Assessment of Non-Consumptive Predation Risk of Coccinella septempunctata (Coleoptera: Coccinellidae) on the Population Growth of Sitobion miscanthi (Hemiptera: Aphididae).

How the non-consumptive effects (NCEs) of predators influence the development, survival, fecundity, and population growth of prey has not been well documented, which is the primary consideration for the compatibility of prey with its natural enemies in agricultural ecosystems. We herein employed the age-stage, two-sex life table to examine the NCEs of the predator Coccinella septempunctata on the life-history traits and population growth of prey Sitobion miscanthi via caged predator (prey co-existing with caged predator) and caged prey (predator co-existing with caged prey) treatments with daily different exposure times (i.e., 0 h (control), 12 h, and 24 h). The results indicated that the predation risk of a caged predator could reduce the first nymphal duration and net reproductive rate (R0) of S. miscanthi at 12 h, and the first nymphal duration, preadult duration, and mean generation time (T) at 24 h. However, the predation risk of the caged prey resulted in the prolongation of the pre-adult development time and total pre-reproductive period (TPRP) as well as lowered the intrinsic rate of increase (r), finite rate of increase (𝜆), R0, life expectancy, and reproductive value of S. miscanthi after both 12 h and 24 h. Furthermore, the predation risk of both the caged predator and caged prey could increase the percent of winged morph at 24 h. These findings indicate that S. miscanthi could respond to the predation risk of the caged predator by either accelerating the developmental rate or reducing the net reproductive rate, while S. miscanthi might reduce their fitness in response to the predation risk of caged prey. Furthermore, S. miscanthi might also alter to winged morphs for dispersal under both of the above treatments. The findings obtained have practical ramifications for managing this economically important pest in wheat production with reduced insecticide applications.

The biological and physiological responses of Leptinotarsa decemlineata Say (Col. Chrysomelidae) to different potato cultivars.

BACKGROUND: The use of pest-resistant or less susceptible plant varieties is of great importance for integrated pest management programs. This study was conducted to evaluate the resistance of seven potato cultivars to a major pest, namely the Colorado potato beetle (CPB), by measuring its bio-physiological aspects. RESULTS: The longest developmental time and the lowest survival rate of CPB were detected on cultivar 'Manitou.' Although the larvae fed voraciously, the food conversion efficiency was the lowest on this cultivar leading to the lowest relative growth rate. Furthermore, larvae reared on Manitou had the lowest total protease activity and specific activity values of cathepsin B compared to the larvae reared on other cultivars. Additionally, the cluster analysis showed that the Manitou cultivar was the least suitable (partially resistant) CPB. Moreover, the results indicated that the protein content was the lowest in the Manitou cultivar; conversely, this cultivar was rich in polyphenol and flavonoid compared to Agria and Santae cultivars. CONCLUSION: The overall results in this study indicated that the Manitou cultivar might be a good candidate to be incorporated into integrated pest management programs. © 2022 Society of Chemical Industry.

Host Deprivation Effects on the Functional Response and Parasitism Rate of Habrobracon hebetor (Hymenoptera: Braconidae) on Ephestia elutella (Lepidoptera: Pyralidae) in the Laboratory.

Habrobracon hebetor (Say) is an important biological control agent for lepidopteran pests of stored products. In this study, the age-specific functional response, paralysis rate, and parasitism rate of H. hebetor under different host deprivation treatments (PC: without host deprivation, used as the control, P1d: host deprivation, but the host was removed after 1 d contact, and PW: host deprivation from beginning) were evaluated at different larval densities (5, 10, 20, 40, and 80) of the Ephestia elutella (Hübner) at 28 ± 1°C, 75 ± 5% RH and 16:8 h L:D. Ages of parasitoid females used were 2, 5, 10, and 20 d old. The logistic regression results indicated that the functional response of H. hebetor females under different host deprivation treatments was type II. The longest handling time was observed in 20-d old females, while the shortest handling time and highest maximum attack rate (T/Th) were estimated at the age of 2 d in all treatments. The paralysis and parasitism rates of H. hebetor were the highest at 2, 5, and 10-d old in all treatments. The results of this study suggest that H. hebetor females up to 10-d old can be used as an efficient biological control agent against E. elutella. The data of this study can also be used to predict the efficacy of different aged H. hebetor females in controlling E. elutella populations.

