Pre-adult Duration Research Articles

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

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

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 shortened preadult duration and preoviposition periods and 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.

Effect of zinc fortified, arid and irrigated wheat varieties flour upon life history parameters of red flour beetle, Tribolium castaneum (Herbest) (Coleoptera: Tenebrionidae)

Red flour beetle, Tribolium castaneum (Herbest) (Coleoptera: Tenebrionidae) is a stored grain pest. Various fortified wheat varieties have been produced but data about the impact of different wheat varieties flour on life history parameters of T. castaneum are poorly understood. This study evaluated the effect of fortified (Zincol-16 T1), arid zone [(BARS-09 T2), and (Fatehjang-2016 T3)] and irrigated zone [(Faisalabad-2008 T4), (Gold-2016 T5), (Manthar-03 T6), (Fareed-06 T7), (Mairaj-08 T8)] wheat varieties flour upon some life history parameters of T. castaneum in the laboratory using age-stage two sex life table. The egg incubation period, adult male and female longevities, and total male and female longevities of T. castaneum were shortest in T5 and T6 as compared to all other treatments. The T5 presented shorter larval and pre-adult duration. Egg incubation, larval, and pupal durations and total male and female longevities were higher in T1. Total longevity (egg to adult) of T. castaneum was lowest in T1 as compared to T3 and T4 but similar to other treatments. Pre-adult duration was longer in T1 as compared to all other treatments. Pre-adult survival was significantly lower in T1 (53%) than all the treatments in which it remained at par. Lowest proportion of female adult (Nf/N) was found in T1 as compared to T3, T4, and T7. Age stage specific survival rate (sxj) was lower on T1, whereas life expectancy (exj) was higher than other varieties. These results suggest that T. castaneum develop poorly upon zinc fortified wheat variety, Zincol as compared to other varieties thus it can be a good integrated pest management tool against this pest.

Transgenerational effects of pyriproxyfen in a field strain of Musca domestica L. (Diptera: Muscidae).

Musca domestica L. (Muscidae: Diptera) is a human and livestock pest especially in tropical and sub-tropical areas. Different insecticides have been used to control this pest that pose serious harmful effects on humans and the environment. The current study was planned to investigate the effects of two concentrations (LC25 and LC50) of pyriproxyfen on biological and population parameters of a field strain of M. domestica. The exposed parents (F0) and their progeny (F1) were studied to examine the transgenerational effects. The results indicated that preadult duration was higher in control (13.68 days) compared to LC50 treated individuals (12.44 days). The male and female longevity was relatively lower in the LC25 treated population i.e. 24.62 and 26.62 days, respectively. The adult pre-oviposition period (APOP) and total pre-oviposition period (TPOP) values were higher in the LC25 treated individuals than those of control. Moreover, oviposition days and fecundity were reduced in the treated individuals as compared to the control treatment. A gradual decrease in the net reproductive rate (R0) was observed (8.46-14.07 per day) while the value of R0 was significantly higher in control. The results suggested that pyriproxyfen can be effectively utilized and incorporated in the management programs of M. domestica.

Pecan, Carya illinoinensis, a New Host Report of Yellowstriped Armyworm, Spodoptera ornithogalli (Guenee) (Lepidoptera: Noctuidae) in the Southeastern US

Yellowstriped armyworm (YSAW), Spodoptera ornithogalli, is a polyphagous pest that infests various crops, including cotton, cabbage, corn, blackberry, grape, etc. We documented egg clusters, larvae and adults of YSAW in pecan orchards in Georgia. Until now, there have been no reports of YSAW infesting pecan and its suitability as a host. To investigate the survival, development, and reproduction of YSAW on pecan, we used the age-stage, two sex life table. The YSAW successfully completed its lifecycle on pecan with an 82% preadult survival rate. The preadult duration and mean fecundity were 47.84 d and 1212.55 offspring per female. The population parameters, including intrinsic rate of increase (r), finite rate of increase (λ), net reproduction rate (R0), and mean generation time (T) were 0.1184 d−1, 1.1257 d−1, 430.67 offspring/female, and 51.05 d, respectively. This study confirms that pecan, Carya illinoinensis, is a potential host plant of YSAW and perhaps more widespread damage could be observed.

