Trophic interaction network and the evolutionary history of Diabroticina beetles (Chrysomelidae: Galerucinae)

Abstract

Understanding the striking diversity of species in the subtribe Diabroticina (Chrysomelidae: Galerucinae: Luperini) is complicated by a lack of ecological and behavioural observations. Adults are mainly pollen feeders and their feeding habits range from highly polyphagous to oligophagous on a single host family. Host breadth for root‐feeding larvae and for adult feeding and oviposition remains largely unknown for the majority of non‐pest species. We used known host plant associations for 43 species of Diabroticina beetles in six genera to summarize trophic interactions between beetles and host plant families. The metrics of ecological network analyses (connectance, modularity, number of interactions and feeding specialization) revealed a heterogeneous pattern of interactions. Most species are connected with few host plants, whereas few species interact with many hosts. A more robust analysis is likely to emerge when a greater representation of neotropical Diabroticina and their host relationships is obtained.

Ecology and Evolutionary History of Diabrotica Beetles—Overview and Update

“…Their distribution and abundance is thus often patchy and restricted to small areas. These habitats are very much in contrast with those used by prairie inhabiting and corn feeding species of the virgifera group, where host plants grow in large, landscape scale monocultures [7,[27][28][29]. For many species, however, the knowledge of non-cultivated host plants remains restricted or unknown, even more so for larval hosts.…”

“…Some species are polyphagous-for example, a number of species in the fucata group-while others show narrow host use-i.e., most species in the virgifera group [8]. Information on host plants, however, remains scarce and difficult to find for most of the Diabroticites that are not of economic importance [7,22]. Diabrotica spp.…”

“…The large diversity of species in this beetle group has been interpreted in different ways based on assumptions of adaptive radiation, coevolution [49], and competitive exclusion plus geomorphological patterns [7,50]. The origin of the Neotropical genus Diabrotica can be dated back to the Cretaceous, and its diversification began about 60 Mya with a peak between 30 and 45 Mya [7].…”

“…The large diversity of species in this beetle group has been interpreted in different ways based on assumptions of adaptive radiation, coevolution [49], and competitive exclusion plus geomorphological patterns [7,50]. The origin of the Neotropical genus Diabrotica can be dated back to the Cretaceous, and its diversification began about 60 Mya with a peak between 30 and 45 Mya [7]. This is much earlier than previously proposed by Metcalf and Lampman [51], who related the diversification in Diabroticite beetles to the agricultural practice of intercropping corn with beans and cucurbits all over the Americas (inter-cropping theory) [34].…”

“…Reliable information on biology, ecology, and above all host plant relationships is scarce or unavailable for many species [7]. To date, most data were published on the few species that are economically important as pest species-namely, Diabrotica balteata Le-Conte, D. barberi Smith & Lawrence, D. undecimpunctata howardi Barber, D. virgifera Le-Conte, and D. speciosa Germar [2,8,9].…”