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 8 h post-molting, followed by a decline 8 h 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 24 h, 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 8 h 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.

Ecdysteroid Biosynthesis Halloween Gene Spook Plays an Important Role in the Oviposition Process of Spider Mite, Tetranychus urticae.

In insects, the ecdysteroid hormone regulates development and reproduction. However, its function in the reproduction process of spider mites is still unclear. In this study, we investigated the effect of the Halloween gene Spook on the oviposition of the reproduction process in a spider mite, Tetranychus urticae. The expression patterns of the ecdysteroid biosynthesis and signaling pathway genes, as analyzed by RT-qPCR, showed that the expression pattern of the Halloween genes was similar to the oviposition pattern of the female mite and the expression patterns of the vitellogenesis-related genes TuVg and TuVgR, suggesting that the Halloween genes are involved in the oviposition of spider mites. To investigate the function of the ecdysteroid hormone on the oviposition of the reproduction process, we carried out an RNAi assay against the Halloween gene Spook by injection in female mites. Effective silencing of TuSpo led to a significant reduction of oviposition. In summary, these results provide an initial study on the effect of Halloween genes on the reproduction in T. urticae and may be a foundation for a new strategy to control spider mites.

Notch Signaling in Insect Development: A Simple Pathway with Diverse Functions.

Notch signaling is an evolutionarily conserved pathway which functions between adjacent cells to establish their distinct identities. Despite operating in a simple mechanism, Notch signaling plays remarkably diverse roles in development to regulate cell fate determination, organ growth and tissue patterning. While initially discovered and characterized in the model insect Drosophila melanogaster, recent studies across various insect species have revealed the broad involvement of Notch signaling in shaping insect tissues. This review focuses on providing a comprehensive picture regarding the roles of the Notch pathway in insect development. The roles of Notch in the formation and patterning of the insect embryo, wing, leg, ovary and several specific structures, as well as in physiological responses, are summarized. These results are discussed within the developmental context, aiming to deepen our understanding of the diversified functions of the Notch signaling pathway in different insect species.

Role of the Hox Genes, Sex combs reduced, Fushi tarazu and Antennapedia, in Leg Development of the Spider Mite Tetranychus urticae.

Mites, the second largest arthropod group, exhibit rich phenotypic diversity in the development of appendages (legs). For example, the fourth pair of legs (L4) does not form until the second postembryonic developmental stage, namely the protonymph stage. These leg developmental diversities drive body plan diversity in mites. However, little is known about the mechanisms of leg development in mites. Hox genes, homeotic genes, can regulate the development of appendages in arthropods. Three Hox genes, Sex combs reduced (Scr), Fushi tarazu (Ftz) and Antennapedia (Antp), have previously been shown to be expressed in the leg segments of mites. Here, the quantitative real-time reverse transcription PCR shows that three Hox genes are significantly increased in the first molt stage. RNA interference results in a set of abnormalities, including L3 curl and L4 loss. These results suggest that these Hox genes are required for normal leg development. Furthermore, the loss of single Hox genes results in downregulating the expression of the appendage marker Distal-less (Dll), suggesting that the three Hox genes can work together with Dll to maintain leg development in Tetranychus urticae. This study will be essential to understanding the diversity of leg development in mites and changes in Hox gene function.

Potential of a winterschmidtiid prey mite for the production of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae).

Mass rearing of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) using natural (prey) methods is costly and laborious, limiting its application in the biological control of pests. A high-production, low-cost method using a prey substitute would help to relieve this problem. Oulenziella bakeri Hughes (Acari: Winterschmidtiidae) could be an alternative prey source, but studies on the reproductive parameters of N. californicus under rearing conditions are lacking. This study evaluated the potential of O. bakeri as an alternative prey in N. californicus rearing by comparing developmental parameters among N. californicus reared on three diets based on an age-stage two-sex life table. We found that the preoviposition period and developmental time of N. californicus did not vary based on diet. The fecundity of N. californicus adults reared on O. bakeri was 29.8 eggs per female, which was lower than that of adults reared on Tetranychus urticae Koch (Acari: Tetranychidae) (42.9 eggs per female); there was no significant difference between O. bakeri and apple pollen (30.2 eggs per female). The oviposition rate of mites fed on O. bakeri was 69% of that fed on T. urticae. Neoseiulus californicus reared on O. bakeri and apple pollen showed the same intrinsic rate of increase (0.25 per day), which was 86% of the rate of those fed on T. urticae. Compared with predatory mites reared on natural prey, N. californicus reared on O. bakeri had a high survival rate and good oviposition and population growth parameters, suggesting that O. bakeri is suitable for the rearing of N. californicus.

