Deutonymphal Stage Research Articles

The chitinase genes TuCht4 and TuCht10 are indispensable for molting and survival of Tetranychus urticae

Insect chitinases (Chts) play a crucial role in the molting process, enabling continuous growth through sequential developmental stages. Based on their high homology to insect Chts, TuCht1 (group II), TuCht4 (group I) and TuCht10 (group IV) were identified, and their roles during molting process were investigated. TuCht1 was mainly expressed in the deutonymphal stage, while TuCht4 was mainly expressed in the nymphal stage and the highest expression level of TuCht10 was observed in the larvae. Feeding RNAi assays have shown that group I TuCht4 and group Ⅳ TuCht10 are involved in mite molting. Suppression of TuCht4 or TuCht10 resulted in high mortality, molting abnormalities and the absence of distinct electron dense layers of chitinous horizontal laminae in the cuticle, as demonstrated by scanning electron microscopy and transmission electron microscopy. The nanocarrier mediated RNAi had significantly higher RNAi efficiency and caused higher mortality. The results of the present study suggest that chitinase genes TuCht4 and TuCht10 are potential targets for dietary RNAi, and demonstrates a nanocarrier-mediated delivery system to enhance the bioactivity of dsRNA, providing a potential technology for green pest management.

The nuclear receptor gene E75 plays a key role in regulating the molting process of the spider mite, Tetranychus urticae.

The nuclear receptor gene Ecdysone-induced protein 75 (E75), as the component of ecdysone response genes in the ecdysone signaling pathway, has important regulatory function for insect molting. However, the regulatory function of E75 during the molting process of spider mites is not yet clear. In this study, the expression pattern of E75 in the molting process of the spider mite Tetranychus urticae was analyzed. The results showed that there was a peak at 8h post-molting, followed by a decline 8h after entering each respective quiescent stage across various developmental stages. During the deutonymph stage, the expression dynamics of E75, observed at 4-h intervals, indicated that the transcript levels of TuE75 peaked at 24h, coinciding with the onset of molting in the mites. To investigate the function of TuE75 during the molting process, silencing TuE75 through dsRNA injection into deutonymph mites at the age of 8h yielded a notable outcome: 78% of the deutonymph mites were unable to progress to the adult stage. Among these phenotypic mites, 37% were incapable of transitioning into the quiescent state and eventually succumbed after a certain period. An additional 41% of the mites successfully entered the quiescent state but encountered difficulties in shedding the old epidermis, leading to eventual mortality. In summary, these results suggested that TuE75 plays a key role in the molting process of T. urticae.

The genus Dendroseius Karg (Acari: Digamasellidae) in Iran, with description of the male and deutonymph of Dendroseius amoliensis

We provide the first descriptions of the adult male, deutonymphal stage and extended morphometric data for adult female of Dendroseius amoliensis Faraji, Sakenin-Chelav and Karg, collected from the rotten stump in Guilan province, Iran. Moreover, Dendroseius vulgaris Ma, Ho and Wang is recorded for the first time from Iran, collected from the livestock manure and decayed rice bran. Morphometric measurements of D. vulgaris based on specimens collected in Iran are given. An updated key to all known species of the genus is also presented.

Integrative Analysis of lncRNA-mRNA Co-expression Provides Novel Insights Into the Regulation of Developmental Transitions in Female Varroa destructor

Varroa destructor is a major pathogenic driver of the Western honeybee colony losses globally. Understanding the developmental regulation of V. destructor is critical to develop effective control measures. Development is a complex biological process regulated by numerous genes and long non-coding RNAs (lncRNAs); however, the underlying regulation of lncRNAs in the development of V. destructor remains unknown. In this study, we analyzed the RNA sequencing (RNA-Seq) data derived from the four stages of female V. destructor in the reproductive phase (i.e., egg, protonymph, deutonymph, and adult). The identified differentially expressed mRNAs and lncRNAs exhibited a stage-specific pattern during developmental transitions. Further functional enrichment established that fat digestion and absorption, ATP-binding cassette (ABC) transporters, mitogen-activated protein kinase (MAPK) signaling pathway, and ubiquitin-proteasome pathway play key roles in the maturation of female V. destructor. Moreover, the lncRNAs and mRNAs of some pivotal genes were significantly upregulated at the deutonymph stage, such as cuticle protein 65/6.4/63/38 and mucin 5AC, suggesting that deutonymph is the key stage of metamorphosis development and pathogen resistance acquisition for female V. destructor. Our study provides novel insights into a foundational understanding of V. destructor biology.

