The net reproductive rate, R0, is how many daughters an average newborn female will leave, accounting for the chance she dies first. If R0 is 40, the population multiplies 40-fold each generation. It is calculated from a life table by summing survival times daughters at each age.
In practice
R0 and r_m are linked through generation time: r_m is approximately ln(R0) divided by the mean generation time T. A pest with modest R0 but very short generations, like a spider mite at 30 C, can outgrow one with a higher R0 and slow generations, like a mealybug.
Don't confuse with
A record of survival and egg-laying at each age for a cohort of pests at set conditions, from which development time, fecundity and r_m are calculated.The average time from a female's birth to the birth of her offspring; at a set temperature it fixes how often a pest population multiplies.Tetranychus urticae, the commonest cannabis mite indoors: a 0.5 mm sap-feeder that stipples leaves pale and spins webbing, breeding fastest in hot, dry rooms.Soft-bodied sap-sucking insects of the family Pseudococcidae, covered in white waxy filaments, that hide in stem joints and roots and excrete honeydew.The number of eggs or live young a female produces, per day or in her lifetime; a key life-table input.The share of offspring that are female; because only females lay eggs, a female-biased ratio speeds population growth.The per-day rate at which an unchecked pest population multiplies under set conditions, from a life table; N(t) = N0 x e^(r_m x t).
