DISCRIMINATION BETWEEN SELF- AND CONSPECIFIC-PARASITIZED HOSTS IN THE APHID PARASITOID PRAON PEQUODORUM VIERECK (HYMENOPTERA: APHIDIIDAE)

1993 ◽  
Vol 125 (5) ◽  
pp. 957-964 ◽  
Author(s):  
T.P. Danyk ◽  
M. Mackauer
Keyword(s):  
Conditional Probability ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Host Quality ◽  
Host Discrimination ◽  
Aphid Parasitoid ◽  
Type Host ◽  
Host Type ◽  
Solitary Parasitoid ◽  
Preference Tests

AbstractWe evaluated host discrimination and oviposition restraint in the wasp Praon pequodorum Viereck, a solitary parasitoid of the pea aphid, Acyrthosiphon pisum (Harris). In dichotomous preference tests, wasps attacked more unparasitized than equally available parasitized aphids, and more self-parasitized aphids than aphids parasitized by conspecific females. The conditional probability of a female laying an egg into an attacked aphid was independent of the host type. Host discrimination apparently involves a volatile and individual-specific pheromone marker. Females expecting to compete with other (conspecific) wasps for a limited host supply may ensure possession of the host by self superparasitism. Because host examination requires considerably more time than oviposition in P. pequodorum (and eggs contain few resources), it may be adaptive for a female to lay an egg in an examined host regardless of variations in host quality.

CONSPECIFIC SUPERPARASITISM IN TWO PARASITOID WASPS, APHIDIUS ERVI HALIDAY AND APHELINUS ASYCHIS WALKER: REPRODUCTIVE STRATEGIES INFLUENCE HOST DISCRIMINATION

1991 ◽  
Vol 123 (6) ◽  
pp. 1229-1237 ◽  
Author(s):  
B. Bai
Keyword(s):  
Reproductive Strategies ◽  
Acyrthosiphon Pisum ◽  
Aphidius Ervi ◽  
Parasitoid Wasps ◽  
Host Discrimination ◽  
Larval Competition ◽  
Parasitoid Species ◽  
Aphid Parasitoid ◽  
Aphelinus Asychis ◽  
Physiological Suppression

AbstractConspecific host discrimination and larval competition in two aphid parasitoid species were studied in the laboratory using the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), as a host. Aphidius ervi Haliday (Hymenoptera: Aphidiidae) used internal host cues to discriminate between unparasitized and conspecific parasitized hosts. When only parasitized hosts were available, females oviposited into recently parasitized ones where their progeny had a good chance to survive, but rejected those parasitized ≥24 h earlier where their offspring normally died. Competitions occurred only after both eggs had hatched. Larvae eliminated supernumeraries by means of physical combat and physiological suppression. In Aphelinus asychis Walker (Hymenoptera: Aphelinidae), factors, or changes in host internal condition, associated with hatching of the first egg resulted in suppression of conspecific competitors which could be in either larval or egg stage. The older larvae always won competitions through physiological means. A wasp’s oviposition decision is shown to be influenced by the probability of its progeny’s survival. Species that have different reproductive strategies may respond differently to identical host conditions.

Electrophoretic study of five aphid parasitoid species of the genus Aphidius (Hymenoptera: Braconidae), including evidence for reproductively isolated sympatric populations and a cryptic species

1998 ◽  
Vol 88 (1) ◽  
pp. 3-13 ◽  
Author(s):  
P. Atanassova ◽  
C.P. Brookes ◽  
H.D. Loxdale ◽  
W. Powell
Keyword(s):  
Cryptic Species ◽  
Acyrthosiphon Pisum ◽  
Genetic Relationships ◽  
Pea Aphid ◽  
Parasitoid Species ◽  
Sympatric Populations ◽  
Electrophoretic Study ◽  
Aphid Parasitoid ◽  
Parasitoid Population ◽  
The Uk