A survey of lifespan in Winterschmidtiidae (Sarcoptiformes: Astigmata)

The Winterschmidtiidae are a family of over 140 species of fungivorous, saprophagous, predatory and/or parasitic mites in insect/vertebrate nests, in decaying organic matter, in soils and on plants worldwide. In this review, I provide a survey of the immature developmental time, adult longevity and lifespan of the Winterschmidtiidae as part of the series on the lifespans in the Acari. The complete life cycle in this family includes five immature stages (the egg, larva, protonymph, deutonymph and tritonymph) and adult male/female, with deutonymphs lost in some genera such as Czenspinskia and Oulenziella. Development or lifespan data have been reported for only three species (< 3%) of the Winterschmidtiidae, and the experimentally measured lifespans of one to two months most likely reflect those of the summer generation. Afrocalvolia nataliae has two generations per year: the summer generation, which has no deutonymph stage, is mainly devoted to feeding and reproduction and lasts for one month only; the winter generation, however, has a deutonymph stage to resist the cold conditions and lasts for as long as 11 months.

Redescription of Panonychus caglei Mellott, 1968, with ontogenetic development (Acari: Tetranychidae).

A redescription of the adult stages of Panonychus caglei Mellott, 1968 (Acari: Tetranychidae), is presented based on new material collected from Japan, and type specimens (holotype and paratypes). Morphological differences in the setation of legs have been reported and measurements of taxonomic characters are added. We also have described the ontogenetic development of the juvenile stages. The ventral idiosomal chaetotaxy in larval stage lacks pregenital and genital setae which are added consecutively through development. The pregenital pair of setae appears in the protonymphs while the first pair of genital setae is firstly observed in the deutonymphal stage.

Effects of B-azolemiteacrylic on life-history traits and demographic parameters of two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

The present study was conducted to evaluate sublethal effects of B-azolemiteacrylic on the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Female adults of T. urticae were exposed to LC10 and LC30 of the acaricide, and the effects on treated females and their offspring were evaluated. The results showed that the fecundity of F0 female adults treated with LC10 and LC30 of B-azolemiteacrylic was reduced by 30.9 and 39.2%, respectively. Longevity and oviposition period of the females were significantly reduced as well. The developmental duration of egg and deutonymph stage of the F1 generation were not significantly different from that of the control. The protonymph stage after LC30 treatment lasted significantly longer, whereas the larva, deutonymph and female stage were significantly shorter than the control. The oviposition period of the F1 generation was significantly shortened, the fecundity of each female decreased significantly, and the ratio of female-to-male was reduced too. Moreover, the average generation period of T. urticae after LC10 and LC30 treatments was shorter than that of the control, and the net production rate (R0), intrinsic rate of increase (rm) and finite rate of increase (λ) were all reduced by 33.3, 7.5 and 1.9% (LC10 treatment) and by 51.3, 14.8 and 3.6% (LC30 treatment), respectively. The population doubling time was prolonged by 7.5 and 14.8% after LC10 and LC30 treatments, respectively, compared with the control. These results indicate that B-azolemiteacrylic may effectively inhibit the development rate of the F0 and F1 populations of T. urticae, which will help design integrated strategies for the comprehensive control of T. urticae and rational use of pesticides in the field.

Redescription of Chiropturopoda nidiphila Wiśniewski & Hirschmann (Acari: Uropodina) from a woodpecker’s tree holes, including all development stages and first notes on its ecology

All development stages of Chiropturopoda nidiphila Wiśniewski & Hirschmann, 1983 are described, which has previously been known only from the deutonymph stage. The species is closely associated with tree holes excavated by woodpeckers. Chiropturopoda nidiphila was redescribed and the genus diagnosis was completed. The description of the species morphology is based largely on scanning (SEM) electronograms. Diagnoses differentiating all of the known species of the genus Chiropturopoda are provided, including their developmental stages.

Molting process revealed by the detailed expression profiles of RXR1/RXR2 and mining the associated genes in a spider mite, Panonychus citri.

