Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature
Trichogramma cordubensis is an egg parasitoid completely infected by endosymbiotic bacteria belonging to the Wolbachia genus and inducing the thelytokous mode of reproduction. Previous results showed that the thelytoky persistence at high temperature is genetically variable. Experimental selecti...
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| Cite this: | Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature / B. Pintureau, P. Bolland // Вестн. зоологии. — 2001. — Т. 35, № 4. — С. 83-86. — Бібліогр.: 6 назв. — англ. |
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Pintureau, B. Bolland, P. 2010-07-02T11:55:11Z 2010-07-02T11:55:11Z 2001 Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature / B. Pintureau, P. Bolland // Вестн. зоологии. — 2001. — Т. 35, № 4. — С. 83-86. — Бібліогр.: 6 назв. — англ. 0084-5604 https://nasplib.isofts.kiev.ua/handle/123456789/9551 575.827 : 595.79 Trichogramma cordubensis is an egg parasitoid completely infected by endosymbiotic bacteria belonging to the Wolbachia genus and inducing the thelytokous mode of reproduction. Previous results showed that the thelytoky persistence at high temperature is genetically variable. Experimental selection was performed to confirm these results and to determine the possibilities of adaptation to the environment assuming cyclic bisexual reproduction. No selection was efficient and the genetic variability of the sex ratio at high temperature is probably lower than previously assumed. This reduces the adaptive possibilities in the studied Trichogramma species. Установлено, что Trichogramma cordubensis - яйцевой паразит, характеризующийся наличием эндосимбионтных бактерий Wolbachia и телитокическим способом размножения. Отмечено, что устойчивость к высокой температуре у телитокических видов генетически варьирует. Проведена экспериментальная селекция линий с высоким и низким половым индексом для определения возможных адаптаций к условиям окружающей среды, вызывающим двуполый способ размножения. Установлено, что селекция выбранных линий была не эффективной. Генетически обусловленная изменчивость полового индекса при высокой температуре оказалась ниже, чем предполагалось. Отмечено, что это уменьшает адаптивные возможности T. cordubensis. en Інститут зоології ім. І.І. Шмальгаузена НАН України Краткие сообщения Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature Возможности селекции линий с высоким и низким половым индексом у вида Trichogramma cordubensis, инфицированного бактерией Wolbachia, при воздействии высокой температуры Article published earlier |
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Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature |
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Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature Pintureau, B. Bolland, P. Краткие сообщения |
| title_short |
Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature |
| title_full |
Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature |
| title_fullStr |
Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature |
| title_full_unstemmed |
Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature |
| title_sort |
response to selection for a high or a low sex ratio in wolbachia-infected lines of trichogramma cordubensis subjected to high temperature |
| author |
Pintureau, B. Bolland, P. |
| author_facet |
Pintureau, B. Bolland, P. |
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Краткие сообщения |
| topic_facet |
Краткие сообщения |
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2001 |
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English |
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Інститут зоології ім. І.І. Шмальгаузена НАН України |
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Article |
| title_alt |
Возможности селекции линий с высоким и низким половым индексом у вида Trichogramma cordubensis, инфицированного бактерией Wolbachia, при воздействии высокой температуры |
| description |
Trichogramma cordubensis is an
egg parasitoid completely infected by endosymbiotic bacteria belonging to the Wolbachia genus and inducing the thelytokous mode of reproduction. Previous results showed that the thelytoky persistence at
high temperature is genetically variable. Experimental selection was performed to confirm these results
and to determine the possibilities of adaptation to the environment assuming cyclic bisexual reproduction. No selection was efficient and the genetic variability of the sex ratio at high temperature is probably lower than previously assumed. This reduces the adaptive possibilities in the studied Trichogramma
species.