Lack of fitness costs associated with resistance to permethrin in Musca domestica

Resistance to permethrin has been reported in Pakistani strains of Musca domestica. The present study explored the performance of biological traits and analyzed life tables to determine whether there is any detrimental effect of permethrin resistance on the fitness of permethrin-resistant strains [an isogenic resistant strain (Perm-R) and a field strain (Perm-F)] compared to a susceptible strain (Perm-S). Perm-R and Perm-F exhibited 233.93- and 6.87-fold resistance to permethrin, respectively. Life table analyses revealed that the Perm-R strain had a significantly shorter preadult duration, longer longevity, shorter preoviposition period, higher fecundity, finite rate of increase, intrinsic rate of increase, net reproductive rate and a shorter mean generation time, followed by the Perm-F strain when compared to the Perm-S strain. Data of the performance of biological traits reveled that permethrin resistance strains had a better fit than that of the Perm-S strain. The enhanced fitness of resistant strains of M. domestica may accelerate resistance development to permethrin and other pyrethroids in Pakistan. Some possible measures to manage M. domestica and permethrin resistance in situations of fitness advantage are discussed.

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.

Demography of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) reared on elicitor-treated tomato plants with an innovative comparison of projected population sizes and application of the multinomial theorem for population survival.

Because of the considerable damage caused by tomato leafminer in tomato crops, the use of integrated methods is recommended. In this study, the effect of three different elicitors, methyl jasmonate, salicylic acid and ascorbic acid, on the life table parameters of Tuta absoluta was evaluated. A paired bootstrap test and different bootstrap percentiles were used to compare projected population sizes on specific dates. Survival probabilities were calculated by innovatively linking life tables and multinomial theorem. Preadult duration and mortality significantly increased, and the net reproductive rate (R0 ), intrinsic rate of increase (r), and finite rate of increase (λ) significantly decreased in all elicitor treatments. The lowest fecundity (F = 71.89 eggs/female) was observed in the salicylic acid treatment, with an R0 value of 13.48 offspring/individual, r of 0.0932 d-1 , and λ of 1.0977 d-1 . The population projection revealed the stage structure of T. absoluta during population growth, which was significantly reduced by the elicitor treatments. The survival probability of bootstrap samples was significantly lowered, whereas the extinction probabilities increased in elicitor treatments compared with control when the survival criterion was set to two fertile pairs. Our results demonstrated that the application of elicitors could reduce the risk of T. absoluta damage. Furthermore, population projection based on life tables is applicable to obtain the frequency distribution of the population size at different times. Combined application of life tables and multinomial theorem can be used to calculate the risk of pest emergence. © 2023 Society of Chemical Industry.

Life history traits and population parameters of the predatory mite Euseius scutalis (Acari: Phytoseiidae) fed on Tetranychus turkestani (Acari: Tetranychidae) and pollen from three different plants

Development, reproduction, and demographic parameters of the predatory mite Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) were determined in the laboratory at 25±1 °C, with a 16L:8D photoperiod and 60 ±5% RH, to evaluate its response to four different diets: Tetranychus turkestani Ugarov and Nikolskii (Acari: Tetranychidae), caster bean pollen, date palm pollen, and hopbush pollen. Male and female mites raised on T. turkestani had a shorter mean pre-adult duration than those grown on date palm, castor, and hopbush pollen. Pre-adult mortality was found to be greater in either the larval stage or protonymphal stage than other stages. The highest and lowest pre-adult mortality rates were recorded on castor bean pollen (31.87%) and T. turkestani (2.94%), respectively. The total pre-oviposition periods (TPOP) on hopbush and castor bean pollen were significantly longer than those on T. turkestani and date palm pollen. The highest egg production and oviposition period were determined when T. turkestani were provided as diet. Overall, the individuals lived considerably longer when provided with T. turkestani and hopbush pollen than the two other diets. The gross reproductive rate (GRR) and net reproductive rate (R<sub>0</sub>) on T. turkestani were greater than the values attained on other diets. The highest intrinsic (r) and finite rates of increase (λ) were found to be 0.2537 and 1.2888 on T. turkestani, respectively. However, R<sub>0</sub>, GRR, r, and λ were almost similar between all pollen diets tested. In general, all diets tested in this study were adequate for development and oviposition in E. scutalis, but T. turkestani was the most favorable diet.

