A study recently discovered the insecticidal activity of Orysata, a lectin
from rice (Oryza sativa L.) belonging to the family of jacalin-related
lectins. The efficacy of Orysata in controlling insect pests was
investigated against three important insect pests: the beet armyworm
(Spodoptera exigua) and two aphids pests: green peach aphid (Myzus persicae)
and pea aphid (Acyrthosiphon pisum)

Orysata was overexpressed constitutively in tobacco plants. An artificial
diet of tobacco leaves containing increasing concentrations of the purified
recombinant Orysata was then fed to the insect pests. Intoxicated larval
stages of S. exigua revealed significant mortality, reductions in larval
weight gain and a retardation of development. Similarly, feeding on leaves
expressing Orysata increased the mortality of the green peach aphids
significantly. In pea aphids, mortality was already high at relatively low
lectin concentrations with the estimated 50% lethal concentration only at 79
?g/ml.

The study revealed that Orysata possessed strong insecticidal activity and
could be considered as a valuable candidate for control agent against both
biting-chewing and piercing-sucking pest insects.

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