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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Insect Control and Cotton Disease Research » Research » Publications at this Location » Publication #318288
Title: Sulfakinin is an important regulator of digestive processes in the migratory locust, Locusta migratoria

Author
item ZELS, SVEN - Catholic University Of Leuven
item DILLON, SENNE - Catholic University Of Leuven
item CRABBE, KATHLEEN - Catholic University Of Leuven
item SPLIT, JORNT - Catholic University Of Leuven
item Nachman, Ronald
item VANDEN BROECK, JOZEF - Catholic University Of Leuven

Submitted to: Journal of Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2015
Publication Date: 6/25/2015
Citation: Zels, S., Dillon, S., Crabbe, K., Split, J., Nachman, R.J., Vanden Broeck, J. 2015. Sulfakinin is an important regulator of digestive processes in the migratory locust, Locusta migratoria. Journal of Insect Biochemistry and Molecular Biology. 61:8-16.

Interpretive Summary: Insect pests have developed resistance to several conventional pesticides, and new approaches are needed for pest management. Although neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions, the neuropeptides hold little promise as pest control agents because they can be degraded in the target pest. New, selective control agents may be developed by designing mimics of these neuropeptides that resist degradation and either inhibit or over-stimulate critical neuropeptide-regulated life functions. Research was conducted that demonstrated that ‘sulfakinin’ neuropeptides reduce food intake, reduce digestive enzyme secretion, reduce food absorbance and protein digestion in the digestive system of the migratory locust, an important agricultural pest. The hormone is shown for the first time to reduce the release of a wide range of digestive enzymes that target carbohydrates, fat, protein and cellulose. The work further identified a specific structural feature of the sulfakinins that is critical for induction of these effects. The research also reveals that this critical structural feature can be replaced by a much more stable component; a result that paves the way for the development of mimetic versions that can resist degradation and disrupt pest insect feeding and digestion. The work provides new insights into the regulation of digestive processes in insects and brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling pest insects in an environmentally friendly fashion.

Technical Abstract: Sulfakinin (SK) is a sulfated insect neuropeptide that is best known for its function as a satiety factor. It displays structural and functional similarities with the vertebrate peptides gastrin and cholecystokinin. Peptidomic studies in multiple insects, crustaceans and arachnids have revealed the 18 widespread occurrence of SK in the arthropod phylum. Multiple studies in hemi- and holometabolous insects revealed the pleiotropic nature of this neuropeptide: in addition to its activity as a satiety factor, SK was also reported to affect muscle contraction, digestive enzyme release, odor preference, aggression and metabolism. However, the main site of action seems to be the digestive system of insects. In this study, we have investigated whether SK can intervene in the control of nutrient uptake and digestion in the migratory locust (Locusta migratoria). We provide evidence that sulfakinin reduces food uptake in this species. Furthermore, we discovered that SK has very pronounced effects on the main digestive enzyme secreting parts of the locust gut. It effectively reduced digestive enzyme secretion from both the midgut and gastric caeca. SK injection also elicited a reduction in absorbance and proteolytic activity of the gastric caeca contents. The characteristic sulfation of the tyrosine residue is crucial for the observed effects on digestive enzyme secretion. In an attempt to provide potential leads for the development of peptidomimetic compounds based on SK, we also tested two mimetic analogs of the natural peptide ligand in the digestive enzyme secretion assay. These analogs were able to mimic the effect of the natural SK, but their effects were milder. The results of this study provide new insights into the action of SK on the digestive system in (hemimetabolous) insects.