Suitability of monotypic and mixed diets for development, population growth and predation capacity of Typhlodromus bagdasarjani (Acari: Phytoseiidae).

We quantified the life table parameters and predation capacity of a generalist predatory mite, Typhlodromus bagdasarjani Wainstein and Arutunjan on five monotypic diets, including Tetranychus urticae Koch (TSSM) eggs in the presence (SW) and absence (SN) of webs, Trialeurodes vaporariorum Westwood (GHWF) eggs (G), honeydew (H), and maize pollen (M) as well as three mixed diets, including SN + M, SN + G, and G + M. Our results showed that the individuals fed on the mixed diets had a considerably shorter developmental time and pre-oviposition period (APOP), higher oviposition days, higher fecundity and population growth rate than those raised on the monotypic diets. Furthermore, we found that the mixed diet of TSSM and GHWF eggs was the most favorable diet, resulted in the highest fecundity and population growth rate, shortest developmental time and APOP. While TSSM eggs alone in the presence of webs and honeydew were the worst diets resulted in the longest developmental time, lower oviposition day, higher fecundity and population growth rate. Our data determined that TSSM has more nutritional benefits than GHWF for T. bagdasarjani. We observed the positive effects of pollen addition to prey on the predatory mite's immature and adult life-history characters; however, it reduced the predation rate. Overall, maize pollen could enhance ecosystem services provided against spider mites and whiteflies by positively impacting the increase of T. bagdasarjani population. This predator may be more effective when two prey species are available than when only one species is present.

Evaluation of recombinant toxin JFTX-23, an oral-effective anti-insect peptide from the spider Selenocosmia jiafu venom gland proteome.

Excessive utilization of chemical pesticides for pest control can lead to adverse consequences for the health of humans and other organisms and may also cause irreversible ecological changes; therefore, the use of biologically derived insecticides can be a safe alternate strategy. Transcriptomic studies have shown JFTX- 23,a small peptide from the spider Selenocosmia jiafuis highly similar to U1-TRTX-Sp1, a well-characterized oral-effective insecticide toxin from the Australian tarantula Selenotypus plumipes. First, we evaluated the JFTX-23 peptide sequence using bioinformatics tools and modeling studies. Preliminary results showed a high similarity of JFTX-23 to JZTX-58 (91.67%) and U1-TRTX-Sp1 (86.11%). Superimposition of the α-carbons of the modeled JFTX-23 and U1-TRTX-Sp1 demonstrated a very high similarity of the 3-D structure of the two peptides (RMSD of 0.02 Å).The injection assay of JFTX-23 in Helicoverpa armigera indicated an LD50 of 0.077 and 0.423 nmol/insect after 24 and 120 h, respectively. JFTX-23 was toxic to H. armigera via oral administration with an LC50 of 1.16 nmol/g food after 5 days, which was comparable to the toxicity of the oral-effective toxin U1-TRTX-Sp1. Our studies have shown that JFTX-23 is a potent oral-effective toxin that can be considered an attractive candidate for the biological control of insect pests.

Pollen Alone or a Mixture of Pollen Types? Assessing Their Suitability for Mass Rearing of Neoseiulus cucumeris (Acari: Phytoseiidae) Over 20 Generations.

The generalist predatory mite, Neoseiulus cucumeris (Oudemans) is known as one of the most effective natural enemies on many pests. This economically important biocontrol agent was reared for 20 generations on date palm and castor bean pollen as well as a mixture of pollen types, including date palm, castor bean, and almond. The performance of this predator was evaluated by comparing its life table parameters after different generations (G1-G20) fed on each diet in a laboratory at 25 ± 1°C, 60 ± 5% RH, and a photoperiod of 16:8 (L: D) h. The development time of the predator reared on all tested diets had no significant difference in G20. The intrinsic rate of increase (r) of N. cucumeris by feeding on the mixed pollen (0.197 day-1) was significantly higher than that on castor bean, or date palm pollen (0.146 or 0.152 day-1 in G1, respectively). Our results indicated that the predator's performance was not affected by long-term feeding on the pollen diets, as well as there was no considerable difference between pollen alone and pollen mixture diets. Furthermore, mites reared on pollen diets had higher quality than those reared on natural prey, Tetranychus urticae Koch.

