Fitness effect and transcription profile reveal sublethal effect of nitenpyram on the predator Chrysopa pallens (Neuroptera: Chrysopidae).

Although neonicotinoids are widely used and important insecticide, there are growing concerns about their effect on nontarget insects and other organisms. Moreover, the effects of nitenpyram (NIT), a second generation of neonicotinoid insecticides, on Chrysopa pallens are still unclear. Therefore, this study purposed to investigate the acute toxicity of NIT to C. pallens using the spotting method. To examine the potential effects of a sublethal dose of NIT (LD30 , 1.85 ng of active ingredient per insect) on C. pallens, we constructed the life tables and analyzed the transcriptome data. The life table results showed that the period of second instar larvae, adult pre-oviposition period and total pre-oviposition period were significantly prolonged after exposure to sublethal dose of NIT, but had no significant effects on the other instars, longevity, oviposition days, and fecundity. The population parameters, including the preadult survival rate, gross reproduction rate, net reproductive rate, the intrinsic rate of increase, and finite rate of increase, were not significantly affected, and only the mean generation time was significantly prolonged by NIT. Transcriptome analysis showed that there were 68 differentially expressed genes (DEGs), including 50 upregulated genes and 18 downregulated genes. Moreover, 13 DEGs related to heat shock protein, nose resistant to fluoxetine protein 6, and prophenoloxidas were upregulated. This study showed the potential effects of sublethal doses of NIT on C. pallens and provided a theoretical reference for the comprehensive application of chemical and biological control in integrated pest management.

Comparison of the biology of Frankliniella intonsa and Megalurothrips usitatus on cowpea pods under natural regimes through an age-stage, two-sex life table approach.

Two thrips, Megalurothrips usitatus (Bagnall) and Frankliniella intonsa (Trybom) are major pests of cowpea in South China. To realistically compare the growth, development and reproductive characteristics of these two thrips species, we compared their age-stage, two-sex life tables on cowpea pods under summer and winter natural environmental regimes. The results showed that the total preadult period of M. usitatus was 8.09 days, which was significantly longer than that of F. intonsa (7.06 days), while the adult female longevity of M. usitatus (21.14 days) was significantly shorter than that of F. intonsa (25.77 days). Significant differences were showed in male adult longevity (10.68 days for F. intonsa and 16.95 days for M. usitatus) and the female ratio of offspring (0.67 for F. intonsa and 0.51 for M. usitatus), and the total preadult period of M. usitatus (16.20 days) was significantly longer than that of F. intonsa (13.66 days) in the winter regime. The net reproductive rate (summer: R0 = 85.62, winter: R0 = 105.22), intrinsic rate of increase (summer: r = 0.3020 day-1, winter: r = 0.2115 day-1), finite rate of increase (summer: λ = 1.3526 day-1, winter: λ = 1.2356 day-1) and gross reproduction rate (summer: GRR = 139.34, winter: GRR = 159.88) of F. intonsa were higher than those of M. usitatus (summer: R0 = 82.91, r = 0.2741, λ = 1.3155, GRR = 135.71; winter: R0 = 80.62, r = 0.1672, λ = 1.1820, GRR = 131.26), and the mean generation times (summer: T = 14.73 days, winter: T = 22.01 days) of F. intonsa were significantly shorter than those of M. usitatus (summer: T = 16.11 days, winter: T = 26.25 days). These results may contribute to a better understanding of the bioecology of different thrips species, especially the interspecific competition between two economically important cowpea thrips with the same ecological niche in a changing environment.

Evaluating the Effects of Cu2+ on the Development and Reproduction of Spodoptera litura (Lepidoptera: Noctuidae) Based on the Age-Stage, Two-Sex Life Table.

