Effects of FABP knockdown on flight performance of the desert locust, Schistocerca gregaria

Abstract

During migratory flight, desert locusts rely on fatty acids as their predominant source of energy. Lipids mobilized in the fat body are transported to the flight muscles and enter the muscle cells as free fatty acids. It has been postulated that muscle fatty acid-binding protein (FABP) is needed for the efficient translocation of fatty acids through the aqueous cytosol towards mitochondrial β-oxidation. To assess whether FABP is required for this process, dsRNA was injected into freshly emerged adult males to knockdown the expression of FABP. Three weeks after injection, FABP and its mRNA were undetectable in flight muscle, indicating efficient silencing of FABP expression. At rest, control and treated animals exhibited no morphological or behavioral differences. In tethered flight experiments, both control and treated insects were able to fly continually in the initial, carbohydrate-fueled phase of flight, and in both groups lipids were mobilized and released into the hemolymph. Flight periods exceeding thirty minutes, however, when fatty acids become the main energy source, were rarely possible for FABP-depleted animals, while control insects continued to fly for more than 2 h. These results demonstrate that FABP is an essential element of skeletal muscle energy metabolism in vivo.

Neuropeptide ACP facilitates lipid oxidation and utilization during long-term flight in locusts

“…The mediating role played by FABP in ACP-controlled flight-related lipid metabolism was further confirmed by knockdown and rescue experiments at the molecular, metabolic, and behavioral levels. The significant role of FABP in prolonged flight has also been reported in the desert locust (Rajapakse et al, 2019), indicating that FABP plays a conserved role in lipid metabolism and long-term flight in locust species.…”

Screening and identification of genes associated with flight muscle histolysis of the house cricket Acheta domesticus

“…Studies have indicated that fatty acid metabolism is an important metabolic mode for long-distance migration of insects ( Arrese and Soulages, 2010 ; Guo et al, 2022 ), combined with the pattern of flight muscle histolysis after migration ( Feng et al, 2019 ), it can be inferred that compared with other metabolic pathways, fatty acid metabolic pathway is more likely to be a regulatory pathway involved in and regulating flight muscle histolysis, and fatty acid transporters are more likely to act as regulatory signals than other proteins with fixed metabolic functions due to their properties of transporting fatty acids. In addition, it is reported that FABP has also been reported to be crucial for long-distance migration of migratory locusts ( Rajapakse et al, 2019 ). That is the reason why this study finally focused on it for research.…”

“…Downregulation of AdomFABP gene expression promotes this process in A. domesticus . FABP has been reported to play an important role in lipid uptake and transport in locust flight muscle and is an essential element of skeletal muscle metabolism involved in sustained muscle activity, the absence of which prevents locusts from migrating long distances ( Rajapakse et al, 2019 ). Increased FABP levels are associated with the flight ability of insects ( Haunerland, 1997 ).…”

Biological Characteristics and Energy Metabolism of Migrating Insects

“…In both desert locust Schistocerca gregaria (Orthoptera: Acrididae) and L. migratoria , the flight duration of individuals was significantly shortened after FABP gene expression was silenced. The flight distance of L. migratoria was also significantly decreased [ 14 , 148 ], mainly due to the silencing of the FABP gene, which seriously affects the oxidative metabolism of fatty acids in the flight muscle during sustained flight. FFA are catalyzed by fatty acyl-coenzyme A on the outer mitochondrial membrane to produce fatty acyl A, which is then transported to the mitochondrial matrix by carnitine palmitoyltransferase (CPT) in the inner and outer membranes of mitochondria [ 136 , 149 , 150 ].…”