Targeting the microRNA pathway core genes, Dicer 1 and Argonaute 1, negatively affects the survival and fecundity of Bemisia tabaci.

BACKGROUND: MicroRNAs (miRNAs) are small regulatory non-coding RNAs that are involved in a variety of biological processes such as immunity, cell signaling and development by regulating gene expression. The whitefly Bemisia tabaci is a polyphagous vector that transmits many plant viruses causing economic damage to crops worldwide. In this study, we characterized and analyzed the expression of the miRNA core genes Argonaute-1 (Ago1) and Dicer-1 (Dcr1) in B. tabaci and explored the effect of their silencing on the insect's fitness. RESULTS: Our results showed that Ago1 and Dcr1 are differentially expressed in different tissues and developmental stages of B. tabaci. To determine the function of the miRNA pathway in B. tabaci, we silenced Ago1 and Dcr1 using specific double-stranded RNAs to the genes. RNA interference (RNAi) of Ago1 and Dcr1 decreased the expression level of the core genes and reduced the abundance of Let-7 and miR-184 miRNAs. Silencing of the miRNA pathway core gene also negatively affected the biology of B. tabaci by reducing fertility, fecundity and survival of this insect pest. CONCLUSIONS: Together, our results showed that silencing the miRNA pathway core genes reduced the miRNA levels followed by reduced fecundity and survival of B. tabaci, which highlighted the importance of the miRNA pathway in this insect. The miRNA core genes are attractive targets for developing an RNAi-based strategy for targeting this notorious insect pest. © 2022 Society of Chemical Industry.

Modeling Temperature-Dependent Development Rate of Neoseiulus cucumeris (Acari: Phytoseiidae) Fed on Two Alternative Diets.

Developmental time of the predatory mite Neoseiulus cucumeris (Oudemans) fed on cattail and almond pollen was determined under laboratory conditions at nine constant temperatures: 10, 15, 20, 25, 27, 30, 32, 35 and 38°C. No development was observed at 10°C. The lower temperature threshold (T0) was estimated to be 10. 97 and 10. 29°C for the almond and cattail pollen, respectively, using the Ikemoto linear model. Thermal constant (K) for pre-adult development of N. cucumeris was 112.8 and 123.5 DD fed on almond and cattail pollen, respectively, using the Ikemoto linear model. The interaction between diet and temperature had a significant effect on the developmental rate of N. cucumeris. The nonlinear Pradhan-Taylor, Janisch/Kontodimas, Briere-1, and Janisch/Rochat models best described the developmental rate of pre-adult stages of N. cucumeris. The estimated Tfast by Pradhan-Taylor model was 31.9 and 33.9°C when fed on almond and cattail pollen, respectively, which was similar to the observed shortest developmental time at 32°C. Our results revealed that N. cucumeris could develop over a wide temperature range (15-35°C), which is a desirable characteristic for a biocontrol agent in biological control programs.

Environmental Temperature, but Not Male Age, Affects Wolbachia and Prophage WO Thereby Modulating Cytoplasmic Incompatibility in the Parasitoid Wasp, Habrobracon Hebetor.

Wolbachia is an endosymbiotic bacterium found in many species of arthropods and manipulates its host reproduction. Cytoplasmic incompatibility (CI) is one of the most common manipulations that is induced when an uninfected female mates with a Wolbachia-infected male. The CI factors (cifA and cifB genes) are encoded by phage WO that naturally infects Wolbachia. Here, we questioned whether an environmental factor (temperature) or host factor (male age) affected the strength of the CI phenotype in the ectoparasitoid wasp, Habrobracon hebetor. We found that temperature, but not male age, results in reduced CI penetrance. Consistent with these results, we also found that the expression of the cif CI factors decreased in temperature-exposed males but was consistent across aging male wasps. Similar to studies of other insect systems, cifA showed a higher expression level than cifB, and male hosts showed increased cif expression relative to females. Our results suggest that prophage WO is present in the Wolbachia-infected wasps and expression of cif genes contributes to the induction of CI in this insect. It seems that male aging has no effect on the intensity of CI; however, temperature affects Wolbachia and prophage WO titers as well as expression levels of cif genes, which modulate the CI level.

