Population growth of Tetranychus truncatus (Acari: Tetranychidae) on different drought-tolerant potato cultivars

Tetranychus truncatus Ehara (Acari: Tetranychidae) has become one of the major phytophagous pests in China in recent years, and is found on a wide range of host plants. However, little information is available on the population performance of this arthropod pest on potatoes. In this study, we explored the population growth of T. truncatus on two drought-tolerant potato (Solanum tuberosum L.) cultivars under laboratory conditions using the age-stage, two-sex life table. Tetranychus truncatus completed its entire life history on both potato cultivars tested, Holland 15 and Longshu 10. There was no significant difference between two potato cultivars in developmental duration. Tetranychus truncatus had shorter adult longevity (20.61 days), adult female longevity (20.41 days), and total female longevity (33.66 days) on Longshu 10 than Holland 15 (21.16 days, 21.19 days, and 34.38 days, respectively). However, it exhibited a higher preadult survival rate, higher fecundity (F = 88.32 eggs per female), and relatively higher population parameters when reared on Longshu 10 than on Holland 15 (F = 75.70 eggs per female). Growth projection also showed that the population size of T. truncatus on Longshu 10 (expand 750-fold) was larger than that on Holland 15 (expand 273-fold) after 60 days. Our results demonstrate that the drought-sensitive potato variety, Holland 15, is relatively resistant to T. truncatus compared with the drought-tolerant variety, Longshu 10, and suggest that T. truncatus exhibited a trade-off between longevity and reproduction on both potato cultivars. Our findings provide information on population prediction, which may aid the management of this pest mite species of potatoes.

Sublethal Effects of Beauveria bassiana Strain BEdy1 on the Development and Reproduction of the White-Backed Planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae)

Rice (Oryza sativa) is the most important food crop all over the world, while white-backed planthopper (WBPH), Sogatella furcifera (Horváth) (Hemiptera: Delphacidae) is an important pest causing rice yield reduction. The purpose of this study is to evaluate the sublethal effects of strain BEdy1 Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) on S. furcifera using the two-sex life table analytical method, compare the life tables of the F0 and F1 generations of WBPHs which were treated with sublethal concentrations (LC10, LC25) of B. bassiana BEdy1 with a control group. The results showed that the duration of the egg, 4th-instar and 5th-instar nymph, pre-adult, total pre-oviposition (TPOP) and mean generation time (T) for the LC25 treatment were significantly longer than those of the control and LC10 treatment. However, the duration of the adult, the longevity of male and female adults and the oviposition days of female adults for the LC25 treatment were significantly shortened. The fecundity of female adults, intrinsic rate of increase (r), net reproductive rate (R0) and finite rate of increase (λ) for the LC25 treatment were significantly decreased compared with those of other treatments. The duration of the egg and pre-adult stage for the LC10 treatment were longer than those of the control group, but the population parameters showed no significant difference. Therefore, the LC25 of B. bassiana BEdy1 can inhibit the population growth of S. furcifera.

Diversity of endosymbionts in camellia spiny whitefly, Aleurocanthus camelliae (Hemiptera: Aleyrodidae), estimated by 16S rRNA analysis and their biological implications

Camellia spiny whitefly, Aleurocanthus camelliae (Hemiptera: Aleyrodidae), is a major pest in tea, which poses a serious threat to tea production. Similar to many insects, various bacterial symbioses inside A. camelliae may participate in the reproduction, metabolism, and detoxification of the host. However, few reports included research on the microbial composition and influence on A. camelliae growth. We first applied high-throughput sequencing of the V4 region in the 16S rRNA of symbiotic bacteria to study its component and effect on the biological trait of A. camelliae by comparing it with the antibiotic treatment group. The population parameters, survival rate, and fecundity rate of A. camelliae were also analyzed using the age-stage two-sex life table. Our results demonstrated that phylum Proteobacteria (higher than 96.15%) dominated the whole life cycle of A. camelliae. It unveiled the presence of Candidatus Portiera (primary endosymbiont) (67.15-73.33%), Arsenophonus (5.58-22.89%), Wolbachia (4.53-11.58%), Rickettsia (0.75-2.59%), and Pseudomonas (0.99-1.88%) genus. Antibiotic treatment caused a significant decrease in the endosymbiont, which negatively affected the host's biological properties and life process. For example, 1.5% rifampicin treatment caused a longer preadult stage in the offspring generation (55.92 d) compared to the control (49.75d) and a lower survival rate (0.36) than the control (0.60). The decreased intrinsic rate of increase (r), net reproductive rate (R ₀), and prolonged mean generation time (T) were signs of all disadvantageous effects associated with symbiotic reduction. Our findings confirmed the composition and richness of symbiotic bacteria in larva and adult of A. camelliae by an Illumina NovaSeq 6000 analysis and their influence on the development of the host by demographic research. Together, the results suggested that symbiotic bacteria play an important role in manipulating the biological development of their hosts, which might help us for developing new pest control agents and technologies for better management of A. camelliae.

