Host Cocoon Research Articles

Mechanism of adult emergence in Xanthopimpla pedator (Fabricius)- a major pupal parasitoid of Tasar silkworm

Aim: The study was conducted to elucidate the mechanism involved in adult emergence behavior of Xanthopimpla pedator a pupal parasitoid of tasar silkworm. Methodology: Behavioral observations were made to study the mechanical approaches used during emergence and SDS-PAGE analysis was carried to know the possibility of proteases in the digestive secretions. Results: The findings of the study suggest that X. pedator uses physical and chemical to achieve safe passage from the host pupae and cocoons. It was observed that during the process of emergence, X. pedator breaks host pupae by means of mandibular action (by biting the pupal shell). Further, it was noticed that to make emergence hole on host cocoon X. pedator found to employ digestive secretion to soften and disintegrate the silken shell, besides it also deploys mandibles to spread out the secretion on intended place of exit hole. SDS-PAGE analysis showed the presence of series of enzymes, possibly involved in cocoon softening. Interpretation: Findings of this study forms the basis that X. pedator, a major pupal parasitoid of tasar silkworm, uses both physical and chemical approaches to achieve safe passage from the host pupae and protective silken cocoon. Key words: Digestive secretion, Mandibular action, Parasitization, Xanthopimpla pedator

Cyclosa omonaga (Araneae: Araneidae), an Alternative Host of the Spider Ectoparasitoid Reclinervellus nielseni (Hymenoptera: Ichneumonidae), with Notes on Behavioural Manipulation

Parasitism upon Cyclosa omonaga (Araneidae) by the ichneumonid ectoparasitoid Reclinervellus nielseni is reported for the first time, based on molecular identification, corroborating that R. nielseni is a specialist parasitoid of members of the genus Cyclosa, having previously been recorded from C. argenteoalba,C. conica and C. laticauda. The parasitoid larva at the time of discovery (11 December) was still tiny in spite of the beginning of winter, indicating it was in its overwintering phase, and this is the first case of the overwintering R. nielseni larva found in Japan. The host's cocoon web, with fibrous and fluffy thread decorations (FTD) resulting from the wasp's behavioural manipulation, produced by the parasitized C. omonaga is described and illustrated, and its potential role is discussed.

Cocoon Web Induced byEruga telljohanni(Ichneumonidae: Pimplinae) inLeucaugesp. (Tetragnathidae)

The hosts and cocoon webs of koinobiont-ectoparasitic wasps in the genus Eruga Townes in Townes & Townes, 1960 are known for only two species. We describe here the host spider and cocoon web of a third Eruga species: E. telljohanni Gauld, 1991. This wasp parasitizes Leucauge White, 1841 species, which are induced to construct a highly modified cocoon web, with a small flat sheet and long radii. The larval cocoon lies along the longest axis attached to the centre of the sheet. This cocoon web differs markedly from the cocoon web induced by E. gutfreundi Gauld, 1991 in Leucauge mariana (Taczanowski in Keyserling, 1881).

Further notes on the biology of Pseudavga flavicoxa Tobias, 1964 (Hymenoptera, Braconidae, Rhysipolinae)

Pseudavga flavicoxa, a solitary koinobiont ectoparasitoid of Bucculatrix thoracella, attacks host larvae early rather than late in their final instar, subsequent development of the parasitoid then occurring within the host cocoon. This paper supplements an earlier contribution outlining other aspects of its biology and taxonomy. The host is stung repeatedly, both into the thoracic region and elsewhere on its body, causing temporary paralysis and also enabling host-feeding, which preceded oviposition in all observed cases. Stung hosts then intercepted without oviposition occurring recovered and (like parasitized hosts) resumed feeding and then constructed a cocoon, but suffered developmental arrest as a prepupa. The egg is invariably laid onto the arthrodial membrane between the first and second thoracic segments, to which it is glued. This site is first prepared by the female by a to-and-fro motion involving contact by the lower valves of the ovipositor, which are somewhat blade-like and sharp-edged. It is unclear whether dried traces of a ‘glue’, presumably originally liquid, subsequently seen at this site were of host origin resulting from a small wound or arose as a secretion from the female wasp, but the former is suggested. The egg was seen to issue from the extreme base of the ovipositor, at most guided onto the prepared patch by the parted lower valves. Although clearly partly plurivoltine, P. flavicoxa is remarkably long-lived as an adult, both sexes being easily kept alive under semi-natural conditions (Edinburgh, U.K.) during the late summer and autumn, males for 8 weeks and females for up to 20, despite their small size (ca 2.2–2.4 mm long). Dissection of gravid females showed that each of the 4 ovarioles carried just one mature egg at a time, with submature eggs remaining only poorly developed until the mature egg was expended.