Identification of the fibroin of Stigmaeopsis nanjingensis by a nanocarrier-based transdermal dsRNA delivery system.

Stigmaeopsis nanjingensis (Ma and Yuan) (Acari: Tetranychidae) is an important pest of bamboo-feeding behavior and silk production by the female adult mites is seriously harmful to bamboo leaves. Due to its small size, silking and cocooning, its management is difficult. This study discusses a fast and easy method for management of the pest by disturbing the spinning behavior. Stigmaeopsis nanjingensis is host specific and feeds only on bamboo leaves. Leaf margins of bamboo are highly hydrophobic, which makes dsRNA difficult to immerse. Hence, it is a challenge to apply the commonly used feeding method to inhibit gene expression in mites. In this study, we deliver dsRNA to interfere with the expression of fibroin by body wall permeation with a nanocarrier-based delivery system. The dsRNA/nanocarrier formulation droplets could enter the body cavity within 2 min after falling on the mite. The fibroin silencing efficiency was 75.4%, and the results of electron microscopy showed that dsRNA/nanocarrier damage the morphological structure of the silk thread. This study demonstrated the effectiveness of a nanocarrier-based percutaneous dsRNA delivery system in S. nanjingensis and its effect on the fibroin gene that influences the spinning behavior of S. nanjingensis. These findings may provide a new delivery system for RNAi-based control of spider mites that utilize protective webbing in the field.

A new species of the genus Sonotetranychus (Acari: Tetranychidae) from New Zealand.

The genus Sonotetranychus consisted of seven species prior to this study. Sonotetranychus menziesii sp. nov., collected on Nothofagus menziesii and N. fusca from New Zealand, is described based on females, protonymphs, deutonymphs and a male. An updated key to the species of Sonotetranychus is provided.

Ontogenetic development and redescription of Tribolonychus collyerae (Acari: Tetranychidae).

Tribolonychus collyerae Zhang & Martin is redescribed based on the larva, protonymph, deutonymph and adult male and female specimens from New Zealand. The ontogenetic development of chaetotaxy in Tribolonychus and the number and position of solenidia on tibia I are discussed. Patterns of setal addition on leg III and IV from larva to adult in Trilobonychus are different from the basic pattern of the Tetranychinae and allied genus Neonidulus.

Hotspots of new species discovery: new mite species described during 2007 to 2012.

The type localities of new mite species described in two journals (Systematic & Applied Acarology and Zootaxa) during the last six years (2007­2012) were surveyed to detect hotspots of new mite species discovery. Among the 642 papers examined, 71% of them contain new species, with 148 new species in 2007, 207 in 2008, 234 in 2009, 208 in 2010, 333 in 2011 and 249 in 2012. Systematic & Applied Acarology published about 3% of the total new species indexed by Zoological Record during 2007­2012, whereas Zootaxa published about 35% of the total. The 1379 new species are distributed unevenly among 150 mite families; the top 15 families accounted for 55% of all the species, and 86 of the 150 families have 1­3 species each. The top family is the Eriophyidae, which alone accounted for nearly 15% of the total new species. Geographically, the new species were described from 92 countries and their distribution among these countries is highly uneven. The top 10 countries accounted for 62% of all the new species and the top country, China, alone accounted for 18% of the total. The average number of new species per country is 15 and no more than a fifth of the countries are above the average, and 40% of the countries have only 1­3 new species each. The top country for each continent is China (248 species) for Asia, Australia (166 species) for Oceania, Brazil (76 species) for South America, Kenya (51 species) for Africa, USA (51 species) for North America and Russia (42 species) for Europe. Increased efforts in discovering and describing new species are much needed for biodiversity-rich countries in South America, Southeast Asia and Africa.

Redescription of three species of Aponychus from China with ontogenetic development and morphological variations of A. corpuzae (Acariformes: Tetranychidae).

