LAUSR

Abstract. Functional response of third-instar larvae of green lacewing, Chrysoperla carnea (Stephen) (Neuroptera: Chrysopidae), to four densities of single-instar larvae of the five instars of obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), was evaluated at 25 ± 1°C in a laboratory. The aims were to determine the type and other characteristics of functional response including predatory capacity of green lacewing for possible use in augmentative biological control in apple (Malus × domestica Borkh; Rosales: Rosaceae) orchards where obliquebanded leafroller was recently introduced in Mexico. Abundance of the pest increased rapidly, causing significant foliar damage and some fruit blemish. Third-instar green lacewing larvae based on logistic regression analysis showed Type II functional response to four densities of single-instar larvae of obliquebanded leafroller. Among the five instars of prey, the largest average number consumed per green lacewing predator was a relative density of four second-instar larvae at a rate of 1.93 in 24 hours. Also, substantial average consumption was by two third-instar prey larvae per predator whereby an average of 1.5 third-instar obliquebanded leafrollers were consumed per third-instar green lacewing in 24 hours. The third-instar predator captured and consumed third-instar prey larvae in the shortest handling time (h), i.e., only 6.46 minutes, whereas the handling times for the other instars ranged from 23.48 minutes for the fifth instar to 31.56 minutes for the fourth instar. However, attack coefficients (a) of green lacewings were slightly greater for third- and fourth-instar prey larvae, with 0.19 hour (11.4 minutes) and 0.15 hour (9.0 minutes) until the first attack, respectively, compared to 0.09–0.11 hour (5.4–6.6 minutes) until the first attack for the other instars. Results indicated that the green lacewing could be considered a prospective candidate for use as a biological control agent against lepidopteran leafrollers.