Development and nutrition of the braconid wasp,Aphidius ervi in aposymbiotic host aphids (original) (raw)
Related papers
Journal of Insect Physiology, 2002
Aphidius ervi Haliday (Hymenoptera, Braconidae) is an endophagous parasitoid of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera, Aphididae). This parasitoid strongly redirects host reproduction and metabolism to favour nutrition and development of its juvenile stages. Parasite-regulated biosynthesis and mobilization of nitrogen metabolites determine a significant increase of host nutritional suitability. The aim of the present study was mainly to investigate the temporal changes of A. pisum amino acid pools, as affected by A. ervi parasitism, and to assess the role of the aphid bacterial endosymbiont Buchnera in determining the observed changes. In parasitized aphids, we observed a very significant increase in total free amino acids, compared with synchronous non-parasitized controls, starting from day 4 after parasitization (+51%). This trend culminated with more than doubling the control value (+152%) on day 6 after parasitization. However, a significant "parasitism" effect was observed only for 10 of the 28 amino acids detected. Tyrosine accumulation was the most prominent parasitoid-induced alteration, with a fourfold increase over control levels registered on day 6. In parasitized hosts, the amino acid biosynthetic capacity of Buchnera was unaltered, or even enhanced for the phenolic pool, and contributed greatly to the definition and maintainance of host free amino acid pools. The hypertyrosinemic syndrome was not dependent on food supply of the aromatic nucleus but was induced by parasitism, which likely enhanced the aromatic shuttle mediating phenylalanine transfer from bacteria to the host tissues, where tyrosine conversion occurs. This process is likely associated with a selective disruption of the host's functions requiring tyrosine, leading to the remarkable accumulation of this amino acid. The possible mechanisms determining these parasitism-induced host alterations, and their nutritional significance for the developing parasitoid larva, are discussed.
Scientific reports, 2016
Low proportion of essential amino acids (EAAs) is one of the barriers for animals to use phloem as a diet. Endosymbionts with EAAs synthesis functions are considered crucial for ameliorating the lack of EAAs in insects' diets. In this study, we transferred the insects from a cabbage-reared Myzus persicae population onto 3 new plant species including eggplant, tobacco and spinach. The performance on these plants was evaluated and the dynamics of endosymbionts in relation to this host alternation were recorded. We found that the EAAs ratio in phloem was largely determined by the concentrations of non-essential amino acids and the higher proportion of EAAs seemed to favor the population establishment on new plant species and the growth of primary endosymbionts inside insects, which indicated that nitrogen quality was an important factor for aphids to infest and spread on new plant hosts.
Amino acid utilization in the aphid Acyrthosiphon pisum infected by the parasitoid Aphidius smithi
Journal of Insect Physiology, 1986
Amino acid levels were determined in the honeydew of pea aphids infected with A. smithi, and compared to those of the holidic diet of the host in order to study the effect of parasitism on amino acid assimilation. Honeydew of both normal and infected aphids contained large amounts of arginine, histidine and homoserine but little of the other 20 amino acids and amides present in the diet. Aphids infected with an egg stage of the parasite assimilated amino acids at reduced rates compared to controls, possibly indicating that infection inhibited protein synthesis in the host aphid. Larval growth of the parasite caused renewed amino acid utilization in the host, the effect being more pronounced for homoserine than for arginine and histidine. The results suggest that the growing A. smithi larva depletes the host of specific nutrients according to its own requirements, thus causing regulatory responses in host feeding and food assimilation.
Canadian Journal of Zoology, 1979
CLOUTIER, C., and M. MACKAUER. 1979. The effect of parasitism by Aphidius smithi (Hymenop-tera: Aphidiidae) on the food budget of the pea aphid, Acyrthosiphon pisum (Homoptera: Aphididae). Can. J. Zool. 57: 1605-161 1. Parasitism by Aphidius smithi affected the food budget of its host, Acyrthosiphonpisum. fed on a synthetic diet. During the embryonic stage of the parasite, the weight-specific rates of feeding, food assimilation, and growth were less in parasitized aphids than in controls. In the presence of a developing parasite larva, aphids ingested more food but assimilated it less efficiently; they achieved the same or a higher relative growth rate than nonparasitized aphids as a result of having either a higher feeding rate or a higher efficiency of incorporation of assimilated food, or both. Honeydew excretion was up to 129% higher in aphids containing a parasite larva. Parasitism by A. smithi did not obviate host feeding and capacity for growth until host size was sufficient for the successful development of the parasite larva.
