The effect of low temperature on preparasitic juveniles of Romanomermis (Nematoda: Mermithidae)

Abstract

Abstract This study showed that at low temperatures (-2 to 2C), more than 90% of the preparasitic juveniles of Romanomermis yunanensis and Romanomermis sp. survived for 8 and 5 days, respectively, but at 26 to 28 C and 16 to 18 C, the 90% survival time for preparasites of these species was 24 and 48 h, respectively. The percentage of mosquitoes infected by preparasites of R. yunanensis maintained at low temperature for 8-11 days was 87.5-94.3%. Preparasites of Romanomermis sp. maintained for 5 days at low temperature infected 81.5 and 55.1% of the mosquitoes in the laboratory and field tests, respectively. This infectivities were not significantly different (P > 0.05) from the pre-storage values. This data indicates that low temperature storage prolonged the survival time and had no effect on the infectivity of the preparasitic juveniles of these Romanomermis species. Effet de basses temperatures sur les juveniles infestants de Romanomermis (Nematoda: Mermithidae)- La presente etude montre qu'a basse temperature (de- 2 a + 2 C) plus de 90% des juveniles preparasites de Romanomermis yunanensis et Romanomermis sp. survivent, respectivement, 8 et 5 jours tandis qu'entre 26 et 28 C ou 16 et 18 C leur survie n'est que de 24 et 48 h, respectivement. Le pourcentage des moustiques infestes par les juveniles preparasites de R. vunanensis maintenus a basse temperature pendant 8 a 11 jours variait de 87,5 a 94,3%. Les juveniles preparasites de Romanomermis sp. maintenus 5 jours a basse temperature infestent 81,5% de moustiques lors de tests au laboratoire et 55,1% lors de tests au champ. Ces taux d'infestivite ne sont pas significativement differents (P > 0 . 05) de ceux releves avant stockage. Ces donnees indiquent que le stockage a basse temperature prolonge le temps de survie des juveniles preparasites de ces especes de Romanomermis et n'a aucun effet sur leur infestivite.