Spider mites have one ecdysone receptor (EcR) and multiple retinoid X receptors (RXRs). However, the function of these RXRs in spider mite development is unknown. Here, we screened the expression dynamics of two PcRXR isoforms at 4 h intervals in the deutonymphal stage of Panonychus citri. The results showed that PcEcR had an expression pattern similar to that of PcRXR2. For PcRXR1, its expression remained at a certain high level, when there was a decrease of both PcEcR and PcRXR2. In situ hybridization showed that PcRXR2 was detected in the central nervous mass, while the ecdysteroid biosynthesis gene PcSpo was mainly expressed at the edge of the central nervous mass. RNAi-based silencing of PcRXR1 or PcRXR2 showed the same phenotype as in mites with that of silencing PcEcR. Furthermore, RNA-seq was used to mine the genes associated with the expression dynamics of PcRXR1 or PcRXR2, which revealed that the heterodimer of EcR-RXR2 in spider mites might be linked with the cell autophagy and tissue remodeling during apolysis, and RXR1 might be linked with new epicuticle and exocuticle secretion during ecdysis. Taken together, these results increase our understanding of the regulation mechanism of ecdysteroid signal pathway in spider mite development.

Suitability of different pollen grains and Tetranychus urticae as food for the predatory mite, Amblyseius swirskii (Acari: Phytoseiidae)

The suitability of eight pollen diets (wild almond, date palm, oak, pomegranate, pistachio, peach, damask rose, and walnut) and also Tetranychus urticae Koch as natural diet on life table of the Amblyseius swirskii (Phytoseiidae) was determined at 25 ± 1 °C, 60 ± 5% relative humidity and photoperiod of 16:8 h (L: D). Results showed that damask rose pollen was not accepted as food and did not support the development of A. swirskii beyond the protonymphal and deutonymphal stage. The highest and lowest values of the intrinsic rate of increase (r) and finite rate of increase (λ) belonged to the pistachio (0.192 and 1.212 day−1) and peach (0.022 and 1.023 day−1) pollen, respectively. The net reproductive rate (R0) values varied from 1.4 offspring for the peach pollen to 29.54 offspring for the pistachio. Furthermore, the highest and lowest fecundity rate was recorded on the pistachio (36.65 eggs/female) and peach (3.23 eggs/female) pollen, respectively. Measured life table parameters of A. swirskii reared on different diets revealed pistachio, and after that, date palm and pomegranate pollen grains to be the most suitable diets. These findings may introduce more suitable pollen diets for the rearing of this predatory mite.

Description of a new species of Acotyledon Oudemans (Acari: Acaridae) feeding on eggs of the Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae), with a method for determining sex in deutonymphal stages

A new species, Acotyledon hookisetoses sp. nov. (Acari: Acaridae), collected from the stock colony of Sitotroga cerealella reared on wheat grains, is described, and illustrated from adults and deutonymphs. Sex-specific morphological differences at the deutonymphal stage are reported and discussed.

Life stages and phylogenetic position of the wool carder bee mite Sennertionyx manicati (Acari: Acaridae).

In mites of the family Acaridae, usually two developmental stages, adult (males, females) and deutonymphal stage (=hypopus) are used for diagnostic descriptions. Because these taxonomically important stages live in different habitats (i.e. deutonymphs are phoretic on a hymenopteran host, while adults live inside the nest of the host), one of these can be missing or they cannot be confidently corelated with each other. Sennertionyx manicati (Acari: Acaridae) was only known from hypopus. Herein, we describe all post-embryonic stages of S. manicati based on material obtained from a nest of Anthidium manicatum in Auckland, New Zealand, and provide a key to all life stages of this species. We also conducted a phylogenetic analysis of the 18S gene and the D2/D3 region of 28S genes from field-collected specimens and GenBank data. The molecular analysis indicated the New Zealand specimen shared the identical 18S and 99.5% identity of the D2D3 region of 28S sequences with S. manicati from Italy, and clustered together in the phylogenetic trees.

RNAi of the nuclear receptor HR3 suggests a role in the molting process of the spider mite Panonychus citri.

