Belidae (Coleoptera: Curculionoidae)

The Belidae Schoenherr 1826 is one of the eight families of weevil, and contains some of the beetles that obligately pollinate zamiacean and stangeriacean cycads (Crowson, 1991), hence their common name, cycad weevils (I’ve also seen them referred to as “primitive weevils”, a rather inaccurate name). There are ~375 species in 38 genera (Slipinsky, Leschen & Lawrence, 2011). The drawings above (taken and modified from Capinera (2008)) show how diverse they can be.

Geographically, most belids have a disjunct distribution, evidently a relictual one, with most being natively found in South America (Argentina, Chile) and Australia, along with Araucaria trees. There are exceptions and more widespread species.

The family is most likely monophyletic, as supported by both morphology (Marvaldi & Morrone, 2000) and molecules (McKenna et al., 2009; diagram above). Only one thorough study I am aware of has recovered it as diphyletic, Lawrence et al. (2011), although it’s worth noting that the relevant section of the tree was poorly-supported and so is open to error.

Their relatively basal position is seen most clearly in the mouthparts. They are the most basal family to have the characteristic female rostrum formed by the fusion of the labrum and clypeus; this enables them to pierce through plant tissues. They lay their eggs inside, and the legless larvae can then develop completely inside the plant. The larvae are also unique in that their anus has three lobes and is shaped like a T or a Y (Lawrence, 1991); I don’t know the phylogenetic significance of this trait, or even if it’s apomorphic.

Assuming the Belidae are monophyletic, they also always come out in the same spot on the weevil family tree, as more derived than the Nemonychidae and Anthribidae (i.e. the sister to Curculionoidea, excluding those two families).

Consult Marvaldi et al. (2006) for reliable information on their taxonomy. There are two subfamilies: the Belinae and the Oxycoryninae. The former is found mostly in Australia, the latter worldwide, including Argentina, where they’re associated with parasitic hydnoraceaean plants (Kuschel, 1995).

Another subfamily, the Aglycyredinae, was found by Kuschel (1995) to be in the Belidae, but they are now accepted as being nested within the Oxycoryninae (Marvaldi et al., 2006).

Ecology-wise, they’re found associated with fern, gymnosperms (incl. cycads) and, in Australia, on Acacia. They’re most famous for their association with cycads, where some species show remarkable specificity: Norstog et al. (1986) found that members of Rhopalotria mollis only inhabit a couple of male Zami furfuracea (cycad) cones instead of going into all of them. These cones are chosen as soon as the belid finishes pupating, and are always the ones who are almost completely mature, at which time they’re warm and emit an attractive fragrance (Pellmyr et al., 1991). For the first few days, the belids are foundon the outside of the cone, feeding on the sporophyll and mating. During all this activity, they of course get covered in pollen, with several pouches in the mandibles and antennae suggested by Crowson (1991) as being pollen baskets.

After mating is done and the sporophyll is eaten away, the belids disperse to other cones. On the way, some pollen is dropped and if it happens to be in the right place on a female cones, a pollen tube forms and pollination is achieved. Female weevils only go to male cones, where they use their snout to dig a hole in the microsporophyll to lay their eggs in. Oncve they hatch, the larvae will feed only on the parenchyma and storage cells, but not on the pollen; when food runs out, cannibalism ensues. Among their food is a toxic substance, BMAA (Vovides, 1991), which is excreted; the excrement is used to build the pupation coccoon and is also toxic, perhaps providing protection from potential predators (Vovides et al., 1993).

This is the life cycle of R. mollis on Z. furfuracea, the most well-studied beetle-cycad system; further study includes things like finding out how the beetles manage to find the cones (how do they identify male vs. female ones, for example), and studying other relationships.

Many belids are Batesian mimics, i.e. non-toxic organisms who mimic toxic ones in a bid to fool a predator into not eating them. They have no sort of chemical defence of their own, so some Australian species mimic local Metriorrhynchus species (Gullan & Cranston, 2005)), brightly coloured lycid beetles that taste bitter and smell noxious.

Fossil-wise, the oldest fossils come from the Jurassic of Karatau, south Kazakhstan, although those early representatives differ so much from the extant members that they’re classified into their own subfamilies (Zherikhin & Gratschev, 1995). Their record continues in the earliest Cretaceous of the Crato Formation, northern Brazil and of Sierra del Montsec, Spain (Whalley & Jarzembowski, 1985), and again from Mid-Cretaceous French amber (Soriano, 2009; pictured above). They are often implicated in discussions on Mesozoic gymnosperm pollination: being one of the few modern gymnosperm-associated insects, it is possible that prior to the cycads, they could have been pollinating the benettitaleans (Labandeira et al., 2007). In fact, the Cretaceous belids are found associated with cycad plants.

