Diet source-dependent functional response of key parasitoids of Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera, Noctuidae)

Foods derived from plants are important sources of food for natural enemies and influence several functions of their existence, including reproduction. The objective of the current study was to assess the effect of different sources of food and host densities on the oviposition efficiency of key parasitoids of Spodoptera frugiperda. The experiment was set up under laboratory conditions in a completely randomized block design with three factors namely parasitoids (four), feeding (groundnut pollen, soybean nectar, honey, starved as control) and host densities (five), a total of 80 treatments. There were five replications for the experimental design while the experiment was repeated four times, a total of 20 replications for each treatment. Results showed that the functional response of adult parasitoids was influenced both by food sources and host densities. Soybean nectar worked the best like honey, followed by groundnut pollen. Soybeans and groundnut may therefore have agroecological interests beneficial for mass rearing to promote key parasitoids as biological agents to control S. frugiperda. As for the host densities, the minimum and maximum of the parasitized host were obtained respectively with the densities of 20 and 100 eggs per female for T. remus, 20 and 80 eggs for Trichogramma sp. and C. insularis and 5 to 50 larvae for C. marginiventris. Taking into account the interesting results obtained which would be favourable to the rapid multiplication of parasitoids, tests in real environments are necessary to test the influence of the main environmental factors on the performance of said parasitoids.