Host Hemolymph Research Articles

Effects of the parasitoid, microplitis croceipes on the haemolymph proteins of the corn earworm, Heliothis zea

1. 1. Parasitism of the corn earworm, Heliothis zea, by Microplitis croceipes, resulted in differences in the number and location of host proteins when separated by disc electrophoresis. 2. 2. These results suggest that the parasitoid may break down or utilize certain host proteins and cause the release or synthesis of other proteins by the host. 3. 3. Additionally, the parasite may utilize or destroy certain host haemolymph proteins while causing a shift in free amino acids of the shot to the bound state or the secretion of other proteins into the haemolymph. 4. 4. The result demonstrates that the parasite extracts or uses a large amount of conjugated protein from the host during its development, while other organic constituents such as lipids appear not to be consumed as fast during the host-parasitoid association.

A CHEMICALLY DEFINED, SYNTHETIC MEDIUM THAT INDUCES OVIPOSITION IN THE PARASITEITOPLECTIS CONQUISITOR(HYMENOPTERA: ICHNEUMONIDAE)

AbstractA chemically defined, synthetic medium that induces oviposition in the parasiteItoplectis conquisitor(Say) has been developed. The medium contains serine (0.5M), arginine (0.05M), leucine (0.065M), and magnesium chloride (0.025M); and it is more effective than host haemolymph in inducing oviposition. This completely artificial oviposition stimulant was developed to facilitate the mass rearing of the parasite on an artificial diet.

Host Discrimination in A Gregarious Parasitoid Nasonia Vitripennis (Walker) (Hymenoptera: Pteromalidae)

ABSTRACT Females of Nasonia vitripennis cannot distinguish newly parasitized hosts from unparasitized ones but after 60 hr parasitization the parasitized puparia are rejected as oviposition sites. The sheath and stylets of the ovipositor have nerves passing down their canals leading to several types of receptor at the tip of the ovipositor shaft. Differences are detectable in the chemical composition of host haemolymph after 3 days parasitization as compared with the unparasitized condition. These may be the factors bringing about discrimination.

Changes in the composition of host haemolymph after attack by an insect parasitoid.

MANY insect parasitoids are capable of distinguishing whether their prospective hosts are healthy or whether the hosts already contain a parasitoid larva of the same or a different species. In many cases discrimination is made possible by an odour or chemical trace left on the surface of the host by the initial parasitoid1, or else gross. physical changes in the host such as desiccation or immobility2. Some endoparasitic ichneumonids can detect a parasitized host solely by penetration with the ovipositor3–5, but nothing is known of the chemical stimuli, in the haemolymph which may elicit this discrimination.

Effects of the parasitoid, Cardiochiles nigriceps, on the growth, development, and tissues of Heliothis virescens

Parasitism of the tobacco budworm, Heliothis virescens, by Cardiochiles nigriceps resulted in a reduction in weight gain by parasitized larvae. Host larvae parasitized during the second or fourth instars developed through the same number of moulting cycles as non-parasitized controls although the head capsule diameter of parasitized larvae was reduced. Both parasitized and control larvae entered the pharate pupal phase at the same time, but the parasitized larvae failed to shed the larval cuticle. When second instar host larvae were parasitized, the parasite emerged in 12 days, 1 day after the controls pupated. Parasites from larvae parasitized during the fourth instar required 11 days for development and emerged 3 days after the controls pupated. The specific gravity of the host haemolymph increased following parasitism. Differences in the number and location of host proteins separated by disk electrophoresis between parasitized and non-parasitized hosts occurred, suggesting the breakdown or utilization of certain host proteins and the release or synthesis of other proteins. Changes in the developing fat body of nonparasitized larvae were observed during the pharate pupal phase which resulted in the deposition of protein globules and enlargement of the fat body. The fat body of parasitized larvae did not change during the pharate pupal phase. Parasite larvae fed exclusively on haemolymph until 2 or 3 days before emergence, when the fat body was attacked.

Component of the Host Haemolymph that induces Oviposition in a Parasitic Insect

To select a host and to oviposit in it, parasitic Hymenoptera may require visual, olfactory and/or chemotactile stimuli1–3. Some species can recognize a host by piercing it with the ovipositor4–6, but nothing is known of the stimuli (supposedly chemical) that elicit such recognition. In the wild the North American ichneumonid, Itoplectis conquisitor (Say), attacks host pupae in cocoons, hollow stems or rolled leaves. In the laboratory, females are attracted to artificial host shelters, such as paper tubes examining them with the antennae and probing them with the ovipositor. If pupae of various Lepidoptera are placed in such tubes eggs are deposited in them. In similar conditions, we have found that eggs are laid in pupal haemolymph of the greater wax moth, Galleria mellonella L., but not in distilled water, saline solution, egg albumin, chicken blood or a mixture of amino-acids. Apparently females can recognize the contents of tubes (for the purpose of oviposition) by probing with the ovipositor. Here we report the isolation of a physiologically active component of G. mellonella haemolymph that induces oviposition by I. conquisitor. To our knowledge this is the first demonstration of a chemical that induces oviposition by a parasitic insect.