Japanese Papilio butterflies puddle using Na+ detected by contact chemosensilla in the proboscis

Abstract

Many butterflies acquire nutrients from non-nectar sources such as puddles. To better understand how male Papilio butterflies identify suitable sites for puddling, we used behavioral and electrophysiological methods to examine the responses of Japanese Papilio butterflies to Na+, K+, Ca2+, and Mg2+. Based on behavioral analyses, these butterflies preferred a 10-mM Na+ solution to K+, Ca2+, and Mg2+ solutions of the same concentration and among a tested range of 1 mM to 1 M NaCl. We also measured the ion concentrations of solutions sampled from puddling sites in the field. Na+ concentrations of the samples were up to 6 mM, slightly lower than that preferred by butterflies in the behavioral experiments. Butterflies that sipped the 10 mM Na+ solution from the experimental trays did not continue to puddle on the ground. Additionally, butterflies puddled at sites where the concentrations of K+, Ca2+, and/or Mg2+ were higher than that of Na+. This suggests that K+, Ca2+, and Mg2+ do not interfere with the detection of Na+ by the Papilio butterfly. Using an electrophysiological method, tip recordings, receptor neurons in contact chemosensilla inside the proboscis evoked regularly firing impulses to 1, 10, and 100 mM NaCl solutions but not to CaCl2 or MgCl2. The dose–response patterns to the NaCl solutions were different among the neurons, which were classified into three types. These results showed that Japanese Papilio butterflies puddle using Na+ detected by the contact chemosensilla in the proboscis, which measure its concentration.Electronic supplementary materialThe online version of this article (doi:10.1007/s00114-012-0976-3) contains supplementary material, which is available to authorized users.

Anthropogenic changes in sodium affect neural and muscle development in butterflies

“…We already see evidence of altered foraging behavior in some species-ants that live closer to roads forage less actively for sodium than those farther from the road (36), and moose also show some preference for roadside ponds because of salt runoff (35). Given that butterflies and moths can detect sodium concentration through contact chemoreceptors (62,63), it is possible that they are also showing changes in foraging behavior. This observation raises the question of whether a thirst for a micronutrient, such as sodium, could lead to increased preference for roadside habitats.…”

K+ Excretion: The Other Purpose for Puddling Behavior in Japanese Papilio Butterflies

“…The fluid samples were stored at -20°C until analysis. As described in [ 5 ], the fluid samples were analyzed with ion chromatography using a PU2080i solvent delivery pump (JASCO, Tokyo, Japan), a JASCO CO-2060 column oven, a CD-5 conductometric detector (Shodex, Kawasaki, Japan), and a JASCO DG-2080-53 online degasser. The separations were achieved on a 4.6-mm ID × 125-mm length fused silica gel column coated with a carboxylic polymer (Shodex IC Y-421) using a guard column (Shodex IC YK-G).…”

“…Previous research has shown that the taste of Na + induces puddling in Papilio glaucus in North America [ 1 ]; Pieris rapae in North America [ 2 ]; Papilio helenus and P . memnon in Borneo, Malaysia [ 3 ]; one of the Papilio machaon group of species in North America [ 4 ]; and in all the Papilio species on the main islands of Japan [ 5 ]. The transference of Na + from male butterflies to females during mating has also been observed [ 6 – 10 ]; hence, it has been suggested that the purpose of puddling is to absorb Na + to enhance fertility.…”

“…We photographed many Southeast Asian Danaidae butterflies, particularly of the genera Tirumala and Euploea , attempting to sip liquid from wet concrete walls or rocks, and some Japanese Lycaenidae butterflies, primarily Celastrina spp., sipping water from wet ash. Papilio males have also been observed to puddle in wet ash [ 5 ]. These butterflies appear to be absorbing substances other than Na + because plant ash contains little Na + , and we surmised that Papilio butterflies might absorb other substances along with Na + .…”

“…machaon in the field is rare compared with that of other Japanese Papilio species, although P . machaon is one of the most common butterfly species in Japan and its taste preferences are the same as those of other Papilio species [ 5 ]. P .…”