Application of ionizing radiation in the coconuts of “Licuri” Syagrus Coronata (mart.) in the control of the Pachymerus Nucleorum beetle (Fabricius, 1792)

Abstract

The “licuri” fruit palm (Syagrus coronata) is harvested extractively from palm trees that grow in native forests, pastures, and in association with other cultures being part of the regional economy in the hinterland of Bahia. Among the problems related to the “licuri” palm is the insect specie Pachymerus nucleorum (Fabricius, 1792), which stands out as a pest of economic importance because it causes direct damages to the “licuri's” almonds. Due to this the objective of the work was to determine the lethal doses of gamma radiation for the phases of egg, larvae and pupae of Pachymerus nucleorum aiming at its control in almonds of coconuts of licuri. A Cobalt 60 irradiator, Gammacell-220 type, installed at the Institute of Energy and Nuclear Research - IPEN / CNEN, located in São Paulo / Brazil, at a dose rate of 748 Gy / h, was used to carry out the research with the Pachymerus nucleorum biological cycle. Each treatment for all stages of egg, larvae and pupae inside of coconuts consisted of 3 replicates with 12 coconuts each, in a total of 216 coconuts per test that were irradiated in the following doses: 0 (control), 50, 75, 100 and 125 Gy. After irradiation, the samples were stored at a temperature of 25 ± 5 ° C and relative humidity of 70 ± 5%, where the development of egg, larvae and pupae stages until adult transformation in irradiated almonds. From the results obtained it is concluded that the dose of 125 Gy was sufficient to interrupt the development of the phases of the insect. Therefore, this dose of radiation can be used for quarantine treatment of the immature stages of Pachymerus nucleorum in the coconuts of “licuri” Syagrus coronata palm.