Density-Dependent Demography and Mass-Rearing of Carposina sasakii (Lepidoptera: Carposinidae) Incorporating Life Table Variability

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.

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.

Comparative demographics, population projections and egg maturation patterns of four eupelmid egg parasitoids on the factitious host Antherae pernyi

BACKGROUND

The genera Anastatus and Mesocomys (both Hymenoptera: Eupelmidae) are important solitary egg endoparasitoids as biological control agents for lepidopterous and hemipterous pests worldwide. Here, we comparatively evaluated the demographic parameters of four important eupelmid egg parasitoids (Anastatus fulloi, A. japonicus, Mesocomys albitarsis and M. trabalae) reared on the factitious host eggs of the Chinese oak silkworm Antheraea pernyi, using age-stage two-sex life tables, their population projections as well as egg maturation patterns.

RESULTS

Both the age-specific net reproductive rate (lx mx ) and reproductive value (vxj ) increased initially and then gradually decreased with increasing age in all four parasitoid species. Overall, the two Mesocomys species had higher survival rates at stable age-stage distribution, peak reproductive values, and intrinsic rates of increase than the two Anastatus species. Mesocomys albitarsis had the longest longevity, whereas A. japonicus had the longest oviposition days and mean generation time. The two Mesocomys species are thus projected to have faster population increase than the two Anastatus species. Adult females of all four parasitoid species emerged with only a few mature eggs (< 6 eggs) and most of their eggs were matured post-emergence (strict synovigeny). The estimated 90% of lifetime complement of reproduction (offspring) and realized days were 374 and 32 for A. japonicus, 337 and 22 for M. trabalae, 330 and 19 for M. albitarsis and 147 and 28 for A. fulloi.

CONCLUSION

Our results indicated that the two Mesocomys species have higher control capacity than the two Anastatus species. Provision of adult food for these strictly synovigenic parasitoids would be essential to prolong their lifespan and continuously produce eggs for parasitizing their hosts for mass rearing or augmentative biological control programs. © 2023 Society of Chemical Industry.

Life table construction for crapemyrtle bark scale (Acanthococcus lagerstroemiae): the effect of different plant nutrient conditions on insect performance

Crapemyrtle Bark Scale (Acanthococcus lagerstroemiae; CMBS) is an invasive pest species that primarily infest crapemyrtles (Lagerstroemia spp.) in the United States. Recent reports have revealed the dire threat of CMBS to attack not only crapemrytles but also the U.S. native species with expanded host plants such as American beautyberry (Callicarpa spp.) and Hypericum kalmianum L. (St. Johnswort). A better understanding of plant-insect interaction will provide better and environmental-friendly pest management strategies. In this study, we constructed the first comprehensive life table for CMBS to characterize its biological parameters, including developmental stages, reproductive behavior, and fecundity. The indirect effects of three plant nutrient conditions (water, 0.01MS, and 0.1MS) on CMBS populations were examined using the age-stage, two-sex life table. The demographic analyses revealed that the plant nutrient conditions had significantly altered CMBS development in terms of the intrinsic rate of increase (r), the finite rate of increase (λ), the net reproductive rate (R₀), and mean generation time (T). Higher r, λ, and R₀ were recorded under nutrient-deficient conditions (water), while CMBS reared on plants with healthier growing conditions (0.1MS) had the most prolonged T. Overall, CMBS shows better insect performance when reared on plants under nutrient-deficient conditions.

Comparison of Artificial Diets and Natural Prey for Mass Rearing of Orius strigicollis (Hemiptera: Anthocoridae) Using Demographic Characteristics to Optimize Cost-Efficiency

Orius strigicollis (Poppius) has been commonly released to control minute pests due to its remarkable foraging and predation ability. Despite decades long history of mass-rearing using eggs of Cadra cautella Walker (Lepidoptera: Pyralidae) as food, the cost of this food impeded the predator's marketing potential. Finding cost-effective artificial diets for mass rearing programs is, therefore, the key to promote the use of this generalist predator in practice. The aim of this study was to explore suitability of alternative diets for mass rearing of this predator, using the age-stage, two-sex life table. Eight recipes of artificial diets were initially screened, and the candidate diets were subsequently evaluated using the population parameters of O. strigicollis. The highest intrinsic rate of increase was found in the O. strigicollis fed on the meridic combined Diet 1, where nymphs and adults were fed different diets. However, the intensive period of oviposition by females reared on oligidic Diet O3 contributed to the shorter rearing period (42 d) and lower rearing cost than that on combined Diet 1 (60 d). Besides, with the harvest rate of 0.919, the minimal population size of 10,774 individuals with a stable age-stage distribution was needed for daily harvesting 1,000 third instars of O. strigicollis reared on Diet O3 at the rearing cost of 0.295 NTD (new Taiwanese dollar) per nymph. Thus, Diet O3 was determined to be the most cost-effective recipe for the mass-rearing of O. strigicollis among those used in this study.

