Effect of host plants on the fitness and demographic parameters of the diamondback moth, Plutella xylostella (L.) using age-stage, two-sex life tables

To design effective management practices against insect pests, it is essential to construct a life table and study demographic parameters. The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is a dreaded pest that affects brassicaceous plants. The present study aims to investigate the effect of five brassicaceous hosts' viz., cauliflower, cabbage, broccoli, mustard and knol khol, on the fitness of P. xylostella under controlled conditions. The demographic parameters were estimated using the TWOSEX MS chart. The highest egg-hatching percentage (96.67%) was recorded on cabbage, similarly total development period was longest on cabbage (20.11 +/- 1.34 days) and shortest on mustard (18.75 +/- 0.94). Females laid significantly more eggs on mustard (234.38 +/- 30.81 eggs) and cabbage crops (231.43 +/- 54.65 eggs). The biotic potential of P. xylostella reared on brassicaceous hosts was as follows: broccoli (1.06 x 10(28)) > mustard (7.70 x 10(27)) > cauliflower (8.77 x 10(26)) > knol khol (6.20 x 10(24)) > cabbage (3.97 x 10(24)). The age-stage-specific survival rate (S-xj) varied across developmental stages, and the survival curves overlapped, indicating different growth rates among individuals. The life expectancy (e(xj)) at age zero was highest on mustard (23.50 days). The intrinsic rate of increase (r) of P. xylostella was lowest on knol khol (0.14) and highest on mustard (0.20). Similarly, the net reproductive rate (R-0) was highest on mustard (62.5 +/- 1.94) and lowest on knol khol (17.7 +/- 0.74). The population doubled every 3.57 +/- 0.036 days on mustard compared to 5.01 +/- 0.111 days on knol khol. These findings indicate that mustard and cabbage are preferred hosts for P. xylostella, while knol khol is comparatively resistant to P. xylostella.