Cocoon Spinning Research Articles

Pyriproxyfen exposure compromises cocoon spinning and damages the Malpighian tubules of the nontarget predator Ceraeochrysa claveri (Neuroptera: Chrysopidae)

Pyriproxyfen has been extensively employed in the Neotropical region for agricultural pest management and insect vectors. However, measuring the sublethal and indirect effects of this active ingredient on nontarget organisms, such as lacewings, is important. Using morphological tools on target organs, we can evaluate these effects and use them as biomarkers for future ecotoxicological studies. Here, we investigated the effects of pyriproxyfen exposure on cocoon spinning and Malpighian tubules in Ceraeochrysa claveri adults. For this purpose, first-instar C. claveri larvae were orally exposed to Diatraea saccharalis egg clusters treated with pyriproxyfen in a solution of 50 or 100 mg a.i. L−1 throughout the larval stage. Insecticide exposure decreases predator survival, mainly in the prepupal and pupal stages, along with changes in the internal and external surfaces and thickness of the cocoon wall. Histopathological and ultrastructural injuries, including cytoplasmic vacuolization, loss of microvilli and a reduction in neutral glycoconjugates, were observed in Malphigian tubule cells of adults (≤24 h old). These changes indicate toxicological effects on Malpighian tubules that in lacewing involve cocoon spinning during metamorphosis and, in the adult stage, act in physiological processes of excretion and osmoregulation. Furthermore, it can affect the efficiency of the cocoon in protecting the specimen during metamorphosis against natural enemies and environmental factors. This organ has demonstrated its applicability as a biomarker for assessing the multisystemic effects of insecticides, thereby assisting in future risk assessments aimed at conserving nontargeted specimens.

Metabolic and transcriptomic characterization of summer and winter dormancy in the solitary bee, Osmia lignaria

The solitary bee Osmia lignaria is a native pollinator in North America with growing economic importance. The life cycle of O. lignaria provides a unique opportunity to compare the physiological and molecular mechanisms underlying two ecologically contrasting dormancies within the same species. O. lignaria prepupae become dormant during the summer to avoid high temperatures. Shortly after adult eclosion, they enter a second dormancy and overwinter as diapausing adults. To compare these two dormancies, we measured metabolic rates and gene expression across development as bees initiate, maintain, and terminate both prepupal (summer) and adult (overwintering) dormancies. We observed a moderate temperature-independent decrease in gas exchange during both the prepupal dormancy after cocoon spinning (45 %) and during adult diapause after eclosion (60 %). We sequenced and assembled a high-quality reference genome from a single haploid male bee with a contiguous n50 of 5.5 Mbp to facilitate our transcriptomic analysis. The transcriptomes of dormant prepupae and diapausing adults clustered into distinct groups more closely associated with life stage than dormancy status. Membrane transport, membrane-bound cellular components, oxidoreductase activity, glutathione metabolism, and transcription factor activity increased during adult diapause, relative to prepupal dormancy. Further, the transcriptomes of adults in diapause clustered into two groups, supporting multiple phases of diapause during winter. Late adult diapause was associated with gene expression profiles supporting increased insulin/IGF, juvenile hormone, and ecdysone signaling.

Self-Searching Writing of Human-Organ-Scale Three-Dimensional Topographic Scaffolds with Shape Memory by Silkworm-like Electrospun Autopilot Jet.

