Natural enemies recovered from Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) larvae infesting the cartridge, ear and stem of corn plants under conventional and organic farming systems in Brazil

The corn cropping system can influence the natural enemy identity and the number of Spodoptera frugiperda J.E. Smith, 1797 (Lepidoptera: Noctuidae) individuals infesting the cartridge, ear and stem of this plant. The objectives were to identify the S. frugiperda natural enemies and differences in the number of individuals infesting the cartridge, ear and stem of corn plants under conventional and organic cropping systems, in Brazil after an initial collection of adult males through semiochemical traps. We also evaluated key morphometrical parameters of the larva and factors contributing with the viability of S. frugiperda. A total of 16 and 136 adult males was trapped, and 1,124 and 1,112 larvae was recovered from conventional and organic systems with 4.7 and 6.7% of them parasitized by dipteran and hymenopteran, respectively. Most of the parasitoids recovered had occurrence in both cropping systems, except Cremastinae and Ophion flavidus Brullé, 1846 (Hymenoptera: Ichneumonidae), which were recorded only in organic and Campoletis sp. (Hymenoptera: Ichneumonidae) only in conventional corns. The number of parasitoids recovered was similar in corn plant samples between both cropping systems. A total of 152 and 31 larvae was recovered from corn ears under conventional and organic systems, respectively. Doru luteipes (Scudder, 1876) (Dermaptera: Forficulidae) was recovered from all samples under conventional system. The larva length was overall similar between cropping systems. Parasitism by dipteran and hymenopteran, infection by microorganisms, larva mortality by undetermined causes, and differences in viability of S. frugiperda stages were factors contributing with the supression of this pest. The new associations and parasitoids reported represent possibilities of expanding the biological control strategies to manage S. frugiperda in corn crops.

Geographical transition zone of Solenopsis fire ants (Hymenoptera: Formicidae) and Pseudacteon fly parasitoids (Diptera: Phoridae) in the state of São Paulo, Brazil

Solenopsis saevissima (Smith) and Solenopsis invicta Buren are the most abundant and widely distributed fire ants in Brazil. The occurrence of the two fire ant species and of their parasitoids Pseudacteon spp. is described for a climatic and phytophysiognomic transition area in the state of São Paulo. Both fire ant species have a parapatric distribution, apparently determined by the climate: S. saevissima predominates in the north part of São Paulo (Aw climate), while S. invicta in the south (Cfa climate). A sympatric area is observed between the latitudes 21ºS and 23ºS. Two different communities of parasitic decapitating flies were associated with S. saevissima in the north and with S. invicta in the south, with a sympatric area in the municipality of São Carlos (21º58'S 47º53'W). The possible causes of this biogeographic pattern are discussed. Preference tests with Pseudacteon flies challenge the association of P. litoralis Borgmeier, P. curvatus Borgmeier, P. wasmanni Schmitz, P. pradei Borgmeier and P. obtusus Borgmeier with S. saevissima, and P. dentiger Borgmeier, P. disneyi Pesquero and P. lenkoi Borgmeier & Prado with S. invicta.