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Vol. 48 No. 5, 2009
Natural History and Leaf Shelter Construction of the Asian Rice Leptispa Beetle Leptispa pygmaea Baly (Coleoptera: Chrysomelidae: Cassidinae: Leptispini)
Kaniyarikkal Divakaran Prathapan1, Caroline S. Chaboo2,*, and Kolandaivelu Karthikeyan3
1Department
of Entomology, Kerala Agricultural University, Vellayani P.O.,
Trivandrum 695 522, Kerala, India
E-mail:prathapankd@gmail.com
2Division of
Entomology, Natural History Museum, and Department of Ecology &
Evolutionary Biology, 1501 Crestline Dr., Suite 140, University of
Kansas, Lawrence, KS 66049-2811, USA. E-mail:cschaboo@ku.edu
3Regional
Agricultural Research Station, Kerala Agricultural University,
Pattambi, Palakkad 679 306, Kerala, India
E-mail:profkarthi@yahoo.co.in
Kaniyarikkal Divakaran Prathapan, Caroline S. Chaboo, and Kolandaivelu Karthikeyan (2009) W.The leaf-roll construction by the Asian rice leptispa beetle Leptispa pygmaea Baly (Cassidinae: Leptispini) was studied. Consistent adult feeding on the adaxial side of tender rice leaves Oryza sativa
Linnaeus (Poaceae) induces partial upward rolling of the leaf
lamina. Adult leaf rolls are ephemeral and not apparent, and they
unfurl once the beetle leaves the leaf. Females oviposit clutches
of up to 8 eggs mostly on the adaxial side of the leaf within such
rolls. Neonate larvae migrate to the base of the leaf axil and
feed by scraping, which induces formation of leaf rolls from the base
where the leaf is already curled up. All 5 larval instars feed in
this manner, migrating to new leaves and forming new leaf rolls.
Pupation occurs within the leaf roll of the 5th instar. Adult
leaf rolls are partial and ephemeral, and therefore offer only limited
protection to eggs and adults. In contrast, larval leaf rolls are
well formed and cohesive compared to those of adults. This is
probably due to the sedentary nature and active feeding of the larvae
resulting in a greater reduction in leaf turgidity. The host
plant, leaf curling, and leaf-roll architecture of Leptispa Baly differ from the leaf ‘sandwiches’ built by some Neotropical cassidines, of the Imatidiini, that glue together Inga
leaves (Fabaceae). Two terms, leaf rolls for Leptispini and leaf
case shelters for Imatidiini, are proposed to reflect the lack of
homology of these structures, although both function as shelters.
We also propose that Leptispa
feeding probably induces loss of turgor pressure that in turn induces
inward curling of the leaf to produce an elongated leaf roll.
This may be regarded as an ideal example of cost-effective shelter
building by an insect.
Key words: Behavior, Animal architecture, Larva, Poaceae, Asia.
*Correspondence: Tel: 785-864-5173. Fax: 785-864-5260.
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