AbstractFour polymorphic enzymes (PEP, PGI, PGM and IDH) were separated from adult individuals of five aphid parasitoid species of the genus Aphidius Nees (A. ervi Haliday, A. microlophii Pennacchio & Tremblay, A. eadyi Starý, Gonzalez & Hall, A. picipes Nees and A. urticae Haliday) using horizontal cellulose acetate plate electrophoresis. These markers were used to investigate the genetic relationships, including reproductive isolation and host adaptation/specificity, in laboratory and field populations. Samples were collected from the pea aphid, Acyrthosiphon pisum (Harris) and/or the nettle aphid, Microlophium carnosum (Buckton) in the UK and Bulgaria between 1991 and 1994. Whilst all loci discriminated between some species, PGM discriminated all five species, one species (A. eadyi) bearing two unique alleles (PGMa and PGMc). Aphidius microlophii (from nettle aphid) and A. ervi (from pea aphid), which are difficult to separate morphologically, possessed unique PGM alleles – PGMb and PGMe, respectively. Both parasitoids occur sympatrically, and whilst hybrids heterozygous for PGM were produced in the laboratory (PGMb,e), such genotypes were not observed in the field populations sampled. Hence, the species appear to be reproductively isolated. Most parasitoid populations studied showed mean heterozygote deficiencies per locus (homozygote excess) compared with Hardy-Weinberg expectations. In particular, A. eadyi bearing PGMa alleles were always homozygous whilst additionally, many were homozygous for another allele, PGIb. This is evidence for the existence of one or more morphologically-indistinguishable ‘cryptic’ species occurring sympatrically within European field populations. A dendrogram of relatedness was produced following calculation of Nei's genetic identity coefficient, I from the parasitoid population allele frequency data. All species showed very high similarity between populations at the intraspecific level (>0.9), but fewer interspecific similarities (0.23–0.63). These values compare well with previously published values for Aphidius populations and for other insects.

scholarly journals Aphids Facing Their Parasitoids: A First Look at How Chemical Signals May Make Higher Densities of the Pea Aphid Acyrthosiphon pisum Less Attractive to the Parasitoid Aphidius ervi

Insects ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 878
Author(s):  
Mohannad Ismail ◽  
Penelope Zanolli ◽  
Frédéric Muratori ◽  
Thierry Hance
Keyword(s):  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Aphidius Ervi ◽  
Aphid Parasitoid ◽  
Aphid Infestation ◽  
Induced Volatiles ◽  
Aphid Density ◽  
Infestation Density ◽  
Series Of Experiments ◽  
The Impact

Herbivore-induced plant volatiles constitute the first indicators of insect host presence, and these can affect the foraging behavior of their natural enemies. The density of insect hosts may affect the nature and concentration of these plant-induced volatiles. We tested the impact of infestation density (low, intermediate, and high) of the pea aphid, Acyrthosiphon pisum (Homoptera: Aphididae), feeding on the broad bean Vicia faba, on the attractiveness of the parasitoid Aphidius ervi (Hymenoptera: Braconidae), using a Y-tube olfactometer (infested vs. non-infested plants). The emitted volatile compounds from both infested and non-infested plants were collected and identified. In addition, two series of experiments were carried out to test the impact of the presence of a conspecific female parasitoid within the aphid/plant complex on the attractiveness to other females. Parasitoids were significantly more attracted to the plants with low and intermediate aphid infestation levels. The volatile blend composition of the infested plants changed in relation to aphid density and may explain the low attraction of parasitoids toward high aphid density. The presence of conspecific females on the aphid patch had no apparent impact on the behavioral choices of other parasitoid females. Our study adds a new aspect to understanding plant–aphid–parasitoid interactions, including the possibility that aphids may manipulate chemical cues of host plants affecting the orientation of parasitoids.

Maternal adjustment of sex ratio in response to host size in the aphid parasitoid Ephedrus californicus

1991 ◽  
Vol 69 (6) ◽  
pp. 1489-1495 ◽  
Author(s):  
C. Cloutier ◽  
C. A. Lévesque ◽  
D. M. Eaves ◽  
M. Mackauer
Keyword(s):  
Sex Ratio ◽  
Acyrthosiphon Pisum ◽  
Female Offspring ◽  
Host Size ◽  
Host Quality ◽  
Experimental Conditions ◽  
Aphid Parasitoid ◽  
Adult Eclosion ◽  
Primary Sex Ratio ◽  
Offspring Sex

It has been suggested that sex ratios dependent on host size are unlikely to evolve in parasitoid wasps developing in growing hosts because future host quality would not be predictable at the time of oviposition by the female. We used logistic regression to estimate the primary sex ratio of a solitary parasitoid of aphid nymphs, using data on offspring sex at the time of adult eclosion. The method corrects for any differential preadult mortality between male and female offspring. Male preadult mortality is estimated separately from data on male-only offspring produced by unmated females. This information is built into the statistical analysis of data on offspring sex at the time of eclosion of progeny of mated females to estimate female preadult mortality and the primary sex ratio. The method was used to demonstrate manipulation of offspring sex by females of the parasitoid Ephedrus californicus parasitizing large (third-instar) and small (first-instar) pea aphids, Acyrthosiphon pisum. Mated E. californicus females fertilized nearly 50% of their eggs laid in large host aphids but only about 20% of those laid in small hosts, the difference being highly significant. Parasitoid survival from oviposition to adult eclosion was about 10% higher in small hosts than in large hosts, but for a given host size, the incidence of survival did not differ significantly between the sexes. Therefore, differential preadult mortality had no effect on modifying the primary sex ratio under the experimental conditions. The results also indicated that female decisions about the sex of offspring were affected by previous experience with the range of host sizes available and were more flexible with large than with small hosts, which were allocated male progeny almost invariably. We discuss the evolution of sex-ratio manipulation in solitary hymenopterous parasitoids of the koinobiotic type, which develop in growing host stages, such as aphid nymphs, as opposed to eggs and pupae. Our data indicate that a growing host can represent a reliable resource that is predictable from its initial size, even though it has not reached its potential size at the time of parasitoid oviposition. At least in species such as E. californicus that attack a range of host instars differing widely in size and thus in potential for parasite growth, the ability to effect sex-ratio adjustments based on host size at the time of oviposition may help to maximize female reproductive success, despite any uncertainty about future host quality.

