Pathogenicity of a Fusarium sp. isolate found infecting the coffee berry borer Hypothenemus hampei

Abstract

During field surveys of native natural enemies attacking the coffee berry borer Hypothene­mus hampei, carried out by the Entomology Department of Cenicafé, the fungus Fusa­rium sp. was observed in several localities at­tacking the borer. Samples were purified in culture, coded and sent to IIBC, UK, where they were identified as E oxysporum and E solani. Aspects of the biology of the isolate Fu 9401 from El Reflejo (Quindío) were stud­ied in the laboratory, viz. percentage germi­nation, radial growth rate, and spore produc­tion. This isolate was cultured in acidified Sabouraud-Dextrose-Agar for 30 days and from this, a preparation was malle of a con­centration of 5.4x10⁸ spores/ml consisting of 100% microconidia and used to evaluate the pathogenicity of the fungus on adults of H. hampei. The insects were immersed in the spore suspension for 2 minutes, and 24 hours later offered either a green coffee berry or a parchment coffee bean (40% humidity). The insects of the check (no immersion) were of­fered parchment beans. Mortalities of 45 ± 17.8% (3Z ± S.D.) were obtained using green berries and 26.3 ±. 14.1% with parchment beans. The average time to reach these mor­talities was 8.6 ± 2.6 days and 7.9± 3.0 days, respectively. It was not possible to calculate the mean lethal time (LT₅₀) from the results. Fur­ther tests need to be carried out using higher concentrations of macroconidia and for the evalu­ation of other isolates collected from the field.