Monitoring reduced accumulation and risk evaluation of Cry1Ca during food chain transfer from genetic engineered plant to endoparasitoid.

The potential risk of insecticidal proteins produced by genetically engineered (GE) plants to non-target organisms have long been an ecotoxicological concern. Apanteles chilonis, an important endoparasitoid of rice pest Chilo suppressalis, is potentially exposed to Bacillus thuringiensis (Bt) endotoxins through a food chain of transgenic Bt rice - C. suppressalis - A. chilonis, thus, a rigorous risk assessment is urgently needed. Here we combined a tri-trophic bioassay system with high dose exposure approach using C. suppressalis hemolymph as the carrier of insecticidal protein to evaluate the biosafety of Cry1Ca to A. chilonis. Cry1Ca protein could be transmitted and retained along the food chain and remains bioactive in the hemolymph of C. suppressalis during the pre-adult duration of A. chilonis. No significant differences in pre-adult period, male and female longevity, adult fecundity and weight, emergence rate, and sex ratio were observed when A. chilonis parasitized C. suppressalis feeding on cry1Ca rice compared to control treatment. However, the pupal period and weight were significantly prolonged and decreased. When A. chilonis parasitized on C. suppressalis injected with a high dosage of Cry1Ca protein, no adverse effects on the life-history parameters, peroxidase (POD), superoxide dismutase (SOD), and glutathione reductase (GR) of A. chilonis were observed, demonstrating that the host quality mediates adverse effects during the food chain. We confirmed that Cry1Ca posed no ecological risk to the non-target endoparasitoid A. chilonis. This study may serve as an example for future risk assessment of transgenic crops to non-target endoparasitoids. This article is protected by copyright. All rights reserved.

Different Host Plants Distinctly Influence the Adaptability of Myzus persicae (Hemiptera: Aphididae)

Piercing–sucking insects are prominent phloem-feeding insect pests and understanding their feeding behavior and life characteristics plays a crucial role in studying insect host adaptability. The green peach aphid, Myzus persicae (Hemiptera: Aphididae), is one of the most prominent pests in tobacco-growing areas around the world. This study evaluated the adaptability of M. persicae to five host plants: tobacco, radish, Chinese cabbage, Brassica oleracea, and rape using the electropenetrography, age-stage, two-sex life table and population dynamics. The results demonstrated that the feeding behavior of M. persicae differed significantly according to the target hosts. M. persicae exhibited reduced pathway activities and increased phloem sap ingestion on radish, whereas the opposite was observed on Chinese cabbage. Additionally, the mechanical difficulties of M. persicae mouthparts in the probe pathway phase were significantly lower on tobacco and radish than on other host plants. Life table parameters indicated that for M. persicae reared on radish, preadult duration, longevity, and total preoviposition increased significantly and the fecundity was the highest. Furthermore, the net reproductive rate (R0) increased significantly. The population number of M. persicae on radish after 15 days was significantly higher than that on other hosts, except for tobacco. Although M. persicae can successfully survive on the five plants, our results demonstrated that radish is the optimal host. These results provide significant information for understanding the population dynamics of M. persicae and on different host crops integrated management strategy.