Monitoring of Mutual Interference Behavior of Trichogramma brassicae (Hymenoptera: Trichogrammatidae) over 45 Generations of Rearing on Angoumois Grain Moth.

Trichogramma brassicae (Bezdenko) is one of the most common species of natural enemies used in augmentative biological control programs in many countries. Understanding of the foraging behavior of a parasitoid can help us to improve its performance under field conditions. This study is the first assessment of trends in mutual interference behavior of T. brassicae under long-term mass rearing (over 45 generations) on a common factitious host, Sitotroga cerealella (Olivier). Our results revealed that the total parasitism rate of T. brassicae reared on S. cerealella eggs was significantly affected by parasitoid densities and number of generations under continuous rearing. Also, parasitoid density and number of generations in rearing had significant effects on the per capita parasitism rate. Meanwhile, per capita searching efficiencies were different in sequential generations and at different densities. The number of hosts parasitized per parasitoid decreased on day 1 of the experiment with increasing parasitoid density, showing the effect of mutual interference. The linear regression between the natural logarithm of per capita searching efficiency and the natural logarithm of parasitoid density showed an inverse relationship. While the m (interference coefficient) values increased, the Q (quest constant) values had a decreasing trend over 45 generations. The highest (- 0.167) and lowest (- 0.242) values of m were observed in G45 and G5, respectively. Accordingly, G5 and G45 had the highest (0.053) and lowest (0.023) Q values, respectively. Thus, it seems the negative effects of mutual interference decreased over generations.

Mass Production of Neoseiulus cucumeris (Acari: Phytoseiidae): An Assessment of 50 Generations Reared on Almond Pollen.

Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), an economically important biocontrol agent, was reared on almond pollen for 50 generations. We evaluated the effect of rearing predators on this pollen by comparing biological parameters at different generations (G1-G50). The shortest and longest development time occurred in G5 and G10, respectively. Females at the fifth and 50th generations laid eggs earlier than those of other generations. Females at G50 laid eggs over a longer period and produced more eggs than females of other generations, although females in the earlier generations had a higher gross reproductive rate and net reproductive rate than later generations. The intrinsic rate of increase, as well as the finite rate of increase of N. cucumeris in the fifth and 50th generations was significantly greater than those in other generations, while the first generation had the lowest values of these parameters. The dorsal shield length of both females and males and the width of females were found to be unaffected by their constant feeding on almond pollen. However, the number of rearing generations significantly affected the width of males. Long-term rearing of N. cucumeris for at least 50 generation on almond pollen did not substantially affect the predator's quality and this food source could be used for the mass production of this predator. Almond pollen should be assessed in rearing other phytoseiid mites that are important in biocontrol strategies.

A comprehensive picture of foraging strategies of Neoseiulus cucumeris and Amblyseius swirskii on western flower thrips.

BACKGROUND: This study evaluated the potential of Neoseiulus cucumeris Oudemans and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) for controlling western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), by determining the functional response, numerical response, prey switching and mutual interference behaviors of the predators. RESULTS: A type II functional response was detected for two predator species fed on WFT first instars. The attack rate was higher for A. swirskii than N. cucumeris, but the handling time of N. cucumeris was shorter. For two predator species, numerical response was affected by both prey density and oviposition time. The per capita searching efficiencies of the two predators decreased significantly with increasing predator densities. The interference coefficient for A. swirskii was less than that of N. cucumeris. Although N. cucumeris switched from feeding on WFT first instars to feeding on second instars, this behavior was not observed in A. swirskii. CONCLUSIONS: Comparison of the two predator species foraging behaviors indicated optimal performance by A. swirskii at lower F. occidentalis densities. N. cucumeris was found to perform optimally at relatively higher prey densities. Moreover, N. cucumeris could be more effective in stabilizing the predator-prey system by switching behavior compared with A. swirskii. At higher predator densities, A. swirskii seemed to be an effective agent owing to its reduced intraspecific competition compared with N. cucumeris. Findings from this study will be useful in selecting appropriate agents and developing effective biocontrol programs to control WFT. © 2021 Society of Chemical Industry.

