Female Cocoons Research Articles

SILKBOT : Orchestrating Silk Symphony - A Comprehensive Approach towards Silk Production and Enhancement in Sericulture Applications

In this paper, the orchestrating of the silk symphony - a comprehensive approach towards silk production and enhancement in sericulture applications is presented. The final year project work undertaken by us involves the design & development of a silkbot, which will give us the comprehensive approach towards Silk Production and Enhancement in the quality of silk produced. The aim of the project is to revolutionize silk production through a comprehensive approach encompassing four critical components that are Segregation of cocoon based on gender, Identification of diseased cocoons to curb disease spread and enhance yield, maintenance of ideal temperature conditions for the enhanced growth of cocoons and Maintenance of optimal feeding conditions tailored to cocoon growth and needs. Cocoon Segregation System - Focuses on the segregation of cocoons based on their genders which will be ensuring optimal silk production and controlled environment for the female cocoon who produce more raw silk than male and prevent Disease Spread. Diseased Cocoon Identification - Aims to implement an automated system for the identification of diseased cocoons, mitigating the spread of diseases that can significantly impact yield and harvest rates. Temperature Control System - Emphasizes the maintenance of ideal temperature conditions for the enhanced growth of Silkworms, optimizing the quality and quantity of silk production. Optimized Feeding System -Tailored feeding based on the growth stages and nutritional needs of the Silkworms for optimal silk production. The work carried out is the seventh semester main-project by the students of Electronics & Communication Engineering under the guidance of the faculties supervision (guide).

Non-destructive silkworm pupa gender classification with X-ray images using ensemble learning

Sericulture is the process of cultivating silkworms for the production of silk. High-quality production of silk without mixing with low quality is a great challenge faced in the silk production centers. One of the possibilities to overcome this issue is by separating male and female cocoons before extracting silk fibers from the cocoons as male cocoon silk fibers are finer than females. This study proposes a method for the classification of male and female cocoons with the help of X-ray images without destructing the cocoon. The study used popular single hybrid varieties FC1 and FC2 mulberry silkworm cocoons. The shape features of the pupa are considered for the classification process and were obtained without cutting the cocoon. A novel point interpolation method is used for the computation of the width and height of the cocoon. Different dimensionality reduction methods are employed to enhance the performance of the model. The preprocessed features are fed to the powerful ensemble learning method AdaBoost and used logistic regression as the base learner. This model attained a mean accuracy of 96.3% for FC1 and FC2 in cross-validation and 95.3% in FC1 and 95.1% in FC2 for external validation.

Effect of Lactic Acid Supplementation on the Growth and Reproduction of Bombyx mori (Lepidopteria: Bombycidae).

Lactic acid is widely used in the food, drugs, cosmetics, and other industries to maintain the microbial stability of low-pH products. However, it is unclear whether lactic acid can affect silkworm (Bombyx mori) growth and reproduction. This study investigated the effects of lactic acid on the growth and reproduction of the silkworm. We analyzed the growth, cocoon quality, and reproductive performance of fifth instar larvae fed on mulberry leaves saturated with different concentrations (0.01, 0.1, 1, and 10%) of lactic acid and the control. Results showed that 0.01, 0.1, and 1% lactic acid supplementation positively affects growth and female cocoon quality, with increased larval weight and female cocoon shell weight compared to the control group. In contrast, 10% lactic acid was toxic to the larvae and significantly decreased growth, leading to larval death. Our study provides a basic reference for the optimal amount of preservatives. In addition, this study can be a desirable intervention for sericulturists and can play an important role in getting high return from silkworm-rearing activities.

Nest Modification Protects Immature Stages of the Japanese Orchard Bee (Osmia cornifrons) from Invasion of a Cleptoparasitic Mite Pest.

Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae) is an effective orchard pollinator. Considering the honey bee population decline in recent years, the conservation and propagation of O. cornifrons as an alternative managed pollinator is important in ensuring adequate pollination of tree fruit crops in the eastern United States. A field study was conducted to determine if nest modifications could reduce mite parasites and parasitoid natural enemies that attack managed O. cornifrons. Paraffin-coated paper liners (straws) were added to create modified nests, and were compared with the unmodified nests (i.e., nests without paper liners). In each nest, we recorded the number of nest cells with cleptoparasitic mites Chaetodactylus krombeini (Baker), and the presence of a parasitoid wasp Monodontomerus obscurus (Westwood). We also recorded the number of cocoons, male pupae, female pupae, and unconsumed pollen-nectar provision masses in these nests. Results showed that using paper liners in nest-tunnels greatly reduced the invasion of natural enemies of managed populations of O. cornifrons. Most notably, the addition of paper liners provided protection from invasion by C. krombeini mites, as the mean number of nest cells with mites were significantly lower in these lined nests compared to the nests without paper liners. A significantly higher number of male and female cocoons of O. cornifrons were recorded in the nests with paper liners. The population of M. obscurus was almost negligible in this field study. These results suggest that using nests with paper liners may accelerate the O. cornifrons population establishment and propagation in commercial orchards of rosaceous fruit crops, and possibly in other crops.

Silkworm cocoon classification using fusion of Zernike moments-based shape descriptors and physical parameters for quality egg production

This paper proposes a novel non-destructive vision-based system to perform automated gender classification of silkworm cocoons for the purpose of improving the quality of egg production. Gender classification is achieved by discriminative learning on samples of male and female cocoons acquired from CSR2 and Pure Mysore silkworm cocoon breeds. Features composed of different combinations of weight, volume, geometric and Zernike moments-based shape properties of cocoons are used for training classifiers of types k-nearest neighbour (kNN), linear discriminant analysis (LDA), neural networks (NNs) and support vector machine (SVM). The experimental results show superiority of the proposed method with respect to the state-of-the-art methods. Specifically, the experimental results indicated the excellent performance of NN and SVM classifiers. An overall classification accuracy of 91.3% was achieved with NN for CSR2 cocoon breed and 100% was attained with SVM for pure Mysore cocoon breed.

Silkworm cocoon classification using fusion of Zernike moments-based shape descriptors and physical parameters for quality egg production

This paper proposes a novel non-destructive vision-based system to perform automated gender classification of silkworm cocoons for the purpose of improving the quality of egg production. Gender classification is achieved by discriminative learning on samples of male and female cocoons acquired from CSR2 and Pure Mysore silkworm cocoon breeds. Features composed of different combinations of weight, volume, geometric and Zernike moments-based shape properties of cocoons are used for training classifiers of types k-nearest neighbour (kNN), linear discriminant analysis (LDA), neural networks (NNs) and support vector machine (SVM). The experimental results show superiority of the proposed method with respect to the state-of-the-art methods. Specifically, the experimental results indicated the excellent performance of NN and SVM classifiers. An overall classification accuracy of 91.3% was achieved with NN for CSR2 cocoon breed and 100% was attained with SVM for pure Mysore cocoon breed.

Distribution and Ecological Characteristics of Cocoons of the Solitary Bees Osmia cornifrons and O. pedicornis (Hymenoptera: Megachilidae)