Long-term effects of cattail pollen on development, population growth potential, and predation capacity of Amblyseius swirskii (Acari: Phytoseiidae)

ABSTRACT The development and demographic parameters of Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) were determined on grains of cattail pollen over 20 consecutive generations (G1-G20). Biological parameters and predation rate of three long-term reread A. swirskii colonies, including those reared on cattail pollen for 10 and 20 generations then switched to Tetranychus urticae (A-G10, A-G20, respectively), and those of A-G10 who fed on T. urticae for three generations (A-G10-3) were evaluated and compared with those fed on T. urticae before long-term rearing (B-G1). According to the results, feeding on pollen for more than 10 generations resulted in a significantly higher intrinsic (r) and finite (λ) rate of increase values than those in the earlier generations. Pre-adult duration of A. swirskii in B-G1 and A-G10 was significantly longer than that in A-G20. Furthermore, r and λ values in B-G1 did not considerably differ from A-G10 and A-G20. The net reproductive rate (R 0) of A-G10-3 was higher than that in A-G10, while it did not vary from B-G1. The r and λ were not affected by the time of feeding on natural prey. The net predation rate (C 0) of A-G20 was lower than B-G1 and A-G10, while its transformation rate (Qp) was higher than the others. Overall, long-term feeding history did not negatively affect the biological and predation parameters of the predator because after switching from pollen to the prey, the predators’ growth and consumption rates did not change. Consequently, cattail pollen can be considered as a good candidate for A. swirskii mass rearing.

Toxicity and sublethal effects of diafenthiuron on life table parameters of Musca domestica L. (Diptera: Muscidae)

Housefly, Musca domestica L. (Diptera: Muscidae), is an important insect-pest owing to its disease transmitting capability in both humans and animals e.g. diarrhea, gastroenteritis diseases, lumpy skin disease, cholera. Residual insecticides are widely used to control houseflies that pose serious threat to human and animal health as well as to the environment. The population resurgence after insecticidal spray is also a common problem in many cases. Transgenerational studies can be very helpful to see the fate of insecticidal sprays. In the current study, we determined transgenerational effects of sublethal doses of diafenthiuron using Age-stage two-sex life table analysis, while focusing on potential use of diafenthiuron in baits. After treating adult flies with three different doses of diafenthiuron viz. LC10, LC20 and LC50, the progeny depicted significant changes regarding pre-adult duration (shorter in control), male and female longevity of their progeny were observed (more adult longevity in control). Additionally, population growth parameters viz. intrinsic rate of growth (r) (−0.03-0.12 per day), net reproductive rate (R0) (0.50–9.98), limiting rate of growth (λ) (0.96–1.13 per day) were also significantly reduced in the progeny of treated adults. Based on the decreased biotic potential i.e. intrinsic rate of growth and other population parameters, diafenthiuron can be recommended as an effective insecticide even at lower doses.

Effect of wavelength on development and demographic parameters of Scolothrips longicornis fed on two-spotted spider mites

The wavelength of light can affect reproduction and development of arthropods. In the present study, we examined the reproduction and development of predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch (Trombidiformes: Tetranychidae) eggs, under five wavelengths: white (all wavelengths), blue (475 nm), green (580 nm), yellow (620 nm) and red (675 nm), at 25 ± 0.5 °C, 16L: 8D and 60 ± 10% rh. Light wavelength did not significantly influence female and male preadult duration, male adult duration, and male total longevity. White and blue light yielded the longest oviposition periods. All life table parameters varied significantly among treatments. The intrinsic rate of increase (rm d−1) was lowest in red light wavelength (0.112 ± 0.009) and highest in white wavelength (0.171 ± 0.008) and blue light wavelength (0.168 ± 0.008). The present research demonstrates that white light conditions positively influence S. longicornis with shorter development time and improved reproductive performance. This information will be beneficial in mass production of S. longicornis for biocontrol programs involving T. urticae.

