scholarly journals Influence of Plant Host Quality on Fitness and Sex Ratio of the Wheat Stem Sawfly (Hymenoptera: Cephidae)

2005 ◽  
Vol 34 (6) ◽  
pp. 1579-1592 ◽  
Author(s):  
H. A. Cárcamo ◽  
B. L. Beres ◽  
F. Clarke ◽  
R. J. Byers ◽  
H.-h. Mündel ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Host Quality ◽  
Plant Host ◽  
Wheat Stem Sawfly

Effect of Time of Seeding Apex Wheat on Infestation and Sex Ratio of the Wheat Stem Sawfly, Cephus cinctus Nort. (Hymenoptera: Cephidae)

1952 ◽  
Vol 84 (3) ◽  
pp. 90-92 ◽  
Author(s):  
L. A. Jacobson ◽  
C. W. Farstad
Keyword(s):  
Sex Ratio ◽  
Field Experiment ◽  
Wheat Stem Sawfly ◽  
Cephus Cinctus

In 1945 a field experiment was designed at the Lethbridge laboratory to augment data on the effect of the time of seeding on infestation by the wheat stem sawfly, Cephus cinctus Nort. At that time one of the recommendations for the control of this insect was to delay seeding wheat until after May 15. The resulting crop escaped infestation because of the retarded plant during the period of the sawfly flight.

scholarly journals Effect of Plant Density on Wheat Stem Sawfly Sex Ratio

2020 ◽  
Vol 2 ◽  
Author(s):  
Héctor Cárcamo ◽  
Brian Beres ◽  
Xiuhua Wu ◽  
Tracy Larson ◽  
Timothy Schwinghamer
Keyword(s):  
Sex Ratio ◽  
Plant Density ◽  
Wheat Stem Sawfly

The influence of host quality on progeny and sex allocation in the pupal ectoparasitoid,Muscidifurax raptorellus(Hymenoptera: Pteromalidae)

1998 ◽  
Vol 88 (3) ◽  
pp. 299-304 ◽  
Author(s):  
J.A. Harvey ◽  
G.J.Z. Gols
Keyword(s):  
Sex Ratio ◽  
Clutch Size ◽  
Adult Development ◽  
Development Time ◽  
Host Quality ◽  
Adult Size ◽  
Female Progeny ◽  
Interspecific Differences ◽  
Adult Parasitoid ◽  
Secondary Sex Ratio

AbstractMuscidifurax raptorellusKogan & Legner is a gregarious pteromalid ectoparasitoid that attacks pupae and pharate adults from several families of the higher Diptera. Egg-to-adult development time, adult parasitoid size and emerging offspring ( = secondary) sex ratio ofM. raptorelluswere compared with clutch size in two hosts that differed greatly in mass, the smallMusca domesticaLinnaeus and the largerCalliphora vomitoriaLinnaeus. The mean number of emerging parasitoids did not vary significantly with host species, although slightly higher clutch sizes were recorded inC. vomitoria. Irrespective of offspring sex, parasitoids completed development more rapidly inM. domesticathan inC. vomitoria. In the small host, the development time and adult size ofM. raptorelluswere negatively correlated with clutch size. By contrast, female parasitoid size was unaffected by clutch size in the larger host,C. vomitoria. In both hosts, female parasitoids were significantly larger than male parasitoids. The secondary sex ratio (percentage males) of emerging parasitoids was significantly lower inC. vomitoria, and varied with clutch size in both hosts. InC. vomitoria, the greatest proportion of females emerged from hosts with the highest clutch sizes, whereas inM. domesticahosts with the highest clutch sizes produced the lowest proportion of female progeny. The results described here show that the development ofM. raptorellusis profoundly affected by interspecific differences in host quality. Our results suggest that mating structure and host quality have potentially different effects on sex ratio decisions inM. raptorellus, and perhaps other gregarious parasitoids.

The failure to discriminate: superparasitism ofTrichoplusia niHübner by a generalist tachinid parasitoid

2009 ◽  
Vol 100 (3) ◽  
pp. 255-261 ◽  
Author(s):  
V. Caron ◽  
J.H. Myers ◽  
D.R. Gillespie
Keyword(s):  
Sex Ratio ◽  
Host Selection ◽  
Trichoplusia Ni ◽  
Cabbage Looper ◽  
Pupal Weight ◽  
Host Quality ◽  
Host Discrimination ◽  
Host Interactions ◽  
Hymenopteran Parasitoids ◽  
The Impact

AbstractParasitoids are dependent on their hosts, which provide all of the resources for larval development. Parasitoid fitness, therefore, is directly related to the host quality, as determined by host size, age and health (e.g. parasitisation status); and this can only be assessed by the female parasitoid during host selection. Most studies of parasitoid-host interactions have focused on hymenopteran parasitoids rather than dipterans that are believed to be less discriminating during host selection. We assessed the impact of host quality and superparasitism on parasitoid fitness inCompsilura concinnataMeigen, a gregarious tachinid dipteran parasitoid, and its lepidopteran host the cabbage looper,Trichoplusia niHübner.FemaleC. concinnataparasitised all host stages ofT. nithat were presented to them, but emergence rates were higher from older hosts. Females readily superparasitised hosts. The number of flies emerging was higher from hosts parasitised at later instars, and flies emerged earlier from heavily superparasitised hosts. Superparasitism decreased parasitoid pupal weight and development time, indicating intra-host competition between parasitoid larvae and skewed the parasitoid sex ratio in favour of males.Host discrimination does not seem to be well developed inC. concinnata. Hosts are superparasitised despite the effects of superparasitism on offspring and sex ratio. This could be due to the wide host range ofC. concinnata; avoiding high superparasitism could occur naturally due to host switching and, therefore, developing host discrimination mechanisms for one host species may not be crucial.

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.

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