|MITCHELL, PAULA - Winthrop University|
|ZEILINGER, ADAM - University Of California|
|Medrano, Enrique - Gino|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 9/30/2017
Publication Date: 2/16/2018
Citation: Mitchell, P.L., Zeilinger, A., Medrano, E.G., Esquivel, J.F. 2018. Pentatomoids as vectors of plant pathogens. In: J.E. McPherson, editor. Invasive Stink Bugs and Related Species (Pentatomoidea): Biology, Higher Systematics, Semiochemistry, and Management. Boca Raton, FL: CRC Press. p. 611-640.
Interpretive Summary: It is broadly known that insects that feed via a piercing-sucking mechanism can vector host pathogens resulting in disease (example: mosquito-malaria transmission). In this book chapter, we discuss the types of relationships between stink bugs that utilize a piercing-sucking apparatus to feed and the plant pathogens that they introduce into cultured crops including cotton. The three basic vector-pathogen interactions include: 1) non-persistent or transient pathogen carriers where the pathogen is lost soon after being acquired; 2) semi-persistent carriers that may be infested with the plant pathogen for their lifespan; and 3) persistent carriers that retain the pathogens and may pass them on to their progeny. Based on the current literature, stink bug species that are cotton pests fall into the semi-persistent mode of transmission category since laboratory-reared insects are cotton “pathogen-free.” Notably, feeding by insects not harboring a pathogen is tolerated by the cotton bolls and disease does not occur. Therefore, we are currently studying the vector-pathogen relationship in order to identify cotton pathogen-infested stink bugs in the field to assist producers in making informed pesticide application decisions.
Technical Abstract: Vector-borne pathogens can be categorized functionally according to the degree of symbiosis that they acquire with their respective vectors. Three modes of transmission have been broadly described: non-persistent, semi-persistent, and persistent. Originally compiled specifically for viruses transmitted by sternorrhynchan and auchenorrhynchan vectors, they can usefully be applied to all taxa of microbial pathogens and hemipteran vectors. The differences in persistence among different transmission forms are directly related to which vector tissue(s) are colonized by the pathogen. The three modes of transmission mentioned above are quite different. Pathogens transmitted in a non-persistent manner tend to colonize the stylets of hemipteran vectors and generally require only brief periods to be acquired by vectors and to inoculate subsequent hosts (on the order of minutes); infectiousness is also lost quickly by vectors thereby requiring the vectors to move quickly from infected to healthy hosts. Semi-persistent pathogens colonize the foregut of their vectors; as a consequence, acquisition and inoculation access periods are longer and vectors remain infective for longer periods of time. Bacterial pathogens such as Xylella fastidiosa (Wells) that colonize the foregut are considered semi-persistent as infections are lost by nymphal vectors when they molt; subsequent infections of adults are nonetheless lifelong. Finally, persistent pathogens colonize vector tissues more systemically, colonizing the digestive system and haemocoel. Importantly, salivary glands eventually are colonized from which inoculation of hosts occurs. In addition, subsets of persistent pathogens also multiply in the tissues of vectors; these “persistent-propagative” pathogens often are transovarially transmitted as well. Although transmission modes can be useful for understanding vector-pathogen relationships, they also relate to patterns of induced phenotypic changes in host plants, are a conserved trait within virus taxa, and define the epidemiology of associated diseases.