Osmia cornifrons and O. pedicornis are a cavity-nesting solitary species used mainly as an apple pollinator in Korea. To elucidate the characteristics of those bees for the efficient the pollination of agricultural crops, we investigated the distribution, the number of cocoons per straw, sex ratio, and characteristics of cocoon at different locations in 2010. We collected four species of Osmia spp. consisting of O. cornifrons, O. pedicornis, O. taurus and O. satoi in Yeongwol, Bonghwa and Yechon locations. O. pedicornis was the dominant species, which accounts for 59.6% to 76.4% in the three locations. The mean number of Osmia spp. was varied in different 3 locations. In the number of cocoons per bamboo straw, there were from 7.6 to 8.5 in O. cornifrons and from 6.8 to 7.1 in O. pedicornis at one side straw, and from 16.3 to 16.5 in O. cornifrons and from 13.3 to 13.5 in O. pedicornis at both sides straw. The sex ratio of Osmia spp. were from 1:1 to 1: 2.8 in O. cornifrons and from 1:2.8 to 1:5.5 in O. pedicornis. The sex ratio of O. cornifrons and O. pedicornis was different in 3 locations. The female and male cocoons of O. cornifrons were the long elliptical-shaped and grey-brown color. The width, length and weight of the female cocoon were 5.6±0.6㎜, 10.2±0.8㎜ and 89.5±20.0㎎, respectively. The width, length and weight of the male cocoon were 5.0±0.4㎜, 9.0±0.6㎜ and 62.1±11.3㎎, respectively. The female and male cocoons of O. pedicornis were the long elliptical-shaped and polished dark-brown color. The female cocoon had the width of 6.5±0.6㎜, length of 12.9±1.0㎜ and weight of 89.5±20.0㎎. In case of the male cocoon, the width, length and weight of were 5.0±0.4㎜, 9.0±0.6㎜ and 151.5±29.4㎎, respectively. In both species of O. cornifrons and O. pedicornis, the cocoon size of the females was significantly larger than that of the male. Between those two species, the latter had a relatively bigger size than the former.

Rapid Technique of Sex Differentiation in Immature Stage of a Parasitoid Wasp, Hyposoter Ebeninus Gravenhorst (Hymenoptera: Ichneumonidae)

Parasitoid populations having optimum male: female ratios are generally released in the field during the cocoon stage for an effective bio-control program. Due to the distinctive habit of forming a cocoon within the shrunken larval body of the host, cocoons of both sexes of the icheneumonid wasp, Hyposoter ebeninus, displayed morphological similarities. Therefore, male and female cocoons cannot be differentiated based on normal morphological parameters. In this report, we tested several combinations of morphological parameters and size indices and developed a simple technique for separation of sexes at the cocoon stage of this wasp. Among ten possible parameters tested, the weight of the cocoon was found to be the most appropriate and reliable parameter for sex separation with a 100% success rate. Since this technique involves only one parameter, it is simple, robust and requires minimum technical skill. This technique would be very useful for research workers, commercial biological control laboratories and other related agencies working on H. ebeninus.

Life History of Antheraea frithi Moore, (Lepidoptera: Saturniidae) on Terminalia arjuna (Roxb.) W&A Syn. in North Eastern Region of India

Antheraea frithi Moore, the source of wild tasar silk, is an indigenous wild silk moth of north-east India. The detailed life history, bionomics and rearing performance of A. frithi in relation to a newly reported food plant, Terminalia arjuna (Roxb.) has been described in the present study. Life cycle of A. frithi has five larval instars. The first instar larva measures 1.98 ± 0.13 cm × 0.198 ± 0.010 cm in length and breadth and 0.0142 ± 0.002 g in weight while the fifth instar larva measures 6.98 ± 0.18 cm × 1.12 ± 0.13 cm in length and breadth and 4.76 ± 0.45 g in weight. Wing span of male and female is recorded as 11.4–13.5 and 13.0–14.7 cm respectively. The incubation period (6–7 days), larval duration (35–39 days), fecundity (162–176 eggs), hatching (78–81 %), effective rate of rearing (57–59 %) and cocoon yield (67–79 nos) has been recorded. The reelable cocoons with a filament length (mts) and filament denier (d) is 493–575 m and 4.6–5.3 respectively. The shell weight (g) of male and female cocoons measures as 0.19–0.39 and 0.2–0.6, respectively. The shell ratio (%) for male and female cocoons stands as 8.1–8.4 and 9.4–9.8 % respectively.

