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Can demographic parameters be estimated from capture-recapture data on small grids? A test with forest rodents

100%

Schlesser M. , Le Boulenge E. , Schtickzelle N.

Acta Theriologica

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2002

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tom 47

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nr 3

EN

This preliminary study proposes small trapping grids as an alternative to traditional large grids for the simultaneous monitoring of several rodent populations by capture-recapture. Monthly trapping sessions of wood mouse Apodemus sylvaticus (Linnaeus, 1758) and bank vole Clethrionomys glareolus (Schreber, 1780) were carried on over a small area (0.015 ha, 21 traps). The coherence of demographic parameter estimates on such small grids with those obtained on classical large grids was checked by performing two trapping sessions on a larger grid (0.9 ha, 110 traps, 10 m mesh) surrounding the small grid. We compared the two grid designs on the basis of sex ratio upon first capture, trap saturation rate, minimum number alive (MNA), monthly survival, and trappability. These demographic parameters proved to be non-biased by the trapped area, even though the precision was lower on the small grid. Small grids seem therefore to give the same picture of population dynamics as classical large grids except for parameters sensitive to an edge effect (eg density). By decreasing significantly the trapping effort, small grids will be of particular interest whenever the simultaneous operation of several trapping grids is needed (eg to compare different environmental conditions).

2

Intersexual attraction in natal dispersing root voles Microtus oeconomus

100%

Gundersen G. , Moe J. A. , Andreassen H. P. , Carlsen R. G. , Gundersen H.

Acta Theriologica

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1999

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tom 44

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nr 3

EN

By an enclosure experiment we tested whether natal dispersing root voles Microtus oeconomus (Pallas, 1776) were prevented from colonising already occupied habitat patches or if they were attracted to habitat patches by potential mates. The treatment consisted of manipulating the presence of animals in immigration patches, either with the presence of a solitary sexually mature male or female, whereas empty patches were used as a control. Immigration patches were separated from a patch used for release of a matriline (mother with her newly weaned titter) by a semipermeable fence allowing only interpatch movements of young animals. We predicted that either a social fence would prevent immigration to treatment patches, or that potential mates would attract dispersing individuals. In particular we expected fewer dispersing males to colonise male occupied patches, and fewer dispersing females to colonise female occupied patches due to intrasexual competition, ie an intrasexual social fence. We found that a higher proportion of females settled in male treatment patches than in female patches, whereas male dispersal was unaffected by treatment. Thus, the observed female immigration pattern appeared to be an attraction to patches occupied by the opposite sex We found no sign that immigration was prevented by a social fence.

3

Biology, ecology and demographic parameters of the hawthorn spider mite (Tetranychus viennensis Zacher) on various host plants

84%

Skorupska A. , Boczek J.

Prace Naukowe Instytutu Ochrony Roślin

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1984

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tom 26

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nr 1

4

Age structure and reproduction rates of the ring-necked pheasant (Phasianus colchicus L.) population in agricultural landscape (Czech Republic)

84%

Zika T. , Salek M. , Hola M. , Hanzal V. , Hart V. , Kusta T. , Jezek M.

Polish Journal of Ecology

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2014

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tom 62

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nr 4

EN

Detailed knowledge of demographic parameters (such as age structure and reproduction rates) is crucial for guiding conservation and management decisions regarding wildlife populations. Such parameters of wild ring-necked pheasant populations in the current agricultural landscape remain very poorly described. We researched age structure and reproduction rates of predominantly wild populations of the ring-necked pheasant (Phasianus colchicus L.) across the intensively managed agricultural landscape of the Czech Republic. The study area is influenced only marginally by hand-reared pheasants (i.e. as shown by comparison of the average number of released individuals in the study area: 0.3 ♂/yr/1km2 and 0.9 ♀/yr/1km2 and average number of released individuals and harvested in the study area: 8.6 ♂/yr/1km2) and there is a long-term huntable pheasant population. To determine the age of individuals, we used proximal primary feather shaft diameters of 1487 feather samples from males hunted between 2009 and 2011. Moreover, we evaluated the age structure of females as well as both sexes together based on the sex ratio and annual game census. We found a relatively high proportion of adults in the population in comparison with other studies. However, the number of adults decreased throughout the years: 2009 (♂ 44.7%; ♀ 69.5%; ♂♀ 60.7%), 2010 (♂ 35.2%; ♀ 61.3%; ♂♀ 51.5%), 2011 (♂ 29.8%; ♀ 57.4%; ♂♀ 47.0%). The decrease of adults went hand in hand with increase of juveniles and reproduction rates of the study population: 2009 (♂ 124%; ♀ 44%; ♂♀ 65%), 2010 (♂ 184%; ♀ 63%; ♂♀ 94%), 2011 (♂ 236%; ♀ 74%; ♂♀ 113%). Only males were hunted in the study area so we determined higher proportions of females in population for all years. This is the main reason why the reproduction rate of females was lower in percentage expression. Generally, our results showed lower productivity of pheasants in the Czech agricultural landscape in comparison with earlier published studies conducted in the US and UK. However, these studies were published many years ago and thus do not reflect the actual environmental conditions and changes which took place recently (i.e. agricultural intensification).