Host–instar selection in the aphid parasitoid Monoctonus paulensis (Hymenoptera: Braconidae, Aphidiinae): assessing costs and benefits

2001 ◽  
Vol 133 (4) ◽  
pp. 549-564 ◽  
Author(s):  
Amanda Chau ◽  
Manfred Mackauer
Keyword(s):  
Body Size ◽  
Acyrthosiphon Pisum ◽  
Search Time ◽  
Pea Aphid ◽  
Potential Fecundity ◽  
Aphid Parasitoid ◽  
Offspring Number ◽  
Host Instar ◽  
Parasitoid Development ◽  
Pupal Mortality

AbstractFemales of Monoctonus paulensis (Ashmead), a solitary parasitoid of aphids, generally select the relatively smaller over equally available larger instars of the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea: Aphididae). Large hosts contain more resources for parasitoid development and hence have presumably higher quality; however, they require more time to subdue and are more likely to escape. We tested the hypothesis that a female’s choice among first (L1), second (L2), third (L3), and fourth (L4) instars of the pea aphid is based on the optimal balance between fitness costs in terms of time and fitness gains in terms of offspring number and size. Prepupal mortality did not vary with host instar, but pupal mortality was greater among parasitoids developing in L4 than in any younger instars. Offspring mortality was not influenced by clutch size in that mortality risk did not differ between parasitoids developing alone and counterparts developing in a clutch. The sex ratio, measured as proportion of daughters among offspring, was female-biased on all four host instars; the degree of bias increased from 0.70 (in L1) to 0.92 (in L4). Parasitoid body size was a function of aphid size at parasitism. Females were larger than males; the magnitude of the difference in body size was constant and independent of host and hence parasitoid size. A female’s potential fecundity as measured by the number of ovarial eggs at eclosion varied with her size and larval ontogeny. The four instars of the pea aphid were ranked in the order L1 > L2 > L3 > L4 both in terms of the number of offspring produced per encountered host and in terms of a female’s time costs; first instars are easier to handle and are more abundant in the field than older instars. The four host types were ranked in the order L2 > L3 > L1 > L4 in terms of the proportion and potential fecundity of daughters among offspring. The observed preference pattern (L1 > L2 > L3 > L4) suggests that, in choosing hosts, females of M. paulensis maximize the number of offspring per unit of search time rather than simply offspring quality.

HOST DISCRIMINATION BY THE APHID PARASITOID APHELINUS ASYCHIS (HYMENOPTERA: APHELINIDAE): WHEN SUPERPARASITISM IS NOT ADAPTIVE

1990 ◽  
Vol 122 (2) ◽  
pp. 363-372 ◽  
Author(s):  
B. Bai ◽  
M. Mackauer
Keyword(s):  
Egg Production ◽  
Acyrthosiphon Pisum ◽  
Host Acceptance ◽  
Parasitoid Species ◽  
Aphid Parasitoid ◽  
Egg Deposition ◽  
Aphelinus Asychis ◽  
Solitary Parasitoid ◽  
Long Time ◽  
Host Rejection

AbstractFemales of the solitary parasitoid Aphelinus asychis Walker discriminated between unparasitized and parasitized second-instar nymphs of the pea aphid, Acyrthosiphon pisum (Harris). Wasps normally avoided superparasitism, except when they were confined with few hosts for a long time. Parasitoid females did not need previous experience with unparasitized aphids (learning) in order to discriminate. They probed with the ovipositor any aphids encountered, a behaviour suggesting that host acceptance and rejection were determined by internal cues. Prolonged ovipositor insertion (>80 s) was correlated with host acceptance and egg deposition, but short insertion times (≤80 s) generally indicated host rejection. Females tended to reject both self- and conspecific-parasitized aphids when provided with two of each kind. We consider hypotheses mat conspecific superparasitism may be adaptive and give examples to show exceptions. We propose that, in egg-limited parasitoid species such as A. asychis, a reproductive strategy based on the regulation of egg production and on oosorption can explain the equal avoidance of self and conspecific superparasitism.

