Reproduction and development of Pratylenchus penetrans were studied on genetically transformed ladino clover roots. Solitary females developing on transformed roots in nutrient gellan gum medium (pH 5.5) deposited 1.2, 1.5, 1.6, 1.8, and 2.0 eggs per day at the respective temperatures of 17, 20, 25, 27, and 30 degrees C. The number of eggs deposited was highly correlated with temperature. A reduction in egg-laying rates at the start of hatching was observed at all temperatures. Juvenile mortality was higher at 17 degrees C (50.4%), 20 degrees C (50.3%), and 30 degrees C (58.4%) than at 25 degrees C (34.6%) and 27 degrees C (37.6%). Life-cycle (egg deposition to egg deposition) duration was 46, 38, 28, 26, and 22 days at the respective temperatures. The developmental zero degrees ( degrees C) and the effective accumulative temperatures (degree-days) required for hatching, female emergence, and onset of oviposition (completion of one generation) of P. penetrans were estimated to be 2.7 and 200, 4.2 and 548, and 5.1 and 564, respectively. Pratylenchus penetrans reproduces over a wide range of temperatures.
Keywords: Pratylenchus penetrans; degree-day; developmental zero degree; effective accumulative temperature; egg-laying rate; ladino clover; life cycle; nematode; reproduction; transformed hairy root.