5

Pirimicarb, an aphid selective insecticide, adversely affects demographic parameters of the aphid predator Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae)

84%

Rahmani S. , Bandani A. R.

Journal of Plant Protection Research

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2016

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tom 56

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nr 4

EN

Demographic toxicology is recommended for toxicity determination of the long term effects of a pesticide since it gives a more accurate and efficient measure of the effect of a pesticide. Thus, in the current study the sublethal effects of pirimicarb (carbamate insecticide) two concentrations of LC30 and LC10 were used against third instar larvae of Hippodamia variegata (Goeze) in order to determine the effects of the pesticide on demographic parameters of the predator under laboratory conditions. Results showed that pirimicarb did not affect individual life parameters such as development time of larva, pupa, adult longevity, female and male longevity, adult preoviposition period (APOP), and total preoviposition period (TPOP). However, population parameters such as intrinsic rate of increase (r), net reproductive rate (R0), mean generation time (T), and finite rate of increase (λ) was affected by sublethal treatment. For example, intrinsic rate of increase (r) was 0.18 day–1 in the controls but it was 0.13 and 0.14 day–1 in the treated insects with LC10 and LC30 concentrations, respectively. Also, there were significant differences between mean generation time (T) of the treatments and the controls i.e. mean generation time of the controls was 29.03 days while mean generation time in the two treatments of LC10 and LC30 was 33.93 and 31.66 days, respectively. The finite rate of increase was also significantly affected by sublethal effects of the pesticide. The results showed that pirimicarb, even at low concentrations, has potential to adversely affect the predatory ladybird, therefore care should be taken when this insecticide is used in the Integrated Pest Management (IPM) program.

6

Reproductive and demographic parameters in two Iberian wild boar Sus scrofa populations

67%

Herrero J. , Garcia-Serrano A. , Garcia-Gonzales R.

Acta Theriologica

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2008

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tom 53

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nr 4

EN

From 1990 to 2006, we studied the demographic, reproductive, and biometric characteristics of two Iberian wild boarSus scrofa (Linnaeus, 1758) populations in contrasting environments. In the Pyrenees (studied in 1990–1993), forest cover is high, hunting pressure is low, and the density of wild boar is high. In the Ebro Valley (studied in 1994–2006), there are few shelter areas for boars, hunting pressure is high, and density is very low. In the second semester of life and after two years of age, the sows in Ebro Valley were heavier than were those in the Pyrenees. Pregnancy during the first year of life was frequent in the Ebro Valley and rare in the Pyrenees. Litter sizes, ovulation rates, and intrauterine mortalities did not differ significantly between the two populations, but the foetal sex ratio in the Ebro Valley was skewed significantly towards males. Life expectancy was lower in the Ebro Valley (6 yr) than it was in the Pyrenees (10 yr). In the Ebro Valley 75% of the wild boar were >24 months old, whereas in the Pyrenees, the proportion was 59%. We suggest that shelter availability influenced the growth, productivity, hunting pressure, and life expectancy in the two Iberian populations of wild boar.

7

Wybrane elementy bionomii i parametry demograficzne anholocyklicznego gatunku Myzus ascalonicus Doncaster, 1946 (Hemiptera: Aphididae)

51%

Durak R. , Borowiak-Sobkowiak B.

Wiadomości Entomologiczne

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2014

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tom 33

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nr 4

EN

Myzus ascalonicus DONCASTER, 1946 is an anholocyclic and polyphagous species. It may infest plants of over 20 families, most frequently Alliaceae, Caryophyllaceae, Compositae, Brassicaceae, Liliaceae and Rosaceae. It is almost worldwide distributed, also in Subantarctic regions. In winter in Poland it can continue developing by infesting greenhouse and house plants. The study was conducted in 2009–2010. The paper defines the length of prereproduction, reproduction and postreproduction stages of wingless M. ascalonicus females developing in winter. Also the total lifespan and fecundity of females was calculated along with demographic parameters of M. ascalonicus population.