Установлено, что Trichogramma cordubensis - яйцевой паразит, характеризующийся наличием эндосимбионтных бактерий Wolbachia и телитокическим способом размножения. Отмечено, что устойчивость к высокой температуре у телитокических видов генетически варьирует. Проведена экспериментальная селекция линий с высоким и низким половым индексом для определения возможных адаптаций к условиям окружающей среды, вызывающим двуполый способ размножения. Установлено, что селекция выбранных линий была не эффективной. Генетически обусловленная изменчивость полового индекса при высокой температуре оказалась ниже, чем предполагалось. Отмечено, что это уменьшает адаптивные возможности T. cordubensis.
|
| issn |
0084-5604 |
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https://nasplib.isofts.kiev.ua/handle/123456789/9551 |
| citation_txt |
Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis Subjected to High Temperature / B. Pintureau, P. Bolland // Вестн. зоологии. — 2001. — Т. 35, № 4. — С. 83-86. — Бібліогр.: 6 назв. — англ. |
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2025-11-27T04:12:23Z |
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2025-11-27T04:12:23Z |
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| fulltext |
Vestnik zoologii, 35(4): 83—86, 2001
© 2001 B. Pintureau, P. Bolland
Последним работал: AL Ostashko/DIMA; E:\My Documents\Verstka\Vestnik\2001\N4\15_Pintureau\pintur_vz.doc; Дата сохранения 8/13/2001 5:40:00 PM; 1 станиц(ы); Число
8196
UDC 575.827 : 595.79
RESPONSE TO SELECTION FOR A HIGH OR A LOW SEX RATIO
IN WOLBACHIA-INFECTED LINES OF TRICHOGRAMMA
CORDUBENSIS SUBJECTED TO HIGH TEMPERATURE
B. Pintureau, P. Bolland
Biologie Fonctionnelle, Insectes et Interactions – UMR INRA/INSA de Lyon, INSA Bâtiment L. Pasteur, 69621
Villeurbanne cedex, France
E-mail: pinture@jouy.inra.fr
Accepted 14 November 2000
Response to Selection for a High or a Low Sex Ratio in Wolbachia-infected Lines of Trichogramma cor-
dubensis Subjected to High Temperature. Pintureau B., Bolland P. – Trichogramma cordubensis is an
egg parasitoid completely infected by endosymbiotic bacteria belonging to the Wolbachia genus and in-
ducing the thelytokous mode of reproduction. Previous results showed that the thelytoky persistence at
high temperature is genetically variable. Experimental selection was performed to confirm these results
and to determine the possibilities of adaptation to the environment assuming cyclic bisexual reproduc-
tion. No selection was efficient and the genetic variability of the sex ratio at high temperature is proba-
bly lower than previously assumed. This reduces the adaptive possibilities in the studied Trichogramma
species.
Key wo rd s : bacterium, egg parasitoid, Hymenoptera, parthenogenesis, symbiosis, thelytoky.
Âîçìîæíîñòè ñåëåêöèè ëèíèé ñ âûñîêèì è íèçêèì ïîëîâûì èíäåêñîì ó âèäà Trichogramma cor-
dubensis, èíôèöèðîâàííîãî áàêòåðèåé Wolbachia, ïðè âîçäåéñòâèè âûñîêîé òåìïåðàòóðû. Ïèíòþ-
ðî Á., Áîëëàíä Ï. – Óñòàíîâëåíî, ÷òî Trichogramma cordubensis – ÿéöåâîé ïàðàçèò, õàðàêòåðè-
çóþùèéñÿ íàëè÷èåì ýíäîñèìáèîíòíûõ áàêòåðèé Wolbachia è òåëèòîêè÷åñêèì ñïîñîáîì ðàç-
ìíîæåíèÿ. Îòìå÷åíî, ÷òî óñòîé÷èâîñòü ê âûñîêîé òåìïåðàòóðå ó òåëèòîêè÷åñêèõ âèäîâ ãåíåòè-
÷åñêè âàðüèðóåò. Ïðîâåäåíà ýêñïåðèìåíòàëüíàÿ ñåëåêöèÿ ëèíèé ñ âûñîêèì è íèçêèì ïîëîâûì
èíäåêñîì äëÿ îïðåäåëåíèÿ âîçìîæíûõ àäàïòàöèé ê óñëîâèÿì îêðóæàþùåé ñðåäû, âûçûâàþ-
ùèì äâóïîëûé ñïîñîá ðàçìíîæåíèÿ. Óñòàíîâëåíî, ÷òî ñåëåêöèÿ âûáðàííûõ ëèíèé áûëà íå
ýôôåêòèâíîé. Ãåíåòè÷åñêè îáóñëîâëåííàÿ èçìåí÷èâîñòü ïîëîâîãî èíäåêñà ïðè âûñîêîé òåìïå-
ðàòóðå îêàçàëàñü íèæå, ÷åì ïðåäïîëàãàëîñü. Îòìå÷åíî, ÷òî ýòî óìåíüøàåò àäàïòèâíûå âîçìîæ-
íîñòè T. cordubensis.
