Ichneumon Wasp Research Articles

Agrypon caribbaeum, a New Species of Ichneumon Wasp (Hymenoptera: Ichneumonidae) from the U.S. Virgin Islands

A new ichneumon wasp, Agrypon caribbaeum , was reared from pupae of the melonworm, Diaphania hyalinata (L.) (Lepidoptera: Pyralidae), on St. Croix, U.S. Virgin Islands. Wasps emerged from 34% of the pupae and may merit further study as a biocontrol agent of melonworms. Adult A. caribbaeum are described.

Structure of chitin-protein complexes: Ovipositor of the ichneumon fly Megarhyssa

A model has been developed for the three-dimensional arrangement of the chitin fibrils and matrix proteins in a typical chitin-protein complex from insect cuticles. This model is based on the X-ray fiber diagrams of ichneumon fly ( Megarhyssa) ovipositor, which is a highly oriented example of one of the most common types of structure in chitin-protein systems. The basic structural unit in the complex is a microfibril with a diameter of 7.25 nm, consisting of a crystalline chitin core surrounded by a sheath of ordered protein. Small and wide angle equatorial reflections show that these fibrils are hexagonally packed, as has been reported in electron microscope studies, and the small angle intensities are in good agreement with the squared Fourier transform of a solid cylinder. The layer-line spacings indicate that the protein repeat along the fibril is 3.06 nm, which corresponds to six. N-acetyl glucosamine residues of the chitin chains. The relative intensities on the layer-lines suggest that the protein consists of subunits arranged in a 6 1 helix around the crystalline chitin core. From the positions of the off-meridional maxima we estimate that the radius of the protein helix is ~2.5 nm, which is close to the center of the protein sheath. Finally, splitting and fanning of the layer-lines indicate that the chitin-protein microfibril has a longer axial repeat of 15.3 nm, possibly due to super coiling.

Parasitic Wasps as Sleuthhounds Response of an Ichneumon Wasp To the Trail of Its Host

Experiments have been performed showing that the ichneumon wasp Poecilostictus cothurnatus, a parasitoid of the advanced larvae of the pine looper, Bupalus piniarius, is able to locate the host by following the trail left on the needles by the crawling caterpillars. Artificial trails can be prepared by moving the skin of a caterpillar over a sheet of paper, showing that one or more chemicals present in the cuticular layer function as signals (kairomone) for the wasp. When no caterpillar is found when she arrives at the end of the trail, the wasp shows a characteristic behaviour known as area-restricted searching. This type of behaviour has been found in several other species of parasitoids, but in all these cases it was performed immediately after having parasitized a host. The observations suggest that in a pine forest host finding is accomplished by alternating short flights with landings on twigs. After a landing there is a short search for the presence of a trail, and, coming across one, the wasp will try to find the host. If this is found and parasitized she flies away, and will probably soon make a new landing elsewhere.

An atlas of the development of eggs of an ichneumon wasp

An atlas of the development of eggs of an ichneumon wasp

A NEW NEARCTIC CAMPOLETIS PARASITE OF PYRALIDAE (HYMENOPTERA: ICHNEUMONIDAE)

AbstractCampoletis pyralidis, a new species of ichneumon fly parasite on several species of Pyralidae in Canada, is described.

The resistance of insect parasitoids to the defence reactions of their hosts.

