Effect of Euphorbia hirta nectar and its component sugars, upon the survival of bethylid parasitoids of the coffee berry borer

In the south of Mexico, attempts to control severe infestations of the coffee berry borer Hypothenemus hampei Ferrari (Coleoptera: Scolytidae), by means of two imported African parasitoids, Cephalonomia stephanoderis Betrem and Prorops nasuta Waterston (Hymenoptera: Bethylidae), have been less than satisfactory. The lack of a suitable alternative food source in the field, such as floral nectar, could be one reason for this result. Both parasitoids have been shown to feed upon the nectar of Euphorbia hirta L. (Euphorbiaceae) under laboratory conditions. In these experiments, females of C. stephanoderis and P. nasuta survived up to 55 and 17 days, respectively, when provided daily with a fresh E. hirta flower. Survival time with diluted honey was 41 and 8 days maximum and in the case of the control (no food or water), 7 and 4 days, respectively. Qualitative analysis of the nectar showed the presence of saccharose, fructose and glucose. Parasitoids, isolated in test tubes, were daily given drops of 1M, 2.5M and 5M solutions of the three sugars (5M, saccharose and glucose only) until death. Saccharose, at a concentration of 2.5M, gave the best survival rates for both parasitoids, up to 59 and 28 days for C. stephanoderis and P. nasuta, respectively. eng