Acceptability and suitability of the European Ostrinia nubilalis Hübner for Macrocentrus cingulum Brischke from Asia and Europe

We examined whether Macrocentrus cingulum (Hymenoptera: Braconidae) of Asian origin could serve as a biological control agent of the maize pest Ostrinia nubilalis (Lepidoptera: Crambidae) in Europe. M. cingulum is already present in Europe, where it does not parasitize O. nubilalis but Ostriniascapulalis, a related species feeding on wild dicotyledons. In contrast, M. cingulum have been imported from Europe and Asia into North America (where O. nubilalis had been accidentally introduced from Europe), and does parasitize O. nubilalis there. We conducted laboratory infestations to assess host acceptability (parasitoid’s propensity to oviposit) and suitability (parasitoid’s ability to develop) of European O. nubilalis for M. cingulum of European and Asian origin, and of Ostriniafurnacalis (their original host) for Asian M. cingulum. Asian M. cingulum parasitized European O. nubilalis as readily as O. furnacalis, and developed equally well in terms of: % female cocoons, time to first emergence from the cocoon, total number of adult offspring, % female offspring and adult longevity. Adult female parasitoids were significantly larger when emerging from O. nubilalis, mixed-sex and male cocoons were significantly more and less frequent, respectively. The acceptability of O. nubilalis was significantly lower for European than for Asian M. cingulum, and its suitability was zero. Asian M. cingulum appears a potential candidate for introduction as a biological control agent of a major maize pest, European O. nubilalis, provided environmental impact studies, economic analyses, and foreseeable interactions with other biological control agents such as the egg parasitoid Trichogramma brassicae (Hymenoptera: Trichogrammatidae) are satisfying.

Muga silkworm (Antheraea assamensis helfer) indoor rearing by integrated “leaf freshness technology”- A new technology

Integrated Muga silkworm indoor rearing technology includes “leaf freshness technology” (LFT), “Nutrient Supplemented Phago-stimulant” and bacterial disease control by streptomycin sulfate. All these techniques were applied in complete indoor conditions up to cocoon formation and, very high positive significant results were achieved in respect of larval survivability, larval biomass growth and error (ERR) percent in comparison to outdoor conventional rearing. Muga silkworm, being wild in nature, is very difficult to rear in indoor condition. Moreover, the detached food plant leafs goes on wilting within few hours. LFT made it possible to rear Muga silkworm completely in indoor conditions and minimized early stage loss of larvae from nature’s vagaries, like pest and predators, souring temperature, hailstorm, wind, etc. The use of Nutrient Supplemented Phago-stimulant resulted to increased leaf nutrient quality, arrestancy of larval movement and increased feeding rate which reflected in the higher biomass growth in comparison to treatment without it use. Spraying of 0.5% streptomycin sulfate solution in the indoor reared Muga silkworm, minimized the bacterial infection thereby contributing to larval survivability. Normal cocoon qualities such as silk ratio, denier, sex ratio of male and female cocoon, were not affected by the use of Nutrient Supplemented Phago-stimulant, chemically treated host plant leafs used in LFT and spray of streptomycin sulfate solution. This new integrated LFT may help in adopting indoor rearing of naturally wild Muga silkworm for more production of Muga silk yean. Key words: Leaf freshness, phago-stimulant, nutrient, biomass, denier, integrated, streptomycin sulfate, indoor.

Generic placement of the Neotropical species of “Phragmatobia” (Erebidae, Arctiinae), with a remarkable matrivorous species from the Peruvian Andes