Bioengineered scaffolds satisfying both the physiological and anatomical considerations could potentially repair partially damaged tissues to whole organs. Although three-dimensional (3D) printing has become a popular approach in making 3D topographic scaffolds, electrospinning stands out from all other techniques for fabricating extracellular matrix mimicking fibrous scaffolds. However, its complex charge-influenced jet–field interactions and the associated random motion were hardly overcome for almost a century, thus preventing it from being a viable technique for 3D topographic scaffold construction. Herein, we constructed, for the first time, geometrically challenging 3D fibrous scaffolds using biodegradable poly(ε-caprolactone), mimicking human-organ-scale face, female breast, nipple, and vascular graft, with exceptional shape memory and free-standing features by a novel field self-searching process of autopilot polymer jet, essentially resembling the silkworm-like cocoon spinning. With a simple electrospinning setup and innovative writing strategies supported by simulation, we successfully overcame the intricate jet–field interactions while preserving high-fidelity template topographies, via excellent target recognition, with pattern features ranging from 100’s μm to 10’s cm. A 3D cell culture study ensured the anatomical compatibility of the so-made 3D scaffolds. Our approach brings the century-old electrospinning to the new list of viable 3D scaffold constructing techniques, which goes beyond applications in tissue engineering.

Descriptions of the Mature Larvae of Three Australian Ground-Nesting Bees(Hymenoptera: Colletidae: Diphaglossinae and Neopasiphaeinae)

Fully fed larvae of three Australian bee species formerly classified as Colletidae: Paracolletini are described and compared in light of recent phylogenetic studies. Two of these species, Leioproctus (Goniocolletes) wanni (Leijs and Hogendoorn) and Trichocolletes orientalis Batley and Houston, belong in the Neopasiphaeinae, while the third, Paracolletes crassipes Smith, belongs in Diphaglossinae: Paracolletini (sensu Almeida et al., 2019). We find that larval characters support the separation of Paracolletes from the neopasiphaeines, in particular the spoutlike salivary gland opening associated with cocoon spinning. In addition, we suggest that nest architecture of P. crassipes includes a feature that prevents flooding of open brood cells, a feature common to a number of other large ground-nesting bees.

The influence of an analog of juvenile hormone on the silk gland of Africanized Apis mellifera larvae reared in vitro

As the larval silk glands of Africanized honey bees are well characterized in hive conditions, we compared the silk glands of larvae of Africanized honey bees from the hive (in vivo - literature information) with larvae reared under laboratory conditions according to a specific bioassay (in vitro rearing of Africanized honey bees). We also continuously exposed the larva to a juvenile hormone analog (JHA), the pyriproxyfen, in three different concentrations: 12.5 mg/L, 25 mg/L, and 50 mg/L. Concerning morphological and histochemical analyses, there were no characteristics in glands that indicated the acceleration of the cocoon spinning time and no features of cell death. The glands seemed to be in secretory activity. Pyriproxyfen-treated larvae had a slightly shorter silk synthesis period than control, although only in the 50 mg/L experimental group, the tactoids from silk were clearly visible in optical microscopy, probably due to a higher secretion activity as the response to JHA. We observed that the presence of lipids under artificial feeding was independent of the nurse bee presence. Thus, we found that pyriproxyfen alters the functioning of the silk gland, under laboratory conditions in morphological, histological, and/or morphometric aspects.

Unstable Indicators of Temperature and Humidity in Large-Scale Special Worm Rearing Houses and the Negative Consequences of Feeding Worms in Them

This article reveals the information on rearing houses for silkworms. It has been observed that the larger the size of silkworm rearing houses, the more difficult it is to maintain a comfortable temperature, relative humidity and other environmental factors, and as a result, the development of silkworms, cocoon spinning processes vary, and the process implementation of agro-technical measures is disrupted. As consequently, scientifically based data show that the viability of industrial cocoons was 14.5-24.5%, and the duration of the larval period was 2-8 days.

Nesting Biology and Offspring Development of the Cavity-Nesting Solitary Wasp Isodontia elegans (F. Smith) from Trap-Nests in Oregon