Temperature-Dependent Biological Control Effectiveness of Tamarixia radiata (Hymenoptera: Eulophidea) Under Laboratory Conditions.

The parasitism rate and host-feeding rate of Tamarixia radiata (Hymenoptera: Eulophidae), an ectoparasitoid of Diaphorina citri (Hemiptera: Liviidae), were evaluated at 20, 27.5, 30, and 35°C, at 70 ± 5% RH, and 14 h of photoperiod. The biological control efficacy of T. radiata was evaluated by linking the age-stage predation rate with the two-sex life table. The net host-feeding rate (C0) by T. radiata was 32.05, 54.40, 17.25, and 1.92 nymphs per female parasitoid at 20, 27.5, 30, and 35°C, respectively. The total net nymphs killing rate (Z0) was 103.02, 223.82, 72.95, and 6.60 nymphs per female parasitoid at 20, 27.5, 30, and 35°C, respectively. Noneffective parasitism rate was observed at 35°C because of high mortality at this temperature. Our results indicated that temperature had meaningful effects on parasitism and host-feeding rate parameters in the laboratory, and may affect biological control efficiency of the parasitoid in the field. The highest host-feeding rate and total biological control efficiency of T. radiata were recorded at 27.5°C. Most importantly, we found that host-feeding activity of the parasitoid is temperature-dependent, and changed across temperature regimes: the host-feeding rate increased as the temperature increased up to 30°C, started to decrease after this temperature and declined to its minimum level at 35°C. This information is valuable for developing biological control and integrated pest management techniques for Asian citrus psyllid management.

Host deprivation effects on population performance and paralysis rates of Habrobracon hebetor (hymenoptera: Braconidae).

BACKGROUND: Habrobracon hebetor (Hymenoptera: Braconidae) is a gregarious ectoparasitoid that attacks the larvae of several species of pyralid and noctuid moths. The reproduction and population dynamics of parasitoids in general are affected by host deprivation. However, how host deprivation affects H. hebetor is unknown. The effect of host deprivation on the parental generation, life table parameters, and the paralysis rate of the F1 generation of H. hebetor were evaluated using the age-stage, two-sex life table under laboratory conditions. RESULTS: The results indicated that the greatest longevity and the least lifetime fecundity of the F0 generation occurred after 19 days of host deprivation (PW-20 treatment). The life table parameters (intrinsic rate of increase, r; finite rate of increase, λ; and net reproductive rate, R0 ) and the paralysis rate parameters (net paralysis rate, C0 ; transformation rate, Qp ; stable paralysis rate, ψ; and finite paralysis rate, ω) of F1 individuals after PW-20 treatment were significantly higher than those of individuals subjected to the control treatment (no host deprivation). However, no difference was detected between the two host deprivation treatments: host deprivation after 1 day of host contact and immediate host deprivation (PW treatment). CONCLUSION: Our results demonstrated that the effectiveness of H. hebetor did not decrease even during host deprivation for 19 days. Meanwhile, it was observed that mass rearing of the parasitoid could be improved by providing 10 individuals of 5th instar larvae of Ephestia elutella (Lepidoptera: Pyralidae) with a 20% honey-water solution. © 2020 Society of Chemical Industry.

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.

