Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/1999
Publication Date: 5/20/2000
Citation: Morales Ramos, J.A., Rojas, M.G., Sitterz-Bhatkar, H., Saldana, G. 2000. Symbiotic relationship between hypothenemus hampei (coleoptera: scolytidae) and fusarium solani (moniliales: tuberculariaceae). Annals of the Entomological Society of America.
Interpretive Summary: Coffee is one of the most important "cash" crops in Latin America providing with an alternative to the growth of narcotics. Cash crop are an important source of prosperity and stability in developing countries. The coffee berry borer (CBB) is the most important pest of coffee in Latin America and the rest of the world. In many countries, such as Columbia, this pest reduces the profitability of the crop to the point that growers abandon th fields and replace them for other more profitable crops, some time narcotics. The CBB has been traditionally controlled by chemical means, but the resistance to pesticides gained by this insect has made this practice inefficient. In more recent years, biological control has shown promise for the control of the CBB in Brazil, Columbia, Mexico, and other coffee producing countries. The release of parasitic wasps imported from Africa has helped in the reduction of CBB populations. However, these wasps need to be mass-produced and released in great numbers to achieve economical levels of control. To achieve this goal, the CBB must first be mass reared in an artifical diet to provide food for the parasitic wasps. This paper provides the basic knowledge of CBB nutrition needed to develop effective artificial diets. For years, attempts to mass-produce the CBB have been made with the assumption that the basic nutrition of this beetle is provided by the coffee bean. Diets developed under this assumption have failed to sustain the growth of the beetle population for more than 4 generations (approximately 4 months). Coffee growers in Latin America will benefit directly by the improvement of CBB control strategies; but, the North American public will benefit indirectly by the reduction in the production of narcotics derived from plants grown in lieu of coffee.
Technical Abstract: We found evidence of a symbiotic relationship between Fusarium solani (Martius) and Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae). Females of H. hampei colonizing coffee beans infested with F. solani produced significantly more progeny than those colonizing sterile beans. Beans infested by F. solani had significant amounts of ergosterol, which was not present in sterile beans. Fecundity and survival of H. hampei was positively correlated with the content of ergosterol in their diet. Other evidence of symbiosis includes the presence of F. solani spores caught in cuticular protuberances, known as asperities, on the pronotal area of female H. hampei. The asperites are flat and arranged in a radial pattern presenting a pronounced inclination directed to the center of this radial pattern which originates at a protuberance on the pronotal area. The asperites appear to increase the chances of fungal deposition on the pronotum when female beetles bore into infested coffee beans. The existence of a mutualistic association between H. hampei and F. solani and the role of the pronotal structures as primitive mycangia are discussed.