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.

Age-Stage, Two-Sex Life Table and Functional Response of Amblyseius orientalis (Acari: Phytoseiidae) Feeding on Different Nutrient Sources

Amblyseius orientalis Ehara is a predatory mite that belongs to the family Phytoseiidae. It is mainly found in Jiangxi, Shanghai, Guangdong, and other areas of China. Although A. orientalis is a dominant predatory mite species in China and is also important for agriculture and biological control, not many studies have investigated it. Thus, research on A. orientalis is necessary. However, its application in biological control is hindered by the absence of techniques for the mass rearing of A. orientalis in captivity. We conducted experiments to determine the growth, development, reproduction, and functional response of A. orientalis in this study by indoor single-head rearing at 25 ± 1 °C, 65 ± 5% relative humidity, and a photoperiod of a 16 h:8 h light/dark cycle under laboratory conditions. The results of the age stage, two-sex life table showed that the individuals in the pollen + yeast and pollen + yeast + sucrose groups had significantly higher oviposition period, fecundity, net reproductive rate (R₀), and gross reproduction rate (GRR) than those in the pollen group. The results of the function response showed that the pollen + yeast + sucrose group was the most favorable for captive breeding of A. orientalis and had the best predatory ability along with rejuvenation and recovery ability. The results of the study provided a theoretical basis for indoor rearing, propagation, and utilization of A. orientalis.

Effects of Nano-Graphene Oxide on the Growth and Reproductive Dynamics of Spodoptera frugiperda Based on an Age-Stage, Two-Sex Life Table

The development and reproduction of the fall armyworm (FAW), Spodoptera frugiperda, which were reared on artificial diets containing nano-graphene oxide (GO), were determined based on age-stage, two-sex life table analysis. The results showed that GO had adverse effects on FAWs. Compared with the control, the duration of the egg stage and first, second, and sixth instar larval stages increased with increasing GO concentrations; however, the lifespan of male and female adults decreased with increasing GO concentrations. Weights of FAW pupae that were supplied with GO-amended diets increased by 0.17-15.20% compared to the control. Intrinsic growth, limited growth, and net reproductive rates of FAWs feeding on GO supplemented diets were significantly lower than the control, while mean generational periods (0.5 mg/g: 38.47; 1 mg/g: 40.38; 2 mg/g: 38.42) were significantly longer than the control. The expression of genes encoding vitellogenin (Vg) and vitellogenin receptor (VgR) expression was abnormal in female FAW adults feeding on GO-amended diets; the number of eggs laid decreased relative to the control, but Vg expression increased. In conclusion, GO prolonged the developmental period of FAWs, decreased fecundity, and led to a decline in the population size. The study provides a basis for the rational use of GO as a pesticide synergist for FAW control.

Demographic Characteristics and Population Simulation of Newly Invasive Fall Armyworm on Arachis hypogaea (Fabales: Fabaceae) and Dominant Green Manure Plant in Taiwan

Spodoptera frugiperda (J.E. Smith) is a severe and fast-spreading pest of numerous agro-economic crops, including miscellaneous, vegetables, and green manure crops. Understanding pest ecology represents a core component in integrated pest management decision-making. In Taiwan, peanut (Arachis hypogaea L.) is an important miscellaneous crop, whereas sesbania (Sesbania roxburghii Merr.) is the most frequently used green manure crop. To improve the S. frugiperda management in Taiwan, the demographic characteristics and population simulation of this pest reared on peanut and sesbania leaves were analyzed using the age-stage, two-sex life table theory. The intrinsic rate of increase, finite rate of increase, and net reproductive rate of S. frugiperda were higher when reared on peanut (0.1625 d-1, 1.1764 d-1, 264.9 offspring) than on sesbania (0.0951 d-1, 1.0997 d-1, and 30.3 offspring). Population projection of S. frugiperda on peanut demonstrated that this crop is a more suitable host plant than sesbania. Yet, this suboptimal host still assures an increasing trend of more than 357-fold individuals in 75 d, from the initial cohort of 10 eggs. Our data suggest that green manure plants in fallowing fields may support the pest's survival all year round, and may be responsible for a successful establishment and unexpected outbreaks of this invasive pest on the neighboring crops in Taiwan. Our study thus highlights the importance of assessing the population dynamics and areawide pest management of an invasive polyphagous pest on a noneconomic crop to mitigate the potential risk of reinfestation and thus outbreaks.