Copper (Cu2+) is a micronutrient that promotes the development and reproduction of organisms. However, with the rapid expansion of modern industry and agriculture, Cu2+ concentrations are increasing, which might have negative impacts on biological and ecological safety. Spodoptera litura is not only an intermittent outbreak pest but also can be used as a model organism to assess environmental and ecological risks. Therefore, the effects of the life history and population parameters of S. litura fed on artificial diets with different Cu2+ concentrations were analyzed using the age-stage, two-sex life table. Our results showed that not only the preadult survival rate but also the intrinsic rate of increase (r) and the finite rate of increase (λ) were significantly increased under exposure to low Cu2+ concentrations (2, 4, and 8 mg/kg). In addition, the population growth of S. litura was significantly faster, indicating that S. litura can adapt well to low concentrations and is likely to undergo outbreaks of damage. Whereas, in addition to a significant reduction in preadult survival rate, population growth rate, pupal weight, pupal length, adult body weight, and oviposition were also significantly reduced under exposure to high Cu2+ concentration (32 mg/kg). And when the concentration reached 64 mg/kg, the survival rate of adults was extremely low, suggesting a decrease in the adaptation of S. litura. These results can help to understand the population dynamics of S. litura and predict potential ecological risks.

Population Growth Performance of Arma custos (Faricius) (Hemiptera: Pentatomidae) at Different Temperatures.

Arma custos (Fabricius) (Hemiptera: Pentatomidae) is a natural predator that can control various agricultural and forestry pests. This study aimed to clarify the effects of temperature on the growth, reproduction, and population of the predator and to simulate its population growth. Using the age-stage, two-sex life table method, 18°C, 22°C, 26°C, 30°C, and 34°C were selected as the temperature conditions. A. custos can complete its life cycle at 18°C-30°C, and the developmental duration of each A. custos stage, adult pre-oviposition period, total pre-oviposition period, and the mean generation time (T) were shortened with the increase in temperature. The pre-adult mortality was significantly reduced at 26°C and 30°C. In addition, the fecundity of a single female and the gross reproductive rate were the highest at 30°C. Significant differences were observed in the intrinsic rate of increase (r) and the finite rate of increase (λ) under different temperature conditions, and both reached the maximum at 30°C. Results showed that adult A. custos raised at 26°C had a longer lifespan and the fecundity was higher at 30°C in comparison with the other temperatures. This study is the first to report the life cycle of A. custos at different temperatures, and the results can provide a scientific theoretical basis for the indoor artificial reproduction, outdoor release, and colonization of A. custos.

Performance of Tetranychus urticae (Acari: Tetranychidae) on three hop cultivars (Humulus lupulus).

Tetranychus urticae Koch (Acari: Tetranychidae) is a major pest species in numerous crops including hop (Humulus lupulus L.). Substantial T. urticae infestation was observed to occur in this recently introduced crop in Brazil. The adoption of less suitable cultivars to the pest species is highly desirable for integrated pest management. We used free-choice trials and two-sex life table analysis to determine the preference and population growth of T. urticae under laboratory conditions using three of hop cultivars currently expanding in Brazil (Mantiqueira, Victoria, and Yakima Gold). We also estimated the density of non-glandular trichomes and lupulin glands found on the abaxial leaf surface of these cultivars and correlated them with performance parameters of T. urticae. Mantiqueira appeared to be the least preferred by adult females for attractiveness and oviposition suggesting existence of antixenosis on this cultivar. Female immature stages developed slower on Yakima Gold and Mantiqueira, but no difference was observed between the latter and Victoria. Fecundity and longevity were significantly lower on Mantiqueira than on Victoria and Yakima Gold. No significant differences were observed among cultivars for intrinsic rate of increase (r), finite rate of increase (λ), and net rate of reproduction (R0), suggesting the absence of antibiosis. Although, lupilin gland densities were higher on Mantiqueira and Yakima Gold than on Victoria, no significant correlations were observed between these defensive traits and performance parameters of T. urticae. However, 30-day population simulations of T. urticae suggest that Yakima Gold is the least susceptible, Mantiqueira is moderately susceptible, and Victoria is highly susceptible.

Skewed distributions of lifetime reproductive success: beyond mean and variance.

