Quality assessment in Lixophaga diatraeae Townsend (Diptera: Tachinidae) mass-rearing.

The sugar cane borer Diatraea saccharalis Fabricius (Lepidoptera: Pyralidae) continues being the principal pest for sugar cane cultivation in Cuba and their control has been focused by means of biological control, where the Cuban fly Lixophaga diatraeae Townsend (Diptera:Tachinidae) is considered as the most efficient natural enemy in our conditions. In 1998, more than 86 millions of flies in sugar cane fields were liberated. This was an important factor to reduce the infestation index of plague from 1.84 until 1.46. The sustained increase has experienced the production of this tachinid in the Entomophage Reproduction Centres, as well as the insufficiency of criteria in order to evaluate the quality of the produced insects and the lack of definition of the biological thresholds they reject, al l this brings about the recycling of the insects that are below the critical threshold. All this motivated the realization of investigations to perfect the criteria of effective quality, by means of the addition of new biological parameters, the establishment of rejection levels for the biological variables and the test of final product in insectary conditions. For this, the flow diagrams were made to describe the general process of production. In the process of Galleria mellonella Linneo (Lepidoptera: Pyralidae) adult breeding, the population parameters intrinsic growth rate (rm) and reproduction net rate (Ro) were evaluated for the first time. Several artificial diets for larval development of G. mellonella that substitute expensive elements as powder milk, wax and honeybee, were made and evaluated. The direct effect of host and indirect effect on parasitoid were analyzed by generalized lineal models. The assay was validated in the massive production. A series of quality criteria in substitution host and parasitoid were undertaken for first time and they were represented in Shewhart charts. The estimate of pupae number of L. diatraeae in the inoculation process is traditionally carried out by counting. In this work, we proposed the evaluation of pupae number by calculating a regression equation of pupae number against pupae volume. This was validated in the production conditions. The parasitic capacity of individual flies and fly lots from laboratory and country populations was evaluated on its natural host Diatraea saccharalis Fabricius (Lepidoptera: Pyralidae) in greenhouse conditions. The percentage of parasitized host larvae was measured. The results showed that diets guaranteed the growth, development, survival and reproduction of substitution hast and parasitoid. The diet 'E' composed of torula yeast, glycerine, corn, soybean flour, wheat and sugar was the best formulation. The optimum Iarvipositional period in G. mellonella is about six days, whereas the female longevity is of ten days. The egg fertility was higher than 80%. It was demonstrated that host larvae quantity in parasitation process could be evaluated by weight. Escaped and dead larvae and host pupae formed during the inoculation process were identified as causes that diminish parasitisrn. The regression equations estimated for the L. dratraeae pupae number showed a higher determination coefficient (97%) and they resulted not very variable once they are established in the production. The L. diatraeae adult emergence and the percent fliers did not show affectation and they were higher than 80% in both cases. There were not significant differences in parasitism between L. diatraeae of Iaboratory and those coming from field.