Development of microsatellite markers and estimation of inbreeding frequency in the parasitoid wasp Melittobia

The parasitoid wasp Melittobia is an important insect for basic and applied biology. Specifically, their extremely female-biased sex ratios, which contrast to the prediction of pre-existing theories, are needed to be explained from the aspect of evolutionary biology. In this study, using next-generation sequencing, 20 microsatellite loci were developed and characterized for M. australica. The developed loci were used to analyze two populations, one from a mainland Japan and one from the Okinawa island region. Both populations showed a smaller observed heterozygosity than expected, and a high inbreeding coefficient. Deviations from Hardy-Weinberg equilibrium were recorded for the majority of the 20 loci, suggesting that both the populations are subdivided due to inbreeding as is expected by the reproductive biology in Melittobia. The sib-mating frequency in the two populations was calculated as 0.873 and 0.996, which is higher than the values estimated by the number of females observed in a host cocoon or cell, implying that closely related females lay eggs on a host. The microsatellite loci developed in this study can be used for more comprehensive analyses to identify genetic structure in natural populations for understanding their sex allocation behavior and for more generally evolutionary and population genetic studies.

Illustrated notes on the biology of Sphinctus serotinus Gravenhorst (Hymenoptera, Tryphoninae, Sphinctini)

Field and experimental observations on the European ichneumonid Sphinctus serotinus as a koinobiont ectoparasitoid of the limacodid moth Apoda limacodes are recorded. The egg is anchored into the extremely thick cuticle of its host but not deeply enough so that it would survive host ecdysis. That may explain the late summer-early autumn flight time of the parasitoid, when practically all host larvae that remain are in their final instar, though avoiding competition from other parasitoids may also play a part. The tough cuticle of the host probably also underlies the lack of host feeding by the adult parasitoid. There is no ability to avoid superparasitism, though self-superparasitism is limited by post-oviposition flight to leave the host. The egg can be laid with its chorion still uncoloured when hosts are in plentiful supply, but such eggs become the usual pale brown colour within a short time. No dumping of eggs in the absence of hosts occurs. The egg normally doesn’t hatch until after the host has prepared its cocoon, and the parasitoid larva, still anchored in the eggshell at first, feeds very slowly through the winter and early summer on the prepupal host. Development through the prepupal and pupal stages within the host cocoon similarly proceed slowly, with no evident diapause at any stage. The various stages of the life cycle are illustrated photographically.

Effect of host‐cocoon mass on adult size in the secondary hyperparasitoid wasp, Pteromalus semotus (Hymenoptera: Pteromalidae)

Abstract Parasitoids have long proven to be model organisms in studying resource‐related constraints on immature development. Here we examine the relationship between host cocoon (= pupal) size in the gregarious endoparasitoid wasp, Cotesia glomerata, and development time and adult size in the solitary idiobiont hyperparasitoid, Pteromalus semotus. Little is known about the biology or ecology of this ecto‐hyperparasitoid species, although it is one of the major secondary hyperparasitoids of C. glomerata. The size of the adult wasp covaried with the size of the host cocoon at parasitism. Moreover, female wasps were larger than male wasps for a given cocoon size. Adult wasps have remarkably long life‐spans, 3 months on average. Longevity did not significantly differ with sex. We also examined how larvae of P. semotus exclude other potential competitors. P. semotus is protandrous, with females taking significantly longer to complete their development than males. In experiments where several eggs of P. semotus were placed on individual pupae of C. glomerata, newly hatched hyperparasitoid larvae moved rapidly over the surface of the host and destroyed the eggs of any conspecifics by biting them before they would initiate feeding on host tissues. Our results are discussed in relation to those with other studies with solitary ichneumonid idiobiont hyperparasitoids of C. glomerata.

