Natural control: new parasitoid–host associations between Trichogramma species and sugarcane stem borers Diatraea

In Colombia, the sugarcane stem borers Diatraea (Lepidoptera: Crambidae) are the most economically important pests in sugarcane. To combat these pests, massive releases of the egg parasitoid Trichogramma exiguum (Hymenoptera: Trichogrammatidae) have been recommended during the last two decades, but no additional studies have been done to validate this recommendation or to verify if any other parasitoid species are associated. This study aimed to characterize different Trichogramma species associated with Diatraea species present in different regions of Colombia and to quantify the level of parasitism. Egg masses of Diatraea were collected in 329 sugarcane fields. Additionally, samples were obtained from commercial insectaries. Morphological and molecular methods were used for taxonomic identification, and parasitism in the field was estimated. Four Trichogramma species were identified: T. exiguum, T. atopovirilia, T. pretiosum and T. lasallei, and three undetermined species: Trichogramma sp. 1, Trichogramma sp. 2 and Trichogramma sp. 3. T. exiguum was the predominant species in all regions and the only one found in commercial insectaries. Mean egg parasitism ranged from 61% to 96%. This study provides new records and taxonomic insights into Trichogramma species associated with sugarcane stem borers in Colombia and highlights their relevance for biological control programs.