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

Carposina sasakii Matsumura is one of the most destructive fruit-boring pests of pome and stone fruit trees in eastern Asia. Because larvae complete their development inside a single fruit, larval density per fruit is a critical factor in their survival, development, and fecundity. The effect of larval density was examined to determine the ideal density for devising an economic and sustainable mass-rearing system for harvesting of C. sasakii. Mass production of insects of the same age of a specific stage is not only important in biological control, but also in pheromone extraction, culturing of entomopathogenic nematodes and fungi, etc. Life history data for six larval densities (1-5, 6-10, 11-15, 16-20, 21-30, and 31-40 larvae/apple) were collected at 25.5 ± 0.5°C, 75.0 ± 5.0% RH, and a photoperiod of 15:9 (L: D) h. Data were analyzed using the age-stage, two-sex life table. The results showed that the highest preadult survival rate (42.00%), fecundity (104.70 eggs), and population parameters (intrinsic rate of increase r = 0.0718 d-1, net reproductive rate R0 = 23.03 eggs, and finite rate of increase λ = 1.0744 d-1) were observed at a density of 1-5 larvae/apple. However, when the rearing costs and production rate were considered, the density of 16-20 larvae/apple was the most economical for mass-rearing C. sasakii in order to achieve a daily harvest rate of 1,000 pupae (from 273 apples per day). To ensure the sustainability of the mass-rearing system, we included the life table variability in the harvesting strategy.

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.

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.

Demographic Parameters of Lipaphis erysimi (Hemiptera: Aphididae) on Different Cultivars of Brassica Vegetables.

Demographic parameters of the turnip aphid, Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae), which is a serious pest of Brassica crops worldwide, were evaluated on five major Brassica vegetables (three varieties of Brassica oleraceae (Linnaeus) (Brassicaceae: Brassicales); kohlrabi, cabbage and ornamental cabbage, and two subspecies of Brassica rapa (Linnaeus) (Brassicaceae: Brassicales); Chinese cabbage and bak choi). The study was carried out under laboratory conditions at 25 ± 1°C, 70 ± 5% RH and 16:8 (L:D) h. Preadult developmental time, survival rate, female longevity, reproduction, and life table parameters were evaluated according to the age-stage specific life table method. The highest population growth parameters, i.e., net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) were recorded on kohlrabi (R0 = 30.45 offspring, r = 0.2174 d-1, λ = 1.2429 d-1). These parameters were the lowest on Chinese cabbage (R0 = 13.00 offspring, r = 0.1503 d-1, and λ = 1.1621 d-1) and bak choi (R0 = 16.30 offspring, r = 0.1614 d-1, λ = 1.1752 d-1). The results attained from population growth parameters, together with population projection estimation based on the age-stage, two-sex life table theory, indicated that both Chinese cabbage and bak choi were less suitable hosts for turnip aphids and should be considered as a possible source for developing resistance in breeding programs and integrated pest management strategies.

Demography and Mass-Rearing Harmonia dimidiata (Coleoptera: Coccinellidae) Using Aphis gossypii (Hemiptera: Aphididae) and Eggs of Bactrocera dorsalis (Diptera: Tephritidae).

We compared rearing Harmonia dimidiata (F.) (Coleoptera: Coccinellidae) on four combinations of Aphis gossypii Glover (Hemiptera: Aphididae), and eggs of Bactrocera dorsalis Hendel (Diptera: Tephritidae), using the age-stage, two-sex life table. The four combinations were: both larvae and adults were reared on aphids; larvae were reared on aphids and adults were reared on fresh fruit fly eggs; larvae were reared on lyophilized fruit fly eggs and adults were reared on aphids; and larvae were reared on lyophilized eggs and adults were reared on fresh eggs. The highest intrinsic rate of increase (r = 0.1125 d-1) and net reproductive rate (R0 = 260.7 offspring) were observed when both larval and adult stages of H. dimidiata were reared on A. gossypii. When B. dorsalis eggs were used as rearing media for larvae, adults, or both, the values of r and R0 were significantly decreased. The lowest values (r = 0.0615 d-1 and R0 = 38.6 offspring) were observed when both larvae and adults were reared entirely on B. dorsalis eggs. Despite the lower r and R0 values, our results showed that B. dorsalis eggs could be considered as an adequate, less expensive alternative diet for rearing H. dimidiata because of the time and labor savings resulting from the ease of preparation and the ability to store the eggs for timely usage. The mass-rearing analysis showed that the most economical rearing system was to rear larvae on A. gossypii and adults on B. dorsalis eggs.