Phragmatobia Stephens is briefly reviewed and a diagnosis is provided. The South American species currently placed in Phragmatobia Stephens are revised to two new genera, Andesobia Schmidt and De Freina, gen. n., and Patagobia Schmidt and De Freina, gen. n. (subtribe Spilosomina). Both Andesobia and Patagobia exhibit adaptations to high altitude habitats, including micropterous females in Andesobia (Patagobia females are unknown) and diurnal flight of males. The adults, immature stages, and mating behaviour of Andesobia jelskii (Oberthür, 1881) are described. Males of Andesobia jelskii enter the female cocoon to mate, and the micropterous, flightless females remain in the cocoon following oviposition where newly hatched larvae feed initially on the female’s body.Four species are included in Andesobia, Andesobia jelskii comb. n. (= Paracles imitatrix Rothschild, 1922, syn. n.), Andesobia flavata (Hampson, 1901), comb. n., Andesobia boliviana (Gaede, 1923), comb. n. (=Turuptiana flavescens Rothschild, 1933, syn. n.), and Andesobia sanguinea (Hampson, 1907), comb. n. Patagobia includes only Patagobia thursbyi (Rothschild, 1910), comb. n., and Patagobia thursbyi pluto Toulgoët is relegated to its synonymy. Patagobia shows affinities to Phaos Walker, 1855 of Australia, Metacrias Meyrick, 1886 of New Zealand, and Pseudophragmatobia Krüger, 2009 of South Africa, suggesting a common ancestry of circumantarctic origin. Phragmatobia karsholti Toulgoët, 1991 is transferred to Venedictoffia Toulgoët, comb. n., an unrelated genus that is removed from subtribe Arctiina and provisionally placed in the Phaegopterina. Phragmatobia oberthueri Rothschild, 1910, described from Tibet, is a synonym of Lachana alpherakii (Grum-Grzhimailo, 1891) [Erebidae: Lymantriinae], syn. n., comb. n.

Mechanism of fluorescent cocoon sex identification for silkworms Bombyx mori

By using silkworms, Bombyx mori, fluorescent cocoon sex identification (FCSI) as an experimental material, direct fluorescence spectrometry of the cocoon surface indicates that the fluorescent color of silkworm cocoons is made up of two peaks of yellow and blue-purple fluorescence emission. The fluorescent difference between male and female cocoons is attributed to the differential absorption of yellow fluorescent substances by the midgut tissue of 5th instar female silkworms. Thin layer chromatography (TLC) and fluorescent spectra indicate that blue-purple fluorescent substances are composed of at least five blue-purple fluorescent pigments, and yellow fluorescent substances are made up of at least three. UV spectra and AlCl₃ color reaction show that the three fluorescent yellow pigments are flavonoids or their glycosides. Silkworm FCSI is due to selective absorption or accumulation of the yellow fluorescent pigments by the posterior midgut cells of female 5th instar larvae. The cells of the FCSI silkworm midgut, especially the cylinder intestinal cells of the posterior midgut have a component which is a yellow fluorescent pigment-specific binding protein that may be vigorously expressed in the 5th instar larvae.

Comparison of Phenotypic and Genetic Performance of Local Silkworm Groups and Two Commercial Lines

Five Iranian native silkworm groups: Baghdad, Khorasan Orange, Guilan Orange, Khorasan Pink, Khorasan Lemon, and 107 and 110 commercial lines (12 families from each breed) were randomly selected and reared during 2003-2005 (five generations in spring and autumn). In each family, 30 male and 30 female cocoons were individually recorded for weight, shell weight and shell ratio. From among the native groups, the highest average in all three traits belonged to Baghdad and Khorasan Pink, and the lowest to Khorasan Orange and Khorasan Lemon. From among the commercial lines, the highest average in all three traits belonged to 107. In comparing heritability for cocoon weight in native groups, the highest heritability belonged to Guilan Orange (0.5147) and Khorasan Orange (0.5036) and the lowest heritability belonged to Khorasan Pink (0.0967). In the two other traits, the highest heritability belonged to Khorasan Orange and Baghdad and the lowest to Khorasan Pink. In the commercial lines, line110 had higher heritability than line107 for cocoon weight and cocoon shell weight. In all the groups, genetic correlations between cocoon weight and cocoon shell weight were high, expect for the Baghdad group. There was medium or low genetic correlation among cocoon weight, cocoon shell weight and cocoon shell ratio.

Olfactory Response of Megachilid Bees, <I>Osmia lignaria</I>, <I>Megachile rotundata</I>, and <I>M. pugnata</I>, to Individual Cues from Old Nest Cavities

The megachilid bees Osmia lignaria Say, Megachile rotundata (F.), and M. pugnata Say were tested for attraction to various components associated with their old nest cavities, or chemical extracts of these components, using a Y-tube olfactory response bioassay. Female bees of these species are known to nest in or near old nest cavities, implying that remnant nest components are important cues for bees looking for nest cavities. Significant results show that female bees were attracted to components that may provide species-specific cues or indicate conspecific nesting activity. Specifically, O. lignaria females showed attraction only to the female cocoon. M. rotundata females were attracted to intact nest cells, the fecal material on the outside of a cocoon, leaf pieces used as nest cell lining, and the extract of leaf pieces. M. pugnata females were attracted to the whole nest cell, the paper straw nesting material with attached cocoon, and feces.