We studied the nesting biology and developmental schedules of the cavity-nesting solitary wasp Isodontia elegans in Oregon, USA. Trap-nests contained 1–15 brood cells each, separated by partitions, which adult females made with grass fragments. Before leaving nests to hunt, females made loose, temporary closures of longer fragments of dried grass and, upon returning, briefly deposited prey just inside the nest entrance before transferring them to a cell. Cells were provisioned with katydids (Meconema thalassinum, an invasive species in North America) and tree crickets (Oecanthus fultoni), the latter predominating as summers progressed. The inner cells of nests, where most daughters developed, were longer and separated from adjacent cells by partitions thicker than those in outer cells, where most sons developed. These observations, along with the fact that daughters are larger than sons (likely because they receive a greater provision mass from mothers), indicate that investment in daughters is considerably greater than that in sons, by multiple measures. Sexual size dimorphism was evident in both cocoon mass (prepupae + cocoon case) and adult mass. From 2013 to 2019, nesting began earlier in the summer when mean maximum daily temperatures in June were higher and when the number of days in June with maximum temperatures <25 °C were fewer. Once nesting began, females typically completed 1 cell per day, the egg being laid on one of the first 3 prey placed in the cell. In the field, eggs hatched in 2–6 d, and larvae completed feeding and began cocoon spinning 5–11 d later. After removal from winter storage, offspring completing development at 29 °C emerged as adults in 22–40 d, with males emerging about 2 d earlier on average. The duration of the postdiapause period leading to adult emergence, however, was not correlated with eventual adult mass in either sex. We discuss interpopulation differences in prey species and nest materials used by I. elegans.

Cocoon-Spinning Behavior and 20-Hydroxyecdysone Regulation of Fibroin Genes in Plutella xylostella.

The diamondback moth Plutella xylostella is a serious pest of crucifers. It has high reproductive potential and is resistant to many insecticides. Typically, the last-instar larvae of P. xylostella, before pupation, move to the lower or outer plant leaves to make a loose silk cocoon and pupate inside for adult formation. To better understand this pivotal stage we studied the cocoon-spinning behavior of P. xylostella and measured three successive phases by video-recording, namely the selection of a pupation site, spinning a loose cocoon and padding the scaffold cocoon. Subsequently, we cloned three fibroin genes related to cocoon production, i.e., fibroin light chain (Fib-L), fibroin heavy chain (Fib-H), and glycoprotein P25. A spatio-temporal study of these three fibroin genes confirmed a high expression in the silk glands during the final larval instar silk-producing stage. In parallel, we did an exogenous treatment of the insect molting hormone 20-hydroxyecdysone (20E), and this suppressed fibroin gene expression, reduced the normal time needed for cocoon spinning, and we also observed a looser cocoon structure under the scanning electron microscope. Hence, we demonstrated that the expression levels of key genes related to the synthesis of 20E [the three Halloween genes Spook (Spo), Shadow (Sad), and Shade (Shd)] decreased significantly during spinning, the expression of the 20E receptor (EcR and USP) was significantly lower during spinning than before spinning, and that the expression levels of CYP18-A1 related to 20E degradation were significantly up-regulated during spinning. The significance of the cocoon and the effects of 20E on the cocoon-spinning behavior of P. xylostella are discussed.

A re-evaluation of silk measurement by the cecropia caterpillar (Hyalophora cecropia) during cocoon construction reveals use of a silk odometer that is temporally regulated.

The late 5th instar caterpillar of the cecropia silk moth (Hyalophora cecropia) spins a silken cocoon with a distinct, multilayered architecture. The cocoon construction program, first described by the seminal work of Van der Kloot and Williams, consists of a highly ordered sequence of events. We perform behavioral experiments to re-evaluate the original cecropia work, which hypothesized that the length of silk that passes through the spinneret controls the orderly execution of each of the discrete events of cocoon spinning. We confirm and extend by three-dimensional scanning and quantitative measurements of silk weights that if cocoon construction is interrupted, upon re-spinning, the caterpillar continues the cocoon program from where it left off. We also confirm and extend by quantitative measurements of silk weights that cecropia caterpillars will not bypass any of the sections of the cocoon during the construction process, even if presented with a pre-spun section of a cocoon spun by another caterpillar. Blocking silk output inhibits caterpillars from performing normal spinning behaviors used for cocoon construction. Surprisingly, unblocking silk output 24-hr later did not restart the cocoon construction program, suggesting the involvement of a temporally-defined interval timer. We confirm with surgical reductions of the silk glands that it is the length of silk itself that matters, rather than the total amount of silk extracted by individuals. We used scanning electron microscopy to directly show that either mono- or dual-filament silk (i.e., equal silk lengths but which vary in their total amount of silk extracted) can be used to construct equivalent cocoons of normal size and that contain the relevant layers. We propose that our findings, taken together with the results of prior studies, strongly support the hypothesis that the caterpillar uses a silk “odometer” to measure the length of silk extracted during cocoon construction but does so in a temporally regulated manner. We further postulate that our examination of the anatomy of the silk spinning apparatus and ablating spinneret sensory output provides evidence that silk length measurement occurs upstream of output from the spinneret.