Temperature-Dependent Demography of Two Geographically Isolated Populations of Sesamia cretica (Lepidoptera: Noctuidae).

The pink stem borer, Sesamia cretica Lederer is considered as the main insect pest of maize and sugarcane worldwide. Reproductive and life table parameters of two populations of S. cretica were studied at 10 constant temperatures ranging from 12 to 36 (±1)°C, 50 ± 10% RH and a photoperiod of 0:24 (L:D) h for the larval stage and 16:8 (L:D) h for the other stages. At 12°C, no eggs hatched and at 15, 35, and 36°C only the incubation period was completed. The longest (135.81 and 156.49 d) and shortest (49.61 and 52.09 d) female life span were observed at 20 and 32°C for the Varamin and Rey populations, respectively. The highest (181.66 and 180.94 eggs/female) and lowest (13.40 and 32.85 eggs/female) total fecundity of the Varamin and Rey populations were found at 20°C and 34°C, respectively. At the same time, these two populations had the highest intrinsic rate of increase (r) (0.0343 and 0.0349 d-1) at 30 and 27°C, respectively. Similarly, both Varamin and Rey populations had the highest finite rate of increase (λ) at 27°C (1.0349 and 1.0355 d-1, respectively). It was found that the geographical populations of S. cretica were different in terms of the life table parameters at the same temperatures, and this issue can affect the results of forecasting studies. Accordingly, it is suggested that in the major corn-growing areas, a comprehensive study should be performed on different pest populations to address their commonalities and differences for future managing programs.

Removal of gut symbiotic bacteria negatively affects life history traits of the shield bug, Graphosoma lineatum.

The shield bug, Graphosoma lineatum (Heteroptera, Pentatomidae), harbors extracellular Pantoea-like symbiont in the enclosed crypts of the midgut. The symbiotic bacteria are essential for normal longevity and fecundity of this insect. In this study, life table analysis was used to assess the biological importance of the gut symbiont in G. lineatum. Considering vertical transmission of the bacterial symbiont through the egg surface contamination, we used surface sterilization of the eggs to remove the symbiont. The symbiont population was decreased in the newborn nymphs hatched from the surface-sterilized eggs (the aposymbiotic insects), and this reduction imposed strongly negative effects on the insect host. We found significant differences in most life table parameters between the symbiotic insects and the aposymbiotics. The intrinsic rate of increase in the control insects (0.080 ± 0.003 day-1) was higher than the aposymbiotic insects (0.045 ± 0.007 day-1). Also, the net reproductive and gross reproductive rates were decreased in the aposymbiotic insects (i.e., 20.770 ± 8.992 and 65.649 ± 27.654 offspring/individual, respectively), compared with the symbiotic insects (i.e., 115.878 ± 21.624 and 165.692 ± 29.058 offspring/individual, respectively). These results clearly show biological importance of the symbiont in G. lineatum.

Generation-Dependent Functional and Numerical Responses of a Naturally Fungus-Infected Colony of Habrobracon hebetor (Hymenoptera: Braconidae) Reared on Ephestia kuehniella (Lepidoptera: Pyralidae) in Iran.

