Temperature-Mediated Competition Between the Invasive Larger Grain Borer (Coleoptera: Bostrichidae) and the Cosmopolitan Maize Weevil (Coleoptera: Curculionidae)

Abstract

Interspecific competition between agricultural pests may affect the species that can establish, and may also affect food production. Prostephanus truncatus (Horn), the larger grain borer, is endemic to Central America, but invaded Africa with disastrous consequences for maize production. Its main competitor is Sitophilus zeamais Motschulsky, the maize weevil, which is cosmopolitan. These insects co-occur in many regions of the world and both are threats to maize. However, the impact of competition between these two species is not well-understood, nor is its effect on grain quality or potential to limit P. truncatus invasion in new areas. The aims of our study were to evaluate the outcome of interspecific competition between P. truncatus and S. zeamais at four different temperatures on a fixed quantity of grain, and determine effects on progeny production, grain damage, and mold growth. We found that coexistence may be possible at a range of 25–30°C, but mixed colonies experienced a direct competitive cost compared to single-species colonies. Prostephanus truncatus performed better at warmer temperatures, while S. zeamais favored cooler temperatures. The majority of grain damage was the result of P. truncatus activity as opposed to S. zeamais. Finally, mold growth was greater where both species were present, and species of mold that produce aflatoxin were identified. Although there are an increasing number of areas where both of these species occur, our results suggest P. truncatus will be capable of destroying much more maize in a shorter period compared to S. zeamais at temperatures greater than 25°C.

A Systematic Review of the Behavioral Responses by Stored-Product Arthropods to Individual or Blends of Microbially Produced Volatile Cues

“…Indeed, an increasing amount of research has demonstrated the importance of stored-product arthropods in mediating the mycoflora present in postharvest environments. For example, feeding by insects such as Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) on grain kernels was shown to provide a favorable environment for the growth of F. verticillioides , as well as promote the production of fumonisin B1 [ 53 , 54 ]. Hotspots of insect infestation in stored grain may significantly elevate the moisture and temperature in the environment, leading to microbial growth and deterioration of the durable commodities [ 55 ].…”

Predicting Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) populations and associated grain damage in smallholder farmers’ maize stores: A machine learning approach

“…This explains our results in the second half of the storage season when insect grain damage and dust quantities had increased. In laboratory experiments conducted with P. truncatus and S. zeamais, it was observed that the latter was AUTHORS ACCEPTED MANUSCRIPT more competitive at lower temperature while the former was responsible for more damage and produced more progeny as temperature rose above 30°C to 35°C (Quellhorst et al, 2019). Similar results were observed in experiments involving P. truncatus and R. dominica with a further observation that that in an enclosure, P. truncatus outcompetes R. dominica in the 30°C to 35°C temperature range, more likely due to P. truncatus having comparatively higher preference for maize grain as a food source than direct competition (Sakka and Athanassiou, 2018).…”

Frass produced by the primary pestRhyzopertha dominicasupports the population growth of the secondary stored product pestsOryzaephilus surinamensis,Tribolium castaneum, andT. confusum

“…It should be mentioned that the recent observations revealed certain beneficial interactions not only between primary and secondary colonisers but also between primary colonizers such as P. truncatus , R. dominica , and Sitophilus spp. (Athanassiou et al ., 2017; Kavallieratos et al ., 2017; Quellhorst et al ., 2020). Frass was also listed among the possible supportive interspecific ecological mechanisms among populations of primary colonisers (Kavallieratos et al ., 2017).…”

“…With the advent of integrated and holistic approaches for commodity protection (Jayas et al ., 1995; White, 1995; Arbogast and Throne, 1997), there has been significant renewed interest in interspecific interactions. Negative interactions, such as predation, parasitism, and competition, are a particular focus of research (Lukas et al ., 2007; Athanassiou et al ., 2017; Quellhorst et al ., 2020). However, interspecific interactions are not necessarily negative.…”