Polyphagous koinobiosis: the biology and biocontrol potential of a braconid endoparasitoid of exophytic caterpillars

Polyphagous koinobiosis might be a novel perspective to help elucidate the evolution of the physiological and ecological traits of parasitoid wasps and determine their use as biocontrol agents. The euphorine braconid Meteorus pulchricornis is a polyphagous koinobiont endoparasitoid of exophytic caterpillars from 15 families within 10 lepidopteran superfamilies. Here, the biology of this common but enigmatic parasitoid wasp is reviewed. The unique cocoon suspension system of M. pulchricornis protects it against predators during and after cocoon spinning. This structural cocoon protection method, as well as robust immune suppression mechanism, likely enables its very wide host range. In Japan, M. pulchricornis can reproduce both sexually and asexually, and the coexistence of sexual and asexual strains might be encouraged by its high polyphagy. In this review, the potential use of M. pulchricornis as a biocontrol agent is also addressed.

The Effects of Juvenile Hormone Analogue, Fenoxycarb on the Last Instar Testes of Bombyx mori

The development and metamorphosis of insects is regulated by juvenile hormone (JH) and ecdysone hormone, which are worked antagonist. Fenoxycarb is an effective juvenile hormone analogue on many insects. In this study, the effect of fenoxycarb on the last larval stage Bombyx mori testes was investigated. Male larvae on the 6th day of the last instar are divided into 2 groups. 1 ng of fenoxycarb dissolved in acetone was topically applied to larvae in the treatment group and the remaining 18 larvae were used as the control group. Control and treated groups were followed to until pupation from day when they showed cocoon spinning behavior. After dissection, several of testes were entreated routine histological processes and photographed. In treatment group, it was seen that fenoxycarb reduced spermatogonium formation by suppressing ecdysone release and caused a decrease in mature sperm. Remaining testes are used to the analysis of total carbohydrate and glycogen content. In conclusion, fenoxycarb has the reducing effect on spermatogenesis and it can cause to decrease of total carbohydrate content because of stress in insects. These histological and biochemical results may be in support of the use of fenoxycarb as an insect growth regulator (IGR) for harmful insects.

Effect of 12-hours delay and anticipation from traditional practice in silkworm mounting to spinning frames on economic traits of Bombyx mori (Lepidoptera: Bombycidae) cocoons

In this study, the aim was to determine the effect of 12 hours delay and time advancement of Bombyx mori larvae transfer to spinning frames on the economic traits of harvested cocoons. Our experience focused on the transfer of three lots of silkworm mature larvae to cocoon frames with 12 hours delay or advancement from usual spinning time. Commercial silkworm eggs were obtained and three replications of 100 larvae per each treatment were used. The larvae and cocoon conditions of hatching and rearing, feeding conditions, silkworm egg production stages were performed based on standard protocols. Rice straws were used as cocoon position (framework) in the cocoon spinning stage separately for each replication. After completion of the pupa development, total cocoon production was collected and classified based on appearance, hardness, softness, and cleanliness levels of the cortex and outer cortex into four categories, viz. good, moderate, low and double cocoons. Economic characteristics were calculated and compared between treatments using the Duncan test at p < 0.05. The comparison of economic traits of cocoons produced in perfected treatments showed no significant difference between treatments and the control. This result suggests that the 12 hours’ time anticipation or delay of larva transfer to cocoons building frames has no effect on the quantity or the quality of produced cocoons. Therefore, it is possible to shorten the rearing duration of Bombyx mori larvae by 12 hours without affecting the cocoon economic traits, and this could improve cocoon production and generate an important economic advantage in commercial sericulture.

