Effects of Tebufenozide on Eggs, Larvae and Adults of Chrysoperla carnea (Neuroptera: Chrysopidae)

SIMPLE SUMMARY: Currently, alternatives for pest control in crops with lower environmental impact and risk are being sought. This study aims to evaluate the compatibility between different control alternatives/agents that can be incorporated into integrated pest management. In this case, compatible control alternatives for reducing larval populations of the harmful insect Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) were assessed. Chrysoperla carnea (Siemens), whose larvae are highly voracious and feed on a wide range of prey, is an attractive biological control option against a variety of insect pests. This predator resides naturally in agroecosystems or can also be added artificially by man. To find new possibilities for joint pest treatments, compatibility of insect growth regulators, IGRs (the most selective chemical insecticides), such as tebufenozide, with the predator C. carnea were investigated. Laboratory tests were conducted to evaluate the lethal (direct) and sublethal (indirect) effects of tebufenozide on C. carnea. Tebufenozide exhibited low toxicity on the developmental stages of egg, larvae and adult and is a valuable contribution to the development of integrated management programmes for S. littoralis that incorporate tebufenozide and C. carnea in a compatible and effective way, choosing the best combinations and the most appropriate time for its application. ABSTRACT: Quantifying compatibility among control agents is essential for development of integrated pest management (IPM). Chrysoperla carnea (Siemens) and insect growth regulator insecticides are widely used in IPM of Lepidoptera. C. carnea is a generalist predator naturally present in the Mediterranean agroecosystems and bred in insectariums for commercial purposes. Here, we evaluated lethal and sublethal effects of tebufenozide on C. carnea under laboratory conditions. The treatment of eggs with tebufenozide 24 or 48 h after they were laid did not affect the hatching rate or survival of the neonate larvae. Toxic effects of tebufenozide on topically treated larvae was low; development times of surviving larvae and pupae decreased significantly compared with controls. In choice bioassays, a high percentage of third-instar larvae chose prey (Spodoptera littoralis) treated with tebufenozide in preference to untreated prey. Moreover, second-instar larvae of C. carnea that had previously consumed tebufenozide-treated prey (0.75 mL/L) had significantly reduced larval development time compared with controls, while longevity of surviving adults, fecundity and egg viability were unaffected. Ingestion of tebufenozide by adults of C. carnea at the recommended field dose had no significant effect on female fecundity, egg viability or adult longevity. Tebufenozide exhibited low toxicity towards the developmental stages of C. carnea and is therefore a candidate for inclusion in IPM strategies.