Ontogenetic development of leg chaetotaxy, stylophore and striae of the dorsal integument, and variations of leg setal counts and length of idiosomal setae in Aponychus corpuzae are discussed. The following changes were observed during the ontogenetic development of A. corpuzae: the depth of the depression in stylophore increases; the dorsal striae gradually reduce in number and prominence; the length of dorsal setae sc1, c12, d12 and e1 reduce in size; adult dorsal setae much thicker than those of immature stages. There are a significant number of setae suppressed in A. corpuzae, often resulting in unique patterns and sexual dimorphism. The adult males and females of Aponychus firmianae and A. taishanicus from mainland China are redecribed, and a key to all Aponychus from mainland China is provided.

The Unique Cauda-Liked Structure Represents a New Subfamily of Cunaxidae: Description of New Taxa and Discussion on Functional Morphology.

A cauda-like structure was found, firstly in Cunaxidae, and with it the new taxa Cunaxicaudinae Chen & Jin subfam. nov., and its two new genera, Cunaxicaudus Chen & Jin gen. nov. (type genus) and Brevicaudus Chen & Jin gen. nov., were erected. Cunaxicaudinae Chen & Jin subfam. nov. differs from the known members of the family Cunaxidae by the unique conspicuous cauda derived from the posterior end of the hysterosoma. The generic features of Cunaxicaudus Chen & Jin gen. nov. are as follows: the posterior of the hysterosoma elongated as a much longer cauda; palp between genu and tibiotarsus without apophysis; e1 closer to d1 than f1; and e1 closer to mid-line than c1 and d1. The generic features of Brevicaudus Chen & Jin gen. nov. are as follows: the posterior of hysterosoma elongated as a short cauda; palp between genu and tibiotarsus with one apophysis; distance between setae e1 and d1 approximately equal to e1; and f1, e1 as close to mid-line as c1 and d1 to mid-line. It is proposed that the specialized cauda may be the result of the evolution of the sperm transfer mode.

Revision of Neotrichobia Tuttle & Baker (Acari, Tetranychidae) with ontogenetic development and redescription of N. arizonensis.

The genus Neotrichobia Tuttle & Baker is redescribed with a revised diagnosis. The type species Neotrichobia arizonensis Tuttle & Baker, 1968 is redescribed based on larvae, protonymphs, deutonymphs and adults including the paratype male and deutonymph.

Genomics, transcriptomics, and peptidomics of the greater wax moth Galleria mellonella neuropeptides and their expression in response to lead stress.

Neuropeptides are crucial in regulation of a rich variety of developmental, physiological, and behavioral functions throughout the life cycle of insects. Using an integrated approach of multiomics, we identified neuropeptide precursors in the greater wax moth Galleria mellonella, which is a harmful pest of honeybee hives with a worldwide distribution. Here, a total of 63 and 67 neuropeptide precursors were predicted and annotated in the G. mellonella genome and transcriptome, in which 40 neuropeptide precursors were confirmed in the G. mellonella peptidome. Interestingly, we identified 12 neuropeptide precursor genes present in G. mellonella but absent in honeybees, which may be potential novel pesticide target sites. Honeybee hives were contaminated with heavy metals such as lead, enabling its bioaccumulation in G. mellonella bodies through the food chain, we performed transcriptome sequencing to analyze the effects of Pb stress on the mRNA expression level of G. mellonella neuropeptide precursors. After treatment by Pb, the expression of neuropeptide F1 was found to be significantly downregulated, implying that this neuropeptide might be associated with responding to the heavy metal stress in G. mellonella. This study comprehensively identified neuropeptide precursors in G. mellonella, and discussed the effects of heavy metals on insect neuropeptides, with the example of G. mellonella. The results are valuable for future elucidation of how neuropeptides regulate physiological functions in G. mellonella and contribute to our understanding of the insect's environmental plasticity and identify potential new biomarkers to assess heavy metal toxicity in insects.

Complete mitochondrial genome of Stigmaeopsis miscanthi (Acari: Tetranychidae).

Complete mitochondrial genome of Stigmaeopsis miscanthi was first reported for the genus Stigmaeopsis in Tetranychidae. The circular mitochondrial genome of S. miscanthi is 15,171 bp in length, with 80.4% AT content, involving 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA, and main one of non-coding regions. The length of 16SrRNA and 12SrRNA gene is 973 bp and 636 bp, respectively. Seven PCGs started with ATT codon, and other PCGs started with ATG and ATA codons. Five PCGs stopped with TAA codon, and the other eight PCGs ended with incomplete stop codons (T). Phylogenetic analysis indicated that S. miscanthi branched with the genus Panonychus.