SELF-SUPERPARASITISM IN THE SOLITARY PARASITOID MONOCTONUS PAULENSIS (HYMENOPTERA: BRACONIDAE, APHIDIINAE): PROXIMATE MECHANISMS

1999 ◽  
Vol 131 (6) ◽  
pp. 769-777 ◽  
Author(s):  
Amanda Chau ◽  
Manfred Mackauer
Keyword(s):  
Clutch Size ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Proximate Mechanisms ◽  
Host Instar ◽  
Egg Number ◽  
Solitary Parasitoid

AbstractMonoctonus paulensis (Ashmead) was reared in the laboratory on the four nymphal instars of the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea: Aphididae). Females frequently laid clutches of two eggs during a single ovipositor probe; however, clutches of more than two eggs were rare. The time needed to capture and position an aphid for oviposition increased with aphid instar but was independent of the number of eggs laid. Oviposition time was proportional to egg number, which shows that eggs were laid one at a time rather than clumped together as a package. Intensity of parasitism (i.e., number of eggs per parasitized host) increased with host instar but declined with the number of hosts attacked in quick succession. Our results suggest that clutch size in M. paulensis is not accidental but controlled by the female.

MARKING THE PACKAGE OR ITS CONTENTS: HOST DISCRIMINATION AND ACCEPTANCE IN THE ECTOPARASITOID DENDROCERUS CARPENTERI (HYMENOPTERA: MEGASPILIDAE)

1999 ◽  
Vol 131 (4) ◽  
pp. 495-505 ◽  
Author(s):  
Andrew Chow ◽  
Manfred Mackauer
Keyword(s):  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Aphidius Ervi ◽  
Host Discrimination ◽  
Contact Pheromone ◽  
Primary Parasitoid ◽  
Alternative Hypotheses ◽  
Marking Behaviour ◽  
Search Template

AbstractDendrocerus carpenteri (Curtis) was reared in the laboratory on prepupae of Aphidius ervi Haliday (Hymenoptera: Braconidae, Aphidiinae) developing in pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). To test alternative hypotheses about host-marking behaviour and discrimination, we transferred unparasitized and previously parasitized A. ervi prepupae from donor to recipient mummies, which were either "unparasitized" or "parasitized." Females accepted already parasitized hosts within unparasitized mummies, but they rejected unparasitized hosts within previously parasitized mummies. Host discrimination was not influenced by self and conspecific parasitism. Eggs were frequently placed directly on the mummy shell, rather than on the primary parasitoid, or on dummies made from dental wax. Prepupae removed from their mummy shell were not accepted for oviposition. We propose that the "search template" of D. carpenteri is defined, primarily, by the aphid mummy, which is being marked with a contact pheromone after oviposition.

AGE-SPECIFIC PATTERN OF HOST DISCRIMINATION BY THE APHID PARASITOID EPHEDRUS CALIFORNICUS BAKER (HYMENOPTERA: APHIDIIDAE)

1990 ◽  
Vol 122 (2) ◽  
pp. 349-361 ◽  
Author(s):  
W. Völkl ◽  
M. Mackauer
Keyword(s):  
Acyrthosiphon Pisum ◽  
Specific Pattern ◽  
Search Rate ◽  
Host Discrimination ◽  
Aphid Parasitoid ◽  
Conspecific Female ◽  
Egg Deposition ◽  
Age Dependent ◽  
Hymenopteran Parasitoids

AbstractThe solitary aphid parasitoid Ephedrus californicus Baker is able to discriminate between unparasitized and parasitized third-instar nymphs of the pea aphid, Acyrthosiphon pisum (Harris). Superparasitism varied with the number of mature eggs (which is age-dependent) present in the ovaries as well as with the number and the quality of any hosts encountered. Conspecific superparasitism varied with wasp age; older females, with a large egg supply, accepted hosts parasitized by a conspecific female if unparasitized aphids were unavailable. Self superparasitism occurred at all ages; it was the least likely behaviour compared with egg deposition in unparasitized and conspecific-parasitized hosts. Prior experience (learning) was not necessary for host discrimination, but it did influence the search rate, which was higher in inexperienced than experienced females. In choice experiments, wasps preferred conspecific- over self-parasitized aphids and thus were able to distinguish between them. It is suggested that oviposition markers vary among conspecific females. The data are discussed with reference to theories about oviposition decisions and progeny allocation in solitary hymenopteran parasitoids.

Sign in / Sign up

Export Citation Format

Share Document