The functional and numerical responses of Habrobracon hebetor (Say) were assessed over 30 sequential generations (G) on different densities (2, 4, 8, 16, 32, 64, and 128 fifth-instar larvae) of the Mediterranean flour moth, Ephestia kuehniella (Zeller). Seven tested generations (G2inf, G4inf, G6inf, G8inf, G10inf, G15inf, and G30inf) had already been naturally infected by a fungus species, whereas only the second generation (G2) had the colonies of both infected (G2inf) and uninfected (G2uninf) individuals. All infected generations, as well as the uninfected generation, showed a Type III functional response. A high variation was found in the handling times (Th) of the parasitoid through 30 sequential generations, and G10inf had the longest handling time. The shortest handling time and the maximum estimated attack rate (T/Th) were observed in G2inf. No significant difference in terms of the number of parasitized hosts was found among all infected generations, as well as between G2inf and G2uninf. Although the handling times in G2inf and G2uninf were close to each other, the attack coefficient of G2uninf was more than that of G2inf. The attack coefficient and handling time of infected generations increased from G2inf to G10inf and then decreased in the higher generations. The most plausible parameters of functional response of infected generations were observed in Ginf. A negative relationship between eggs laid and host densities was observed in the infected generations (G2inf, G4inf, G6inf, G8inf, and G10inf). G2uninf and, among infected generations, Ginf were the best generations for practical utilization in inundative release programs.

Quality control of the parasitoid wasp Trichogramma brassicae (Hymenoptera: Trichogrammatidae) over 45 generations of rearing on Sitotroga cerealella.

Trichogramma brassicae (Bezdenko) is an important biological control agent that has been used widely against many lepidopteran pests. Commonly, colonies of Trichogramma are mass reared on factitious hosts such as Sitotroga cerealella (Olivier) over many generations. In this study, we evaluated the quality and performance of a colony of T. brassicae that had been reared for over 45 generations (G) using two-sex life table parameters and parasitism capacity. We found that female adult longevity was significantly different among sequential generations, ranging from 5.58 ± 2.5 d (at G5) to 3.75 ± 1.42 d (at G45). However, no significant difference was found in male adult longevity among different generations. Although female wasps survived longer until the 15th generation, they allocated more days for egg laying at G5 and G10. The highest values of gross reproductive rate (GRR), net reproductive rate (R0 ), intrinsic rate of increase (r), finite rate of increase (λ) and mean generation time (T) were found in G5 and G10, which also showed significantly higher c0 . No significant difference in the finite parasitism rate (ω) was found among generations up to G15. These results suggest that T. brassicae wasps held under continuous laboratory rearing can be used successfully in biological control programs until the 15th generation without any loss of quality or performance. However, laboratory mass rearing colonies declined in quality after 15 generations and we suggest that they should be rejuvenated regularly by adding field-collected parasitoids periodically.

Age-Dependent Functional and Numerical Responses of Neoseiulus cucumeris (Acari: Phytoseiidae) on Two-Spotted Spider Mite (Acari: Tetranychidae).

The age-specific functional and numerical responses of Neoseiulus cucumeris Oudemans (Mesostigmata: Phytoseiidae) on eggs of the two-spotted spider mite, Tetranychus urticae Koch (Prostigmata: Tetranychidae), were assessed in the laboratory using bean leaf discs. Densities of 2, 4, 8, 16, 32, 64, and 128 prey were provided to 4- (protonymph), 6- (deutonymph), 8-, 13-, 18-, 23-, 28-, 33-, and 40-d-old N. cucumeris individuals. The functional response of 28- and 40-d-old N. cucumeris fitted type II, whereas the other ages displayed a type III functional response. The longest handling time observed at the age of 4 d was 0.515 h, whereas the shortest handling time and highest value of maximum attack rate (T/Th) were associated with the age of the 28-d-old treatment (0.261 h and 91.95 prey/d, respectively). The numerical response of N. cucumeris showed a significant increase with increasing prey density, but its rate gradually decreased at higher densities. Therefore, the efficiency of conversion of ingested food was relatively higher at low two-spotted spider mite densities, whereas it was reduced at high two-spotted spider mite densities. The stronger functional response and predation capacity of N. cucumeris on two-spotted spider mite eggs indicated the high potential of this predatory mite as an effective biological control agent against two-spotted spider mite especially at its early and middle ages and also when higher prey densities are present.

