Differences in morphology and reproductive traits of Galerucella nymphaeae from four host plant species

Abstract

The water lily beetle Galerucella nymphaeae L. (Coleoptera: Chrysomelidae) exploits different hosts, including Nuphar lutea Sm. and Nymphaea alba L. (both Nymphaeaceae), as well as Polygonum amphibium L. and Rumex hydrolapathum Hudson (both Polygonaceae). The present study investigates whether within‐species differences in morphological and reproductive traits are associated with differences in host species exploitation. A total of 1103 adult beetles were collected from 11 localities in The Netherlands, one of which contained all four hosts and three other localities contained hosts from both families (sympatric localities). Adults originating from Nuphar and Nymphaea were on average darker in colour and larger in size and had disproportionally bigger mandibles than beetles originating from Polygonum and Rumex across the 11 localities. Head capsules of first instar larvae from Nymphaeaceae hosts were between 17% and 28% larger than those of larvae from Polygonaceae hosts. Furthermore, beetles from Nuphar and Nymphaea laid larger sized eggs, but fewer eggs per clutch than beetles originating from Polygonum and Rumex. Although host related variation was less pronounced at the sympatric localities than in the allopatric localities, differences in larval and adult size were still highly significant at the sympatric localities. It is not clear whether the observed differences are genetically based, as opposed to host induced. However, leaf toughness varied among species in a way suggesting that leaf toughness may be partly responsible for host related differences in G. nymphaeae.

Host preference and larval performance suggest host race formation in Galerucella nymphaeae

“…The results on preference and performance agree closely with previous data from beetle morphology (Pappers et al 2001): both sets of traits distinguish two groups. The bigger and darker beetles live on Nymphaeaceae and show a feeding and oviposition preference for Nymphaeaceae hosts.…”

“…The average head capsule width of first-instar larvae collected on Nymphaeaceae is on average also larger than that of larvae collected on Polygonaceae. Beetles from Nuphar and Nymphaea lay larger eggs and have a smaller clutch size than beetles from Rumex and Polygonum (Pappers et al 2001).…”

“…The aquatic form produces hairless floating leaves, whereas the terrestrial form has erect hairy leaves. Previous results showed that these four hosts differ in leaf toughness as measured with penetrometer-like equipment, Nuphar having the toughest leaves and Polygonum (the aquatic form), the least tough leaves (Pappers et al 2001).…”

“…G. nymphaeae is a good candidate for host race formation since it is a polyphagous herbivorous beetle living on at least four different host plants in the Netherlands (Laboisière 1934;Lohse 1989): Nuphar lutea, Nymphaea alba (both Nymphaeaceae), Rumex hydrolapathum and Polygonum amphibium (both Polygonaceae). Previous results showed that beetles from Nymphaeaceae hosts differ in morphology from beetles collected on Polygonaceae hosts (Pappers et al 2001). Preliminary results on breeding beetles from different hosts in the laboratory revealed that they mated freely and produced viable and fertile offspring (personal observation), indicating that they belong to the same biological species (Mayr 1942).…”

Effect of a vitamin supplement and three species of food plants (Fabaceae) on the production of Morpho helenor butterflies (Nymphalidae:Lepidoptera)

“…El tamaño de la capsula cefálica para las orugas de Morpho helenor utilizadas en esta investigación fueron influenciadas por la alimentación, al igual que lo mencionado por otros autores (Savopoulou-Soultani & Tzanakakis, 1990;Goldson, McNeill, Proffitt & Baird, 2001;Pappers, Dommelen, Velde & Ouborg, 2001). Otros factores que pueden influenciar en el crecimiento de los insectos son la temporada, la generación, el parasitismo, sexo y temperatura (Nealis, 1987;Margaix & Garrido, 2000;Frouz, Ali & Lobinske, 2002).…”