Evaluation of damage of some food commodities by larger grain borer–Prostephanus truncatus(Horn) {Coleoptera: Bostrichidae} and microbial composition of frass induced by the insect

Abstract

The microbial composition of the frass from maize (Zea mays) grains and seven dried root and tuber crops (R&TC) infested by Prostephanus truncatus were evaluated. Five cubes (6 cm 3 ) of each R&TC as well as 100 g of maize grains were separately infested with 15 pairs of 1-2 day old adult LGB in 250 cm 3 sized Kilner jars and incubated for 90 days at 28 + 18C and 79-82% RH. At 90 days post-infestation, the microbiological assay of frass from the commodities was performed. The results indicated the presence of 10 bacterial species, namely Bacillus cereus, B. macerans, Proteus mirabilis, P. morganic, P. rettgeri, Proteus sp., Pseud geniculatum, Pseud fragii, Pseud putela, Serratia marcences and six fungal species, namely Aspergillus niger, A. tamari, A. parasiticus, A. ochraceus, Fusarium compacticum and F. oxysporum. Infested cubes of M. esculenta have the highest population of adult LGB (168.3) and frass from its damaged cubes had the highest mean bacterial count of 30.0 6 10 7 colony forming units (CFU) and it was significantly (P 5 0.05) higher than LGB infestation and bacterial infection of other R&TC. The bacterial count from the damaged commodities correlated positively and significantly (P 5 0.05) with weight of frass, percentage damage and percentage weight loss. The results revealed that frass from the LGB-infested and damaged commodities were infected by bacteria and fungi. Maize grains and dried R&TC should therefore be protected from LGB infestation to avoid quantity reduction and microbial infection.

Correlation of Chemical Compositions of Cassava Varieties to Their Resistance to Prostephanus truncatus Horn (Coleoptera: Bostrichidae)

“…(1996) report the ability of the adult beetle of P. truncatus and its larval stages to damage wide range of commodities including some roots and tubers, cereals, pulses, cocoa, coffee, groundnut, and wooden structures. Similarly, Nyakunga (1982) and Osipitan et al . (2011) also reported the ability of P. truncatus to damage and breed on dried root and tuber crops.…”

“…Although no preferred breeding sites have yet been discovered, laboratory tests show that P. truncatus is able to breed successfully on dried wood from a range of trees, as well as the dried stems of cassava and maize plants ( Nansen et al. 2004 , Osipitan et al. 2011 ).…”

Modeling the potential range expansion of larger grain borer, Prostephanus truncatus (Coleoptera: Bostrichidae)

“…Both models consistently identified tropical and sub-tropical areas as climatically highly-suitable for establishment of P. truncatus . This is important because cassava is a primary crop in the tropics and subtropics, and many of the publications documenting the rapid spread and dispersal of P. truncatus in Africa cite the species’ quick adaptation to cassava as an alternate agricultural host as a primary contributing factor 15,55 . In Africa, infestations often occur when cassava is stored as dried chips.…”

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

“…Biotic interactions are much more complex and dynamic (Arbogast and Mullen, 1988) since they usually involve multiple relationships among arthropods, microorganisms, and different types of stored commodities (Crombie, 1941; Sinha, 1969; LeCato, 1975; Sinha and Sinha, 1990; Dukic et al ., 2016; Fleurat-Lessard, 2017; Rumbos et al ., 2019). Complexity is also increased by diverse arthropod reactions to chemical changes in grain caused by previous grain infestations (e.g., Stewart-Jones et al ., 2004; Trematerra, et al ., 2007; Stewart-Jones et al ., 2009) and the effects associated with the gut enzymes and microbiome composition of arthropods (e.g., Osipitan et al ., 2011; Hubert et al ., 2016; Naseri et al ., 2017).…”

“…Earlier resources claimed (e.g., Potter, 1935) that frass of R. dominica mainly consists of food material that is chewed off but not eaten. It is currently known that frass contains not only the original non-ingested food material (grain) itself, but also faeces and additional components such as microorganisms and various chemical compounds (Breese, 1960; Osipitan et al ., 2011; Edde, 2012; Boiocchi et al ., 2017). Several previously published works (e.g., Bekon and Fleurat-Lessard, 1992; Kavallieratos et al ., 2017) listed frass of primary colonizers among the factors positively influencing colonization and population performance of secondary colonizers.…”