The RPW and SAPW as vectors of nematodes

Adults of Rhynchophorus, both ferrugineus (Olivier, 1790; RPW) and palmarum (Linnaeus, 1758; SAPW) (Coleoptera: Curculonidae) usually carry several associate or symbiotic organisms. We present evidences of nematodes regularly found and born by RPW females. In this contribution we consider the presence of paired pouches, which open on both sides of the membranes between the spiculum ventrale and vaginal base. Such structures, never observed previously, can be inflated and everted by injecting and pressuring the weevil with human physiological solution. In vivo and EtOH study by macrophotography, stereoscopy, bright field light microscopy LM, SEM and Cryo-SEM shows microtrichia-decorated ventral membrane and somewhat sclerotized dorsal cuticle. The cuticle is pitted by single or grouped apparent duct openings. Such openings may correspond to gland outlets and are served either by a pore-channeled sieve or by a long and ducted end-apparatus, on the body side of cuticle. Study of tenth of just cached vagrant wild RPW females reports the regular presence of a number of living nematodes aggregated inside the pouches, and the active dispersion of the worms when disturbed during the weevil genitalia dissection. These nematodes have been isolated and molecularly identified as Monochoides macrospiculum, by sequencing the D2-D3 expansion domains of the 28S rRNA gene. This finding confirms previous observations that the nematode reproduce in the body of RPW and the close association with RPW.In the case of R. palmarum, there was a related association with the nematode Bursaphelencus cocophilus. Dauer juveniles can be found in the tracheal sacs and move to the ovipositor of females to be injected into host palm to induce the red ring disease (RRD). In the same way B. cocophilus, Teratorhabditis palmarum and Diplogasteritus sp. (syn. Acrostichus rhynchophori), nematode species that co-participates of the etiology of RRD in coconut palms in Brazil, cohabit into the insect digestive tract (gut) and fecal material, as from studies with LM and SEM. Dauer juveniles of T. palmarum were also recovered from the excised genital capsules of newly emerged female weevils. More recently, the nematode B. fungivorus was found affecting coconut palms in the state of Para in Brazil, co-determining the RRD. In America, dauer juveniles of RPW could spread the RRD in healthy palms, by using the same mechanism of infection of R. palmarum. Evidences suggest a close interrelationship between the weevils and proper species of nematodes, that will be demonstrated in future studies. By the time, authors speculate about the synecological role of the nematodes and the consequence on damages inflicted to infested host palms, in connection with eventual further plant pathogenic partners. The given evidences enforce the presumed weevils vector role and suggests to consider the story of RPW not the introduction and subsequent invasion of a single species, but the biologically coordinated actions of a guild of symbionts.