The comparative biology of the solitary endoparasitoid Meteorus gyrator (Hymenoptera: Braconidae) on five noctuid pest species

The comparative biology of the solitary endoparasitoid Meteorus gyrator (Thun.) was investigated in five noctuid pest species. Meteorus gyrator parasitized all larval stages of the noctuid pests Lacanobia oleracea, Mamestra brassicae, Spodoptera exigua, Spodoptera littoralis and Chrysodeixis chalcites. When female parasitoids were offered host larvae of all developmental stages, host larvae in their third stadium were parasitized most frequently in all species. When the parasitoid was offered a choice of third stadium larvae from each of the five lepidopteran host species, L. oleracea was the most frequently parasitized, followed by M. brassicae. The growth of L. oleracea and M. brassicae was markedly reduced when larvae were parasitized by M. gyrator, with the effect of parasitism on the remaining species being much less pronounced. In excess of 94% of parasitized hosts gave rise to live wasps in L. oleracea, whilst in M. brassicae only 52% of parasitized hosts gave rise to a live wasp, the remainder dying (44.6%) or pupating (3.1%). The larval development of the parasitoid was also strongly influenced by the host species. Thus, the development (egg to cocoon) of female wasps was most rapid in C. chalcites (9.7 ± 0.09 days), and longest in M. brassicae (17.2 ± 1.08 days). The cocoon weight of wasps was also significantly affected by host species, with the heaviest female cocoons being derived from C. chalcites (10.4 ± 0.16 mg) and the lightest female cocoons being derived from M. brassicae (7.0 ± 0.14 mg). In all cases, the development times and cocoon weights of male parasitoids were less than those of female wasps.

The effect of host stage and temperature on selected developmental parameters of the solitary endoparasitoid Meteorus gyrator (Thun.) (Hym., Braconidae)

Abstract: The development of the solitary endoparasitoid Meteorus gyrator was compared in the six larval stages of its host, the tomato moth Lacanobia oleracea, and at five constant temperatures. The host instar at the time of parasitism had a marked effect on the larval developmental period of the parasitoid, such that larvae derived from eggs oviposited in first instar hosts took approximately 18 days to egress, whilst those derived from eggs oviposited in sixth instar hosts took <10 days. The weight of cocoons was greatest when oviposition was into final instar hosts, where female cocoons averaged 12.8 mg, and lowest in those derived from eggs oviposited into first instars (9.2 mg). The parasitoid's larval development rate in third instar hosts increased with temperature increments in a linear fashion up to 25°C, after which development times were only marginally increased. At 10°C, the mean larval development time was approximately 90 days and pupal development 35–40 days, whilst at 25°C development times were 10–11 days for larvae and 6–7 days for the pupae. In the majority of cases, overall development times were marginally longer (<1 day) in females than in males.

SEASONAL VARIATION IN NESTING BEHAVIOR OF OXYBELUS BIPUNCTATUS (HYMENOPTERA: SPHECIDAE)

Abstract The nesting behavior of >300 females of Oxybelus bipunctatus was studied for 15 straight weeks in a sandpit in central New York during late spring-summer 1985. Cool and rainy weather in late spring induced moldy conditions in the cells that caused much larval mortality. Successive generations of wasps emerged in the field and laboratory every four to six weeks. Cells were always excavated in moderately damp sand. Cell depth varied inversely with soil moisture as tied to the amount of rainfall. Female cocoons were larger and heavier than male cocoons, but they did not occupy deeper or shallower cells. One-celled nests were predominant in this species. The number of prey per cell was rather uniform throughout the nesting season despite much variation in the prey fly families. Individual and aggregate prey weight per cell decreased slightly through the summer. Male Cyclorrapha were preyed upon more than any other taxon.

