Novel In vitro Procedures for Rearing a Root-Feeding Pest (Heteronychus arator) of Grasslands

Abstract

Optimizing plant protection against insect herbivory relies on testing plant defense mechanisms and how the insect response to these defensive strategies. Such experiments benefit from using insects generated from standardized rearing protocols since this reduces stochastic variation. Such protocols can be challenging to devise, however, especially for root herbivores. These insects generally have complex and long life cycles, which are often only poorly described. Moreover, using field-captured root herbivores is often suboptimal because it involves extensive excavation from sites selected by chance (their location is not obvious) and larval stages are frequently indistinguishable beyond the family level. We investigated in vitro procedures to improve the availability of the African Black Beetle (ABB) Heteronychus arator, an invasive alien pest in both Australia and New Zealand. Native to Africa, this scarab beetle has established in Australian and New Zealand grasslands, pastures, and crops. Adults feed on the stem of young plants just beneath the soil surface. During the mating season, gravid females lay eggs in the soil, giving rise to larvae feeding on grass roots, causing severe damage, and impairing plant growth. Here, we propose laboratory approaches to collect eggs from field-captured adult beetles, to hatch eggs, and to rear neonate larvae to adults. We propose that these methods will provide plant scientists and entomologists with a better and more controlled supply of ABB larvae for laboratory and field assays. In turn, this will assist with the collection of important information for the management of this insect pest and enhanced protection of plants in crop and grassland ecosystems.

Silicon supplementation and jasmonate activation synergistically increase phenolic defences against a legume herbivore

“…Dried leaf material was separated from stems and ball-milled to a fine powder prior to chemical analyses. Total Si concentrations (% of dry mass) were determined from all 128 plants with an X-ray fluorescence spectrometer (Epsilon-3x, PANalytical, EA Almelo, The Netherlands) using small mass holders, following the protocol described by Hiltpold et al . (2016).…”

Climatic Drivers of Silicon Accumulation in a Model Grass Operate in Low- but Not High-Silicon Soils

“…We determined leaf Si concentrations using ca. 100 mg of ground shoot tissue placed into small receptacles (Malvern PANalytical, Malvern UK), which were then analysed with an X-ray fluorescence spectrometer (Epsilon 3×, PANalytical) using the procedure and certified reference material described in Hiltpold et al [40]. This method was based on the methodology developed by Reidinger, et al [41].…”

A method for rearing and assessing the health of the sugarcane pestDermolepida albohirtum(Coleoptera: Scarabaeidae)

“…Some rootfeeding scarabs (e.g., New Zealand grass grub: Costelytra zealandica, European cockchafer: Melolontha melolontha, pine chafer: Polyphylla fullo, and H. arator) kept in the laboratory have commonly been fed with pieces of vegetables (e.g., potato tuber and pieces of carrots) or grassroots as a cheap and convenient alternative to artificial diets (Egert et al, 2005;Erler & Ozgur Ates, 2015;Fowler, 1974;King et al, 1981). However, in the case of bioassays, it is preferable to feed insects with a chemically defined artificial diet which maximises their development and health as pieces of vegetable and grassroots may be suboptimal feeding options (Archibald et al, 1975;Hiltpold et al, 2016). Additionally, artificial diets, which are chemically defined, are better suited for comparative bioassays as the nutritional value of vegetables and grassroots may vary depending on the variety used and the growing conditions, affecting the repeatability of assays.…”