SummarySome of the following propositions are to be read as suggestions or hypotheses, supported by circumstantial or direct evidence, but not yet rigorously demonstrated. An estimate of the significance to be attached to each should be gathered from the body of the paper rather than from the following brief statements.1.The problem is posed: how do endophagous parasitoids counteract the haemocytic defence reactions of their usual hosts?2.It has been demonstrated that the egg and young first‐instar larva of Nemeritis canescens have a coating on their surface which enables them to escape the attention of the haemocytes of their usual host, and to develop without exciting a defence reaction. The coating is applied to the egg before it is laid, and to the cuticle of the larva before it hatches. A little evidence suggests that some other ichneumon wasps of the subfamily Ophioninae may use this mechanism of resistance.3.Older first‐instar larvae, and the second and later instars, of many parasitoids, both hymenopterous and dipterous, probably overcome the haemocytic reaction of their host by rapid feeding, which depletes its blood both of cells and of nutrients, and so drains its resources that haematopoiesis is prevented and encapsulation becomes impossible.4.The common habit of parasitoids of lingering in the first instar, before ingesting much food, while the host goes on developing to another stage or undergoes diapause, may enable the larva to retain a protective coating that would have become ineffective if it had grown. When at length the larva does feed and grow, the preceding mechanism (3) comes into play.5.The teratocytes and pseudogerms formed by many species in several families of Hymenoptera absorb nutrients on a large scale from the blood of the host. They act quickly, as soon as the larva hatches. I suggest that by their attrition of the host's reserves of food, and its consequent debility, they prevent an effective haemocytic reaction to the young parasitoid.6.Some dipterous and hymenopterous parasitoids first inhabit the intestine of their host, and do not penetrate the body cavity until they are ready to overwhelm the defence reactions by rapid and gross feeding.7.Parasitoids that live temporarily inside an organ of the host may there acquire a coating which protects them from reaction by the blood cells.8.Species of parasitoids that occupy an organ of the host for a long period, and develop inside it, escape a defence reaction because they live within the connective tissue covering the organ, to which the blood cells do not react.9.Eggs of hymenopterous parasitoids laid within the embryos of their hosts may be treated by the embryonic blood cells as a developing organ, and become covered with connective tissue as those organs are. Thereafter they would not be recognized as foreign bodies.10.Parasitoid eggs laid in the eggs or the young larvae of their host may be coated with host substances, or covered by connective tissue (9), before the blood of the host be comes capable of vigorousdefence reactions. They would there after escape recognition as foreign bodies. This may be the advantage of the habit of the so‐called egg‐larval parasitoids.11.Reasons have been given by Schneider (1950) for his belief that the serosa of the ichneumon wasp Diplazon fissorius secretes something that locally inhibits the defence reactions of its hosts. The trophamnion and pseudoserosa of some parasitoid eggs may have this function.12. Some parasitoids, especially second‐ and third‐instar larvae of Tachinidae, physically repulse the haemocytes of their host, moulding them into a capsule that serves the maggot as a respiratory sheath.

A NEW NEARCTIC SPECIES OF BARYLYPA (HYMENOPTERA: ICHNEUMONIDAE)

AbstractBarylypa irona, a new species of ichneumon fly from Michigan, is described.

The defense reactions of three species of Hypera (Coleoptera, curculionidae) to an ichneumon wasp

The principal result of the investigation is to show that the parasite Bathyplectes curculionis exists in two strains, one in northern California parasitizing Hypera postica, and one in southern California developing on Hypera brunneipennis. About 94% of the eggs of the northern strain evoked a defense reaction in H. brunneipennis, 91% a reaction so strong that the parasite could not develop; about 50% of the eggs of the southern strain met a defense reaction in H. brunneipennis, but it was usually weak, and fewer than 15% of the parasite eggs were prevented from developing. Of the larvae of H. brunneipennis parasitized by the northern strain, not more than 10% would have been destroyed; of those parasitized by the southern strain, 100%. In Hypera postica less than 1% of the eggs of the northern strain, evoked a hemocytic reaction, and it was weak; but 15% of the eggs of the southern strain evoked a reaction and in some cases it was effective. Observations of secondary importance show that eggs of Bathyplectes that escaped encapsulation in one larva of H. brunneipennis were usually encapsulated when transferred to a second larva of the same species. Families of H. brunneipennis reared from isolated female weevils did not differ significantly in their reaction to northern parasites. A few instances were observed of larvae of Bathyplectes being encapsulated in H. brunneipennis. Eggs and larvae of Bathyplectes implanted in larvae of Hypera punctata were thickly encapsulated and melanized.