The ‘usurpation hypothesis’ revisited: dying caterpillar repels attack from a hyperparasitoid wasp

It has been posited that some parasitoid wasps ‘usurp’ their dying hosts as ‘bodyguards’ to protect the vulnerable parasitoid cocoons against attack from natural enemies such as predators or hyperparasitoids. Thus far, however, the hypothesis has been supported only in studies with insect predators. Two factors may account for this: first, hyperparasitoids, being more specialized than predators, are probably less easily rebuffed by the presence of an attending caterpillar; second, the host cocoon is used for reproduction by hyperparasitoids, but not by predators. We compared the survival of a solitary primary parasitoid, Microplitis sp., and successful parasitism by a secondary hyperparasitoid, Gelis agilis, from parasitoid cocoons with and without the presence of an ‘attending’ larva of the host, the armyworm, Mythimna separata. Mature Microplitis sp. larvae always emerge through the same host segment, leaving the posterior segments paralysed and attached to cocoons and the anterior segments freely moving. When disturbed by G. agilis females, M. separata larvae exhibited aggressive behaviour that repeatedly drove off approaching hyperparasitoids. In choice and no-choice experiments performed at 24 h intervals over 96 h, G. agilis successfully parasitized cocoons without attending caterpillars, but few cocoons with attending caterpillars were ever parasitized. Choice experiments, in which G. agilis wasps were released onto corn plants containing 24 h-old parasitoid cocoons with and without attending caterpillars, produced similar results. We provide the first experimental evidence that a solitary parasitoid usurps the behaviour of its host over several days as a ‘bodyguard’ against hyperparasitoids.

Life‐history traits in closely related secondary parasitoids sharing the same primary parasitoid host: evolutionary opportunities and constraints

AbstractThus far, few studies have compared life‐history traits amongst secondary parasitoids attacking and developing in cocoons of their primary parasitoid hosts. This study examines development and reproduction in Lysibia nana Gravenhorst and Acrolyta nens Hartig (both Hymenoptera: Ichneumonidae), two related and morphologically similar secondary parasitoids that attack pupae of the gregarious endoparasitoid, Cotesia glomerata L. (Hymenoptera: Braconidae). On black mustard, Brassica nigra L. (Brassicaceae) plants in a field plot, adults of L. nana and A. nens frequently emerged from the same cocoon broods of C. glomerata. Based on similarities in their phylogeny and morphology, it was hypothesized that both species would exhibit considerable overlap in other life‐history traits. In both L. nana and A. nens, adult wasp size increased with host cocoon mass at parasitism, although L. nana wasps were slightly larger than A. nens wasps, and completed their development earlier. Adult females of both species emerged with no eggs but matured eggs at similar rates over the following days. When provided with 20 host cocoons daily, fecundity in female L. nana was slightly more skewed towards early life than in A. nens, although lifetime fecundity did not differ between the two species. Longevity was significantly reduced in females of both species that were provided with hosts. Both parasitoids were found to exhibit strong similarities in life‐history and development traits and in their ecological niche, thereby supporting our general hypothesis. Competition between L. nana and A. nens is presumably diffused because their preferred host (C. glomerata) is relatively abundant in open habitats.

Intraspecific Competition Between Adult Females of the Hyperparasitoid Trichomalopsis Apanteloctena (Hymenoptera: Chelonidae), for Domination of Cotesia kariyai (Hymenoptera: Braconidae) Cocoons

Abstract The development of parasitoid wasps is dependent on the finite resources contained in a single item of resource (=host) that is frequently not much larger than the adult parasitoid. When the costs of egg production are high, and host distribution is highly aggregated, parasitoid females may spend prolonged periods guarding their eggs and host resources as an adaptive strategy to optimize their inclusive fitness. Here, we examine aggressive interactions between the females of the secondary hyperparasitoid Trichomalopsis apanteloctena (Crawford) (Hymenoptera: Chelonidae), for control of cocoon clusters of their primary parasitoid host Cotesia kariyai (Watanabe) (Hymenoptera: Braeonidae). Generally, larger female hyperparasitoids were more successful at defending cocoon clusters than smaller female hyperparasitoids. However, when first encountering host cocoons, larger females behaved more aggressively toward conspecific wasps than smaller females. After occupation of a host cocoon cluster, females of similar size rarely engaged in physical combat, but both females primarily exhibited threatening behavior toward each other. However, larger females usually displaced smaller females which had initially occupied cocoon clusters. Some small females chewed through the outer cocoon silk layer to avoid being displaced by larger females and these wasps were able to continue parasitizing cocoons of C. kariyai. Extended bouts of aggression tended to reduce the number of eggs laid by the guarding female because of disruption of oviposition behavior. The relationship between the size of host cocoons and body mass in T. apanteloctena was also examined. The size of hyperparasitoid progeny was strongly correlated with host size. However, the relationship between maternal size, the number of matured eggs in her ovarioles and body mass in her offspring was not significant.

