Starvation-induced lipid reserve depletion in Pratylenchus brachyurus leads to decreased infectivity in maize roots

Abstract

Nematode body neutral lipid (triacylglycerol) content has been related to infectivity and has direct implications in control strategies. In this study, Pratylenchus brachyurus populations were split into two groups: i) freshly hatched second-stage juveniles (J2) containing lipids stored during embryogenesis; ii) third- and fourth-stage juveniles (J3/J4) plus females that replenished their lipid reserves by feeding on maize (Zea mays) roots. These groups were subjected to starvation to study their lipid consumption dynamics by staining with Oil Red O, which binds specifically to neutral lipids. Before starvation, freshly hatched J2 had 27% of their body area stained, whereas J3/J4 and females had 75%. Freshly hatched J2 starved for 28 days at 25°C in water lost 63.8% of the original neutral lipid content, which caused a reduction of 91% of infectivity in maize roots. By contrast, J3/J4 and females exposed to the same conditions lost 56.7% of the original neutral lipid content, which resulted in less than 50% reduction in infectivity. During the period of food deprivation, J2 had a mean daily neutral lipid consumption rate of 0.63% and the other infectious stages (J3/J4 and females) had a mean daily neutral lipid consumption rate of 1.46% per day. This study adds information on the dynamics of lipid utilisation that supports the use of longer waiting periods for planting crops after fallow in soils infested with P. brachyurus as compared to Meloidogyne spp.-infested soils.