Changes in some ecological characters of the almond moth caused by the selective action of an ichneumon wasp in their interacting system

changes in some ecological characters of the almond moth caused by the selective action of an ichneumon wasp in their interacting system

Changes in some ecological characters of the almond moth caused by the selective action of an ichneumon wasp in their interacting system

Changes in some ecological characters of the almond moth caused by the selective action of an ichneumon wasp in their interacting system

Experimental studies in insect parasitism. X. The reactions of some endopterygote insects to an alien parasite

Eggs of an ichneumon fly, Nemeritis canescens , have been injected into endopterygote insects to which this parasite was alien. In larvae, pupae and adults of Tenebrio molitor (Coleoptera) almost all the eggs hatched; and within 24 h haemocytes enveloped the parasite larvae and melanin was deposited over their mouth and anus. The pattern of these reactions was the same in all cases and at all stages. When individuals of Tenebrio were given repeated injections at weekly intervals, they reacted to the last parasite exactly as to a first. Female individuals that had been repeatedly injected were allowed to develop and to lay eggs; when larvae reared from those eggs were injected they made the same characteristic reactions. No trace of increased tolerance or resistance on the part of Tenebrio was observed in either experiment. Larvae and pupae of Diataraxia oleracea (Lepidoptera) rapidly encapsulated parasites injected into them; adults made no visible reaction. Nemeritis larvae fed, grew and ecdysed in these adults, and only the premature death of the moth prevented the parasite’s development. In feeding larvae, resting larvae and adults of Calliphora erythrocephala (Diptera), the haemocytic and melanin reactions to injected parasites were both weak; in pupae the haemocytic reaction was weak but the melanin reaction strong. In the adult blowflies, parasite larvae lived as long as 7 days, but did not grow and seemed unable to use the food they had ingested. Observations recorded in this and the two preceding papers of the series are compared and discussed. The haemocytic reaction to Nemeritis , as observed in several orders of insects, is a true defence reaction and, when strong enough, leads to the death of the parasite. Deposition of melanin acts as a defence reaction only fortuitously, when the deposit is so sited as to prevent a vital activity, such as the hatching or the feeding, of the parasite. The reactions to Nemeritis of the different kinds of hosts so far investigated are distinguishable, but no constant difference has been observed that would serve to distinguish the reactions of exopterygote from those of endopterygote insects.

Experimental studies in insect parasitism. IX. The reactions of a stick insect to an alien parasite.

Eggs and larvae of an ichneumon fly, Nenteritis canescens , injected into adults of a stick insect, Carausius morosus , elicited two defence reactions. Dark material, probably melanin, was deposited on their surface; and they were invested with haemocytes which, within 24 h, formed unorganized clumps of irregular shape about them. The haemocytic reaction was less vigorous in confined spaces than in the main blood stream, and several observations support the view that the haemocytes did not flock to the parasite from a distance but accumulated by chance encounter of, at most, a small chemotactic field. The size of the clumps reached a maximum about 24 h after injection of the parasite. The melanin reaction, on the other hand, was as strong in confined spaces as in the main blood stream, and was progressive, eventually encasing the parasite in a brittle black sheath. In nymphs of 1/2, and in young nymphs of 1/20, adult weight, the two reactions were essentially the same as in adults; the melanin reaction was indistinguishable from that in the adult; the haemocytic reaction in the large nymphs was a little, and in the small nymphs was much, less massive. The deposition of melanin about the parasite was inhibited by simultaneous injection of phenylthiourea. The haemocytic reaction could not be inhibited by injections of Chinese ink, because blood cells blackened by the carbon particles they had engulfed nevertheless invested the parasite. The two reactions were elicited both by living and by dead parasites; the haemocytic reaction appeared to be elicited by clean glass rods, but the melanin reaction was not. Most Nenteritis eggs failed to hatch in Carausius although the fully developed larva could be seen moving within them, and no Nenteritis larva was observed to live longer than 48 h in this host. But larvae that had hatched in Carausius and after 24 h were transferred to the normal host, Ephestia , lived and developed. Moreover, eggs hatched normally in the blood of Carausius in hanging-drop cultures, and the larvae lived as long as 75 h. The death of this parasite in Carausius does not appear to be due either to toxic properties of the blood as a fluid, or to its unsuitability as food, but to active processes, the haemocytic and melanin reactions, that take place in the living host.