Brood attending by females of the hyperparasitoid Trichomalopsis apanteloctena (Hymenoptera: Pteromalidae) on cocoon clusters of its host, Cotesia kariyai (Hymenoptera: Braconidae) and its effects on reproduction, development and survival

Theoretical models predict that brood guarding may evolve in situations where eggs are costly to produce or when handling times are long. This study reveals that females of the secondary hyperparasitoid Trichomalopsis apanteloctena guarded cocoon broods of Cotesia kariyai, a gregarious endoparasitoid. Hyperparasitoid females also monopolized host resources and protected their offspring by driving away other conspecific hyperparasitoid females. The females exhibited antagonistic behavior towards competitors through threatening body postures, biting and chasing. Using a video camera to determine how long a hyperparasitoid female attended and parasitized cocoons within a single host brood, it was found that after about 4 days, cocoon guarding behavior became much less apparent. Moreover, more than 90% of hosts were typically parasitized by a hyperparasitoid female over the course of 4 days after she commenced brood guarding. Observations of egg production during a female's lifetime revealed a physiological interval rhythm that typically lasted 3-4 days, which correlates almost exactly with the period during which the cocoons were guarded. To confirm the giving-up time for a host cocoon brood, hyperparasitoid females were given access to 24 h-old cocoon clusters, each containing 60-100 individual cocoons. Ninety percent of the females remained on cocoons for approximately 72 h. Furthermore, twenty-five percent of wasps continued attending and presumably guarding host cocoon broods for more than 138 h after the female first attended the brood. C. kariyai larvae pupate within a few hours of egression from their host and emerge as adults about 5 days (120 h) later. Therefore, many hyperparasitoid females continued to guard older host cocoons of greatly reduced quality as a resource for their progeny and some even after eclosion of the primary parasitoid. Late-brood guarding enabled a hyperparasitoid female to protect her own progeny from other hyperparasitoid females that readily attacked and killed them when she was removed. Our study thus reveals that extended guarding behavior is an adaptive mechanism that probably plays an important role in the survival of the original brood.

Remarkable similarity in body mass of a secondary hyperparasitoid Lysibia nana and its primary parasitoid host Cotesia glomerata emerging from cocoons of comparable size

Lysibia nana is a solitary, secondary idiobiont hyperparasitoid that attacks newly cocooned pre-pupae and pupae of several closely related gregarious endoparasitoids in the genus Cotesia, including C. glomerata. Prior to oviposition, the female wasp injects paralysing venom into the host, thus preventing further development. Here, host fate, emerging hyperparasitoid mass, and egg-to-adult development time was compared in hosts parasitized at different ages over 24-h intervals. Cocoons of C. glomerata were parasitized by L. nana at 12, 36, 60, 84, and 108 h post-egression from the secondary host, Pieris brassicae. Hyperparasitoid survival exceeded 80% in hosts parasitized within the first 60 h after pupation, but dropped thereafter, with no hyperparasitoids emerging in hosts aged 108 h. The mass of hyperparasitoids was positively correlated with the mass of the host cocoon, and this relationship remained consistent in hosts up to 60 h old. Within each host age cohort, the mass of male and female wasps was not significantly different. Development time in L. nana was uniform in hosts up to 60 h old, but increased significantly in 84-h-old hosts, and male wasps completed their development earlier than female wasps. Regulation of host growth varied with the age of the host at parasitism, with the early growth of older hosts reduced much more dramatically than young hosts. Unlike most parasitoids, pupal hyperparasitoids do not make cocoons but instead pupate within the already prepared cocoon of the host parasitoid. Consequently, for a given mass of cocoon, newly emerged L. nana adults were remarkably similar in size with male and female adults of C. glomerata. This reveals that L. nana is extremely efficient at exploiting its primary parasitoid host.