Êëþ÷åâûå ñëîâà : áàêòåðèè, ÿéöåâîé ïàðàçèò, Hymenoptera, ïàðòåíîãåíåç, ñèìáèîç, òåëèòî-
êèÿ.
Introduction
The genus Trichogramma (Hym.: Trichogrammatidae) includes numerous species of egg parasitoids
worldwide distributed and used in biological control against agricultural lepidopterous pests. Most of the
species show a bisexual mode of reproduction and some species/populations have a parthenogenetic mode of
reproduction (thelytoky) often induced by symbiotic bacteria belonging to the genus Wolbachia, and more
precisely to the B supergroup of this genus (Rousset et al., 1992; Stouthamer et al., 1993; Zhou et al., 1998).
Trichogramma species are generally not completely Wolbachia-infected. However, the infection is com-
plete in some totally thelytokous species as T. cordubensis Vargas & Cabello (Pintureau, 1994). In
T. cordubensis, thelytoky shows a greater or lesser resistance to high temperature, and a part of this variability
has a genetic origin (Pintureau et al., 1999). Bisexual reproduction can thus reappear more or less easily and
the process allowing genetic recombinations could be selected to facilitate the adaptation of the population to
the environment. The aim of the present work was to confirm or to refuse the possibility of such a process by
means of experimental selection.
B. Pintureau, P. Bolland 84
Material and methods
Experiments were carried out in the strain 1148 of Trichogramma cordubensis established from parasi-
toids collected in 1995 in S. Jorge Island, Azores. In the strain 802 from S. Miguel, Azores, the within- and
between-line variances of the sex ratio (proportion of males) at 30°C, compared by an ANOVA, were signifi-
cantly different (p=0.0001) (Pintureau et al., 1999). A genetic variability was thus present and assumed to be
similar in the strain 1148.
Mass selection was applied to the character sex ratio or proportion of males. About 500 prenymphs of
the thelytokous strain 1148, parasitizing Ephestia kuehniella (Lep.: Pyralidae) eggs, were placed at 29°C
(F1 generation). The two subsequent generations (F2 and F3), also reared at 29°C, were established with a
similar number of individuals. After emergence and mating, 100 females of the F3 were isolated in glass
tubes where they were offered E. kuehniella eggs as hosts and a drop of diluted honey as food. The
F4 progenies reared at 23°C were selected or not to establish three lines. The low line, i. e. the line estab-
lished from the 10 progenies with the lower proportion of males, is expected infected by Wolbachia resistant
to high temperature. The high line, i. e. the line established from the 10 progenies with the higher proportion
of males, is expected infected by Wolbachia sensitive to high temperature. The control line was established
from 10 progenies taken at random among those not selected for the preceding lines. To establish the high
line, progenies with a sex ratio of 1 (only males) were rejected because they correspond to unmated aposym-
biotic females. Progenies including less than 10 individuals were never taken into consideration.
The applied high temperature was set at 29°C because this temperature is compatible with a sufficient
number of parasitized hosts by T. cordubensis and with a great deactivation of symbionts (Pintureau, Bolland,
2001). The three lines were reared until the F51 generation with cycles of temperature including two genera-
tions at 23°C (F4, F5; F9, F10; etc.) and three generations at 29°C (F6, F7, F8; F11, F12, F13; etc.). Sex
ratios were calculated and selection was performed at each cycle, at the first generation at 23°C (F9, F14,
etc.), as described for the F4. Two additional generations at 29°C (F39) or 23°C (F42) prolonged the cycle
of selection (6 instead of 5 generations). The selection pressure planned was 10% (10 pro-genies out of 100).
