Interaction between Steinernema feltiae SC125 and Metarhizium anisopliae sensu lato 9236 for control of the Guatemalan potato moth

The Guatemalan potato moth (Tecia solanivora) is one of the most destructive pests affecting potatoes in Colombia. Our objective was to evaluate the susceptibility of T. solanivora to a combination of entomopathogenic nematodes and entomopathogenic fungi, to study the interactions of these two agents under laboratory conditions. We evaluated the mortality of fourth instar larvae against 200 Infective Juveniles (IJs) per larva of ten strains of entomopathogenic nematodes, and 104–108 conidia per larva of Beauveria bassiana sensu lato Bb9205 and Metarhizium anisopliae sensu lato Ma9236. We found that Steinernema feltiae SC125 caused a mortality rate of 98.2% with an LC50 of 33 IJs/larva. M. anisopliae sensu lato Ma9236 achieved a mortality rate of 88.8% with an LC50 of 6.9 × 105 conidia/larva. We selected these strains for the interaction tests. We determined that the interaction test results were statistically additive regardless of any difference in application times of the entomopathogens and despite the observation of signs of infection in the hosts from both the nematode and the fungus. Despite not having found synergistic interactions between the evaluated control agents, these laboratory tests suggest a possible strategy of combining entomopathogenic nematode and fungi for biological management of the guatemalan moth T. solanivora in potato crops.