Superparasitism in the solitary ectoparasitoid Aptesis nigrocincta: the influence of egg load and host encounter rate

AbstractTheory predicts that the acceptance of hosts already parasitized by a conspecific will depend both on egg load and the availability of hosts. In the present laboratory study, we tested the effect of egg load and host encounter rate on the propensity of superparasitism in the solitary parasitoid Aptesis nigrocincta Gravenhorst (Hymenoptera, Ichneumonidae), a synovigeneous ectoparasitoid of prepupae of the European Apple Sawfly. Parasitoid females carry few voluminous eggs at a time and the egg maturation rate is less than one egg per day. Egg load was manipulated by giving females access to hosts one week prior to the start of treatments and host availability by giving females access to either one host cocoon every day or every other day. In the first treatment where females had a high egg load of 5.3 egg in their ovaries and encountered host cocoons at low rates, we found that parasitized hosts were accepted to the same degree as healthy hosts. In females with significantly decreased egg load (3.8 eggs) encountering hosts at the same rate we found a slight but non‐significant decrease in the acceptance of parasitized hosts compared with healthy hosts. In contrast, A. nigrocincta females accepted significantly fewer parasitized hosts at a high host encounter rate that would lead them to the point of egg limitation in the near future. Within the range of egg loads tested, the host encounter rate appears to be the most important determinant for a females decision to oviposit onto hosts already parasitized by a conspecific.

Gustatory sensilla sensitive to protein kairomones trigger host acceptance by an endoparasitoid.

Proteins isolated from the host cocoon of Acrolepiopsis assectella (Lepidoptera: Yponomeutoidea) act as kairomones for host acceptance by the endoparasitoid wasp Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae). In this study, morphological, ultrastructural and electrophysiological studies were carried out in order to identify the contact chemoreceptive sensilla on the parasitoid antennae that perceive the protein kairomones. Three types of sensillum on the antennae of the females were found to have a chemosensory function. The receptor cell(s) of one sensillar type were shown to give a positive electrophysiological response to protein kairomones. This sensillar type is apically multiporous and female specific. Consequently, this sensillum could be the one implicated in the perception of the protein kairomone that triggers the host-acceptance behaviour of D. pulchellus females.

Comportamento de oviposição e tempo de desenvolvimento de Brachymeria villosa (Oliver) (Hymenoptera, Chalcididae)

The oviposition behavior and development time of Brachymeria villoso (Oliver, 1790) on Trypoxylon albitarse Fabricius, 1804 (Sphecidae) is reported. The parasitism occurs through a little hole made by the parasitoid female in the host nest wall. This hole is used by the parasitoid offspring after its emergence to left the host nest. The parasitoid egg is laid on the host larva before it built its cocoon, when such structure is made the parasitoid egg hatch into a larva that feeds on the living host larva and the parasitoid growth enclosed in the host cocoon without build its own. The development time of B. villosa was 65 days. From two nest of T. albitarse were reared 12 females and one male of B. villosa.

Behavioral Response of the ParasitoidLariophagus distinguendus(Forst) (Hymenoptera:Pteromalidae) to Extracts from Cocoons ofLasioderma serricorneFab. (Coleoptera Anobiidae) and Their Effects on Subsequent Oviposition Responses

Abstract Antennation and oviposition responses of the parasitoidLariophagus distinguendus(Forst) females to water and organic solvent extracts from cocoons ofLasioderma serricorneFab. were studied in the laboratory. A combination of water and methylene chloride extracts elicited the strongest antennation and probing responses. Responses increased with extract dose. Oviposition onto beetle pupae through artificial cocoons made from cellulose domes was studied as a function of prior experience of the wasps and of the presence of host cocoon extracts on the domes. Wasps that had oviposited into normal cocoons oviposited readily through domes that were treated with the water and methylene chloride extracts of cocoons, but untreated domes were ignored. Inexperienced naive wasps oviposited far less readily than experienced wasps.

