Biological characterization and mating compatibility of Helicoverpa gelotopoeon (D.) (Lepidoptera: Noctuidae) populations from different regions in Argentina.

Helicoverpa gelotopoeon, the South American bollworm, is a polyphagous pest of the Heliothinae complex that causes damage to soybean, cotton, and chickpea crops. Some species within this complex have developed resistance to genetically modified crops and insecticides, which has led to increased interest in their genetic diversity and population structure. The objective of this study was to characterize biological and reproductive parameters of two populations of H. gelotopoeon collected in two different provinces of Argentina. Intra- and inter-population crosses revealed that H. gelotopoeon populations from both regions of Argentina did not present evidence of pre-zygotic and post-zygotic incompatibility, suggesting that Tucumán and Córdoba populations of H. gelotopoeon belong to a single wide-ranging species. Our data support the occurrence of substantial gene flow between H. gelotopoeon populations, probably due to the widely documented, long-range migratory capacity of Heliothinae species.

Reproductive isolation between two populations of Diatraea saccharalis (F.) (Lepidoptera: Crambidae) from different host plant species and regions in Argentina.

The sugarcane borer, Diatraea saccharalis (F.), has a widespread distribution throughout the Western Hemisphere and is a pest of many crop plants including sugarcane, corn, sorghum and rice. The use of Bacillus thuringiensis (Bt) corn has been the primary tool for managing this species in corn fields. Sugarcane borer control has been recently threatened by observations of susceptibility and/or resistance to certain varieties of Bt corn and the protein used in many newer varieties. This has led to increased interest in understanding sugarcane borer genetic diversity and gene flow within and among its populations and the consequent exchange of alleles between geographically distant populations. The objective of this study was to examine reproductive compatibility between host-associated geographic populations of D. saccharalis in Argentina and to determine whether this pest represents a complex of host-associated cryptic species rather than a wide ranging generalist species. Intra and inter-population crosses revealed that D. saccharalis populations from the northwestern and Pampas regions presented evidence of prezygotic and postzygotic incompatibility. Such a result is likely to be the product of an interruption of gene flow produced by either geographic or host plant associated isolation, suggesting that Tucumán (northwestern) and Buenos Aires (Pampas) populations of D. saccharalis are a distinct genotype and possibly an incipient species.