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

MICIELI, MARÍA VICTORIA; RISSO PAULA; ACHINELLY, MARÍA FERNANDA; VILLAR M. DE LOS MILAGROS; TARQUINI JULIANA

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 C and 14:10 (L:D) and 16 C 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 C and 12:12 (L:D) produced the maximum percent of emerged J2s (30 ± 15%). Preparasites were recorded by 7 (25 C) and 14 (16 C) 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 C and 16 C, respectively) suggested a nonsynchronous hatching, possibly through nonuniform egg embryonation. The time of exposure to drought in the assays did not significantly affect the total average percentage of J2s obtained at 25 C and 14:10 (L:D), whereas at 16 C the number of emerged J2s diminished with a prolongation of the drying period. The oviposition period was also recorded only at 16 C 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.