Preference and performance of a willow-feeding leaf beetle: soil nutrient and flooding effects on host quality

Abstract

The distribution and abundance of herbivores on plants growing under different environmental conditions may depend upon preference and/or performance. Soil nutrients and water availability are key determinants of herbivore distribution, as both influence plant growth and tissue quality. However, the effects of water on plant quality may depend upon the availability of nutrients and vice versa. Surprisingly few studies have examined the interactions between the two. We investigated the effects of soil nutrient and water availability on (1) the growth and chemistry of the silky willow (Salix sericea Marshall), and (2) the preference and performance of the imported willow leaf beetle (Plagiodera versicolora Laichartig). We conducted two common garden experiments using a similar 2x2 fully factorial design with two levels of soil nutrients (low, high) and two levels of water availability (field capacity, flooded). In the first experiment (larval performance), larval development time and pupal weight were not influenced by nutrient or water availability to the plant. This occurred despite the fact that plants in the high nutrient treatments had higher protein concentration and lower foliar concentrations of the phenolic glycoside 2'-cinnamoylsalicortin. In the second experiment (adult preference), we caged four plants (one from each treatment) and released beetles into cages. We found that plant growth and leaf protein depended upon the interaction between nutrient and water availability. Plant growth was greatest in the high nutrient-field capacity treatment and leaf protein was greatest in the high nutrient-flooded treatment. In contrast, adults settled and oviposited preferentially on the high nutrient treatment under flooded conditions, but we found no evidence of interactions between nutrients and water on preference. Thus, at least under flooded conditions nutrients affect adult preference. We also found that foliar protein was correlated positively with adult oviposition preference and per capita egg production. Our results, then, suggest that soil nutrients can influence adult preference, and that adults choose high-quality hosts (high protein) that promote egg production.

Relationship Between Insect Damage and Chlorophyll Content in Mediterranean Oak Species

“…another, the response mechanisms may be more evident and may include changes in foliage quality and quantity. In this sense, Lower et al (2003) indicated that change in foliage quality could influence a herbivore's ovipositing and feeding preferences, possibly resulting in a change in the intensity of the herbivore attack (Mizumachi et al, 2006). In addition, Compte and Caminero (1982) described a strong relationship between woodborer activity and high incidence of phytophagous (Lepidoptera caterpillar), so that the trees affected by any harmful pest are more vulnerable to suffer a second attack than healthy trees.…”

Biology and Management of Insect Pests in North American Intensively Managed Hardwood Forest Systems,

“…However, tree fertilization under flooded conditions increased adult P. versicolora feeding and oviposition (86). This suggests that adult P. versicolora choose trees with higher-quality foliage for feeding, which in turn encourages egg production.…”

Contribution to the knowledge of development and harmfulness of imported willow leaf beetle (Plagiodera versicolora) (Coleoptera, Chrysomelidae)

“…As already mentioned in the paper introduction the trophic value of leaves (mainly the content of proteins) is mainly dependent on the content of available water and nutrients (eg nitrogen) in soil. Therefore, imagoes more often damage and lay eggs on species with the higher content of proteins in leaves (LOWER et al 2003). In species growing on nutrient-rich sites, the chrysomelid usually has got better conditions for its development and also more frequently exhibits mass outbreaks.…”

“…Effects of nutrition and reserves of water in soil on the growth and content of proteins and phenolglycosides in leaves of S. sericea studied LOWER et al (2003). According to the authors, well supplied species have got the higher content of proteins which supports (in spite of the lower content of phenolglycosides) laying and production of eggs.…”