Reproductive limits and heterogeneity of male twospotted spider mites

Abstract

This paper determines reproductive limits and variation in performance of male twospotted spider mites Tetranychus urticae Koch when virgin females are provided ad libitum over the first eight days of adult life. Three phases of male reproduction were studied: copulations, insemination and reproduction. An average one day old male copulated 15 times, inseminated 15 females, and contributed to 336 daughters. All parameters declined with age. The average male inseminated 70 females and contributed to 1145 daughters in the first days. Variability between males was small for all parameters considered. These data suggest that the number of sperm transferred at each insemination, rather than the number of inseminations, is the limiting step to higher male reproductive output. Résumé Limites et hétérogénéité des possibilités reproductives du mâle de Tetranychus urticae Koch, en présence d'un nombre illimité de femelles La reproduction est un processus qui nécessite généralement un mâle et une femelle. Cependant la biologie des populations ne s'est traditionnellement intéressée qu'à la contribution des femelles dans ce processus. Un effet de cet accent sur les femelles est que l'activité reproductrice des mâles a été très ignorée. Cet article examine, dans un contexte démographique, l'activité reproductrice des mâles de T. urticae, acarien arrhénotoque et phytophage. Trois séquences de l'activité reproductrice des mâles ont été examinées: 1) la copulation, 2) l'insémination, 3) la reproduction. En moyenne un mâle de 1 jour a copulé 15 fois, inséminé 15 femelles et a eu 336 filles. Pendant les 8 premiers jours, le mâle moyen a inséminé 70 femelles et a eu 1145 filies. Ces résultats suggèrent que le nombre de spermatozoïdes transférés à chaque insémination, plus que le nombre d'inséminations, est le facteur limitant d'une forte contribution du mâle à la reproduction.

Temperature and sex allocation in a spider mite

“…1. Male-biased sex ratios at the end of the oviposition period could also arise either from reduced sperm viability over time (de Moraes and McMurtry 1987), from a physiological degradation of the female's ability to fertilize eggs (Krainacker and Carey 1989), or from a decrease in overall quality of eggs produced by aging females.…”

Complex Evolutionary Dynamics of Massively Expanded Chemosensory Receptor Families in an Extreme Generalist Chelicerate Herbivore

“…A similar procedure was followed to obtain males for RNA extraction, except that resulting F1 virgin females were transferred to new bean leaf arenas (±100 mites/leaf) and allowed to lay eggs for 16 h (with F1 virgin females transferred to a new bean leaf arena every 4 h). Eggs of F1 virgin females were incubated at 27 °C, 65% RH and 16:8 LD and resulting 1- to 2-day-old mature males (Krainacker and Carey 1989) were collected for RNA. Four RNA samples were obtained for each sex and RNA was extracted using the RNeasy mini kit (Qiagen, Belgium).…”

Quantitative genetics of aerial dispersal behaviour and life-history traits in Tetranychus urticae

“…Mites were individually reared on the first foliage leaves that provided each full-sib family with adequate space and nutrition for development. Mothers were removed from the leaves 8 days later because the eggs laid on the first day were about to develop into the adult stage, and the majority of eggs had been laid within the first 8 days (Krainacker & Carey, 1989). Soon after the removal of the mothers, the leaves were cut from the plants and set on top of new leaves rested on wet cotton in trays for offspring collection.…”