The biology, ecology, and management of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

Authors: QUELLHORST, HANNAH - Kansas State University; ATHANASSIOU, CHRISTOS - University Of Thessaly; Morrison, William - Rob

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2021
Publication Date: 12/1/2021
Citation: Quellhorst, H., Athanassiou, C.G., Morrison III, W.R. 2021. The biology, ecology, and management of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae). Journal of Stored Products Research. 94. Article e101860. https://doi.org/10.1016/j.jspr.2021.101860.
DOI: https://doi.org/10.1016/j.jspr.2021.101860

Interpretive Summary: The invasive larger grain borer is a devastating pest of maize in Africa where it was accidentally introduced in 1981, and an occasional pest of stored products in Meso-America. Despite an increasing number of publications on this pest in the last 40 years in every decade, this pest is still difficult to manage. This review aimed to synthesize all major areas of research on this pest in a single contribution to provide stakeholders and workers a useful resource to consult when dealing with this pest. We found that larger grain borer has been recorded in 36 countries across the globe, including many in Africa. The range of the larger grain borer is expected to shift with climate change, potentially bringing the US into a higher zone of risk for invasion by this pest, which is considered a pest of concern by USDA APHIS. Adults respond to their two component, male-produced aggregation pheromone early after emergence, but quickly switch to other cues as they age. At close-range, larger grain borer may use food cues, but host volatiles are not involved in long-range host-finding of post-harvest commodities. Very little is known about interactions between larger grain borer and microbes in the food supply. Research on managing larger grain borer has mostly focused on chemical control to the detriment of other tactics. Many outstanding areas of basic behavior and ecology remain to be assessed, and we highlight what these areas are. Overall, our work contributes to an improved understanding of this important invasive stored maize insect.

Technical Abstract: The invasive larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) is a devastating stored product pest of maize and cassava, originating from Meso-America. This species can destroy up to 40% of stored maize after only three months. Despite four decades of research, P. truncatus has spread throughout Africa in its introduced range, while decimating maize production. The goal of this review is to provide an updated and comprehensive record of the distribution, biology, ecology, and management of P. truncatus. We found that P. truncatus has been recorded in 36 countries across the globe, including many in Africa. A recent predictive model found that the insect has been limited to tropical and subtropical regions and could likely spread to temperate regions as temperatures rise with climate change. Despite its preference for food crops, P. truncatus has been found in trees attacked by other insects and can reproduce in a variety of woody hosts. Conspecifics respond to their two component, male-produced aggregation pheromone early after eclosion, but quickly switch to other cues as older adults. At close-range, P. truncatus may use food cues, but host volatiles are not involved in long-range host finding of commodities. Research on managing P. truncatus has mostly focused on chemical control to the detriment of other tactics. Many outstanding areas of basic behavior and ecology remain to be assessed for P. truncatus. We highlight specific areas that should be prioritized for further work in order to better manage and reduce the impact of this invasive insect pest.