Demography of Tetranychus urticae (Acari: Tetranychidae) under different nitrogen regimes with estimations of confidence intervals

In order to study the effect of nitrogen fertilization on the population growth rate of two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), life table data on common bean, Phaseolus vulgaris L. (Fabaceae), were collected at 25 ± 1 °C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) h. Bean plants were treated with four nitrogen levels (0, 75, 150, and 225 kg N ha-1). Data were analyzed based on the age-stage, two-sex life table. The better performance of T. urticae (e.g., shorter total preadult duration, shorter total preoviposition period, longer adult longevity, more oviposition days, and higher fecundity) were observed with 225 kg N/ha (r = 0.2918 d-1) and 150 kg N/ha (r = 0.2744 d-1). Because the application of nitrogen fertilizer should be aimed to maintain optimal plant physiology while minimizing pest growth (i.e., optimize crop protection), we recommend the optimal N fertilization as 150 kg N/ha. By using the multinomial theorem, we demonstrated that 100,000 bootstrap resamplings can generate stable and precise estimates of population parameters and their confidence intervals. On the contrary, the 1000 bootstrap resamplings might underestimate the confidence intervals and lead to failure of pest control.

Life table parameters of Amblyseius swirskii and Neoseiulus californicus (Acari: Phytoseiidae) reared on two strawberry cultivars

ABSTRACT The effect of two strawberry cultivars (029 and Wanter star) on the biology and life table parameters of the two phytoseiid mites, Amblyseius swirskii Athias-Henriot and Neoseiulus californicus (McGregor), preyed on Tetranychus urticae Koch, was evaluated in the present study. The number and length of leaf trichomes varied between the two tested cultivars; where Wanter star leaves had significantly more and longer trichomes than 029 ones. Both phytoseiid mites successfully completed their development on the two strawberry cultivars. The pre-adult duration and female longevity of both phytoseiids were shorter and longer, respectively on 029 leaves than on Wanter star leaves. Fecundity of both phytoseiids reared on 029 cultivar was significantly higher than that on the other strawberry cultivar. For the two predators, the values of the intrinsic rate of increase, the finite rate of increase and the net reproductive rate parameters were higher and the generation time (T) was shorter when the predators were reared on 029 cultivar comparing to Wanter star one. This difference in response of the two predators to the leaf surfaces of strawberry cultivars must be taken into consideration to improve the role of these predacious mites in the biological control programs in strawberry field.

The Survival and Parasitism Rate of Tamarixia radiata (Hymenoptera: Eulophidae) on Its Host Exposed to Beauveriabassiana (Ascomycota: Hypocreales)

The effect of the entomopathogenic fungus Beauveria bassiana (BB-12) on the biological characteristics of Tamarixia radiata parasitizing Diaphorina citri was studied under laboratory conditions. Twenty 3rd–5th instar nymphs were exposed to a single already-mated female parasitoid (1 day old) and removed after 24 h. Subsequently, the nymphs were sprayed at 1, 24 and 48 h post-exposure with 1 × 108 conidial mL−1 suspension. The percentage of parasitism recorded was 22%, 35% and 41% at 1, 24 and 48 h, respectively. The emergence rate varied between 28%, 51% and 49% at 1, 24 and 48 h, respectively. In a subsequent experiment, nymphs of D. citri were sprayed with 1 × 108 conidial mL−1 suspension and then exposed to T. radiata at 1, 24 and 48 h post-spraying to allow for parasitism to occur. The percentage of parasitism recorded was 18%, 27% and 28% at 1, 24 and 48 h, respectively, significantly lower than the parasitism rate recorded in the control (48%). The percentage of emergence varied between 24%, 44% and 45% at 1, 24 and 48 h, respectively. In both experiments, no significant difference was observed in the pre-adult duration (days) and the sex ratio of F1 generation. Meanwhile, significant differences were observed in the longevity of the F1 generation of females and males of T. radiata in a treatment consisting of spraying the fungal suspension and the control. Overall, the findings of the current study revealed a negative interaction between T. radiata and B. bassiana in controlling D. citri nymphs. This outcome is believed to be a result of the antagonistic effects of B. bassiana on the developmental process of the pre-adult stages of the parasitoid. However, our results also show that with a properly timed application (allowing parasitism to occur over an extended period of time before the application of the fungus), T. radiata could potentially be used in combination with B. bassiana for the successful biological control of D. citri. This should be carried out in order to minimize the potentially negative interactions between these two biological agents.