Population Growth of Dysaphis pyri (Hemiptera: Aphididae) on Different Pear Cultivars With Discussion on Curve Fitting in Life Table Studies.

Population growth parameters of the Dysaphis pyri (Boyer de Fonscolombe) (Hemiptera: Aphididae) were evaluated on four different cultivars (Coscia, Ankara, Williams, and Santa-Maria) of pear (Pyrus communis L.) under field conditions in the Van region of Turkey. Aphids were kept on leaves of 10-yr-old pear trees in Plexiglas clip-cells (20 mm in diameter and 10 mm in height, with the upper side covered with muslin). For the description of the stage differentiation during population growth, we analyzed raw data of developmental time, survival, and fecundity using the age-stage, two-sex life table to take the variable developmental rate among individuals into account. Results indicated that the Coscia and Ankara cultivars are less favorable hosts for D. pyri because of the longer preadult developmental time, higher preadult mortality rate, and lower total fecundity on these cultivars. The intrinsic rate of increase (r), the net reproduction rate (R0), and the finite rate of increase (λ) values were lower on the Coscia and Ankara cultivars. We discussed the application of the Weibull function, polynomial model, and Enkegaard model in life table studies. Because these models are often inaccurate in describing survival and reproduction parameters, we suggest that their application in life table research should be reevaluated.

Fast Population Growth in Physogastry Reproduction of Luciaphorus perniciosus (Acari: Pygmephoridae) at Different Temperatures.

Luciaphorus perniciosus Rack is one of the most serious pests of several cultivated mushroom species including Ganoderma lucidum (Fr.), Flammulina velutipes Karst., Auricularia polytricha (Mont.) Saac., Lentinus polychrous Lev., and Lentinus squarrosulus (Mont.) Singer in Thailand. Adult female Lu. perniciosus produce offspring inside their physogastric hysterosomas, with all embryos developing through to the adult stage while remaining in the abdomen. Once the abdomen ruptures, the female parent dies and the offspring consisting of mostly fertilized female adults along with a few male adults continue to emerge from the cadaver of the mother for a period of several days. This peculiar type of reproduction after the death of the mother is a special case for life table analysis and has not been discussed previously in demographic analyses. In this study, the life table data of this mite fed on Le. squarrosulus were collected at 25, 30, and 35 °C and analyzed by using the age-stage, two-sex life table. The standard errors of population parameters were estimated by using the bootstrap technique (200,000 bootstraps). At 25, 30, and 35 °C, females started reproduction at ages 9, 5, and 3 d, respectively; the net reproductive rates (R0) were 192.27, 253.81, and 234.11 offspring. Due to their rapid development and high fecundity, the r values were as high as 0.4189, 0.8653, and 1.0892 d-1 at 25, 30, and 35 °C, respectively. Computer projection indicated that the mushroom mites Lu. perniciosus is capable of a threefold daily increase at 35 °C.

Demographic Analysis of Sex Ratio on Population Growth of Bactrocera dorsalis (Diptera: Tephritidae) With Discussion of Control Efficacy Using Male Annihilation.