[Effects of temperature on growth, survival, and reproduction of Conogethes punctiferalis feeding on corn kernels]

In order to examine the effects of temperature on the growth, survival, and reproduction of Conogethes punctiferalis (Lepidoptera: Crambidae) feeding on corn kernels, the life table parameters of C. punctiferalis at 21, 24, 27, 30 ℃ were calculated based on the age-stage two-sex life table theory, and then population dynamics of C. punctiferalis was projected based on these parameters. The results showed that the life cycles of the pest could be finished at all the four temperature treatments. The developmental duration of each stage shortened with increasing temperature, and there were significant differences among treatments. The highest fecundity (116.7 eggs per female), preadult survival rate (84.7%), and proportion of female (0.46) were observed at 24 ℃. The intrinsic rates of increase at 24, 27, 30 ℃ were 0.1059, 0.1101, and 0.1045 d^-1, respectively. The finite rates of increase were 1.1117, 1.1164, and 1.1102 d^-1, respectively. There was no significant difference among the three treatments, but the r and λ values were significantly higher than those at 21 ℃. The net reproductive rates (R₀) at 21, 24, 27, 30 ℃ were 17.3, 53.7, 36.9, and 19.8, respectively. R₀ at 24 ℃ was the highest. It suggested that survival rates, fecundities and female proportions of C. punctiferalis population were high at 24-27 ℃, which was the suitable temperature range for its growth, survival, and reproduction.

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.

Yacon as an alternative host plant for Encarsia formosa mass-rearing: validating a multinomial theorem for bootstrap technique in life table research

BACKGROUND

Yacon (Smallanthus sonchifolius) is a broadleaf host plant suitable for rearing the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Here, the possibility of using yacon as an alternative host plant for production of the parasitoid, Encarsia formosa Gahan, one of the most important natural enemies of whiteflies, was explored. Data on the demographic characteristics, parasitism rate, and host-feeding rate were collected and analyzed using the TWOSEX-MSChart, CONSUME-MSChart, and TIMING-MSChart computer programs, and then contrasted with comparable data from the more commonly utilized host plant, tobacco.

RESULTS

Higher fecundity (F) (190.13 eggs/female) and more oviposition days (O_d ) (16.60 days) were observed in E. formosa when yacon was used as the host plant for rearing T. vaporariorum, compared with when tobacco was used (F = 150.13 eggs/female, O_d = 15.27 days). The intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R₀ ) were significantly higher in E. formosa parasitizing T. vaporariorum reared on yacon compared with those parasitizing tobacco-reared T. vaporariorum. Furthermore, the net host-feeding rate (C₀ = 40.87 prey/parasitoid), net killing rate (Z₀ = 239.73 prey/parasitoid), and finite killing rate ( υ  = 0.2560/day) for E. formosa on yacon-reared whiteflies were significantly higher than those from tobacco-reared whiteflies.

CONCLUSION

Our results showed that yacon is more suitable than tobacco as a host plant for mass-rearing E. formosa for biological control programs to manage whiteflies. An innovative application of the multinomial theorem for calculating the exact probability of bootstrap samples in life table research was also introduced. © 2021 Society of Chemical Industry.

Consuming Parasitized Aphids Alters the Life History and Decreases Predation Rate of Aphid Predator

Simple Summary

Intraguild predation is a common phenomenon between predators and parasitoids. Despite numerous studies on the performance of intraguild predators by consuming on intraguild prey, the entire two-sex life table and predation rates of intraguild predators fed on intraguild prey remain poorly known. In this study, we investigated the effect of parasitized Myzus persicae aphids by Aphidius gifuensis (Ashmead) on the entire two-sex life table and predation rates of Aphidoletes aphidimyza (Rondani). Our results showed that feeding on parasitized aphids did not influence the survival rates of immature A. aphidimyza individuals but significantly increased the development time of A. aphidimyza individuals and markedly reduced their longevity. The predation rate of immature A. aphidimyza individuals was also adversely affected by feeding on parasitized aphids. These results provide basic data for the potential use of A. aphidimyza in combination with A. gifuensis in M. persicae control programs.