Lifetime reproductive performance is quantified here by the LRS (lifetime reproductive success), the random number of offspring an individual produces over its lifetime. Many field studies find that distributions of LRS among individuals are non-normal, zero-inflated and highly skewed. These results beg the question, what is the distribution of LRS predicted by demographic models when the only source of randomness is demographic stochasticity? Here we present the first exact analysis of the probability distribution of LRS for species described by age + stage models; our analysis starts with estimated vital rates. We illustrate with three examples: the Hadza, human hunter-foragers (age-only), the evergreen tree Tsuga canadensis (stage-only) and Roe deer, Capreolus capreolus (age + stage). For each we obtain the exact distribution of LRS, but also calculate and discuss the first three moments. Our results point to important questions about how such LRS distributions affect natural selection, and life history evolution.

Effects of bistrifluron resistance on the biological traits of Spodoptera litura (Fab.) (Noctuidae: Lepidoptera).

Spodoptera litura is one of the major insect pests of vegetables in Sichuan, China, and it has developed serious resistance to many traditional chemical insecticides. In this present study, S. litura individuals collected from five regions in Sichuan in 2017, which were detected the resistance to bistrifluron. We found that the resistance ratios (RRs) bistrifluron were in the ranges of 15.9- to 77.7-fold, respectively, compared with a laboratory susceptible (Lab-HN) strain. To elucidate the effect of bistrifluron on the life history parameters of S. litura, we established the bistrifluron-susceptible (Bis-UNSEL) and bistrifluron-resistant (Bis-SEL) strains based on the DY field population with the highest RR of 77.7-fold among the all field populations to bistrifluron compared with a laboratory Lab-HN strain. The results show that the Bis-SEL strain developed a 113.8-fold RR while that of the Bis-UNSEL strain was almost equal to that of the Lab-HN strain (with overlapping confidence intervals (CI) of their LC50 values, P < 0.05). Meanwhile, the life span of the egg and pupa stage of the Bis-UNSEL strain was prolonged, and the strain also showed shorter adult duration and lower fecundity. Demographic characteristics, such as the intrinsic rate of increase (r), finite rate of increase (λ) and net reproductive rate (R0) in the Bis-SEL strain were significantly higher than the Bis-UNSEL strain, whereas the mean generation time (T) and gross reproduction rate (GRR) were lower. The results clearly showed that the developing resistance of bistriflueon on S. litura promoted its population growth. Therefore, the present study could provide useful informations for determining potential management methods to prevent the development of bistrifluron resistance in S. litura.

Peanut cultivars display susceptibility by triggering outbreaks of Tetranychus ogmophallos (Acari: Tetranychidae).

The peanut red spider mite, Tetranychus ogmophallos Ferreira and Flechtmann (Acari: Tetranychidae), is an important pest of peanut in Brazil and is considered a quarantine pest in other countries. This study investigates the development, reproduction, survival and life table parameters of T. ogmophallos on five peanut cultivars-three with high levels of oleic acid [high oleic] and recently released: Granoleico, IAC OL 3 and IAC 503; and two regular and previously used by farmers: Runner IAC 886, IAC Tatu ST 3-and two breeding lines (L. 8008 and L. 322) in the growth chamber. There were differences between the developmental times of all immature stages, the oviposition period, fecundity and adult longevity of T. ogmophallos reared on the peanut cultivars and breeding lines. The longest duration of the immature stage and lowest fecundity occurred on cultivars Granoleico and Runner IAC 886, and breeding line L. 322, which also displayed the lowest intrinsic rate of increase (r), finite rate of increase (λ) and net reproductive rate (R0) and the shortest mean generation time (T). The highest fitness occurred on the IAC Tatu ST, IAC OL 3, IAC 503 and L. 8008. Our study shows that peanut cultivars belonging to the group with high oleic trait and recently released (IAC OL 3 and IAC 503) are susceptible to T. ogmophallos, except Granoleico, which is resistant. The regular and previously used cultivar Runner IAC 886 and breeding line L. 322 are resistant to the peanut red spider mite.

Age × stage-classified demographic analysis: a comprehensive approach.