The life table data for the oriental fruit fly, Bactrocera dorsalis (Hendel), at different adult sex ratios (1♀: 1♂, 1♀: 50♂, 50♀: 1♂ free-choice mating, and 50♀: 1♂ no-choice mating) were collected to determine the effects of sex-ratio manipulation on current pest control procedures. At 1♀: 1♂, females mated, on average, 2.3 times during their lifetime with a mean fecundity (F) of 1,122 eggs. The net reproductive rate (R0), intrinsic rate of increase (r), finite rate (λ), and mean generation time (T) were 561.0 offspring, 0.1693 d- 1, 1.1844 d- 1, and 37.4 d, respectively. At 50♀: 1♂ free-choice mating, males mated 46.7 times during their lifetime, while at 50♀: 1♂ no-choice mating, males mated on average 50 times during their lifetime, and all females mating only once in both treatments. The values for F, r, and λ were significantly lower for both 50♀: 1♂ treatments than those in the 1♀: 1♂ group; the R0 values, however, were either equal to or even higher than those in the 1♀: 1♂ treatment. In the male-biased sex ratio (1♀: 50♂), fecundity was the highest (1,610 eggs) and female average life span the longest (166 d), while the R0 was the lowest (31.6 offspring) among all treatments. Population projections showed that even at a sex ratio of 50♀: 1♂, B. dorsalis could still produce a large number of offspring. These findings demonstrate that management strategies for controlling B. dorsalis could be properly evaluated by using demographic methods. Because female annihilation appears to be a more effective control strategy, it should be considered as a viable alternative.

Genetically Engineered Ricin Suppresses Bactrocera dorsalis (Diptera: Tephritidae) based on Demographic Analysis of Group-Reared Life Table.

The oriental fruit fly, Bactrocera dorsalis (Hendel), reduces the quantity and quality of many host fruits through the process of oviposition and larval feeding, and this insect has been considered a major insect pest in several Asian countries for decades. Using an earlier-developed, female-specific system that combines the toxicity of the ricin A chain (RTA) and the alternative RNA splicing property of doublesex ( Bddsx ), we show that transgenic male flies harboring the RTA-Bddsx transgene unevenly repress the pest population through inheritable effects. In age-stage, two-sex life-table analyses, high larval mortality and a delay in pupation were observed after introducing the transgene. The high male to female ratio in DsRed + flies demonstrates the lethal effect of ricin on females. The fitness of both the DsRed + - and DsRed - -transformed females was reduced as shown in the decrease of the net reproductive rate ( R0 ), intrinsic rate ( r ), and finite rate (λ) values compared with the wild-type populations. The integrity of the RTA-Bddsx transgene remained in more than 80% of DsRed + males after ten generations, supporting the stable inheritance of the transgene. All of the data from this study support the proposed RTA-Bddsx SIT approach, which provides a species-specific and environmentally friendly method of suppressing, rather than eradiating, B. dorsalis.

Survival and Reproductive Strategies in Two-Spotted Spider Mites: Demographic Analysis of Arrhenotokous Parthenogenesis of Tetranychus urticae (Acari: Tetranychidae).

Tetranychus urticae Koch is a cosmopolitan pest whose rapid developmental rate enables it to produce colonies of thousands of individuals within a short time period. When a solitary virgin female colonizes a new host plant, it is capable of producing male offspring through the arrhenotokous parthenogenesis; once her sons mature, oedipal mating occurs and the female will produce bisexual offspring. To analyze the effect of arrhenotokous reproduction on population growth, we devised and compared separate life tables for arrhenotokous and bisexual populations of T. urticae using the age-stage, two-sex life table theory. For the cohort with bisexual reproduction, the intrinsic rate of increase (r), finite rate (λ), net reproductive rate (R0), and mean generation time (T) were 0.2736 d(−1), 1.3146 d(−1), 44.66 offspring, and 13.89 d, respectively. Because only male eggs were produced during the first 8 d of the oviposition period and the cohort would soon begin bisexual reproduction, it would be theoretically wrong to calculate the population parameters using the survival rate and fecundity of an arrhenotokous cohort. We demonstrated that the effect of arrhenotokous reproduction could be accurately described and evaluated using the age-stage, two-sex life table. We also used population projection based on life table data, quantitatively showing the effect that arrhenotokous reproduction has on the growth potential and management of T. urticae.

Demography and Consumption of Spodoptera litura (Lepidoptera: Noctuidae) Reared on Cabbage and Taro.