Comparison of new castor (Ricinus communis L.) genotypes in the mediterranean area and possible valorization of residual biomass for insect rearing

Despite its high suitability to European climates and a considerable commercial-grade for industrial applications (about 25% of global castor oil production is processed in EU), castor crop is inexistent in the European farming systems. The revival of castor in Europe could result in an attractive opportunity not only for the production of domestic oil, but also for potential strategic uses of residual biomass at harvest in the bio-based economy. In the light of the recent inclusion of insect-derived products in the list of “Novel Food” (EC 16/11/2015), a very interesting use of castor leaves is for feeding eri silkworm (Samia cynthia ricini), a wild moth able to produce textile fiber from the cocoon, as well as to accumulate interesting oil and protein amounts in the pupae. Two screening trials comparing four different castor hybrids were set in Bologna (Italy) and Aliartos (Greece) in 2015; moreover, two of them, contrasting for the morphological habitus, were tested in Bologna to set up artificial diets for rearing eri silkworms. The artificial diets were prepared starting from both green (GADiet) or senescent leaves (SADiet), and the insect rearing performance was evaluated in comparison to a standard rearing on fresh leaves (FCLeaf). Castor hybrids demonstrated to be well adapted to both Mediterranean environments. More favorable temperatures and regular irrigation led to significantly better productive performance in Greece (up to 54% oil yield): higher biomass accumulation, increased seed yield (+34%) and seed oil content (+9%), even though the best hybrids were found the same in the two environments. The performance of the artificial diets in eri silkworm rearing was inferior compared to the fresh castor leaves, but the majority of the larvae fed with artificial diets (∼85% of total, on average of the two artificial diets) was anyhow able to complete the development until the cocoon spinning. The administration of artificial diets caused higher mortality, a general elongation of the duration of larval stage (30d for SADiet>24d for GADiet>17d for FCLeaf), and a reduced cocoon weight. The fatty acid composition of lipid extracted from the pupae was also significantly influenced by the rearing diet, with FCLeaf fed silkworms accumulating more linolenic acid compared to those fed on artificial diets. In conclusion, castor plant showed satisfactory seed yields in both Mediterranean locations; the use of senescent leaves to set up an artificial diet to rear eri silkworms for bio-based applications resulted a promising and affordable route for valorizing residual biomass under the biorefinery concept.

Molecular characterization of the gene feminizer in the stingless bee Melipona interrupta (Hymenoptera: Apidae) reveals association to sex and caste development

In highly eusocial insects, development of reproductive traits are regulated not only by sex determination pathway, but it also depends on caste fate. The molecular basis of both mechanisms in stingless bees and possible interaction with each other is still obscure. Here, we investigate sex determination in Melipona interrupta, focusing on characterization and expression analysis of the feminizer gene (Mi-fem), and its association to a major component of caste determination, the juvenile hormone (JH). We present evidence that Mi-fem mRNA is sex-specifically spliced in which only the female splice variant encodes the full length protein, following the same principle known for other bee species. We quantified Mi-fem expression among developmental stages, sexes and castes. Mi-fem expression varies considerably throughout development, with higher expression levels in embryos. Also, fem levels in pupae and newly emerged adults were significantly higher in queens than workers and males. Finally, we ectopically applied JH in cocoon spinning larvae, which correspond to the time window where queen/worker phenotypes diverge. We observed a significantly increase in Mi-fem expression compared to control groups. Since up to 100% of females turn into queens when treated with JH (while control groups are composed mainly of workers), we propose that fem might act to regulate queens' development. Our findings provide support for the conserved regulatory function of fem in Melipona bees and demonstrate a significant correlation between key elements of sex and caste determination pathways, opening the avenue to further investigate the molecular basis of these complex traits.

