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Sire effect on early and late embryonic death in French Holstein cattle
- D. Ledoux, C. Ponsart, B. Grimard, J. Gatien, M. C. Deloche, S. Fritz, R. Lefebvre, P. Humblot
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We investigated the effect of maternal sire on early pregnancy failure (between D0, day of insemination and D90) in their progeny during the first and second lactations (n=3508) in the Holstein breed. The estimated breeding value (EBV) for cow fertility of 12 bulls (reliability⩾0.95) was used to create the following three groups: low, medium and high EBV (EBV from −0.7 to 1 expressed as genetic standard deviation relative to the mean of the breed). In their daughters (93 to 516 per bull), progesterone measurement was carried out on the day of artificial insemination (AI; D0) to check whether the cows were in the follicular phase and on D18 to 25 to assess non-fertilisation-early embryonic mortality (NF-EEM). Late embryonic mortality (LEM) and early foetal death (FD) were determined by ultrasonography on D45 and D90 and by the return to oestrus after the first AI. Frequencies of NF-EEM, LEM, FD and pregnancy were 33.3%, 11.7%, 1.4% and 48.5% and incidences were 35.1, 19.0, 2.7 and 51.1, respectively. Sire EBV was significantly related to the incidences of pregnancy failure between D0 and D90, fertilisation failure-early embryonic mortality (FF-EEM) and LEM but not to the incidence of FD between D45 and D90 of pregnancy. The relative risk (RR) of FF-EEM was significantly higher (RR=1.2; P<0.05) for the progeny group of low EBV bulls when compared with high EBV bulls. The same effect was observed when comparing LEM of the progeny groups from the low EBV bulls to those from moderate and high EBV bulls (RR, respectively, of 1.3 and 1.4; P<005). The incidence of FF-EEM was significantly higher when cows were inseminated before 80 days postpartum compared with later, and for the extreme values of the difference between milk fat and protein content measured during the first 3 months of lactation. FF-EEM was also significantly related to the year of observation. The incidence of LEM was higher for the highest producing cows and was influenced by interaction between milk yield×lactation rank and milk yield×milk protein content. In conclusion, this study showed large differences in early pregnancy failure between progeny groups and highlights the interest of accurate characterisation of embryonic death in order to identify potential candidate genes for female fertility.
Timing acaricide treatments to prevent Varroa destructor (Acari: Varroidae) from causing economic damage to honey bee colonies
- R. W. Currie, P. Gatien
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- Journal:
- The Canadian Entomologist / Volume 138 / Issue 2 / April 2006
- Published online by Cambridge University Press:
- 02 April 2012, pp. 238-252
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This study consisted of two field experiments designed to assess the effects of acaricide treatment timing on the mean abundance of the mite Varroa destructor Anderson and Trueman and its impact on honey production and colony survival in honey bees, Apis mellifera L. (Hymenoptera: Apidae). In the first experiment, replicated colonies with different levels of infestation by V. destructor were given one of six treatments: untreated, with a low level of infestation by V. destructor; untreated, with a moderate level of infestation by V. destructor; exposed to fluvalinate for 42 days; exposed to two applications of Perizin®; or exposed to four applications of a pour-on formulation of formic acid at 4- or 10-day intervals. The six treatments were applied in either spring or fall. In experiment two, replicated colonies with a high level of infestation by V. destructor were left untreated, exposed to fluvalinate for 42 days, exposed to five applications of formic acid at 7-day intervals, or exposed to an equivalent amount of formic acid applied as a slow-release formulation. For each experiment, V. destructor densities, measured by alcohol wash, and colony survival were monitored for 1 year, and honey production was assessed in the year in which the spring treatment was applied. The results showed that all of the acaricide treatments were effective in reducing the mean abundance of V. destructor. However, efficacy varied with season. Fluvalinate was effective in controlling varroa under either spring or fall treatment conditions. Fall applications of Perizin® provided better control than spring applications. Formic acid provided consistent control of V. destructor in spring applications, regardless of the interval between treatments or whether pour-on or slow-release formulations were used, but was ineffective in the fall. Honey production was improved by spring acaricide treatments in both years. When the mean abundance of V. destructor was 0.02 ± 0.005 mites per bee (2 mites per 100 bees) in mid-April, honey production increased from 66 ± 17 kg per colony in untreated colonies to up to 116 ± 23 kg per colony in colonies treated with acaricide. When V. destructor levels were 0.21 ± 0.02 mites per bee (21 mites per 100 bees) in mid-May, spring acaricide treatments increased honey production from 1.3 ± 2.3 kg per untreated colony to up to 48 ± 17 kg per acaricide-treated colony. For the prairie region of Canada, producers will need to assess colonies in both spring and fall and treat when the mean abundance of V. destructor is more than 0.02 mites per bee (2 mites per 100 bees) in spring to prevent losses in honey production. Producers should treat when the mite level is greater than 0.04 mites per bee (4 mites per 100 bees) in late August to early September to prevent fall or winter colony loss. In this study, tracheal mite (Acarapis woodi (Rennie)) (Acari: Tarsonemidae) levels were very low, so interactions between mites were not studied. If both tracheal and varroa mites are present, lower fall thresholds might be required. In the absence of tracheal mites, colonies with varroa mite levels of more than 0.17 mites per bee (17 mites per 100 bees) in late fall experienced significant winter loss.
Timing of acaracide treatments for control of low-level populations of Varroa destructor (Acari: Varroidae) and implications for colony performance of honey bees
- P. Gatien, R.W. Currie
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- Journal:
- The Canadian Entomologist / Volume 135 / Issue 5 / October 2003
- Published online by Cambridge University Press:
- 02 April 2012, pp. 749-763
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The timing of acaracide treatments for control of low-level populations of Varroa destructor Anderson et Trueman has implications for colony performance of honey bees, Apis mellifera L. (Hymenoptera: Apidae). Replicated colonies with low levels of V. destructor were left untreated, exposed to fluvalinate at each of two doses for 42 days, or exposed to three applications of formic acid, with the four treatments applied in either spring or fall. Varroa destructor densities were measured by alcohol wash and drop boards, and both gave similar estimates. Over the course of one season, the mean abundance of V. destructor increased from 0.002 to 0.11 mites per bee. Extended broodless periods during winter reduced the mean abundance of V. destructor by 28%, but mite mortality over winter was not high enough to prevent the need for treatment the following year. Apistan® was more effective than formic acid in both spring and fall treatments. Doses of one or two strips of Apistan® per colony were equally effective in spring or fall treatments. The mean abundance of V. destructor remained low throughout the season following spring treatment with either dose of Apistan®. Fall formic-acid treatments were more effective than spring treatments. Fluvalinate residues in samples of honey and wax collected from brood chambers and from honey supers were slightly higher in colonies treated with two strips of Apistan® than with one strip, but no detectible residue was found in extracted honey from 4500 commercial colonies treated in spring with Apistan® one strip per brood chamber for single or double storey hives. The levels of V. destructor in this study did not affect honey production or colony survival over winter.