Reproductive performance of Plutella xylostella for different cruciferous vegetables across 18 generations

The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is one of the most important pests of Brassicaceae in Brazil and worldwide, causing serious damage to cabbage, kale, and broccoli. The aim of the present study was to evaluate the reproductive performance of 18 generations of DBMs to various cruciferous vegetables, namely, Brassica oleracea var. acephala (HS-20 kale), B. oleracea var. italica (Piracicaba broccoli), and B. oleracea var. capitata (Bobcat cabbage). Three separate batches of P. xylostella pupae were reared in the laboratory and exclusively fed kale leaves. Each batch was maintained on different substrates, wherein three populations comprised the initial rearing by using various feeding and oviposition substrates (i.e., kale, broccoli, and cabbage). Every three generations of DBMs derived from each rearing substrate were separated and observed the survival, duration of each development phase and number of eggs laid by females. Then, the fertility life table parameters were estimated. In the F3 generation DBMs fed on broccoli showed higher values for net reproductive rate R₀ (90.1 females/female) and intrinsic rate of population increase r_m (0.393 females/female*day). However, in the last generation evaluated (F18) insects reared with cabbage and kale showed the highest values for R₀ (53.9 females/female for two substrates) and r_m (0.334 and 0.337 females/female*day, respectively). Thus, considering that this is the first study that analyzed the performance reproductive of DBM over several generations on different substrates and that the results were very variable over time, further research should be conducted to understand these differences.