This paper presents a comprehensive theory for the demographic analysis of populations in which individuals are classified by both age and stage. The earliest demographic models were age classified. Ecologists adopted methods developed by human demographers and used life tables to quantify survivorship and fertility of cohorts and the growth rates and structures of populations. Later, motivated by studies of plants and insects, matrix population models structured by size or stage were developed. The theory of these models has been extended to cover all the aspects of age-classified demography and more. It is a natural development to consider populations classified by both age and stage. A steady trickle of results has appeared since the 1960s, analyzing one or another aspect of age × stage-classified populations, in both ecology and human demography. Here, we use the vec-permutation formulation of multistate matrix population models to incorporate age- and stage-specific vital rates into demographic analysis. We present cohort results for the life table functions (survivorship, mortality, and fertility), the dynamics of intra-cohort selection, the statistics of longevity, the joint distribution of age and stage at death, and the statistics of life disparity. Combining transitions and fertility yields a complete set of population dynamic results, including population growth rates and structures, net reproductive rate, the statistics of lifetime reproduction, and measures of generation time. We present a complete analysis of a hypothetical model species, inspired by poecilogonous marine invertebrates that produce two kinds of larval offspring. Given the joint effects of age and stage, many familiar demographic results become multidimensional, so calculations of marginal and mixture distributions are an important tool. From an age-classified point of view, stage structure is a form of unobserved heterogeneity. From a stage-classified point of view, age structure is unobserved heterogeneity. In an age × stage-classified model, variance in demographic outcomes can be partitioned into contributions from both sources. Because these models are formulated as matrices, they are amenable to a complete sensitivity analysis. As more detailed and longer longitudinal studies are developed, age × stage-classified demography will become more common and more important.

Demographic characteristics and population projection of Phytonemus pallidus fragariae reared on different strawberry cultivars.

The strawberry mite, Phytonemus pallidus fragariae (Banks) (Acari: Tarsonemidae), is one of the most important pests of greenhouse grown strawberry plants. Field grown strawberries may also be infested by the pest in high humid conditions. Life tables give the most comprehensive description of the development, survival, stage differentiation, reproduction and consequently population growth of a population, and thus it is an important base of population ecology and pest management. In this study, to provide a comprehensive evaluation of an ecology-based and cost-effective control program, life history and demographic parameters of the strawberry mite were studied. The experiment was conducted under laboratory conditions providing 20 ± 1 °C, 80 ± 10% RH and L16:D8 photoperiod. The data were analyzed based on the age-stage, two-sex life table theory. The population parameters net reproduction rate (R0 = 6.14 offspring), intrinsic rate of increase (r = 0.1317 day-1), and finite rate of increase (λ = 1.1407 day-1) on cv. Aromas were lower than those on the other cultivars tested. Based on the population characteristics, Aromas is a less favorable cultivar for the population growth of strawberry mite.

Age and stage of breast cancer in Pakistan: An experience at a tertiary care center.

OBJECTIVE: To determine the age and stage of breast cancer in a tertiary care center in Karachi, Pakistan. METHODS: This retrospective, descriptive study was conducted at Breast Unit, Department of Surgery, Liaquat National Hospital Karachi, Pakistan. From 1994 to 2016 all biopsy-proven breast cancer patients were reviewed and their age and stage at presentation were noted . RESULTS: In the given time period 10, 018 patients with Breast cancer were registered. The most frequent age at diagnosis was in the fourth decade of life (28.51%). The majority of patients were diagnosed in stage 2 (47.26%) and only less than 4% were detected in stage 1. The stage of presentation did not differ between young and older age group of women. CONCLUSIONS: Breast cancer is diagnosed at a younger age group in Pakistan, at least a decade earlier than the west and at an advanced stage, commonest being stage 2.

Age-Stage, Two-Sex Life Table Characteristics of Aedes albopictus and Aedes Aegypti in Penang Island, Malaysia.