Ecdysteroids regulate molting in arthropods by binding to heterodimers of the ecdysone receptor and retinoid-X-receptor, homologous to the ultraspiracle protein, to induce the expression of downstream signal response genes including the nuclear receptor HR3. However, the detailed expression dynamics of HR3 during molting in spider mites are not yet clear. In this study, the full length of PcHR3 was retrieved based on the genome of citrus red mite, Panonychus citri. The open reading frame is 1707 bp encoding 568 amino acids, which contains a DNA binding domain and a ligand binding domain. Then, the expression pattern of PcHR3 was analyzed throughout the development of the deutonymph by RT-qPCR. The result showed that PcHR3 was mainly transcribed in the late deutonymph stage, when the deutonymph was at least 24 h old and motionless, the critical point at which the mites started molting. Transcription reached the highest level in 32-h-old deutonymphs and decreased by 36 h, where the mites remained in a quiescent state. Further silencing of PcHR3 by leaf-disc-based delivery of dsRNA to 8-h-old deutonymph mites, resulted in retarded development and death of 58% of deutonymphs. In summary, we suggest that PcHR3 regulates the latter stages of molting in P. citri.

Evaluation of Trombidioid (Acari: Parasitengona) Larval Exuviae And Its Importance In Diagnosis

Konak üzerinde parazit olan trombidioid larvası, yeteri kadar beslendikten sonra konaktan ayrılır ve protonimf (hareketsiz) safhasına, sonrasında larva derisini atarak deutonimf safhasına geçer. Bu çalışmada, konak üzerinden toplanan parazit larvalar ile konak üzerindeki diğer larvalardan elde edilen deutonimflerin aynı tür olduğu tespit edildi. Bu tespit, larvalar ile deutonimfe geçerken atılan larva derilerinin (exuviae) karşılaştırılmasıyla sağlandı. Bu yöntemle, bir otbiçen (Opilionida) ve iki sinek (Diptera) türü (Rhagio sp., Musca domestica) üzerinden toplanan parazit akarlardan, Allothrombium sp., Trichotrombidium muscarum (Riley, 1878) ve Trombidium holosericeum (Linnaeus, 1758) olmak üzere üç akar türü teşhis edildi. Aynı zamanda daha önceki çalışmalarda gözlenen ancak bugüne kadar üzerinde durulmayan larva derilerinin, larvalar ile aynı karakteristik özellikleri gösterdiği ve morfolojik teşhiste kullanılabileceği belirlendi

Feeding potential of phytoseiid predator, Neoseiulus baraki Athias-Henriot on Coconut eriophyid mite, Aceria guerreronis Keifer

Experimental results showed that the overall daily prey consumption rate of individual larva, protonymph and deutonymphal stage of N. baraki were consumed 6.33 ± 0.50, 11.00 ± 0.75 and 13.45 ± 0.89 prey mites, respectively. Whereas, the consumption rate of adult male and female were 14.07 ± 0.56 and 15.91 ± 0.45 preys, respectively. The total prey consumption rate of larval, protonymph and deutonymphal stage of N. baraki were 12.65 ± 1.00, 22.00 ± 1.50 and 40.35 ± 2.69 preys, respectively. However, total consumption rate for adult male and female were 219.40 ± 5.86 and 477.97 ± 5.51 prey mites, respectively. The prey consumption rate during entire life period of male was 294.40 ± 14.09 preys, while female of 552.97 ± 14.09 prey mites. Thus, the present finding clearly suggest that N.baraki could be a highly efficient biological control agent of A. guerreronis.

A preliminary study of growth and development of Cheyletus malaccensis (Oudemans) under different humidity conditions

Cheyletus malaccensis (Oudemans) is a species of predatory mite, which is widely distributed in grain storage, and is a potential natural enemy of stored-product pests. Based on the typical temperatures and humidities that occur in granaries, the growth and development of C. malaccensis was studied at 24°C with different relative humidities (RH 65±2%, 75±2%, 85±2% and 95±2%). During this study, C. malaccensis was fed on Acarus siro (Linnaeus), a very important stored grain pest to investigate its potential to control this pest and production of this natural enemy in the laboratory. The results showed that C. malaccensis has five developmental stages, egg, larva, protonymph, deutonymph and adult. The deutonymph stage is absent in males. For females, the developmental time from egg to adult was shortest at 85±2 % RH and averaged 16.3 days; developmental time was longest at 65±2 % RH and averaged 18.6 days. The male mites in the 95±2% RH trials had the shortest developmental time which averaged 12.6 days; it was longest at 65±2% RH where it averaged 14.7 days. At 95±2% RH, the male adult lived 83.5 d and its longevity from egg to adult was 95.8 d. Humidity had a significant effect on how long the adults lived and the duration of all developmental stages. At 85±2 % RH, the maximum average number of eggs per female, oviposition period and daily fecundity were 493.0, 46.2 d, and 10.3, respectively. This study provides basic biological parameters for C. malaccensis, a potential biological control agent for mite pests infesting stored grain.

