Effect of temperature, photoperiod, flooding, and drying on the hatching pattern of the eggs of Strelkovimermis spiculatus (Nematoda: Mermithidae).

MICIELI, M. V.; RISSO, P.; ACHINELLY, M. F; VILLAR, M. DE LOS M.; TARQUINI, J.

JOURNAL OF INVERTEBRATE PATHOLOGY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2012 vol. 110 p. 114 - 117

0022-2011

We assessed the number of Strelkovimermis spiculatus preparasites obtained from a known initial number of nematode eggs and the effect of abiotic conditions (temperature, photoperiod, flooding-drying) on the number of emerged preparasites. Two egg groups were maintained: one continuously flooded, another with flooding-drying; cycles (every 15, 30, 60 days) Each egg group was studied at 25 ºC and 14:10 (L:D) and 16 ºC and 12:12 (L:D). The flooded eggs contained a higher overall percentage of S. spiculatus preparasites compared to the wet-dry-cycle eggs. The conditions of continuous flooding at 16 ºC and 12:12 (L:D) produced the maximum percent of emerged J2s (30 ± 15%). Preparasites were recorded by 7 (25 ºC) and 14 (16 ºC) days, suggesting this period as the minimum time for embryonic development. The preparasite-emergence time observed from the same flooded-egg batch (98 and 112 days at 25 ºC and 16 ºC, respectively) suggested a nonsychronous hatching, possibly through nonuniform egg embryonation. The time of exposure todrought in the assays did not significantly affect the total average percentage of J2s obtained at 25 ºC and 14:10 (L:D), whereas at 16 ºC the number of emerged J2s diminished with a prolongation of the drying period. The oviposition period was also recorded only at 16 ºC and 12:12 (L:D): S. spiculatus eggs were detected at 12.6 days after postparasite emergence, and oviposition was complete at 51 days under those conditions. We propose a flooding schedule to optimize the mass-rearing of S. spiculatus