LONG-TERM EFFECTS OF DEFOLIATION ON RED PINE SUITABILITY TO INSECTS FEEDING ON DIVERSE PLANT TISSUES

Evidence that defoliation can induce long-term responses in perennial plants that can regulate insect population dynamics is based largely on studies using deciduous trees and folivores, particularly Lepidoptera. Studies with evergreen trees, and with insects feeding on other plant parts, have yielded more variable results. This study examined the effects over several seasons of controlled defoliation on the suitability of an evergreen conifer, red pine (Pinus resinosa) to insects and pathogens that exploit foliage, stem phloem, and root tissue. Test insects included a folivorous sawfly (Hymenoptera) and two species of stem- and root-colonizing beetles (Coleoptera). Each of these species undergoes periodic population irruptions. Controlled defoliations were administered to 10-yr-old trees at levels that mimic naturally occurring sawfly outbreaks. Additional studies were conducted on seedlings in a glasshouse. Foliar suitability to the redheaded pine sawfly (Neodiprion lecontei) varied in a nonlinear fashion with defoliation intensity one year after treatment. However, not all parameters of sawfly success were equally affected. Female cocoon mass was related to foliar concentrations of nutrients, but not monoterpenes or diterpene acids. Suitability to the stem boring pine engraver (Ips pini) increased 2 yr after defoliation. Moderate defoliation reduced stem resin flow rate by 50% and increased stem phloem colonization rate by the beetle’s mutualistic fungus, Ophiostoma ips. Defoliation also affected host suitability to adult pales weevils, Hylobius pales. Weevil feeding increased 1 yr after defoliation, but this response dissipated 2 yr after treatment. The observation that intermediate defoliation stress can either decrease or increase foliar suitability in an evergreen conifer, depending on intensity, is consistent with elements of both the plant stress and carbon:nutrient balance hypotheses. Moreover, host responses to a single stress agent may significantly and differentially influence the population dynamics of insects and pathogens that exploit different plant tissues. Implications of these results for plant stress and carbon:nutrient theories, plant-herbivore interactions, and chronic forest declines are discussed.

Ontogenetic, Reproductive, and Nutritional Effects on the Cuticular Hydrocarbons of the Host-Specific Ectoparasitoid Cephalonomia tarsalis (Hymenoptera: Bethylidae)

Cuticular hydrocarbons have been identified from adult males and females of the bethylid wasp Cephalonomia tarsalis (Ashmead). The 2 sexes possess the same cuticular hydrocarbons, but in different amounts and proportions. Hydrocarbon components identified include n-alkanes (C23–C37), 5-methyl alkanes (5-MeC25-5MeC29), 5,X-dimethyl alkanes (5,17-and 5,19-diMeC29 and 5,17- and 5,19-diMeC33), and a homologous series of Z-monones with double bonds at Δ11, Δ9, and Δ7 (C25:1-C37:1). The n-alkanes and alkenes are the predominant components in all cases, the 5-methyl alkanes being only minor components. The dimethyl components are present in only trace amounts. Age, mating status, and, for females, host-feeding status, were examined for their effect on hydrocarbon quantities and proportions. Males showed little change in their hydrocarbon profiles, but females showed strong age, host feeding, andage × host feeding effects on total hydrocarbon quantities and on individual hydrocarbon components. Mating status did not affect female hydrocarbons. The silk cocoons from which theparasites emerged yielded the same cuticular hydrocarbon components as were found on the newly emerged male and female wasps, but n-alkanes were now the major components. Hydrocarbon profiles of female cocoons differed from male cocoon hydrocarbons primarily in the relative abundances of the monene isomers. Bioassays of male response to hexane extracts of female and male cocoons indicated that the male could differentiate between the two. The primary gender recognition cue is not the cocoon hydrocarbons, but rather a female-produced sex pheromone, the hydrocarbons serving as a secondary recognition cue.