Stable isotope methods for insect physiology

Insects are successful largely because they are highly efficient at optimizing nutrients for reproduction. To understand this efficiency, we have used the stable isotope tracer-tracee-based technique mass isotopomer distribution analysis (MIDA) to follow metabolic allocation in insects in vivo. Based largely on application of these techniques, we had three aims during the fellowship:  
a)    To adapt MIDA to study allocation of carbohydrates acquired during host feeding by the parasitoid Eupelmus vuiletti to fat production.
b)    To study sex pheromone storage in a moth (Bombyx mori).
c)    To write a significant, high impact review on insect physiology.
We successfully adapted MIDA to study fat acquisition in E. vuiletti. Essentially, females allowed to feed on a glucose drop, turned over their hemolymph trehalose substantially (ca. 30-40%). However, very little of this acquired sugar was converted to fat. Moreover, isotopic enrichment of fat was substantially less than that of the trehalose, indicating that other (non-labeled) sources of precursor are used for this fat synthesis. This supports the finding that parasitoids can synthesize fat, but only in very small amounts in comparison to their carbohydrate acquisition. These techniques were transferred to staff and students at IRBI.
Problems with supply of insects meant that we could not fully study sex pheromone storag in B. mori. However, we were able to demonstrate that females, when synthesizing pheromone, stored most pheromone on the gland cuticular surface, rather than intracellularly, thereby facilitating emission of pheromone.  
Finally, we wrote and submitted a proposal for a review on insect exocrine glands for the highly prestigious Annual Review of Entomology (2022 IF = 23.8). We were notified of the success of our proposal in December 2022. Thereafter , a considerable portion of the visit was dedicated to researching, synthesizing, and writing this review. The manuscript will be submitted in January 2024 and, hopefully, published in January 2025.