Modeling population dynamics of yeast-like symbionts (Ascomycota: Pyrenomycetes: Clavicipitaceae) of the planthopper Delphacodes kuscheli (Hemiptera: Delphacidae). Symbiosis

LILJESTHROM, G.; BRENTASSI, ME; ANA M. MARINO DE REMES LENICOV

SYMBIOSIS

SPRINGER

Lugar: Berlin; Año: 2016

0334-5114

Delphacodes kuscheli establish mutualistic relationshipwith yeast-like symbionts (YLS) that live in the fatbody and are necessary for host survival and reproduction.Weestimated for a host of age t, its body weight, W(t), and thenumber of YLS per host, YLS(t). The host body weight wascalculated as:W(t)=Lm/[1+ e (d?kt)], (Lm= the maximum observedweight,and d and k are constants), and the fat body wasconsidered a fixed proportion ofW(t).We calculated the numberof YLS per unit host body mass: α(t)=YLS(t)/W(t). Wealso calculated the number of YLS per host, cYLS(t), andanalyzed the pattern of variation in both sexes adapting theexpression of the logistic model: cYLS(t)=KNoert/K+(ert -1)No, (No = initial number of YLS, r = intrinsic per capita rateof natural increase, and K = variable carrying capacity). Infemales the carrying capacity varied according to a constantproportion of the host?s weight:K(t) = αW(t). Inmales α(t) wasconsidered a decreasing function of the host age:K(t) = α(t)W(t). The coefficients No, α, and r were subjectedto parameterization. We found that the patterns of W(t) andYLS(t) of D. kuscheli were similar to other planthoppers. Infemales YLS increased up to the adult stage and thenremained almost constant, varying similarly to individualweight. In males YLS increased up to the 5th instar nymphas the individual weight did, but the number of YLS decreasedin the adult stage and the correlation was not so good. Thecalculated number of YLS per host matches reasonably wellwith the number estimated experimentally both in females andmales. This is the first study that quantified and modeled thedynamics of YLS endosymbionts in a Neotropicalplanthopper pest. The models will be used in future studiesfor better understand the experimental reduction of YLS inyoung nymphal stages.Keywords Argentina . Maize . Yeast-like symbionts .Planthoppers . Delphacodes kuscheli