Alicia Pelicano

IMPACTO DEL ESTRÉS HÍDRICO Y LA PROCEDENCIA DE EUCALYPTUS GLOBULUS LABILL. SOBRE EL COMPORTAMIENTO DE HERBIVORÍA DE ACROMYRMEX LUNDI GUÉRIN

Las diferentes especies de hormigas aceptan la mayor parte de las plantas que se les ofrecen; sin embargo, ha sido probado cierto comportamiento selectivo y en plantas bajo estres hidrico se ha reportado mayor dano por su herviboria. Dos ensayos fueron llevados a cabo con la hormiga negra comun, sobre siete procedencias de tres subespecies de Eucalyptus globulus. Tales procedencias fueron ofrecidas en nido artificial en laboratorio y bajo estres hidrico, en nidos a campo. En laboratorio, la preferencia expresada como tiempo de acarreo fue significativamente diferente entre procedencias, aunque no entre subespecies. En campo, el area promedio removida fue significativamente mayor en plantas sometidas a estres hidrico. Este parecio incrementar la atraccion para las hormigas cortadoras, superando la preferencia relativa por las procedencias, manifestada en laboratorio. Por lo tanto, la utilizacion de procedencias menos preferidas es una alternativa de manejo solo en aquellas areas donde el estado hidrico puede ser controlado. La heterogeneidad del suelo causaria areas relativamente mas secas y tales situaciones localizadas de estres hidrico podrian tornar a ciertos individuos mas atractivos y, por lo tanto, mas danados.

Efecto de la propagación asexual y prolongación del período vegetativo de Morus alba en la producción de capullos de seda

A. Pelicano, M. Divo de Sesar, N. Zamuner, J. L. Danelon, and M. Yoshida. 2007. The effect of asexual propagation and persistence of the vegetative growth of Morus alba on silk cocoon production. Cien. Inv. Agr. 34 (2):81-89. The goal of this work was to establish an effi cient protocol for vegetative propagation of Morus alba. At the same time this study aimed to evaluate the infl uence of this propagation protocol on the feeding of the larvae of Bombyx f mori and crude silk production. Vegetatively propagated mulberry plants were transplanted to 4 L containers and treated with 15 g of fertilizer, N:P:K (15:15:15,), and/or 6-benzyladenine (5 mg·L -1 ) (Ck). In autumn and spring, leaves were used for the feeding of one cohort of third stage larvae. It was observed that 60% of the plants treated with Ck sprouted before the others, in July, and the rest in August. Although the fertilized plants (TF) and those fertilized and treated with 6-benzyladenine (TFCk) sprouted shortly before the control (T), the Ck treated plants were notably uniform and had more and larger leaves. In the TFCk treatment, the percentage of fi ber, insoluble in neutral detergent (FIND) free from ash, was minor (29.73%). The quality of the food was refl ected in the weight gain and in crude silk percentage. Although interaction between TF and Ck was not signifi cant, there were signifi cant differences between control plants (T) and those treated with TF, TCk and TFCk. In the autumn test, the TCk treatment negatively affected the larvae of B. mori. These larvae twisted, assiduously inducing intestine evacuation. This caused reduced food consumption, and it was a transitory effect, but that meant a lower fi nal weight. The results of this work are very promising and useful for massive production since a longer vegetative cycle for M. alba would allow a greater number of B. mori generations per year.