Parameters of ontogeny and population dynamics modeling of Panagrolaimus detritophagus (Nematoda: Rhabditida) in vitro

Abstract

The parameters of individual development and population cycle in in vitro nematodes Panagrolaimus detritophagus were revealed. The nematodes are bacterial feeders and commensals of the cerambycid Monochamus galloprovincialis from the pine Pinus sylvestris; nematodes use beetles as vectors. Mean development time (T) from egg to juvenile is 1–2 days for J2, 3–4 days for J3, and 4–7 days for J4; to adults (G, generation) 7 (6–8) days. In vitro the population cycle is equal to 4 generations and ends with 90% of survival juveniles (J3, day 34). In the growth phase of the population, the proportion of eggs exceeds the proportion of other stages of the developmental cycle: 39±11% for 7 days; 53±10% for 21 days. The average oviposition rate of females is 4.5±1.3/day and only 56±12% of eggs proceed to immediate development (hatching and molting of juveniles). The remaining mass of eggs enter development only after 27 days (4 individual generations). This feature may be considered as a form of delay or a brief diapause at the egg stage. Individual females may accumulate up to 4 synchronous eggs in the body and lay them simultaneously. The average life span of an adult female is 13–20 days. Formulas for the exponential growth of the number of females and the total nematode population have been developed.