Spodoptera litura (F.) causes considerable economic damage to multiple agro-crops annually in many countries. In this study, the demography of S. litura reared on cabbage and taro was investigated using the age-stage, two-sex life table at 25±1°C, 60±10% relative humidity, and a photoperiod of 12: 12 (L:D) h. Our results showed that the net reproductive rate, intrinsic rate, and finite rate of population increase on cabbage (1893.1 offspring, 0.2374 d(−1), and 1.2679 d(−1)) were all not significantly different from those on taro (1361.0 offspring, 0.2298 d(−1), and 1.2584 d(−1)). The net consumption rate on cabbage (439.1 cm2) was, however, three times higher than that on taro (141.7 cm2). According to the population parameters, both cabbage and taro are suitable host plants for S. litura. When both the population growth rate and the consumption rate were taken into consideration, the finite consumption rate on cabbage (ω=3.8054) was significantly higher than that on taro (ω=1.3184). In Taiwan, taro and cabbage are commonly planted in adjacent farm plots, with taro being grown from March to November and cabbage from October to April. Because of the overlapping growth periods of the two crops, S. litura can easily propagate throughout the year by switching between the adjacent crops during the overlap periods. Pest management strategies for controlling S. litura must be thoroughly reevaluated based on ecological characteristics, including its life table and consumption rate on its major host plants.

Linking Life Table and Predation Rate for Biological Control: A Comparative Study of Eocanthecona furcellata (Hemiptera: Pentatomidae) Fed on Spodoptera litura (Lepidoptera: Noctuidae) and Plutella xylostella (Lepidoptera: Plutellidae).

To better understand the predator-prey relationship and to compare predation rates, we studied the life table and predation rate of the predator Eocanthecona furcellata Wolff (Hemiptera: Pentatomidae) when reared on two major crucifer pests, Spodoptera litura (F.) (Lepidoptera: Noctuidae) and Plutella xylostella L. (Lepidoptera: Plutellidae). The net reproductive rate, intrinsic rate of increase, finite rate, and net predation rates of E. furcellata reared on P. xylostella were 292.4 offspring, 0.1389 d(-1), 1.1490 d(-1), and 644.1 third instars of P. xylostella, respectively. These values are significantly higher than those reared on S. litura, i.e., 272.3 offspring, 0.1220 d(-1), 1.1298 d(-1), and 863.1 third instars of S. litura. To evaluate the predation potential of E. furcellata fed on P. xylostella and S. litura, we combined both the growth rate and predation rate to calculate the finite predation rate (ω); our results showed that E. furcellata is an effective predator of both S. litura (ω = 1.6029) and P. xylostella (ω = 1.4277).

Demographic Assessment of Plant Cultivar Resistance to Insect Pests: A Case Study of the Dusky-Veined Walnut Aphid (Hemiptera: Callaphididae) on Five Walnut Cultivars.

To provide a comprehensive evaluation of walnut cultivar resistance to the dusky-veined walnut aphid, Panaphis juglandis (Goeze), we collected the life table data of this aphid reared on five cultivars of walnut ('Akça I,' 'Chandler,' 'Fernette,' 'Fernor,' and 'Pedro') under field conditions. The raw data of the developmental time, survival rate, and fecundity was analyzed using the age-stage, two-sex life table to account for the variable developmental rate and stage differentiation among individuals. Due to the species' longer immature developmental time, shorter adult longevity, shorter reproduction period, and lower fecundity, the net reproduction rate (R0=5.9 offspring), intrinsic rate of increase (r=0.0983 d(-1)), and finite rate (λ=1.1034 d(-1)) were the lowest when aphids were reared on the Fernor cultivar, while those reared on Akça I exhibited the highest population parameters (R0=18.0 offspring, r=0.2031 d(-1), and λ=1.2252 d(-1)). Based on the population characteristics, Fernor is a less favorable cultivar for the development and reproduction of P. juglandis. We also demonstrated the advantages of using bootstrapping for the analysis of standard errors of developmental time, longevity, fecundity, and other parameters as well. Our results indicated that demographic analysis of pest development, survival, and reproduction based on the age-stage, two-sex life table offers a comprehensive assessment of pest growth potential on different crop cultivars.