Characterization of a novel Pantoea symbiont allows inference of a pattern of convergent genome reduction in bacteria associated with Pentatomidae.

Phytophagous stink bugs typically harbor nutritional symbiotic bacteria in their midgut, to integrate their unbalanced diet. In the Pentatomidae, most symbionts are affiliated to the genus Pantoea, and are polyphyletic. This suggests a scenario of an ancestral establishment of symbiosis, followed by multiple symbiont replacement events by akin environmental bacteria in different host lineages. In this study, a novel Pantoeaspecies ('CandidatusPantoea persica') was characterized from the gut of the pentatomid Acrosternum arabicum, and shown to be highly abundant in a specific portion of the gut and necessary for the host development. The genome of the symbiont (2.9 Mb), while presenting putative host-supportive metabolic pathways, including those for amino acids and vitamin synthesis, showed a high level of pseudogenization, indicating ongoing genome reduction. Comparative analyses with other free-living and symbiotic Pantoea highlighted a convergent pattern of genome reduction in symbionts of pentatomids, putatively following the typical phases modelized in obligate nutritional symbionts of insects. Additionally, this system has distinctive traits, as hosts are closely related, and symbionts originated multiple independent times from closely related free-living bacteria, displaying convergent and independent conspicuous genome reduction. Due to such peculiarities, this may become an ideal model to study genome evolutionary processes in insect symbionts.

Supplementation of natural prey with pollen grains exerts an influence on the life table parameters of Neoseiulus californicus.

Better performance of generalist predators, as well as an increase in their density, may be an incentive factor in the ability of the predators to exploit more than one food item or mixed diets. In this study, the effects of four pollen grains (cedar, pear, apricot, and pistachio) when provided to Neoseiulus californicus in mixed diets with prey, Tetranychus urticae, were evaluated. The result indicated that the fastest female developmental time was observed on pistachio pollen + T. urticae, together with apricot pollen + T. urticae. Females reared on the mixed diet comprising pistachio pollen reflected the longest total life span duration, while the shortest total life span was observed in those on the diet that included pear pollen. Furthermore, the lowest fecundity, as well as the shortest reproduction period, was determined on the diets that included pear pollen, while the highest fecundity and the longest reproduction period were observed in pistachio pollen + T. urticae. In addition, the intrinsic (r) and finite rate of increase (λ), net (R0) and gross (GRR) reproductive rates were highest in pistachio pollen + T. urticae. These findings have important implications for developing a comprehensive biological control program of T. urticae, which will be discussed.

Age stage, two-sex life table of Habrobracon hebetor (Braconidae) on Spodoptera exigua (Noctuidae) reared on different sugar beet genotypes.

The present study was carried out to unveil interactive relevance among consecutive and alternate members of a tritrophic system comprised of sugar beet genotypes, beet armyworm, Spodoptera exigua (Hübner), and its parasitoid, Habrobracon hebetor (Say) using demographic parameters. To do so, H. hebetor was reared on S. exigua fed on 10 sugar beet genotypes, including SB26; SB27; SB29; SB33; SB34; (7112*SB36)*Sh-1-HSF-5; FC220; FC301; SBSI006; and HM 1339RZ in a growth chamber at 25 ± 1 °C, 60 ± 5% RH, and 16:8 (L: D) h photoperiod. The data was analyzed based on the age-stage, two-sex life table theory. Our results revealed high variation in duration of different life stages of H. hebetor on S. exigua reared on different sugar beet genotypes examined. The shortest (10.605 days) and longest (13.721 days) pre-adult period of H. hebetor was on S. exigua reared on SB26 and SB34, respectively. The longest (17.2 days) and shortest adult longevity (7.5 days) was on S. exigua reared on SB26 and SB27, respectively. The highest values of the intrinsic rate of increase (r) (0.209 day-1) and finite rate of increase (λ) (1.233 day-1) were observed on S. exigua reared on SB34 and their lowest values (0.159 and 1.172 day-1, respectively) were recorded on SB27. Resistant and susceptible genotypes to S. exigua, FC301 and (7112*SB36)*Sh-1-HSF-5, respectively, were only genotypes on which H. hebetor had greater and approximately equal r compared with S. exigua. This finding indicates high capability of H. hebetor to be successfully employed against S. exigua on sugar beet genotypes which are extremely different in resistance to this pest.