How does feeding on different diets affect the life history traits of Neoseiulus californicus?

ABSTRACT We examined how feeding on different diets affects the life-history traits of Neoseiulus californicus using seven pollen grains (pistachio, walnut, date palm, wild almond, pomegranate, oak, and peach) as well as a natural prey (two-spotted spider mites (TSSM)). The pre-adult duration of individuals reared on TSSM was significantly longer, whereas duration on oak and peach pollen was shorter than all the others. Females fed on peach, wild almond, and walnut pollen showed low fecundity. The highest number of eggs was laid by the females reared on TSSM. When the mites were reared on pistachio pollen, the fecundity was higher compared with other pollen grains. The net reproductive rate (R 0) varied from 1.77 (on peach pollen) to 26.28 offspring (on TSSM). The cohort reared on pistachio pollen had the highest intrinsic rate of increase (r) as well as the finite rate of increase (λ); however they were insignificant to the values obtained for the cohort reared on the date palm, oak, and pomegranate pollen. Pistachio and date palm pollen provide commensurate nutritional effects on survivorship, development, and fecundity of N. californicus. Knowledge about the profitability of different pollens can be used to optimize rearing systems for phytoseiid predators.

Evaluation of two factitious preys for rearing Neoseiulus barkeri (Acari: Phytoseiidae)

ABSTRACT Neoseiulus barkeri (Hughes) is a generalist predatory mite with economic potential to control thrips and two spotted spider mites in protected cultivation. We evaluated the development and reproduction of N. barkeri on Ephestia kuehniella Zeller and Mycetoglyphus fungivorus Oudemans in the first (G1), third (G3), and sixth (G6) generation of rearing. On M. fungivorus, pre-adult duration was significantly longer in G6 than in G1 and G3, while on E. kuehniella the corresponding periods were equal in G3 and G6, meanwhile longer than that in G1. Fecundity and oviposition rate were higher on E. kuehniella than on M. fungivorus. The intrinsic rate of increase and the finite rate of increase were the highest when E. kuehniella eggs were offered in G1, whereas the lowest rates were obtained on M. fungivorus in G6. Female’s N. barkeri did not lose their capacity to capture and consume nymphs of Tetranychus urticae Koch after six generations of rearing on tested prey. Rearing of N. barkeri on M. fungivorus and E. kuehniella for six generations suggested their potential for mass production of the predator or sustaining its population in the crop after release.

Demography of Cacopsylla chinensis (Hemiptera: Psyllidae) Reared on Four Cultivars of Pyrus bretschneideri (Rosales: Rosaceae) and P. communis Pears With Estimations of Confidence Intervals of Specific Life Table Statistics.

The psyllid Cacopsylla chinensis (Yang & Li) (Hemiptera: Psyllidae) is a serious pest of pears in China. To determine and contrast the fitness of the psyllid on two endemic cultivars of Pyrus bretschneideri (i.e., BHXS and BSL) and two introduced cultivars of Pyrus communis (i.e., CB and CRB), we analyzed data on the development, survival, and fecundity from C. chinensis individuals reared on the four cultivars. The age-stage, two-sex life table theory was used in order to enable the inclusion of males in the analysis as well as a means of identifying the variation in developmental durations among individuals. Results indicated that C. chinensis can successfully develop and reproduce on all four pear cultivars. However, based on the lower preadult survival rate, longer preadult duration, longer total preoviposition period (TPOP), and lower fecundity that occurred on both cultivars of P. communis, these two cultivars are less favorable hosts for C. chinensis than the P. bretschneideri cultivars. The lower intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0) on CB and CRB pears showed these two introduced cultivars are more resistant to C. chinensis than the endemic BHXS and BSL pears. These resistant cultivars would be appropriate candidates for managing C. chinensis. We used the bootstrap technique to estimate the uncertainty of the population parameters (r, λ, R0, etc.), while also demonstrating that it can be used for estimating the 0.025 and 0.975 percentile confidence intervals of the age of survival rate.