Abstract

Intraguild predation interactions have substantial theoretical and practical implications for the dynamics of natural competitor populations used for biological control. Intraguild predation on parasitized aphids not only has a direct, negative effect on the parasitoid species, but it may indirectly influence the predator’s development, survival, reproduction and predation rates. In this study, we used two-sex life table theory, life table parameters and predation rates of Aphidoletes aphidimyza (Rondani) to compare when its populations fed on aphids (Myzus persicae Sulzer) (Hemiptera: Aphididae) that were either unparasitized or parasitized by Aphidius gifuensis (Ashmead) (Hymenoptera: Braconidae). Our results showed that individuals of A. aphidimyza were capable of completing their development and attaining maturity when they fed on parasitized aphids. Although feeding on parasitized aphids did not influence the survival rates of immature A. aphidimyza, it did significantly slow their development and extended their longevity, thereby reducing the fecundity and predation rates of A. aphidimyza. These findings may be pivotal for better understanding the sustained coexistence of predators with parasitoids in the biological control of aphids.

Age-Stage, Two-Sex Life Tables of the Predatory Mite Cheyletus Malaccensis Oudemans at Different Temperatures

Cheyletus malaccensis Oudemans is a predatory mite inhabiting grain depots in China. The relationship between temperature and the population growth rate of C. malaccensis is useful for predicting its population dynamics. Age-stage, two-sex life tables of the predator, C. malaccensis, reared on Acarus siro were constructed under laboratory conditions at 22, 24, 28, 30, and 32 °C, 75% relative humidity, and a 0:24 h (L:D) photoperiod. Increasing temperature shortened the development time of the immature stages. The complete generation time of C. malaccensis ranged from 11.10 d to 27.50 d. Life table parameters showed that 28 °C was the optimum temperature for the growth and development of C. malaccensis; populations could increase rapidly at this temperature. The highest net reproductive rate (R₀ = 290.25) and highest fecundity (544.52) occurred at 28 °C. Temperature significantly affected the intrinsic rate of increase (r), fecundity, and finite rate of increase (λ). The values of age-specific fecundity (high to low) were 28 °C > 24 °C > 30 °C > 32 °C > 22 °C, while the values of age-stage-specific fecundity had the same trend.

Heat sensitivity of eggs attributes to the reduction in Agasicles hygrophila population

Agasicles hygrophila has been introduced worldwide as a control agent for the invasive weed Alternanthera philoxeroides. However, global warming has potential impact on its controlling efficacy. The aim of this research was to explore the primary factors responsible for the greatly reduced A. hygrophila population in hot summers. To imitate the temperature conditions in summers, different developmental stages of A. hygrophila were treated with high temperatures from 32.5 °C to 45 °C for 1-5 h. Based on the survival rate, the heat tolerance of each developmental stage was ranked from lowest to highest as follows: egg, 1st, 2nd, 3rd instar larva, adult and pupa. Eggs showed the lowest heat tolerance with 37.5 °C as the critical temperature affecting larval hatching. Heat treatment of the A. hygrophila eggs at 37.5 °C for 1 h decreased the hatch rate to 24%. Our results indicated that when compared with the control at 25 °C, 1 h treatment at 37.5 °C prolonged the duration of the egg stage, shortened the duration of oviposition and total longevity, and changed the reproductive pattern of A. hygrophila. The net reproductive rate, intrinsic rate and finite rate were all significantly reduced. The results suggest that low heat tolerance of the eggs was the major factor responsible for the reduction of A. hygrophila populations, and the key temperature was 37.5 °C. Therefore, appropriate measures should be taken to protect eggs in order to maintain the efficacy of A. hygrophila in the biological control of A. philoxeroides in hot summers.

Effect of Temperature and CO2 on Population Growth of South American Tomato Moth, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) on Tomato

The effects of different temperatures (26, 28, 30, and 32°C) and CO2 concentrations (380 and 550 ppm) on the life table of Tuta absoluta were evaluated. The life history raw data of T. absoluta were analyzed by using the age-stage, two-sex life table. Results showed that increase in temperature reduced the larval developmental time of T. absoluta, whereas the elevated CO2 concentration (eCO2) extended the larval developmental time. Highest fecundity rate was recorded at 30°C at ambient CO2 (aCO2) condition (88.10 eggs). Total fecundity significantly reduced under eCO2 at 28°C and 30°C. There was a 5-10% higher mortality observed under eCO2 than aCO2 condition. With rise in temperature from 26-30°C, T. absoluta reared under eCO2 condition showed lower net reproductive rate, intrinsic and finite rate of increase in comparison to aCO2. However, these parameters started decreasing at 32°C under both eCO2 and aCO2 conditions.

