The energy relations of the mites Tetranychus cinnabarinus Boisduval and Phytoseiulus persimilis Athias-Henriot.

The energy relationship between the phytophagous mite Tetranychus cinnabarinus and the predatory mite Phytoseiulus persimilis was investigated at 25 °C and 55% RH using mites cultured on broad bean (Vicia faba) plants. Development is very rapid, juvenile mortality is very low and oviposition rates are very high in both species. Life and fecundity tables were constructed for each species and used to calculate the finite rate of increase (lambda), which is higher in P. persimilis than in T. cinnabarinus. Both species grow very rapidly. Growth rate is fairly constant in female T. cinnabarinus but in P. persimilis it increases following fertilization. Food consumption rates are high in gravid females of both species which consume up to three times their body weight in 24 h. Respiration rates of all life stages of T. cinnabarinus and P. persimilis were determined using a Cartesian Diver micro-respirometer. Respiration rates in P. persimilis are up to three times those in corresponding stages of T. cinnabarinus. There is a linear relationship between weight and respiration rate in T. cinnabarinus. It is argued that in P. persimilis there is no similar, single meaningful relationship but that different relationships apply for different groups of life stages. Energy budgets were constructed for all life stages of T. cinnabarinus and P. persimilis using calorific values determined with a Phillipson oxygen micro-bomb calorimeter. Both species have high assimilation and production efficiencies. The energetic efficiencies of P. persimilis are similar to those of other invertebrate predators but the efficiencies of T. cinnabarinus are higher than those of most invertebrate herbivores and it is suggested that this is due to its feeding method. An energy model for the interaction between populations of T. cinnabarinus and P. persimilis was developed and used to predict the times taken for elimination of T. cinnabarinus populatuons using different predator:prey ratios. The predicted times agree closely with those determined experimentally by other workers. It is suggested that this model may be used to achieve effective spider mite control.