The role of host-plants resistance on development of Plutella xylostella (L.) (Lep., Plutellidae) in laboratory

Host-plant resistance is one of the effective and sustainable strategies in pest management programs against diamond-back moth، Plutella xylostella (L.) (Lepidoptera، Plutellidae). In this regard، the effect of host plant type on life-history parameters، such as survival and developmental period of P. xylostella was determined under the constant environmental condition. The experiments were carried out with five host plants، including Brassica pekinensis (Chinese cabbage) cv. Hero، B. oleracea var. botrytis (cauliflower) cv. Royal، B. oleracea var. capitata (common cabbage) cv. Globe Master and cv. Red Dynasty، and B. napus (rape) cv. SLM046. Batches of 10 neonate P. xylostella larvae were placed on leaf discs within individual Petri dishes (6 cm dia.) containing a moistened filter paper. To prevent starvation of larvae، the leaf discs were replaced every 24 h. Pupae were transferred to Petri dishes and kept until eclosion. Life stage and mortality were recorded every 24 h until all the insects had either died or emerged as adults. Each treatment (plant) was replicated 17 times (in total، 170 host larvae for each plant). Theresults showed that there were significant differences between host plants for life-history parameters measured. The highest and lowest developmental times (from neonate larva to eclosion) of the host occurred on Red Dynasty (17. 3 days) and Hero (10. 5 days)، respectively. The most survival (from neonate larva to eclosion) of the host was observed on Hero (72%)، whereas the least survival happened on Red Dynasty (16%) and SLM046 (20%). The mean pupal weight of the hosts fed on Hero (4. 3 mg) was significantly greater than that on Royal (3. 8 mg) and Red Dynasty 3. 7 mg)، which in turn، were significantly greater than that on SLM046 (2. 9 mg). These results indicated that Hero was the most susceptible host plant to be attacked by P. xylostella، whereas Red Dynasty and SLM046 were partially resistant compared to other host plants. These findings emphasize on using the partially-resistant varieties such as Red Dynasty and SLM046 in pest management programs against diamondback moth.