Linking Demography and Consumption of Henosepilachna vigintioctopunctata (Coleoptera: Coccinellidae) Fed on Solanum photeinocarpum (Solanales: Solanaceae): With a New Method to Project the Uncertainty of Population Growth and Consumption

Because life tables are capable of providing the most comprehensive description on the survival, stage differentiation, and the reproduction of animal populations, they can be considered as the bases of population ecology and pest management. Researchers concerned with studies involving life tables inevitably face the problem of describing the variabilities that occur in the survival, stage differentiation, and fecundity data. Finding a means to include these variabilities in population projections concerning pest management may be problematic. Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae) is a pest of many plant species in Asia, including cultivated crops, ornamentals, and wild plants. The raw life history data (survival, stage differentiation, and fecundity) and consumption rate of both sexes of H. vigintioctopunctata reared on Solanum photeinocarpum Nakamura et Odashima (Solanales: Solanaceae) were collected in the laboratory and analyzed based on the age-stage, two-sex life table theory. The intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), mean generation time (T), and net consumption rate (C0) of H. vigintioctopunctata were 0.1312 d-1, 1.1402 d-1, 603.5 offspring, 48.8 d, and 77.8 cm2, respectively. By using the bootstrap technique with 100,000 samples, we demonstrated that the life tables constructed based on the 2.5th and 97.5th percentiles of R0 and λ can be used to describe the variabilities found in the survival and fecundity curves and to project the uncertainty of population growth.

Host Plant-Herbivore-Predator Interactions in Chrysoperla carnea (Neuroptera: Chrysopidae) and Myzus persicae (Homoptera: Aphididae) on Four Plant Species Under Laboratory Conditions

The common green lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), is a well-known biocontrol agent. The current study examined host plant-herbivore-predator interactions with C. carnea and Myzus persicae on four host plants (peach, almond, pepper, and potato). The experiments were carried out at 25 ± 1°C and 65 ± 5% RH at a photoperiod of 16:8 (L:D) h). Duration of the preadult growth period, adult longevity, fecundity, and population growth parameters were analyzed based on the age-stage, two-sex life table theory. The shortest and longest preadult developmental times of the predator were observed on the peach and potato, respectively. The highest and lowest predation rate, oviposition period, and male and female longevity of predator were also observed on the peach and potato, respectively. The lowest intrinsic rate of increase (r) and finite rate of increase (λ) were observed on the potato (0.1087 and 1.11 d-1, respectively) and the highest on the peach (0.1460 and 1.15 d-1, respectively). The maximum and minimum mean generation times (T) were 41.84 and 35.59 d in the potato and peach, respectively. Overall, peach was found to be a more appropriate host than the other host plants for development and predation fitness of C. carnea. These findings reveal that information on tritrophic interactions and subsequent life table evaluation of natural enemies improves integrated pest management programs.

Comparison of Demographic Parameters and Predation Rates of Orius strigicollis (Hemiptera: Anthocoridae) Fed on Eggs of Tetranychus urticae (Acari: Tetranychidae) and Cadra cautella (Lepidoptera: Pyralidae)

Orius strigicollis (Poppius) is an anthocorid bug with high foraging ability on thrips as well as on mites, and the bug has been considered as a potential biological control agent in Taiwan. Life table and predation studies of O. strigicollis fed on Cadra cautella (Walker) and Tetranychus urticae (Koch) eggs were conducted at 25 ± 1°C. Data were analyzed and compared using TWOSEX-MSChart and CONSUME-MSChart software. O. strigicollis fed on eggs of C. cautella, a substitute prey, showed significantly higher survival rate and developmental rate than individuals fed on their natural prey, T. urticae eggs. The fecundity of O. strigicollis fed on C. cautella eggs was, on average, 13.2 times higher than that of those fed on T. urticae eggs, despite of the fact that during the entire nymphal stage, the consumption rate of O. strigicollis on T. urticae eggs was ca. 9 times higher than on almond moth eggs The conversion rate (i.e., number of prey eggs needed to produce one predator egg) for this predatory bug reared on T. urticae eggs and almond moth eggs were 604.6 and 6.0, respectively, indicating that almond moth eggs served as an effective alternative prey for ensuring the predator's reproduction. This is the first study pertaining to the population parameters and predation rates of O. strigicollis using the age-stage two-sex approach to describe differences between O. strigicollis populations reared on natural and alternative preys. This information may be useful in mass rearing programs and field application involving this biological control agent.