Some mesostigmatic mites (Acari: Parasitiformes) of Khuzestan province, southwestern Iran

Animal droppings constitute an ephemeral habitat where specialized invertebrate communities including significant abundance of mites live together. In order to study the Mesostigmata mites associated with manure, samples were taken from different manure types of domestic animals and poultry in Ahvaz and its vicinity in Khuzestan Province, southwestern of Iran, over a period of two years (2015-2017). Here we report 20 species belonging to eight families of Mesostigmata, among which 14 species are new records for the fauna of Khuzestan Province. The genus and species Leitneria pugio (Karg, 1961) is newly recorded from Iran. The genus and species were previously only recorded in Europe. Also, Uroobovella varians Hirschmann & Zirngiebl-Nicol, 1962 is recorded for the first time from Iran based on deutonymph stage. We further provide collection data for each species along with a key for known Iranian species of the genus Uroobovella .

Factitious prey and artificial diets: do they all have the potential to facilitate rearing of Typhlodromus bagdasarjani (Acari: Phytoseiidae)?

ABSTRACTThe rearing possibility of Typhlodromus bagdasarjani (Phytoseiidae) on three factitious prey (Ephestia kuehniella eggs, cysts of Artemia franciscana and Tyrophagus putrescentiae), and nine artificial diets including a basic artificial diet (AD1) and the others (AD2–AD9) consisted of 80% AD1 enriched with different nutrients including maize pollen, haemolymph of Plusia gamma L., Ephestia eggs, Artemis cysts, Ephestia larvae, multivitamin syrup, bovine serum albumin and bull sperm, as well as a natural pollen diet (almond+ maize pollen) were investigated. None of the three factitious prey supported development of T. bagdasarjani beyond protonymphal stage. The highest GRR (gross reproductive rate), R0 (net reproductive rate), r (intrinsic rate of increase) and λ (finite rate of increase) were obtained when the adults were reared on cysts of Artemia, immediately after their emergence. On pollen diet, all population growth parameters except T (mean generation time) were higher than artificial diets. The mites reared on AD6 and AD8 could not develop beyond deutonymphal stage. Although r was negative on both AD3 and AD5, its value on AD3 was higher. In conclusion, except pollen diet, none of diets tested is recommendable for mass rearing of this predator and utilizing on crop as alternative food.

Neottialges (Caloenectes) vulturis (Dubinin, 1956) (Acari: Hypoderatidae) from the Eurasian griffon vulture (Gyps fulvus) in Italy: first record in Europe, redescription and pathological changes in the host

Deutonymphs of the astigmatan mite Neottialges (Caloenectes) vulturis (Dubinin, 1956) comb. n. (Astigmata: Hypoderatidae) were found during the anatomo-histopathological study of a Eurasian griffon vulture, Gyps fulvus, found dead in Central Italy. After skinning, numerous cystic formations were visible in the subcutaneous tissue of the vulture, each containing a parasitic mite. Microscopically, subcutaneous tissue showed large areas of severe granulomatous inflammation. To our knowledge, this is the first record of this poorly known hypoderatid mite in Europe, about five thousand kilometers west from the type locality in Kirghizstan. The deutonymphal stage of N. (C.) vulturis is redescribed following modern standards of taxonomic description for astigmatan mites. This mite, previously unassigned to a subgenus, is now placed in the subgenus Caloenectes Fain, 1966.

Immature stages and male of Paraseiulus amacroporus Faraji et al., (Acari: Mesostigmata: Phytoseiidae) from Southwestern Iran

This study presents the morphological characteristics of immature and adult male stages of Paraseiulus amacroporus Faraji, Jalaeian and McMurtry, 2008 (Phytoseiidae) collected from pistachio trees, Pistacia atlantica Desf. (Anacardiaceae), Shiraz vicinity (Fars province), South west Iran. The genders of the deutonymphal stage can be determined by the number of paired setae in the opisthogaster (six in female vs. four in male).