Actividad biológica de la azadiractina sobre Nezara viridula (L.)

Se ha estudiado la acción reguladora del desarrollo de diferentes dosis de azadiractina, aplicadas tópicamente sobre ninfas Nezara viridula (L.) de 5 o estadio. Igualmente se ha evaluado la fecundidad y la fertilidad de adultos, machos y hembras, procedentes de ninfas tratada con dicho compuesto a varias dosis subletales. Con dosis iguales o superiores a 200 ng/insecto se alcanzaron porcentajes de mortalidad en la muda superiores al 85 %, estos adultos poseían además un elevado número de características ninfales y resultaron inviables. A dosis inferiores, desde 50 a 2 ng/insecto, se obtuvo un porcentaje de adultos aparentemente normales superior al 50%. El efecto esterilizante eductor de fecundidad de la azadiractina se observo tratando hembras y machos con dosis de 5 ng/insecto. El número de huevos/insecto tratado fue significativamente inferior al testigo control. Finalmente azadiractina a dosis de 1 (J-g/cm^ dispuesta sobre el área de puesta, mostró un claro efecto disuasor de la oviposición sobre hembras fecundadas de la especie.The potential of azadirachtin as insect growth regulator has been evaluated by applying several doses of the product on 5 th. instar nymphs Nezara viridula. Fertility and fecundity of adults, males and females, proceeding from nymphs treated at several lower doses of the product were also studied. At a dose of 200 ng/insect a percent of mortality higher than 85% was obtained during the molt, and all the adults had got a great number of nymph characteristics and died very soon. At the lower tested doses, from 50 to 2 ng/insect, more than 50% of adults looked normally. No effect on the last nymph instar lasting was observed, even at the highest applied dose. A clear reduction effect on the fertility of males and females were found at a dose of 5 ng/insect. The number of eggs/treated insect were significantly lower than the controls. Finally azadirachtin used at a dose of 1 jo.g/cm2 on the oviposition area, showed an important disruption in the egg lying behavior of the gravid females