Spatio-temporal distribution of stored-product insects around food processing and storage facilities

Grain storage and processing facilities consist of a landscape of indoor and outdoor habitats that can potentially support stored-product insect pests, and understanding patterns of species diversity and spatial distribution in the landscape surrounding structures can provide insight into how the outdoor environment can be more effectively monitored and managed. The spatial and temporal distribution of stored-product pests was assessed at three food processing facilities using two types of traps and the influence of landscape features on their outside distribution was evaluated. For corrugated traps, targeting walking individuals, placed both inside and outside facilities, the predominant groups, accounting for 59% of captures, were Cryptolestes spp. (Coleoptera: Laemophloeidae), Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae) and Sitophilus spp. (Coleoptera: Curculionidae). Numbers captured in outside corrugated traps tended to be less than captures inside structures, and while level of species diversity was similar fungal feeding species were more common in outside traps. In outside corrugated traps, Cryptolestes spp., Typhaea stercorea (L.) (Coleoptera: Mycetophagidae) and O. surinamensis were most abundant and in outside Lindgren traps that targeted flying individuals, T. stercorea, Cryptolestes spp. and Ahasverus advena (Waltl) (Coleoptera: Silvanidae) were most abundant. No correlation was observed between total captures and species diversity between inside and outside traps. Distribution of stored-product insects in corrugated traps tended not to be spatially clustered (Global Moranʹs I values ranged from −0.25 to 0.22). However, Anselin local Moranʹs I indicated that at local level some traps with greatest captures had traps in the vicinity with similar values, but these specific locations were temporally variable. Landscape around each outside corrugated trap was characterized, and increased captures were associated with proximity to grain storage or processing structures, but not with presence of spillage as originally hypothesized. Overall, results support hypothesis that there is considerable movement of insects in landscape surrounding facilities, resulting in limited spatial pattern other than temporally variable hot spots inside or near structures.