Oviposition site selection on oats: the effect of plant architecture, plant and leaf age, tissue toughness, and hardness on cereal leaf beetle, Oulema melanopus

Abstract

In sequentially planted oat stands, the cereal leaf beetle (CLB), Oulema melanopus (L.) (Coleoptera: Chrysomelidae: Lemini), is found in greater numbers, and lays more eggs, on later planted (younger) oats (Avena sativa L.) (Poaceae). Plant characteristics that could explain this ovipositional preference were examined in a series of experiments. Cage and open field whole plant preference tests confirmed the attraction of ovipositing females to younger oats. A cage effect illustrated the role of plant architecture (plant height) in CLB host selection. Two multiple‐choice and one no‐choice excised leaf experiments determined that characteristics of individual leaves associated with leaf insertion level (leaf number from base to apex) and age influence ovipositional site selection. Leaves of higher insertion level have higher nitrogen content, but fewer eggs are laid on those leaves. Two experiments examining the interaction between total leaf nitrogen and leaf insertion level showed that only leaf insertion level affected oviposition choice. Published literature suggests variation in secondary plant compounds cannot explain O. melanopus ovipositional preference among leaves. Grass leaves of higher insertion level have more extensively developed cells associated with tissue toughness and hardness. The data and supporting literature suggest tissue toughness and hardness are deterring oviposition on oat leaves of higher insertion level. However, newly eclosed larvae are able to feed on leaves usually avoided as oviposition sites. The explanation for this result may be a lack of correlation between host suitability and ovipositional preference.

Laboratory and field tests of predation on the cereal leaf beetle, Oulema melanopus (Coleoptera: Chrysomelidae)

“…Several researchers have investigated the biology and field dynamics of CLB across different regions and agro-ecosystems, including southern Alberta (Gutierrez et al, 1974;Hoffman & Rao, 2011;Kher et al, 2016). Cereal leaf beetle has one generation per year in Alberta (Kher et al, 2011), but a second generation has been reported in Virginia (McPherson, 1983b).…”

“…Plant quality and characteristics are shown to affect CLB fecundity. For instance, Hoffman and Rao (2011) found that CLB laid more eggs on younger (later planted) oat plant leaves, and were deterred from laying eggs on older oat plants. The same authors also reported that females laid more eggs on younger and lower tiller leaves compared with flag leaves.…”

Complex tritrophic interactions in response to crop domestication: predictions from the wild

“…Crop domestication also frequently selects for the enlargement of economically important structures (Meyer et al, ), which may lead to higher herbivore attack rates because insect herbivores tend to lay more eggs on larger plants or on more rapidly growing structures (Craig et al., ; Awmack & Leather, ; Ishino et al., ). Therefore, artificial selection on plant morphology and chemistry can alter the abundance and within‐plant distribution of insect herbivores (Chen & Welter, ; Michaud & Grant, ; Hoffman & Rao, ). Once nymphs or larvae are feeding on a plant, variation in the chemical resistance and nutritional quality may strongly affect the likelihood of insect herbivore survival and developmental rate (Chen & Welter, ; Harvey & Gols, ; Zaugg et al., ).…”

The Influence of Maturity and Variety of Potato Plants on Oviposition and Probing ofBactericera cockerelli(Hemiptera: Triozidae)

“…A core element of P-P is the fact that immature stages of herbivores often have limited mobility and subsequently will be forced to feed from those plants on which they emerge, and thus a female should choose plants on which larvae will best survive and develop. However, because fecundity is often associated with the nutritional quality of host plants (Heisswolf et al 2005), studies of P-P have also been known to incorporate adult feeding behavior (Coyle et al 2011, Hoffman andRao 2011).…”