Entomologia Experimentalis Et Applicata, 2010
In order to reduce parasite-induced mortality, hosts may be involved in mutualistic interactions in which the partner contributes to resistance against the parasite. The pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), harbours secondary bacterial endosymbionts, some of which have been reported to confer resistance against aphid parasitoids. Although this resistance often results in death of the developing parasitoid larvae, some parasitoid individuals succeed in developing into adults. Whether these individuals suffer from fitness reduction compared to parasitoids developing in pea aphid clones without symbionts has not been tested so far. Using 30 pea aphid clones that differed in their endosymbiont complement, we studied the effects of these endosymbionts on aphid resistance against the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae), host-parasitoid physiological interactions, and fitness of emerging adult parasitoids. The number of symbiont species in an aphid clone was positively correlated with a number of resistance measurements but there were also clear symbiont-specific effects on the host-parasitoid interaction. As in previous studies, pea aphid clones infected with Hamiltonella defensa Moran et al. showed resistance against the parasitoid. In addition, pea aphid clones infected with Regiella insecticola Moran et al. and co-infections of H. defensa-Spiroplasma, R. insecticola-Spiroplasma, and R. insecticola-H. defensa showed reduced levels of parasitism and mummification. Parasitoids emerging from symbiontinfected aphid clones often had a longer developmental time and reduced mass. The number of teratocytes was generally lower when parasitoids oviposited in aphid clones with a symbiont complement. Interestingly, unparasitized aphids infected with Serratia symbiotica Moran et al. and R. insecticola had a higher fecundity than unparasitized aphids of uninfected pea aphid clones. We conclude that in addition to conferring resistance, pea aphid symbionts also negatively affect parasitoids that successfully hatch from aphid mummies. Because of the link between aphid resistance and the number of teratocytes, the mechanism underlying resistance by symbiont infection may involve interference with teratocyte development.
Physiological Entomology, 2016
The facultative endosymbionts Hamiltonella defensa and Regiella insecticola are commonly found in aphids. They are linked with various ecological benefits but generally occur at low prevalence, which indicates a possible harboring cost. Little is known about how the presence of facultative endosymbionts is reflected in honeydew composition. Honeydew is the key mediator of the aphids' mutualism with tending ants. The present study examines whether endosymbionts have an influence on aphid honeydew quality by comparing the amino acid and carbohydrate concentrations between infected and uninfected aphids. To this end, two genetic lines of the aphid Aphis fabae Scopoli were experimentally infected with different strains of Hamiltonella and Regiella. Infected aphids were shown to have reduced concentrations of amino acids in the honeydew compared to uninfected aphids. However, the presence of endosymbionts had no effect on the absolute amount of carbohydrates produced. Nevertheless, interclonal variation in honeydew composition between aphid genotypes was observed for both carbohydrate and amino acid production. These results imply that the nutritional value of honeydew depends on aphid genotype as well as on the presence of secondary bacterial endosymbionts, which suggests there is a physiological cost of harboring endosymbionts and which could also impact aphid attractiveness to tending ants.
Pea aphid clonal resistance to the endophagous parasitoid Aphidius ervi
Journal of Insect Physiology, 2002
The physiological mechanism of resistance to the endophagous braconid Aphidius ervi Haliday (Hymenoptera, Braconidae) by a pink clone (PC) of Acyrthosiphon pisum (Harris) (Homoptera, Aphididae) has been investigated. Comparative data on parasitoid development and associated host biochemical changes in the resistant PC aphids and in a susceptible green clone (GC) of A. pisum are reported. When the PC aphids were attacked as early 4th instars, the developing parasitoid larvae showed a strongly reduced increase in size, compared to those synchronously developing in GC aphids, and were unable to produce a regular mummy. In contrast, parasitism of 2nd instar PC aphids, allowed completion of parasitoid development, but adults had a prolonged developmental time, due to a longer duration of parasitoid's final (3rd) instar. In all cases, teratocytes, cells deriving from the A. ervi serosal membrane, and the proteins abundantly synthesised by them, were never found in the haemolymph of parasitised PC aphids. Host castration, as demonstrated by total protein incorporation into reproductive tissues, was total in the majority of early (2nd instar) parasitised host aphids, while it was limited when later instars (4th) of PC aphids were parasitised. This is partly due to the absence of the cytolytic activity of teratocytes on host embryos, which, through their persistence, may compete for nutritional resources with the developing parasitoid larvae. In parasitised PC aphids, this competitive effect is further aggravated for the parasitoid by the absence of the regulated amino acid titre increase in the host haemolymph, which is regularly observed in GC aphids. Failure of teratocyte development in the PC clone of the pea aphid is, then, the major functional constraint accounting for the reduction/inhibition of A. ervi larval growth. The reported results allow to assess in vivo the role of teratocytes in the host physiological redirection and nutritional exploitation by the parasitoid, and to integrate and validate the proposed physiological model of hostparasitoid interactions in the system A. pisum-A.ervi.