Graphical marginal analysis of the economics of natural enemy production: An example using a pilot mass rearing system for green lacewing

Augmentative and inundative biological control releases of arthropod natural enemies require the production of high-quality product at low prices. This might be achieved by optimizing biological inputs, and can be visualized using graphical marginal analysis. Using a pilot production system for Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) we investigated the efficiency of production in relation to per capita availability of prey eggs, and determined the input and output values for the smallest unit of the system. We determined the efficiency of larval-rearing units (lru), based on the capacity and time to produce lacewing eggs for sale, under different prey and predator egg (biological input) combinations. We also determined the costs of production of the lru based on the per unit inputs, per mg of prey eggs and per predator egg. The value of the lru was based on value of eggs produced, per mg of prey eggs. The efficiency of the lru increased and the incremental value of the lru decreased with increasing biological inputs. Labor costs were examined as an example of a fixed costs, and these were the largest component of the production costs. Graphical marginal analysis demonstrates that, although increases in both production efficiency and quality of natural enemy products can be realized from manipulation of biological inputs, biological control producers may be constrained by costs of labor and other fixed inputs. Overall, graphical marginal analysis is a useful tool for researchers and producers to evaluate the economics of natural enemy production systems.

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► We conducted graphical marginal analysis of a rearing system for green lacewings.
► We determined the capacity of the system to produce lacewing eggs for sale.
► Efficiency increased and incremental value decreased with increasing inputs.
► Fixed costs constrained the gains realized by optimizing biological inputs.
► Graphical marginal analysis is useful to evaluate economics of biocontrol production.