Increasing host age does not have the expected negative effects on the fitness parameters of an egg parasitoid

2014 ◽  
Vol 151 (2) ◽  
pp. 106-111 ◽  
Author(s):  
Y. Zhou ◽  
P. K. Abram ◽  
G. Boivin ◽  
J. Brodeur
1987 ◽  
Vol 119 (1) ◽  
pp. 75-82 ◽  
Author(s):  
J. Lashomb ◽  
D. Krainacker ◽  
R.K. Jansson ◽  
Y.S. Ng ◽  
R. Chianese

AbstractParasitism of the Colorado potato beetle, Leptinotarsa decemlineata (Say), by Edovum puttleri Grissell, an exotic egg parasitoid, was studied in relation to the age of host eggs, the age of adult, female parasitoids, and temperature. Parasitism was greater in eggs ≤2 days old than in eggs older than 2 days. Eggs older than 2 days were killed primarily by probing and consequent desiccation. The percentage of eggs killed by probing was positively correlated with host age and negatively correlated with percentage parasitism. Total mortality of eggs from parasitism and probing did not differ among age classes. Following a 3-day preoviposition period, parasitism and probing increased with an increase in the age of females, peaked when adults were ca. 13 days old, and subsequently declined. Parasitism and probing were influenced by temperature: at 15 °C, no parasitism or probing was observed; above 15 °C, mortality from parasitism and probing increased with an increase in temperature up to 30 °C; above 30 °C, the number of eggs that were parasitized and probed decreased with an increase in temperature.


2017 ◽  
Vol 149 (2) ◽  
pp. 251-264 ◽  
Author(s):  
T.P.N. Hariprasad ◽  
N.J. Shetty

AbstractAnopheles stephensi Liston (Diptera: Culicidae), an urban malaria vector in India, is controlled by insecticides. Sublethal concentrations can be effective in reducing mosquito populations and disease transmission by reducing its reproductive fitness. In this study, sublethal effects of alphamethrin, a synthetic pyrethroid, were assessed on selected fitness parameters. Late third instars of the Goraguntepalya strain, Bangalore, were exposed to three sublethal doses, LC10 – 0.00006, LC30 – 0.0004, and LC50 – 0.0014 mg/L and their effects on fecundity, egg hatchability, sex ratio, and longevity in parental, F1 and F2 generations. The morphology of gonads, pattern of pupation, and adult emergence were also assessed. We found a significant reduction in fecundity and hatchability among the sublethal concentrations as well as across generations. Survival analysis showed significant reduction in lifespan of exposed groups. Delay in pupation, eclosion, and no distortion in sex ratio was observed. The results suggest that sublethal concentrations of alphamethrin may have negative effects on exposed individuals and subsequent generations.


1991 ◽  
Vol 81 (1) ◽  
pp. 65-76 ◽  
Author(s):  
A. van Huis ◽  
M. G. Wijkamp ◽  
P. M. Lammers ◽  
C. G. M. Klein Goldewijk ◽  
J. H. van Seeters ◽  
...  

AbstractUscana lariophaga Steffan is an egg parasitoid of bruchid species in West Africa. The hosts are Callosobrucbus maculatus (Fabricius) and Bruchidius atrolineatus Pic, insect pests of stored cowpea. Experiments were carried out to study the selection between hosts of different ages and of different species in choice and no-choice situations. Results were obtained through parasitization studies and by direct behavioural observations. A description of the parasitization behaviour of Uscana lariophaga is given. At 30°C, C. maculatus eggs of 0–2 day old are readily accepted for parasitization, but in a choice situation the 0 day old eggs are preferred. Of the older eggs only those of 3 days old are parasitized but significantly less than those of 0–2 days. At 30°C, B. atrolineatus eggs older than 24 hours are significantly less parasitized than younger eggs also in the no-choice situation. When eggs are older than one day, the time needed for penetrating the egg increases with host age. Both bruchid species are suitable hosts for U. lariophaga. In a choice situation B. atrolineatus is the preferred host and especially so when U. lariophaga has been reared on this species. However, in a no-choice situation the highest rate of successful parasitization is obtained on hosts of the species from which they have been reared. The higher parasitization rate of C. maculatus in the field in Niger can be explained by the difference in the susceptible period between the two host species.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sarah Biganski ◽  
Sabrina Fückel ◽  
Johannes A. Jehle ◽  
Regina G. Kleespies

AbstractMicrosporidian infections of insects are important natural constraints of population growth, often reducing lifespan, fecundity and fertility of the infected host. The recently discovered Tubulinosema suzukii infects Drosophila suzukii (spotted wing drosophila, SWD), an invasive pest of many fruit crops in North America and Europe. In laboratory tests, fitness effects on larval and adult stages were explored. High level infection after larval treatment caused up to 70% pupal mortality, a decreased lifespan and a 70% reduced oviposition of emerging adults in biparental infection clusters. A shift to higher proportion of female offspring compared to controls suggested a potential parthenogenetic effect after microsporidian infection. A clear sex-linkage of effects was noted; females were specifically impaired, as concluded from fecundity tests with only infected female parents. Additive effects were noted when both parental sexes were infected, whereas least effects were found with only infected male parents, though survival of males was most negatively affected if they were fed with T. suzukii spores in the adult stage. Although most negative effects on fitness parameters were revealed after larval treatment, infection of offspring was never higher than 4%, suggesting limited vertical transmission. For that reason, a self-reliant spread in natural SWD populations would probably only occur by spore release from cadavers or frass.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jin-Cheng Zhou ◽  
Yuan-Yuan Li ◽  
Quan-Quan Liu ◽  
Su-Fang Ning ◽  
Wu-Nan Che ◽  
...  

AbstractThelytokous Wolbachia-infected Trichogramma spp. are widely used egg parasitoids against lepidopteran pests in biological control programs. Wolbachia may manipulate host wasps for superparasitism and is sensitive to temperature. To explore effects of temperature and superparasitism, we compared fitness parameters and Wolbachia-mediated phenotype of thelytokous Wolbachia-infected Trichogramma dendrolimi between those emerging from superparasitised or single-parasitised hosts at 17, 21, 25, or 29 °C. Infected mothers of T. dendrolimi showed reduced superparasitism and parasitism increased with temperature. Wolbachia titre decreased with temperature when females emerged from singly-parasitised hosts, but there was no correlation in superparasitised hosts. Females showed higher Wolbachia titres at 21, 25, or 29 °C when developing from superparasitised hosts. The daily male ratio of offspring increased with temperature, and the day-age threshold for 5%, 50%, or 95% daily male ratio decreased with temperature in both parasitism forms. Females that emerged from superparasitised hosts had a shorter life span and reduced fecundity. These results indicate that Wolbachia may affect host behaviour by increasing superparasitism to enhance its spread, but this has negative effects on thelytokous Wolbachia-infected T. dendrolimi.


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