Influence of Arbuscular Mycorrhizae on the Development and Attack of Leaf-Cutting Ants in Clonal Seedlings of Eucalyptus urophylla x Eucalyptus camaldulensis

Abstract

The present study aimed to evaluate the effect of the mycorrhizal association in the development and attack of leaf-cutting ants Atta sexdens (Linnaeus, 1758) in clonal seedlings of Eucalyptus urophylla x Eucalyptus camaldulensis hybrid. The treatments consisted of inoculated and uninoculated seedlings with 100 grams of sand containing spores from arbuscular mycorrhizal fungi (AMF) collected on native soil from four different areas of the amazon: native forest area (NF), permanent preservation area recovered to three years (PPA03), permanent preserved area degraded (PPAD) and permanent preservation area recovered to four years (PPA04). At 45 and 90 days after inoculation (d.a.i.), height, fresh and dry matter of shoot and root, root development, number of leaves, stem diameter and tolerance to leaf-cutting ants were evaluated. In the first group of plants (45 d.a.i.), mycorrhizal plants presented the higher root volume with the use of APP04, APP03 and NF all with 6.16 mm. For the second group of plants (90 d.a.i.), the highest root volume was also found on mycorrhizal plants with the soil of APP03 and control with 7.16 mm. For the attractiveness test of ants, 16 discs were taken from the non-inoculated seedlings. Regarding the disks of mycorrhizal seedlings with the soil of APP04, only 9 were taken. Although the use of AMF to stimulate plant resistance to attack by leaf-cutting ants is a new study, studies related to the influence of mychorrizas on plant development are quite common and the results presented in this study did not evidence the influence of mychorrizas on plant development. However, it was observed that the early inoculation of the seedlings can reduce the attractiveness of leaf-cutting ants by the seedlings of the hybrid Eucalyptus urophylla x Eucalyptus camaldulensis, already in the first 45 d.a.i of the seedlings and the inoculum used can interfere in this process.