Construction of Nest Defensive Structure According to Offspring Value and Its Effect on Predator's Attack Decision in Paper Wasps

AbstractVarious organisms are known to build nests with defensive structures to protect their offspring from predation, but our understanding of plasticity in the nest structure remains poor. In this study, we investigated whether a paper wasp, Polistes chinensis antennalis, adjusted the construction of nest defensive structure according to the value of their offspring, and we also analysed the effect of adjusting the construction of the structure on predator's decision to attack. P. chinensis antennalis foundresses start a colony and maintain her nest alone until the emergence of workers. During this stage, foundresses often construct a defensive structure on cocoon caps of pupae using nest materials (pulp), which prevents predation of pupae by conspecifics from other nests. The value of pupae to the foundress varies among those in a nest, where the value is higher in pupae that spun the cocoon (and initiated pupation) earlier than other pupae in the nest. From field observations, we found that foundresses constructed a larger pulp structure on the cocoons of pupae that cocooned earlier in the order of cocoon spinning, even after considering confounding factors. We also found that the probability of a pupa being attacked by conspecific intruders decreased with the size of pulp structure on the cocoon. This indicates that intruders avoid attacking cocoons with larger pulp structures. Our study indicates that foundresses adjust the construction of nest defensive structures according to their offspring value, and this allows them to protect the high‐value offspring efficiently and effectively.

Multifaceted defense against antagonistic microbes in developing offspring of the parasitoid wasp Ampulex compressa (Hymenoptera, Ampulicidae).

Effective antimicrobial strategies are essential adaptations of insects to protect themselves, their offspring, and their foods from microbial pathogens and decomposers. Larvae of the emerald cockroach wasp, Ampulex compressa, sanitize their cockroach hosts, Periplaneta americana, with a cocktail of nine antimicrobials comprising mainly (R)-(-)-mellein and micromolide. The blend of these antimicrobials has broad-spectrum antimicrobial activity. Here we explore the spatio-temporal pattern of deployment of antimicrobials during the development from egg to adult as well as their physico-chemical properties to assess how these aspects may contribute to the success of the antimicrobial strategy. Using gas chromatography/mass spectrometry (GC/MS) we show that larvae start sanitizing their food as soon as they have entered their host to feed on its tissue. Subsequently, they impregnate the cockroach carcass with antimicrobials to create a hygienic substrate for cocoon spinning inside the host. Finally, the antimicrobials are incorporated into the cocoon. The antimicrobial profiles on cockroach and wasp cocoon differed markedly. While micromolide persisted on the cockroaches until emergence of the wasps, solid-phase microextraction sampling and GC/MS analysis revealed that (R)-(-)-mellein vaporized from the cockroaches and accumulated in the enclosed nest. In microbial challenge assays (R)-(-)-mellein in the headspace of parasitized cockroaches inhibited growth of entomopathogenic and opportunistic microbes (Serratia marcescens, Aspergillus sydowii, Metarhizium brunneum). We conclude that, in addition to food sanitation, A. compressa larvae enclose themselves in two defensive walls by impregnating the cocoon and the cockroach cuticle with antimicrobials. On top of that, they use vaporous (R)-(-)-mellein to sanitize the nest by fumigation. This multifaceted antimicrobial defense strategy involving the spatially and temporally coordinated deployment of several antimicrobials in solution and vapor form has apparently evolved to reliably protect the larvae themselves and their food against a broad range of antagonistic microbes.

