Isofemale line as an alternative to maintain quality of Telenomus remus Nixon, a biological-control agent for fall armyworm

This study evaluated whether rearing a regular line and an isofemale line of Telenomus remus Nixon for successive generations in laboratory conditions changed its flight capacity, parasitism, and longevity, desirable characteristics for a biological-control agent. The regular line of T. remus was re-introduced to laboratory rearing conditions from the field. The isofemale line was selected through inbreeding for nine generations, reducing its genetic variability. Flight capacity, parasitism, and longevity were evaluated over 11 generations in the regular strain, adding more two evaluations of parasitism and longevity (F17 and F19) and 20 generations in the isofemale line. Flight capacity was evaluated in flight-test units. Parasitism and lifespan were evaluated by offering egg-masses of S. frugiperda daily to individual females and counting the number of parasitized eggs, until the wasps died. The regular line of T. remus was affected by laboratory rearing over time. The proportion of flying individuals decreased by around 20 % between generations F1 and F6; the parasitism capacity was similar across generations; and longevity was similar in F1 and F6 (around 12 days), differing from F11 (8 days). Parasitism did not differ significantly in the T. remus isofemale line in the three generations evaluated, with no large variations in the parasitism potential in recently emerged female in any generation. The longevity of the parasitoid females was similar in generations F1 and F20 (7.3 and 8.1 days respectively) but differed from the F10 generation (15.2 days). Laboratory rearing of the regular line of T. remus over successive generations changed its flight capacity, parasitism, and longevity. Use of a T. remus isofemale line may be an alternative to maintain flight capacity and parasitism of this S. frugiperda biological-control agent over generations.