A species-specific nematocide that results in terminal embryogenesis

Abstract

Nematode-insect interactions are ubiquitous, complex and constantly changing as the host and nematode coevolve. The entomophilic nematode is found on a myriad beetle species worldwide, although the molecular dynamics of this relationship are largely unknown. To better understand how host cues affect embryogenesis, we characterized the threshold of sensitivity to the pheromone ()-7-tetradecen-2-one (ZTDO) by determining the minimum exposure duration and developmental window that results in embryonic lethality. We found early-stage embryos exposed to volatile ZTDO for as few as 4 h all display terminal embryogenesis, characterized by punctuated development up to 48 h later, with abnormal morphology and limited cavity formation. To determine if the pheromone arrests pre-hatching development by suffocating or permeabilizing the eggshells, we raised embryos under anoxic conditions and also examined eggshell permeability using the lipophilic dye FM4-64. We found that asphyxiating the embryos arrested embryogenesis in a reversible manner but did not phenocopy the effects of ZTDO exposure, whereas the ZTDO-induced disruption of embryogenesis did correlate with increased eggshell permeability. The effects of ZTDO are also highly specific, as other lipid insect compounds do not produce any detectable embryocidal effect. The high specificity and unusual teratogenic effect of ZTDO may be important in mediating the host-nematode relationship by regulating development.

Multidimensional competition of nematodes affects plastic traits in a beetle ecosystem

“…Potentially however, the abundance of bacteria might not be the issue, but the bacterial type, which may explain why P. pacificus is not regularly found on G. bupthalma. In addition, some beetle hosts produce pheromones antagonistic to nematode presence, inducing embryonic arrest and inhibiting dauer exit, that may affect population sizes ( Cinkornpumin et al, 2014 ; Renahan and Hong, 2017 ). Pristionchus pacificus dauers were not as prone to actively disperse as beetle-derived dauers (until t = 6 weeks, they were restricted to the beetle compartment) ( Figure 4 ), suggesting another effect of domestication.…”

Adult Influence on Juvenile Phenotypes by Stage-Specific Pheromone Production

“…Different reproductive strategies also exist, and hermaphroditic species have an advantage over gonochoristic species when colonizing a new niche, such as an insect carcass ( Campos-Herrera, 2015b ). Meanwhile, insect hosts and colonizing nematodes have their own distinct pheromone-based attraction and toxicity ( Cinkornpumin et al., 2014 ; Renahan and Hong, 2017 ). Finally, the renaissance of C. elegans sampling from around the world ( Cook et al., 2017 , Evans et al., 2016 , Félix et al., 2013 , Petersen et al., 2014 , Poullet and Braendle, 2015 ) is rapidly building a resource of wild isolates that will almost certainly have different and fascinating ecologies.…”

Nematode biphasic ‘boom and bust’ dynamics are dependent on host bacterial load while linking dauer and mouth‐form polyphenisms

“…However, whether nematodes are attracted to Oryctes grubs is currently unknown and awaits future investigations. Another P. pacificus host, the oriental beetle Exomala orinetalis, produces a sex pheromone that attracts yet paralyses and arrests various developmental stages of P. pacificus (Cinkornpumin et al, 2014;Renahan and Hong, 2017), though nematodes also rely on olfactory cues to identify hosts (Hong et al, 2008;Dillman et al, 2012a, Dillman et al, 2012b. This antagonism complicates the ability of different worm stages to infect specific beetle stages.…”