In fact, the pressure varied from 9% (F19) to 26% (F34) with a mean of 14% in the high line, and from
11% (F24) to 40% (F40) with a mean of 16% in the low line (tabl. 1).
Results
We were unable to increase or decrease the sex ratio in the selected lines and to
discriminate them from the control line (tabl. 1, fig. 1, A). The difference between the
male proportion observed in the selected lines and in the control line illustrates the
absence of efficient selection (tabl. 1, fig. 1, B). No correlations of the male propor-
tion with the generation number or regressions against this number were significant
(tabl. 2).
Tab l e 1 . Variation of the male proportion (total number of males/total number of individuals in all studied
progenies) in three Wolbachia-infected lines of T. cordubensis at 29°C
Òàáëèöà 1. Âàðüèðîâàíèå ïîëîâîãî èíäåêñà (ñîîòíîøåíèÿ êîëè÷åñòâà ñàìöîâ ê îáùåìó êîëè÷åñòâî
îñîáåé âî âñåõ èçó÷åííûõ ïîêîëåíèÿõ) â 3 ëèíèÿõ T. cordubensis, èíôèöèðîâàííûõ Wolbachia ïðè 29°Ñ
Control line High line Low line
Gene-
rations N (1)
Male
pro-
portion
N (1)
Male
propor-
tion
Male
prop./cont-
rol (2)
Sel.
pres-
sure
(3)
N (1)
Male
propor-
tion
Male
prop./cont-
rol (2)
Sel.
pres-
sure (3)
4 74 (1030) 0.12 74 (1030) 0.12 0 0.12 74 (1030) 0.12 0 0.14
9 71 (977) 0.44 68 (925) 0.33 -0.11 0.12 43 (540) 0.33 -0.11 0.23
14 55 (790) 0.07 64 (840) 0.16 0.09 0.16 63 (855) 0.10 0.03 0.16
19 81 (1209) 0.56 69 (983) 0.40 -0.16 0.09 67 (996) 0.46 -0.10 0.15
24 88 (1760) 0.15 71 (1146) 0.27 0.12 0.14 88 (1471) 0.09 -0.06 0.11
29 12 (156) 0.44 17 (208) 0.60 0.16 0.18 63 (829) 0.52 0.08 0.16
34 42 (496) 0.38 38 (566) 0.42 0.04 0.26 56 (723) 0.49 0.11 0.18
40 31 (397) 0.30 45 (615) 0.26 -0.04 0.16 10 (117) 0.33 0.03 0.40
46 60 (921) 0.28 70 (1034) 0.31 0.03 0.14 75 (1074) 0.17 -0.11 0.13
51 79 (1413) 0.25 91 (1923) 0.27 0.02 97 (1917) 0.09 -0.16
No t e . 1 – progeny number and, in brackets, total number of individuals; 2 – male proportion in the high or
the low line – male proportion in the control line; 3 – selective pressure, i. e. the number of progenies used to
establish the next generation/total number of progenies studied.
Two lines were selected for a high or a low sex ratio, and one line was not selected (control). The selective
pressure applied each five or six generations is figured.
Selection for a Sex Ratio in Wolbachia-infected Lines of Trichogramma cordubensis … 85
Conclusions and discussion
The unsuccessful selection can be explained by several factors. Heritability of the
selected trait could be lower than assumed from the comparison of within- and be-
tween-line variances, and/or lower in the strain 1148 than in the strain 802. Moreover,
the selection pressure applied, inferior to the planned one, could be insufficient. The
frequency of the selection pressure (each 5 or 6 generations) could also be too low.
