Species-specific and female host-biased ectophoresy in the roundworm Caenorhabditis japonica

Abstract

Caenorhabditis japonica is a bacteriophagous nematode species that was discovered on the semi-social burrower bug, Parastrachia japonensis, which demonstrates egg-guarding and provisioning behaviors. To understand the life history of C. japonica in relation to P. japonensis, we demonstrated the specificity of this association and fluctuations in nematode number on the insect throughout the year. C. japonica dauer larvae (DL), larvae in a nonfeeding diapause stage, were predominantly found as clumps on the adult female insects but rarely found on the male insects in all populations examined. This female-biased association was consistent throughout the year, but after the nymphs hatched, nematodes were not detected on the mother insects showing provisioning behavior. DL appeared on the nymphs, and the number of DL on the newly emerged female insects gradually increased thereafter. C. japonica has never been detected on other invertebrates collected from the P. japonensis habitat thus far. Our data suggest that the life cycles of C. japonica and P. japonensis are synchronized.

Specialist versus generalist life histories and nucleotide diversity inCaenorhabditisnematodes

“…By contrast, Caenorhabditis japonica, a gonochoristic (i.e. dioecious) species endemic to Japan, forms a specialized phoretic association with its dispersal host, the shield bug Parastrachia japonensis, such that the nematode life cycle synchronizes with that of the insect [39]. The shield bug is also a specialist species, feeding only on the fruits of the tree Schoepfia jasminodora, and having synchronized its own life cycle such that its reproductive period matches fruit availability [40].…”

Conditions for disembarkation of Caenorhabditis japonica from its carrier insect Parastrachia japonensis

“…In our previous studies, we found that C. japonica forms a species-specific and female-host biased phoretic/necromenic association with P. japonensis (Okumura et al, 2013a, b;Yoshiga et al, 2013). The survivorship of C. japonica DL is maintained at high levels over months on P. japonensis while it is low without P. japonensis (Tanaka et al, 2010b(Tanaka et al, , 2012.…”

Species-specific recognition of the carrier insect by dauer larvae of the nematode Caenorhabditis japonica

“…Adult P. (Yoshiga et al, 2013). Erthesina fullo was selected because it was a similar size to that of P. japonensis and it was readily available.…”