References:

Capinera JL (ed.). 2008. Encyclopedia of Entomology, 2nd ed, Vol. 4.

Crowson RA. 1991. Relationships to cycads. In: Zunino M, Belles X & Blas M (eds.). Advances in Coleopterology.

Gullan PJ & Cranston PS. 2005. The Insects: An Outline of Entomology.

Kuschel G. 1995. A phylogenetic classification of Curculionoidea to families and subfamilies. Memoirs of the Entomological Society of Washington 14, 5-33.

Labandeira CC, Kvaček J & Mostovski MB. 2007. Pollination drops, pollen, and insect pollination of Mesozoic gymnosperms. Taxon 56, 663-695.

Lawrence JF. 1991. Order Coleoptera. In: Stehr FW (ed.). Immature Insects, Vol. 2.

Lawrence JF, Ślipiński A, Seago AE, Thayer MK, Newton AF & Marvaldi AE. 2011. Phylogeny of the Coleoptera Based on Morphological Characters of Adults and Larvae. Annales Zoologici 61, 1-217.

Marvaldi AE & Morrone JJ. 2000. Phylogenetic systematics of weevils (Coleoptera: Curculionoidea): A reappraisal based on larval and adult morphology. Insect Systematics & Evolution 31, 43-58.

Marvaldi AE, Oberprieler EG, Lyal CHC, Bradbury T & Anderson RS. 2006. Phylogeny of the Oxycoryninae s. l. (Coleoptera Phytophaga) and evolution of plant-weevil interactions. Invertebrate Systematics 20, 447-476.

McKenna DD, Sequeira AS, Marvaldi AE & Farrell BD. 2009. Temporal lags and overlap in the diversification of weevils and flowering plants. PNAS 106, 7083-7088.

Norstog KJ, Stevenson DW & Niklas KJ. 1986. The Role of Beetles in the Pollination of Zamia furfuracea L. fil. (Zamiaceae). Biotropica 18, 300-306.

Pellmyr O, Tang W, Groth I, Bergström G & Thiens LB. 1991. Cycad cone and angiosperm floral volatiles: Inferences for the evolution of insect pollination. Biochemical Systematics and Ecology 19, 623-627.

Schoenherr CJ. 1826. Curculionidum dispositio methodica cum generum characteribus, descriptionibus atque observationibus variis, seu prodromus ad synonymiae insectorum. Partem 4.

Slipinski SA, Leschen RAB & Lawrence JF. 2011. Order Coleoptera. In: Zhang Z-Q (ed.). Animal biodiversity: an outline of higher-level classification and survey of taxonomic richness.

Soriano C. 2009. First record of the family Belidae (Insecta, Coleoptera) in amber. New genus and species from the uppermost Albian amber of France. Geodiversitas 31, 99-104.

Vovides AP. 1991. Cone Idioblasts of Eleven Cycad Genera: Morphology, Distribution, and Significance. Botanical Gazette 152, 91-99.

Vovides AP, Norstog KJ, Fawcett PKS, Duncan MW, Nash RJ & Molsen DV. 1993. Histological changes during maturation in male and female cones of the cycad Zamia furfuracea and their significance in relation to pollination biology. Botanical Journal of the Linnean Society 111, 241-252.

Whalley PES & Jarzembowski EA. 1985. Fossil insects from the Lithographic Limestone of Montsech (late Jurassic-early Cretaceous), Lerida Province, Spain. Bulletin of the British Museum, Geology 38, 381-412.

Zherikhin VV & Gratschev VG. 1995. A comparative study of the hind wing venation of the superfamily Curculionoidea, with phylogenetic implications. In: Pakaluk J & Slipinski SA (eds.). Biology, Phylogeny, and Classification of Coleoptera. Papers Celebrating the 80th Birthday of Roy A. Crowson, Vol. 2.

Zherikhin VV & Gratschev VG. 1997. The Early Cretaceous weevils from Sierra del Montsec, Spain (Insecta: Coleoptera: Curculionoidea). Cretaceous Research 18, 625-632.

Research Blogging necessities :)

Norstog, K., Stevenson, D., & Niklas, K. (1986). The Role of Beetles in the Pollination of Zamia furfuracea L. fil. (Zamiaceae) Biotropica, 18 (4) DOI: 10.2307/2388573

Soriano, C. (2009). First record of the family Belidae (Insecta, Coleoptera) in amber. New genus and species from the uppermost Albian amber of France Geodiversitas, 31 (1), 99-104 DOI: 10.5252/g2009n1a8

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