On the other hand, selection was performed on Wolbachia effects on sex ratio and
not on the Wolbachia density. These effects, only determined by genes of symbionts or
also by genes of parasitoids, could show an important epigenetic variability disrupting
the selection progress. For instance, females may be mated or not, that especially in-
fluences the sex ratio when the female is aposymbiotic. Moreover, the effects could
originate from the Wolbachia inactivation, which is probably revertible, and not from
Fig. 1. Male proportion in three lines of T. cordubensis selected for a low sex ratio (low line) or a high sex ratio
(high line), or not selected (control line), during 51 generations regularly placed at 29°C for three generations
(A), and difference between male proportions in selected lines and control line (B).
Ðèñ. 1. A – ïîëîâîé èíäåêñ â 3 ëèíèÿõ T. cordubensis, âûðàùåííûõ ïðè 29°Ñ â òå÷åíèå 3 ïîêîëåíèé;
B – êîýôôèöèåíò ðàçëè÷èÿ ìåæäó ïîëîâûì èíäåêñîì â êîíòðîëå è â ëèíèÿõ ñ âûñîêèì (“high”) è
íèçêèì (“low”) ïîëîâûì èíäåêñîì.
B. Pintureau, P. Bolland 86
the Wolbachia elimination. The high temperature resistance of Wolbachia could vary
in one parasitoid or only in different parasitoids, and combination of the degree of
resistance and of the number of resistant symbionts could exist and make the selection
difficult. Finally, in the high line, a selected progeny of 90% males can originate from
an unmated female infected by some active Wolbachia and not from a mated female
without Wolbachia. To select these latter females, it would be preferable to reject high
and low sex ratios and keep progenies with about 30% males.
However that may be, no selection was efficient and the genetic variability of the
studied trait could be low. In this case, no advantage for a Trichogramma population to
be associated to high temperature sensitive Wolbachia, allowing bisexual cycles of re-
production in hot regions, could be selected. This would reduce the possibilities of ad-
aptation to the environment (Pintureau et al., 1999) and the interest to be completely
infected and thelytokous.
Pintureau B. Frequency and geographical distribution of thelytokous parthenogenesis in European species of
Trichogramma (Hym.: Trichogrammatidae) // Norw. J. Agric. Sci. – 1994. – 16, suppl. – P. 411.
Pintureau B., Bolland P. A Trichogramma species showing a better adaptation to high temperature than its
symbionts // Biocontrol Sci. Technol. – 2001. – 11. – P. 13—20.
Pintureau B., Chapelle L., Delobel B. Effects of repeated thermic and antibiotic treatments on a Trichogramma
(Hym., Trichogrammatidae) symbiont // J. Appl. Entomol. – 1999. – 123, N 8. – P. 473—483.
Rousset F., Bouchon D., Pintureau B. et al. Wolbachia endosymbionts responsible for various alterations of
sexuality in arthropods // Proc. R. Soc. Lond. B. – 1992. – 250. – P. 91—98.
Stouthamer R., Breeuwer J. A. J., Luck R. F. et al. Molecular identification of microorganisms associated with
parthenogenesis // Nature. – 1993. – 361. – P. 66—68.
Zhou W., Rousset F., O’Neill S. L. Phylogeny and PCR-based classification of Wolbachia strains using wsp
gene sequences // Proc. R. Soc. Lond. B. – 1998. – 265. – P. 509—515.
Ta b l e 2 . Correlation with and regression against the generation number (n=10) of the male proportion in
three Wolbachia-infected lines of T. cordubensis, selected or not at 29°C for a high or a low sex ratio
Òàáëèöà 2. Êîððåëÿöèÿ è ðåãðåññèÿ êîëè÷åñòâà ïîëîâîãî èíäåêñà â ðÿäå ïîêîëåíèé (n=10) â 3 ëèíèÿõ
T. cordubensis, ïîìåùåííûõ â óñëîâèÿ ñîäåðæàíèÿ ïðè 29°Ñ
Ratio Line Correlation, p>0.05 (2) Regression (2)
Male proportion Control 0.159 0.66
High 0.297 0.40
Low 0.006 0.99
Male prop./control (1) High 0.142 0.69
Low -0.259 0.47
No t e . 1 – Ratio of male proportion in the high or the low line to male proportion in the control line; 2 –
proportions were arcsine transformed (for “male prop./control”, calculations were performed from differences
between two transformed proportions).
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