|LANGE, ANGELA - University Of Toronto|
|KACZMAREK, KRZYSZTOF - Technical University Of Lodz|
|ZABROCKI, JANUSZ - Technical University Of Lodz|
Submitted to: Peptides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2016
Publication Date: 5/15/2016
Citation: Lange, A.B., Nachman, R.J., Kaczmarek, K., Zabrocki, J. 2016. Biostable insect kinin analogs reduce blood meal and disrupt ecdysis in the blood-gorging Chagas’ disease vector, Rhodnius prolixus. Peptides. 80:108-113.
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. Neuropeptides of the ‘insect kinin’ class regulate aspects of digestion and water balance that are critical for insect survival. Research was conducted that demonstrates that stable mimics of this class delivered by oral route interfere with blood feeding of the assassin bug, an insect that transmits Chaga’s disease to humans. The mimics caused a large reduction in the blood meal and the insects failed to molt. The synthetic mimics therefore disrupt normal growth and development in this important transmitter of disease. This discovery provides a template for the design of neuropeptide-like compounds capable of disrupting the critical life function of digestion in these insect pests. This work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling insect pests that transmit deadly diseases in an environmentally friendly fashion.
Technical Abstract: Rhodnius prolixus is a blood-gorging hemipteran that takes blood meals that are approximately 10 times its body weight. This blood meal is crucial for growth and development and is needed to ensure a successful molt into the next instar. Kinins are a multifunctional family of neuropeptides which have been shown to play a role in the control of feeding in a variety of insects. In this study, two biostable Aib-containing kinin analogs were tested to see if they interfere with blood-feeding and subsequent development into the next instar. One of the analogs, 1729 (Ac-R[Aib]FF[Aib]WGa), had no effect on the size of the blood meal or on the subsequent molting of the insect into the next instar. This analog also did not interfere with either short-term or long-term diuresis. The second analog, 1728 ([Aib]FF[Aib]WGa), appeared to be an ant¬¬ifeedant. Insects feeding on blood containing this analog (15 uM) only consumed 60% of the blood meal taken by insects fed on blood without analog. Insects feeding on blood containing 1728 had a slower rate of rapid diuresis (diuresis in the first 3-5 h after feeding) leading to less urine being excreted by 5 days post feeding. The consequence of these effects was that insects fed on 1728 did not molt. This data indicates that the biostable Aib-containing analog 1728 disrupts normal growth and development in the blood-feeding insect, R. prolixus.