Coinfection of the secondary symbionts, Hamiltonella defensa and Arsenophonus sp. contribute to the performance of the major aphid pest, Aphis gossypii (Hemiptera: Aphididae).

Bacterial endosymbionts play important roles in ecological traits of aphids. In this study, we characterize the bacterial endosymbionts of A. gossypii collected in Karaj, Iran and their role in the performance of the aphid. Our results indicated that beside Buchnera aphidicola, A. gossypii, also harbors both Hamiltonella defensa and Arsenophonus sp. Quantitative PCR (qPCR) results revealed that the populations of the endosymbionts increased throughout nymphal development up to adult emergence; thereafter, populations of Buchnera and Arsenophonus were diminished while the density of H. defensa constantly increased. Buchnera reduction caused prolonged development and no progeny production. Furthermore, secondary symbiont reduction led to reduction of the total life span and intrinsic rate of natural increase as well as appearance of the deformed dead offspring in comparison with the control insects. Reduction of the secondary symbionts did not affect parasitism rate of the aphid by the parasitic wasp Aphidius matricariae. Together these findings showed that H. defensa and Arsenophonus contributed to the fitness of A. gossypii by enhancing its performance, but not through parasitoid resistance.

A new species of Adamystis (Acari: Trombidiformes: Adamystidae) from Iran.

A new species, Adamystis ekaterinae Ghasemi-Moghadam Saboori sp. nov. is described and illustrated based on adult females collected from soil in the Chitgar Forest Park, Iran. This new species is distinguished by having dimpled vacuoles between sci and sce on lateral propodosoma; one pair of eyes associated with postocular bodies; smooth dorsal idiosomal shield; setae h1, h2, ps1 and ps2 on smooth platelets and lacking lens like structures.

The microRNA pathway is involved in Spodoptera frugiperda (Sf9) cells antiviral immune defense against Autographa californica multiple nucleopolyhedrovirus infection.

The microRNA (miRNA) pathway is an epigenetic mechanism that plays important roles in various biological processes including host-virus interactions by regulating gene expression of the host and/or the virus. Previously, we showed that the cellular microRNAome in Spodoptera frugiperda (Sf9) cells is modulated following Autographa californica multiple nucleopolyhedrovirus (AcMNPV) infection suggesting that miRNAs may contribute in the cellular antiviral immunity. Here, we investigated the role of core components of the miRNA pathway in Sf9-AcMNPV interaction. Gene expression analyses showed that the expression levels of Dicer-1 (Dcr1), Argonaute-1 (Ago1) and Exportin-5 (Exp5) increased following AcMNPV infection particularly at 16 h post infection (hpi). Ran expression levels, however, decreased in response to virus infection. The expression levels of cellular miRNAs, miR-184 and let-7, also diminished at the post infection times further confirming differential expression of the cellular miRNAs following AcMNPV infection. To determine the role of the miRNA pathway in the interaction, we silenced key genes in the pathway using specific dsRNAs. RNAi of Dcr1, Ago1 and Ran enhanced viral DNA replication and reduced the abundance of miR-184 and let-7 underscoring the importance of the miRNA pathway in antiviral immunity in Sf9 cells. Suppression of the miRNA pathway in mock and infected cells had no effect on Ran expression levels suggesting miRNA-independent downregulation of this gene after virus infection. In conclusion, our results suggest the antiviral role of the miRNA pathway in Sf9 cells against AcMNPV. To modulate this immune response, AcMNPV represses host miRNAs likely through downregulation of Ran to enhance its replication in the host cells.