Comparative Performance of the Fall Armyworm (Lepidoptera: Noctuidae) Reared on Various Cereal-Based Artificial Diets

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera, Noctuidae), is a polyphagous and highly destructive agricultural pest that invaded mainland China in 2019. To facilitate research on this pest, it is important to formulate and formalize a suitable artificial diet based on local ingredients. In this study, the life histories of fall armyworm reared on corn leaves and four artificial diets were recorded. The four artificial diets used were: soybean and sucrose-based (SS), soybean and wheat germ-based (SW), chickpea and wheat germ-based (CPW), and corn and soybean-based (CNS). The intrinsic rates of increase were 0.1957, 0.1981, 0.1816, 0.1748, and 0.1464 per day in the fall armyworm populations fed corn leaves, CNS, SW, CPW, and SS, respectively. The highest fecundity (F = 1225.4 eggs per female) and net reproduction rate (R0 = 544.7 offspring per individual) were observed for the fall armyworm reared on the CNS diet. Moreover, the developmental rate, survival rate, and fecundity were used to calculate the projection of the population growth. Projection results showed that the fall armyworm populations can increase considerably faster when fed the CNS diet compared with the other diets. In addition, the mass-rearing system showed that the most efficient and economical strategy would be to rear the fall armyworm on the CNS diet. The results indicated that the CNS diet was the most suitable diet for the fall armyworm mass rearing.

Demography and Mass Rearing of Amblyseius swirskii (Acari: Phytoseiidae) Fed on Two Species of Stored-Product Mites and Their Mixture

Amblyseius swirskii (Athias-Henriot) is one of the most important biological control agents and has been used in many countries. In this study, the suitability of Carpoglyphus lactis L. (Acari: Carpoglyphidae), Tyrophagus putrescentiae (Schrank), and their mixture for rearing A. swirskii was evaluated by using the two-sex life table. When reared on C. lactis, the durations of egg, deutonymph, total preadult, total preoviposition period, and adult male longevity of A. swirskii (1.95, 1.17, 6.13, 6.30, and 10.09 d, respectively) were significantly shorter than those reared on the mixed prey (2.05, 1.45, 6.55, 6.64, and 15.56 d, respectively). When reared on the mixed prey, however, the fecundity (110.21 eggs/female) of A. swirskii was significantly higher in comparison with those solely reared on C. lactis (82.17 eggs/female) or on T. putrescentiae (98.23 eggs/female). When reared on the mixed diet, the intrinsic rate of increase (r = 0.3792 d-1), finite rate of population increase (λ = 1.4611 d-1), and net reproductive rate (R0 = 79.69 offspring) of A. swirskii were significantly higher than those on single-species diets. For a daily production of 10,000 eggs of A. swirskii, a smaller population size (2,626 individuals) of A. swirskii is needed when reared on the mixed diet, in contrast to the 4,332 individuals on C. lactis and 3,778 individuals on T. putrescentiae. The population projection and mass-rearing analysis based on life table showed that the mixed diet was the most suitable and economical diet for the mass-rearing of A. swirskii.

Sublethal effects of three insecticides on fitness parameters and population projection of Brevicoryne brassicae (Hemiptera: Aphididae)

The cabbage aphid, Brevicoryne brassicae (L.), is one of the major insect pests of cole crops in Iran. In most instances outbreaks are normally kept under control by application of insecticides. In this study, the sublethal effects (LC30) of three insecticides, acetamiprid, buprofezin, and thiamethoxam-lambda cyhalothrin, (TLC) were evaluated on the population growth rate of the progeny of insecticide-treated cabbage aphid adults. The age-stage, two-sex life table method was used to analyze the collected data. The results indicated that the insecticide applications affected the duration of the preadult period, their survival, reproduction, life span/longevity, and consequently, the population growth rate of the F1 generation. The indicators of the greatest sublethal effects were noted in the progeny of the TLC-treated adults. These included the lowest net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ), and the longest mean generation time (T). The highest values of r, λ, R, and the lowest value of T occurred in the control group followed by, in order, the acetamiprid and buprofezin groups. These research findings will be useful in the development and implementation of future aphid management programs.

Demography of Thrips palmi (Thysanoptera: Thripidae) Reared on Brassica oleracea (Brassicales: Brassicaceae) and Phaseolus vulgaris (Fabales: Fabaceae) With Discussion on the Application of the Bootstrap Technique in Life Table Research

In order to contrast the fitness of Thrips palmi Karny reared on two of its hosts plants, Brassica oleracea L. leaves and Phaseolus vulgaris L. beans, life tables were constructed for T. palmi individuals reared on the two hostplants at 25°C using the age-stage, two-sex life table. The durations of the egg, first instar larva, pupa, and total immature stages of T. palmi reared on P. vulgaris were significantly longer than those reared on B. oleracea, whereas the adult preoviposition period, female adult longevity, and number of oviposition days of T. palmi reared on B. oleracea were significantly longer/greater than those on P. vulgaris. The fecundity (F) of T. palmi reared on B. oleracea (159.71 offspring/female) was significantly higher than in females reared on P. vulgaris (F = 122.98 offspring/female) despite the higher proportion of female adults that emerged on P. vulgaris. Although there were no significant differences in the intrinsic rate of increase (r), finite rate (λ), net reproductive rate (R0), and mean generation time (T) between the two populations, computer projection showed that the T. palmi population will increase faster when reared on B. oleracea than on P. vulgaris. Our results demonstrate that population projection based on life table data is potentially an important tool in pest management. Furthermore, we used the bootstrap technique to demonstrate the variable effect that survival rate and fecundity at different ages can have on population parameters.