inequality in mortality among developed and longevous populations.

Age-Stage, Two-Sex Life Table of Atractomorpha lata (Orthoptera: Pyrgomorphidae) at Different Temperatures.

Atractomorpha lata Motschoulsky (Orthoptera: Pyrgomorphidae) has recently emerged as an important agricultural pest in China. Understanding the impact of temperature on its developmental period is crucial for predicting its population dynamics. This study systematically observed the biological characteristics of A. lata at five temperatures (16, 20, 24, 28, and 32 °C) using the age-stage, two-sex life table method. The effects of temperature on the developmental period, survival rate, and fecundity of A. lata were studied using fresh bean leaves as host. The results demonstrated that as temperature increased from 16 °C to 32 °C, the developmental period, preadult time, adult longevity, adult preoviposition period (APOP), and total preoviposition period (TPOP) significantly decreased. The developmental threshold temperatures for various stages were calculated, ranging from 10.47 °C to 13.01 °C, using the linear optimal method. As temperature increased, both the intrinsic rate of increase (r) and the finite rate of increase (λ) also increased, while the mean generation time (T) decreased. The optimal values of the net reproductive rate (R0 = 54.26 offspring), gross reproductive rate (GRR = 185.53 ± 16.94 offspring), and fecundity (169.56 ± 9.93 eggs) were observed at 24 °C. Similarly, the population trend index (I) for A. lata peaked at 24 °C (61.64). Our findings indicate that A. lata exhibits its highest population growth rate at 24 °C, providing a scientific basis for predicting its population dynamics in the field.

Intergenerational Sublethal Effects of Flonicamid on Cotton Aphid, Aphis gossypii: An Age-Stage, Two-Sex Life Table Study.

Flonicamid is a novel systemic insecticide widely used against aphids. However, the intergenerational sublethal effects of flonicamid on cotton aphid, Aphis gossypii, have not been fully studied. This study aimed to evaluate the sublethal effects of flonicamid on the biological parameters of adult A. gossypii (F0) and its subsequent intergenerational effects on the offspring (F1 generation) through age-stage, two-sex life table analysis. The results of the bioassays indicate that flonicamid exhibits significant toxicity toward adult A. gossypii, as evidenced by an LC50 value of 0.372 mg L-1 after a 48-h exposure period. The longevity, fecundity, and reproductive days of adult cotton aphids (F0) were significantly decreased when treated with the sublethal concentrations of flonicamid. The pre-adult stage exhibited an increase, whereas the adult longevity, total longevity, and fecundity experienced a notable decrease in F1 aphids after the exposure of F0 aphids to sublethal concentrations of flonicamid. Furthermore, the key demographic parameters, including r, λ, R0, and RPd, showed a significant decrease, while the total pre-reproductive period (TPRP) experienced a significant increase in the F1 generation. Collectively, our findings indicate that sublethal concentrations of flonicamid impact the demographic parameters of A. gossypii, resulting in suppression of population growth. This study presents comprehensive information on the overall impact of flonicamid on A. gossypii, which could potentially aid in managing this major pest.