The life table developmental attributes of laboratory colonies of wild strains of Aedes albopictus and Aedes aegypti were analyzed and compared based on the age-stage, two-sex life table. Findings inclusive in this study are: adult preoviposition periods, total preoviposition period, mean intrinsic rate of increase (r), mean finite rate of increase (λ), net reproductive rates (R0), and mean generation time (T). The total preadult development time was 9.47 days for Ae. albopictus and 8.76 days for Ae. aegypti. The life expectancy was 19.01 days for Ae. albopictus and 19.94 days for Ae. aegypti. Mortality occurred mostly during the adult stage. The mean development time for each stage insignificantly correlated with temperature for Ae. albopictus (r  =  -0.208, P > 0.05) and (r  =  -0.312, P > 0.05) for Ae. aegypti. The population parameters suggest that Ae. albopictus and Ae. aegypti populations are r-strategists characterized by a high r, a large R0, and short T. This present study provides the first report to compare the life parameters of Ae. albopictus and Ae. aegypti strains from Penang island, Malaysia.

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.

The application of demographic characteristics of Ectropis grisescens (Lepidoptera: Geometridae) in pest risk assessment of IPM.

Ectropis grisescens Warren is one of the most important pests of tea plants. In this study, data on the development, survival, and fecundity of E. grisescens were collected at 15, 22, and 32 °C and analyzed by using the age-stage, two-sex life table. At 15 °C, the duration of the preadult period of E. grisescens was significantly prolonged (81.06 days), with high mortality (69.0%), and the proportion of emerged female adults was extremely low (7.0%). At 32 °C, the preadult period was significantly shortened (29.12 days), with high preadult mortality (74.0%), and a low proportion of emerged female adults (15.0%). At 22 °C, with low preadult mortality (24.0%), and a high proportion of emerged female adults (26.0%). The overall effects of the shorter preadult duration, higher preadult survival rate, higher proportion of emerged female adults, higher fecundity (F = 350.88 eggs/♀), and higher net reproductive rate (R0 = 91.23 offspring/individual) at 22 °C resulted in the highest values of the intrinsic rate of increase (r = 0.1054 days-1) and finite rate of increase (λ = 1.1112 days-1). Computer simulation showed that E. grisescens populations can increase much faster at 22 °C than at 15 and 32 °C. The weighted population size and cumulative weighted insect-days provided the dynamics necessary for estimating the damage potential of E. grisescens in devising economical pest management programs. Our results demonstrate that populations of E. grisescens were able to develop at a broad range of temperatures and adapt to the high temperatures. These finding can be utilized to improve the management of E. grisescens.

Feeding Appropriate Nutrients during the Adult Stage to Promote the Growth and Development of Carposina sasakii Offspring.

Nutrients consumed during the adult stage are a key factor affecting the growth, development, and reproduction of insect offspring and thus could play an important role in insect population research. However, there is absence of conclusive evidence regarding the direct effects of parental (F0) nutritional status on offspring (F1) fitness in insects. Carposina sasakii Matsumura is a serious, widespread fruit-boring pest that negatively impacts orchards and the agricultural economy across East Asia. In this study, life history data of F1 directly descended from F0C. sasakii fed with seven different nutrients (water as control, 5 g·L-1 honey solution, 10 g·L-1 honey solution, 5 g·L-1 sucrose solution, 10 g·L-1 sucrose solution, 15 g·L-1 sucrose solution, and 20 g·L-1 sucrose solution) were collected under laboratory conditions. The growth and development indices, age-stage specific survival rate, age-stage specific fecundity, age-stage specific life expectancy, age-stage specific reproductive value, and population parameters of these offspring were analyzed according to the age-stage, two-sex life table theory. The results showed that the nutritional status of F0 differentially affects the growth, development, and reproduction of F1. The F1 offspring of F0 adult C. sasakii fed with 10 g·L-1 sucrose had significantly higher life table parameters than those of other treatments (intrinsic rate of increase, r = 0.0615 ± 0.0076; finite rate of increase, λ = 1.0634 ± 0.0081; net reproductive rate, R0 = 12.61 ± 3.57); thus, 10 g·L-1 sucrose was more suitable for raising C. sasakii in the laboratory than other treatments. This study not only provides clear evidence for the implications of altering F0 nutritional conditions on the fitness of F1 in insects, but also lays the foundation for the implementation of feeding technologies within the context of a well-conceived laboratory rearing strategy for C. sasakii.

