Succinyl-CoA synthetase/ligase (SCS) is a mitochondrial enzyme that catalyzes the reversible process from succinyl-CoA to succinate and free coenzyme A in TCA cycle. SCS deficiencies are implicated in mitochondrial hepatoencephalomyopathy in humans. To investigate the impact of SCS deficiencies in Drosophila, we generated a null mutation in Scs alpha subunit (Scs alpha) using the CRISPR/Cas9 system, and characterized their phenotype. We found that the Drosophila SCS deficiency, designated Scs alpha(KO), contained a high level of succinyl-CoA, a substrate for the enzyme, and altered levels of various metabolites in TCA cycle and glycolysis, indicating that the energy metabolism was impaired. Unlike SCS alpha deficiencies in humans, there was no reduction in lifespan, indicating that Scs alpha is not critical for viability in Drosophila. However, they showed developmental delays, locomotor activity defects, and reduced survival under starvation. We also found that glycogen breakdown occurred during development, suggesting that the mutant flies were unable to produce sufficient energy to promote normal growth. These results suggested that SCS alpha is essential for proper energy metabolism in Drosophila. The Scs alpha(KO) flies should be useful as a model to understand the physiological role of SCS alpha as well as the pathophysiology of SCS alpha deficiency. (C) 2016 Elsevier Inc. All rights reserved.