Effects of neem oil (Azadirachta indica A. Juss) on the replacement of the midgut epithelium in the lacewing Ceraeochrysa claveri during larval-pupal metamorphosis

Larvae of the lacewing Ceraeochrysa claveri were fed on eggs of Diatraeasaccharalis treated with neem oil at concentrations of 0.5%, 1% and 2% throughout the larval period. Pupae obtained from treated larvae were used in the study at five days after the completion of cocoon spinning to investigate the effects of neem oil on the replacement of the midgut epithelium during the larval-pupal transition. We observed that the old larval epithelium was shed into the midgut lumen and transformed into the yellow body. Old cells from the yellow body were destroyed by apoptosis and autophagy and were not affected by neem oil. However, neem oil did affect the new pupal epithelium. Cells from treated pupae showed cellular injuries such as a loss of microvilli, cytoplasmic vacuolization, an increase of glycogen stores, deformation of the rough endoplasmic reticulum and dilation of the perinuclear space. Additionally, the neem oil treatment resulted in the release of cytoplasmic protrusions, rupture of the plasma membrane and leakage of cellular debris into the midgut lumen, characteristics of cell death by necrosis. The results indicate that neem oil ingestion affects the replacement of midgut epithelium, causing cytotoxic effects that can alter the organism’s physiology due to extensive cellular injuries.

Development of Pull Strips Mountage forSamia riciniDonovan and Mounting Performances Over Traditionally Used Mountages

The materials used and the interior environment in mountage system are two important factors that directly influence the cocooning process. Considering these factors, a pull strips mountage (PSM) system has been designed and fabricated using wood, cloth and sand mica. Comparative cocooning performance in the PSM of ripen Eri larvae from the same crop lot is found to be superior to other mountages widely use by the farmers. Good cocoon spinning is 98% in PSM. Flimsy and double cocoon formation is restricted to 0.5% only, whereas dead/non-cocooning larvae are found to constitute 1%. Good cocooning in PSM is 6.5% higher (at an average) than the other mountage systems. In flimsy cocoon formation, PSM shows a difference of 3.375% less than the average of 3.875% in other systems. In dead/non-cocooning larvae, PSM has been found have 2.125% economy over other systems. Further, in comparison to the rest of the mountage systems, cocoon spine in PSM is of superior quality in terms of cocoon and shell weight, which gives a higher silk ratio of 13.4%, indicating more yean recovery than cocoons’ spine in other systems. For equal quantity of cocoon, PSM's cocoon gives 0.94% more yean than that of other systems. Since, this is a labour-intensive process, PSM facilitates 88.73% less labour cost over the rest of the systems on an average.

On the Nest Structure in Two Species of the Genus Leptochilus (Hymenoptera, Vespidae, Eumeninae)

Abstract Two nests of the wasps Leptochilus alpestris (de Saussure, 1855) and Leptochilus regulus (de Saussure, 1855) collected in the Crimea were described. The nest of L. alpestris was found in the empty snail shell of Monacha fruticola under a stone; it contained one cell sealed with plug made of glued gravel bits. The nest of L. regulus was found in 3 mm hole of a reed stem from trap-nest; it contained 9 cells separated with partitions made of gravel and mud. The unusual larval habit was discovered in L. regulus - they moved mud from the plug of the cell to its bottom before cocoon spinning. Distinctions of the studied nests from ones of the other species of the genus Leptochilus de Saussure, 1853 were discussed.

Action of neem oil (Azadirachta indica A. Juss) on cocoon spinning in Ceraeochrysa claveri (Neuroptera: Chrysopidae)

Neem oil is a biopesticide that disturbs the endocrine and neuroendocrine systems of pests and may interfere with molting, metamorphosis and cocoon spinning. The cocoon serves protective functions for the pupa during metamorphosis, and these functions are dependent on cocoon structure. To assess the changes in cocoon spinning caused by neem oil ingestion, Ceraeochrysa claveri larvae, a common polyphagous predator, were fed with neem oil throughout the larval period. When treated with neem oil, changes were observed on the outer and inner surfaces of the C. claveri cocoon, such as decreased wall thickness and impaired ability to attach to a substrate. These negative effects may reduce the effectiveness of the mechanical and protective functions of cocoons during pupation, which makes the specimen more vulnerable to natural enemies and environmental factors.