Comparison of the effect of tea shoots during different seasons in Arma chinensis (Hemiptera: Pentatomidae) reared on Ectropis grisescens (Lepidoptera: Geometridae) pupae.

In this study, we compared the growth, development, and fecundity of Arma chinensis (Fallou) reared on pupae of the geometrid Ectropis grisescens Warren fed on tea shoots during different seasons of the year. The raw data on life history were analyzed using the age-stage, 2-sex life table. When reared on spring or winter geometrid pupae, the duration of the immature stage of A. chinensis was significantly longer than in those produced during the summer or autumn. The survival rate of immature A. chinensis reared on autumn geometrid pupae was significantly lower compared to other treatments. Reproductive diapause was observed in adult A. chinensis reared on winter geometrid pupae. The adult preoviposition period (APOP), total preoviposition period (TPOP), and total longevity were significantly longer in A. chinensis reared on winter pupae than in the other treatments. The fecundity of A. chinensis reared on spring geometrid pupae was significantly lower than in the other treatments. The higher intrinsic rate of increase of the A. chinensis reared on summer pupae (r = 0.0966 day-1) and autumn pupae (r = 0.0983 day-1) resulted in higher fecundity, shorter immature duration, and shorter TPOP compared to the winter and spring populations. These findings can be utilized to enhance and sustain biological control of E. grisescens in tea plantations.

Safety evaluation and sublethal effect of broflanilide on Aphidius gifuensis.

Ensuring the safety of insecticides to natural enemy insects of pests is crucial for integrating chemical and biological control strategies. Broflanilide, a novel meta-diamide insecticide, exhibits high insecticidal activity against Myzus persicae (Sulzer) (Hemiptera: Aphididae). To integrate chemical and biological control against M. persicae, we assessed the toxicity of broflanilide to Aphidius gifuensis, and evaluated its safety and sublethal effects. The LC10, LC25, and LC50 values of broflanilide against A. gifuensis were 0.733 mg/L, 1.613 mg/L, and 3.852 mg/L, respectively. The selectivity toxicity ratio of broflanilide to A. gifuensis was 1.516, indicating higher toxicity to M. persicae compared to A. gifuensis. The risk quotient of broflanilide to A. gifuensis adults was 6.18. The percent reduction in the emergence of the parasitoid pupae was -1.15, with a risk grade of 1. The sublethal concentration of broflanilide had no significant influence on the intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and mean fecundity (F) of A. gifuensis in the F1 generation. The mean generation time (T) increased by 0.51 days and 0.39 days in the LC10 and LC25 treatments, respectively; the difference between LC10 treatment and the control was significant, while the difference between LC25 treatment and the control was not significant. The results showed that the sublethal concentration of broflanilide did not have a significant inhibitory effect on the population growth of A. gifuensis.

Cost-effectiveness evaluation of mass-rearing Cadra cautella (Lepidoptera: Pyralidae) based on harvest theory for sustainable alternative prey production.

Cadra cautella (Walker) (Lepidoptera: Pyralidae) is a pest in barn, and its eggs are often utilized as an alternative prey or as hosts for mass production of insect predators and parasitoids. To aid in developing a mass-rearing system for C. castella, the suitability of using an artificial diet based on brown rice flour and whole brown rice was compared using the age-stage, 2-sex life table. Compared with those reared on brown rice, the insects reared on an artificial diet had a shorter preadult period (32.08 vs 37.38 d), higher fecundity (468.14 vs 356.20 eggs/female), greater intrinsic rate of increase (0.1509 vs 0.1145 d-1), and higher net reproductive rate (199.28 vs 103.52 offspring). Small populations were required to rear the moth on an artificial diet to achieve the same daily production of C. cautella. Still, the food expense was only 60.2% of that of C. cautella reared on brown rice. Approximately 99.44% of the eggs in each rearing procedure could be supplied as alternative prey for predators, with the remainder served to maintain the colonies for subsequent batches. Only eggs laid within 6 d would be utilized to ensure the high quality of alternative prey for the mass production of predacious bugs. Additionally, a multifunctional device was designed for moth rearing and egg collection, reducing labor input and minimizing health risks for workers coping with inhaled scales. To encourage the production of natural enemies, a cost-effective diet for maintaining a sustainable colony, and a system for daily egg-harvesting of alternative prey were proposed.