A new species of Aponychus (Acariformes, Tetranychidae) from China.

Aponychus mai sp. nov. is the fourth reported species of Aponychus collected from bamboo in Baoshan City, Yunnan Province in Mainland China. We described this new species based on a larva, three deutonymphs and ten adults, and also explored the ontogenetic development, especially the discussion of the development in leg chaetotaxy.

Redescription of Bdella muscorum Ewing, 1909 (Bdellidae: Bdellinae) from China with Its First Description of Ontogeny.

Bdella muscorum Ewing, 1909 was redescribed and illustrated in detail, and its ontogeny was described and illustrated for the first time, including pro dorsal apodeme and chaetotaxy. Chaetotaxy changes in Bdella are mainly focused on ventral hypostomal setae (vh), setae on palpal basifemur, aggenital setae (ag), genital setae (g), anal setae (ad) and leg setae. Furthermore, an original key to the Bdella species from China was also provided.

Review on the Genus Stylophoronychus (Acari: Tetranychidae), with Description of a New Species.

Only two species of the genus Stylophoronychus, S. baghensis (Prasad, 1975) and S. guangzhouensis (Ma and Yuan, 1980), have been recorded in China. Herein we describe a new species Stylophoronychus wangaePan, Jin & Yi sp. nov. based on characteristics of the deutonymphs and adults. The synonym of S. guangzhouensis (Ma and Yuan, 1980) and S. lalli (Prasad, 1975) with S. vannus (Rimando, 1968) is proposed. A redescription of S. vannus (Rimando, 1968) based on the adults of both sexes, deutonymphs and a protonymph is given. The ontogenetic changes of leg chaetotaxy in two species are given and discussed. The updated key to the species of Stylophoronychus of the world is provided.

Morphological changes and ontogenetic development of Amblyseius eharai Amitai & Swirski (Acari: Phytoseiidae).

This paper describes the immature and mature characteristics of Amblyseius eharai Amitai & Swirski in detail to determine its morphological ontogeny based on laboratory-reared specimens. The main changes during ontogeny are as follows: the pronotal shield extends to j6 level and opisthosoma is unsclerotized in the larva; the dorsum has two shields in the protonymph, pronotal shield slightly expended comparing to that of the larva, and the opisthonotal shield smooth and weakly sclerotized. The podonotal and opisthonotal shields in the deutonymph are partially fused, and the dorsal shield is complete, covering almost the entire opisthonotum in adults in both sexes. There are nine pairs of dorsal setae in the larva, 14 pairs in the protonymph, and 19 pairs in both deutonymph and adult. In deutonymphs, gender could be distinguished by the number of setae in the area around the anal valves. In protonymphs, all dorsal, hypostomal setae, and the macrosetae of leg IV appear and are consistent with the subsequent stages. The development of morphological traits in the ontogeny of A. eharai may provide some basic knowledge to distinguish it from closely related species.

Redescription and new record of Odontoscirus nipponicus Shiba, 1985 (Bdellidae: Odontoscirinae) from China with a description of its ontogeny.

Odontoscirus nipponicus Shiba, 1985 is recorded from China and is redescribed; male, tritonymph, deutonymph, protonymph, and larva are described and illustrated for the first time. Morphological observations on the ontogeny of this species are also provided.

Two New Species and a New Combination of the Subfamily Erythraeinae Based on Larval Stage (Acari: Trombidiformes: Erythraeidae) from China.

The species Eatoniana yangshuonicus (Haitlinger) comb. nov. is transferred from the genus Erythraeus to Eatoniana based on the basifemoral setal formula 2-2-1. Two new species, Eatoniana nanlingensis Xu and Jin sp. nov. and Erythraeus (Erythraeus) kunyuensis Xu and Jin sp. nov. are described and illustrated based on larvae. Eatoniana nanlingensis sp. nov. from the Oriental region (Guangdong Province), Er. (Er.) kunyuensis sp. nov. from the Palaearctic region (Shandong Province). An updated key to larval species of the genus Eatoniana of the world is presented.