Published online by Cambridge University Press: 31 May 2012
Laboratory studies of diapause induction in the horn fly Haematobia irritans irritans (L.) indicated that the incidence of diapause was unrelated to daylength or the number of day–night cycles. Transfer experiments were conducted to estimate the beginning and end of diapause sensitivity and the required number of days for diapause induction. On average, sensitivity was between the ages 0.10 and 0.82 on a physiological age scale of immature development. The number of days required for 50% diapause was estimated as 19.1 days. A model was developed relating the proportion of insects in diapause to the number of days spent in the interval 0.10–0.82. Additional experiments revealed that diapause in the puparia was related to the mean temperatures experienced by immatures during the interval of sensitivity. An equation relating the proportion in diapause to temperature was also developed and compared with the required day number model. Both models provided similar estimates of the proportion of horn flies entering diapause.
L’étude en laboratoire de la diapause chez la Mouche des cornes, Haematobia irritans irritans (L.), a démontré que le déclenchement de la diapause n’est géré ni par la longueur de la photopériode, ni par le nombre de cycles nycthéméraux. Des expériences de transfert ont permis de déterminer le début et la fin de la période de sensibilité à la diapause et d’estimer le nombre de jours nécessaires au déclenchement de la diapause. En moyenne, la période de sensibilité se situe entre les âges 0,10 et 0,82 sur l’échelle physiologique de l’âge au cours du développement. Le nombre de jours requis pour que 50% des insectes soient en diapause a été évalué à 19,1. Un modèle a permis d’établir la relation entre le nombre relatif d’insectes en diapause et le nombre de jours passés dans l’intervalle 0,10–0,82. Des expériences additionnelles ont démontré que la diapause dans le puparium est reliée aux températures moyennes subies par les larves au cours de la période de sensibilité. Une équation reliant la proportion de la population en diapause et la température a été élaborée et comparée au modèle établissant le nombre de jours requis. Les deux modèles donnent des estimations semblables de la proportion de la population de Mouches des cornes qui subissent la diapause.
[Traduit par la Rédaction]
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