An evaluation of the growth, development, reproductive characteristics and pest control potential of three Trichogramma species on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

BACKGROUND: Tuta absoluta is an invasive alien species that has caused major losses in the Chinese tomato industry. Investigating the growth, development, reproduction and pest control effects of three native species of Trichogramma species on the eggs of T. absoluta could provide an ecological tool for preventing and controlling T. absoluta in China. In this study, we constructed age-stage two-sex life tables for three common species of Trichogramma and determined their relative abilities to control T. absoluta in greenhouse insect cages, thus allowing us to identify the species with the most effective ability to prey on T. absoluta eggs. RESULTS: Analysis showed that the net reproductive rate (R0), gross reproduction rate (GRR) and intrinsic rate of increase (r) of Trichogramma ostriniae were the highest of the three species at 22.85, 32.58 and 1.31, respectively. In the presence of 10 eggs and under ideal conditions, T. ostriniae, Trichogramma chilonis, and Trichogramma dendrolimi produced 9451.04, 5199.56, and 1902.95 offspring, respectively. Following the release of T. ostriniae, tomato leaves incurred a damage index of 1 after the first week, while the number of T. absoluta reduced to 24.60 individuals by week 10 (8.75% of the control treatment). CONCLUSION: Of the three species of Trichogramma tested in this study, T. ostriniae exhibited the best growth, development, reproductive capacity and predatory ability against T. absoluta, and has broad application prospects. © 2024 Society of Chemical Industry.

The intrinsic growth rate as a predictor of population viability under climate warming.

1. Lately, there has been interest in using the intrinsic growth rate (rm) to predict the effects of climate warming on ectotherm population viability. However, because rm is calculated using the Euler-Lotka equation, its reliability in predicting population persistence depends on whether ectotherm populations can achieve a stable age/stage distribution in thermally variable environments. Here, we investigate this issue using a mathematical framework that incorporates mechanistic descriptions of temperature effects on vital rates into a stage-structured population model that realistically captures the temperature-induced variability in developmental delays that characterize ectotherm life cycles. 2. We find that populations experiencing seasonal temperature variation converge to a stage distribution whose intra-annual pattern remains invariant across years. As a result, the mean annual per capita growth rate also remains constant between years. The key insight is the mechanism that allows populations converge to a stationary stage distribution. Temperature effects on the biochemical processes (e.g. enzyme kinetics, hormonal regulation) that underlie life-history traits (reproduction, development and mortality) exhibit well-defined thermodynamical properties (e.g. changes in entropy and enthalpy) that lead to predictable outcomes (e.g. reduction in reaction rates or hormonal action at temperature extremes). As a result, life-history traits exhibit a systematic and predictable response to seasonal temperature variation. This in turn leads to temporally predictable temperature responses of the stage distribution and the per capita growth rate. 3. When climate warming causes an increase in the mean annual temperature and/or the amplitude of seasonal fluctuations, the population model predicts the mean annual per capita growth rate to decline to zero within 100 years when warming is slow relative to the developmental period of the organism (0.03-0.05°C per year) and to become negative, causing population extinction, well before 100 years when warming is fast (e.g. 0.1°C per year). The Euler-Lotka equation predicts a slower decrease in rm when warming is slow and a longer persistence time when warming is fast, with the deviation between the two metrics increasing with increasing developmental period. These results suggest that predictions of ectotherm population viability based on rm may be valid only for species with short developmental delays, and even then, only over short time-scales and under slow warming regimes.