Ultrastructural study on the leaf surface of four mulberry (Morus sp.) genotypes and the influence of foliar trichomes on egg layings by Spilosoma obliqua (wlk.) (Lepidoptera Arctiidae)


A scanning electron microscopic study on the micro-morphology of four mulberry genotypes viz., Kanva2 (K2), Morus multicalis, Morus lavigata and Morus serrata was under taken to find out the influence of oviposition by the gravid females of Spilosoma obliqua (Wlk.). The results of the present study reveal that the genotype K2 was observed with minimum number of foliar non-glandular and glandular trichomes resulting in the highest number of eggs laid by the moths. On an average, a total number of eggs laid were recorded 533.44±96.02. The genotype of M. multicalis has more number of trichomes than K2 genotype and the number of eggs laid by the pest was 486.22±70.56. The genotype M. lavigata ranked third in respect of number of trichomes and oviposition and the number of laid eggs were 340.93±39.96. The leaves of M. serrata genotype were highly pubescence, therefore, in choice tests, the moths of S. obliqua did not prefer the genotype for oviposition, and this may be because of finding difficulty for the feeding organs of neonate larvae to reach the site of feeding. Statically significant difference was found among four mulberry genotypes in respect to the preference of oviposition by the moths of S. obliqua. These findings indicate that M. serrata is a source of trichome-based resistance to S. obliqua and may be of value to mulberry breeding programs attempting to expand the genetic base of host plant resistance to insect pests.


Leaf surface; genotypes; Morus sp.; egg laying; S. obliqua; ultrastructure

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