Experimental studies in insect parasitism. VIII. Host reactions following artificial parasitization.

A method of artificial parasitization has been devised which allows eggs of insect parasitoids to be injected into any given species of host. By this means, eggs of an ichneumon fly, Nemeritis canescens , have been put into larvae of eight species of Microlepidoptera, none of which has ever been recorded as a host of that parasite. Three species encapsulated the parasite egg and prevented its hatching. In three species the egg hatched but the host reacted to the parasite larva: in two species by encapsulation, in one species by the blocking of its alimentary tract with melanin. Two species gave feeble reactions or none, and were partly or wholly susceptible to the parasite. The defence reactions of all these hosts to the same parasite took two principal forms: encapsulation and the deposition of melanin. Each species of host was capable of both forms, but each species reacted in a manner that was characteristic and peculiar to it. Nevertheless, hosts belonging to the same family reacted to the parasite in similar ways so that, within the limits of this preliminary survey, the defence reactions of a group of hosts to the same parasite reflect the relationships of the hosts.

Aquatic Hymenoptera in America

This article is intended primarily to call attention to an almost entirely neglected field of entomological research, at least in this country, namely—the study of the habits and life-histories of those minute hymenopterous insects that have assumed aquatic life. In Europe considerable work has been done along this line. As early as 1836, F. Walker observed Agriotypus armatus (an anomalous Ichneumon fly) descend some distance into the water. Von Siebold (1858), W. Muller (1888), and others have shown that it is parasitic on Trichopterous larvae. In 1863 Sir John Lubbock published his well known account of Polynema natans and Prestwichia aquatica , both with aquatic habits, the former swimming by means of its wings, the latter using its legs. Nothing was known by him regarding their earlier stages. Enock, Heymons and Willem have since reared Prestwichia aquatica from a variety of insect eggs, including Notonecta, Ranatra, Dytiscus and Pelobius.

STUDIES IN THE GENUS INCISALIA

Hymenopterous parasite.— On April 13th, 1906, chrysalis No. 112 gave birth to an ichneumon fly, which Mr. D.B. Yound has kindly identified for me as Anomalon pseudargioli.

EXOCHILUM MUNDUM, SAY, ATTACKING THE FALL WEB-WORM

One hot afternoon in the early part of August, 1893, while out collecting, I found a large web of the Fall Web-Worm (Hyphantriacunea, Drury), on a young apple tree. Reaching up to cut off the twigs to which the web was attached, my attention was attarcted by an unusual disturbance among the immates of the web. Closer insepection revealed the fact that a medium-sized Ichneumon fly had intruded within the family circle, and was proving herself a most unwelcome visitor. Tearing into the web with her feet she would force her way along until she arrived under the skeletonized leaves upon which the larvæ were resting and through which they were plainly visible.

ENTOMOLOGICAL GLEANINGS

on the 21st of July at a quarter past seven in the evening we were passing around among the currant and gooseberry bushes watching the manipulations of a few of those well known foes, the larva of Nematus ventricosus. They were feeding away voraciously with perennial appetites, when a disturber of their peace appeared among them in them of a small black ichneumon fly which fastened itself on the body of one of their number, and began to deposit its eggs by means of a sharp ovipositor, dexterously thrust through the skin of its victim, whose jerks and writhings while indicating a very uneasy state, failed to shake off the tormontor.