Role of a parasitoid with a low fecundity, Praestochrysis shanghaiensis (Hymenoptera: Chrysididae), in the population dynamics of its host

1. Analysis of life tables of the oriental moth,Monema flavescens, obtained for 8 generations over 4 years, disclosed that the cocoon parasitoid,Praestochrysis shanghaiensis, acted as a density-disruptive factor. 2. The density of the host cocoon remained stable (max./min.=3.2), whereas that of the host adult varied (max./min.=14.3) although both showed similar fluctation patterns. 3. Stability of the host population was associated with the density-dependence in the ratio of first generation cocoons to overwintered generation moths, which was the key factor for the rate of change throughout the year. Chrysidid parasitism among the first generation cocoons ranged from 37.7 to 70.1%, and that among the second generation cocoons from 16.7 to 63.2%, each showing an inverse density-dependence and acting as the main determinant (key-factor) of the between-year variation in the density of the adult moths. 4. The density-dependence of the rate of change from overwintered generation adults to first generation cocoons was so strong that the parasitism on the second generation hosts had not effect on the cocoon density of the first generation. On the other hand, the density-dependence of the rate of change from first generation adults to second generation cocoons was weak, and the parasitism on the first generation hosts became the key factor for the between-year variation of the second generation cocoons. 5. It is suggested that the stability of the parasitoid-host system will be disrupted without three parasitism-restricting factors: asynchrony in the parasitoid attack on the second generation hosts, high mortality among parasitoid larvae of the second generation, and the high proportion of those first generation parasitoids that enter diapause. These factors are considered to be effective only in cooler parts of the distribution of the parasitoid.

Biology ofTetrastichus pantnagarensis (Hymenoptera: Eulophidae) a hyperparasite ofDiaphania indica (Lepidoptera: Pyralidae) throughApanteles taragamae (Hymenoptera: Braconidae)

Tetrastichus pantnagarensis Khan (Hymenoptera: Eulophidae) was recorded as a hyperparasite ofDiaphania indica (Saunders) (Lepidoptera: Pyralidae) throughApanteles taragamae Viereck (Hymenoptera: Braconidae). Studies were conducted on its biology. This solitary endoparasite oviposited in the host pupa within the host cocoon and the larva passes through 3 instars. Mean development time from egg to adult is 12–18 days at 26–43±2–53°C. After a preoviposition period of 1–2 days oviposition continued for 7–10 days. Mean adult longevity for males was 8·51 days and for females 11·41 days.

Biology ofAphanogmus fijiensis (Fernere) (Hymenoptera: Ceraphronidae) a hyperparasite ofDiaphania indica (Saunders) (Lepidoptera: Pyralidae) throughApanteles taragamae Viereck (Hymenoptera: Braconidae)

Studies were conducted on the hyperparasiteAphanogmus fijiensis (Fernere) (Hymenoptera: Ceraphronidae) to determine its biology throughApanteles taragamae Viereck (Hymenoptera: Braconidae).Aphanogmus fijiensis is a gregarious ectoparasite and developed on the prepupal and pupal stages of Apanteles taragamae present inside the host cocoon. Mean development time from egg to adult was 12–28 days at 26·43±2·53°C. There is no preoviposition period; the host is paralysed before oviposition, freshly formed to 3-day old cocoons are preferred for oviposition and mean longevity for both sexes was 4·86 days.

PARASITES AND PREDATORS ASSOCIATED WITH THE PONDEROSA PINE TIP MOTH, RHYACIONIA ZOZANA (KEARFOTT) (LEPIDOPTERA: TORTRICIDAE), IN CALIFORNIA AND OREGON

AbstractSixteen hymenopteran and one dipteran species of parasites were recovered from Rhyacionia zozana (Kearfott) larvae and pupae collected in California and Oregon. Total percentage parasitism was high, averaging 47.2% in quantitative studies. The ichneumonid wasp, Glypta zozanae Walley and Barron, was the most abundant parasite, attacking over 30% of the hosts collected. Parasitization rates were presented for each parasite species recovered. Two suspected predators, Phyllobaenus binotatus (Chapin) (Coleoptera: Cleridae) and Leptothorax sp. (Hymenoptera: Formicidae), were found in association with R. zozana cocoons. A single Aegilips sp. (Hymenoptera: Figitidae) was recovered from a host cocoon; the relation between this parasite and R. zozana is as yet undetermined. Parasite biologies were discussed.