Susceptibility of Chrisoperla externa and C. asoralis to three insecticides

HARAMBOURE M; MIRANDE I; REGUILÓN C; ALZOGARAY R; SCHNEIDER M

Ghent

Simposio; 65th International Symposium on Crop Protection; 2013

Ghent University

Great La Plata, Argentina, is a very important region of horticultural crops production of Buenos Aires province, with the 62% of protected culture area. The more relevant harmful insects associated to these crops are aphids, whiteflies, several lepidopterans and thrips. Chrysopids are considered as effective biological control agents of the preys above mentioned. In Argentina there had been cited four species of Chrysoperla genus: C. externa, C. asoralis, C. argentina and C. defreitasi, but just the first one has been recorded in Great La Plata area so far. The taxonomy of the group is particularly difficult due to similar morphological characteristics between them, even though the larval stages are recognizable. On the other hand, the susceptibility of this genus to pesticides has not been deeply documented yet because the studies done in the Neotropical Region are referred to C. externa. In the frame of Integrated Pest Management, the selectivity of pesticides is a crucial for the joint use of pesticides and biological control agent. The objectives of this work were: a) field sampling of adults and eggs of Chrysopidae organisms in greenhouses of sweet pepper Capsicum annuum without history of pesticides, b)taxonomical determination at level specie following the taxonomic characteristics of larvae; c) rearing of different species in laboratory; d) to evaluate the susceptibility of third larval instar and pupae of the most abundant chrysopid species toward three insecticides commonly used in greenhouses of Great La Plata for controlling sucking pests at full field concentrations of each one: cypermethrin (pyrethroid), acetamiprid (neonicotinoid) and pyriproxyfen (IGR). The exposure was by topical application, using a Burkard® hand microapplicator (1 μl/insect). The ecotoxicological endpoints were: short term effects (mortality at 24 h after treatment) and long term effects (development time, reproductive capacity of females and abnormalities in emerged adults from treated organisms). The taxonomical determination was provided for Dra. Carmen Reguilón (Entomology Institute, Miguel Lillo Foundation, Tucumán). The species found corresponded to C. externa, C. asoralis and C. argentina. It is important to highlight that this is the first record for C. asoralis and C. argentina in Great La Plata Region. Moreover, it is also novelty their association to sweet pepper horticultural crops. The most abundant species were C. asoralis and C. externa. Regarding to ecotoxicological evaluations, C. asoralis was more susceptible than C. externa to cypermethrin (mortality at 24 h after treatment). However none short term effect was observed in acetamiprid and pyriproxyfen treatments. Furthermore, the reproductive capacity of females was variable depending on the pesticide. Adult emergence of both species was disrupted; some of preimago were not be able to molt to the adult stage.