Double cuticle barrier in two global pests, the whiteflyTrialeurodes vaporariorumand the bedbugCimex lectularius

Abstract

The integument protects the organism against penetration of xenobiotics and water that would potentially interfere with homeostasis. In insects that play key roles in a variety of agricultural and ecological habitats, this inward barrier has barely been investigated. In order to advance knowledge in this field, we studied integumental barrier (cuticle) permeability in the two global pests Trialeurodes vaporariorum (greenhouse whitefly) and Cimex lectularius (bedbug), applying a simple dye-penetration assay. In agreement with our recent findings in Drosophila melanogaster, we show that the surface of these insects is regionalised. We also show that, in contrast to the single barrier in D. melanogaster, two barriers with distinct temperature-sensitive and lipid-based physico-chemical material properties act in parallel to protect these insects against penetration of hydrophilic molecules. These findings imply the existence of unexplored mechanisms by which the cuticle acts as a protective coat against the penetration of water and xenobiotics, including pollutants and insecticides.

Involvement of integument‐rich CYP4G19 in hydrocarbon biosynthesis and cuticular penetration resistance in Blattella germanica (L.)

“…Cuticular permeability can be determined by a new in situ staining method using the inert dye of Eosin Y under light microscopy . The ability of insects to take up Eosin Y reflects cuticle barrier function at the tissue level …”

“…21 The ability of insects to take up Eosin Y reflects cuticle barrier function at the tissue level. 21,22 The German cockroach, Blattella germanica (L.) is an obligate household pest worldwide. They harbor and transmit human enteric pathogens, trigger asthma, 23,24 and have been targeted with various insecticides.…”

The composition of lipid profiles in different developmental stages of Dermestes ater and Dermestes maculatus and their susceptibility to the entomopathogenic fungus Conidiobolus coronatus

“…The way fungi infect insects is made up of several stages including: (1) spore germination on the cuticle of the insect, (2) formation of the invasive structures disrupting cuticle with the help of enzymes (proteases, chitinases, and lipases) degrading the main components of the cuticle such as proteins, chitin and lipids, (3) colonization of the body cavity, and (4) the formation of spores on the insect's surface allowing fungus to spread in the environment (Gillespie et al 2000;Ortiz-Urquiza and Keyhani 2013). The defense of insects against the attack of pathogenic fungi takes place with the help of an immune system equipped with hemocytes (insect immunocompetent cells) and numerous antimicrobial peptides, but the main line of defense is the cuticle, which outer layer is covered with lipids (Vilcinskas and Götz 1999;Wojda et al 2009;Boguś et al 2007;Wang et al 2017). Structure and chemical composition of insect cuticle is very heterogeneous and depends on species and developmental stage of insects (Andersen 2012).…”

The C-type lectin Schlaff ensures epidermal barrier compactness inDrosophila

“…To further inspect cuticle barrier integrity, we performed a dye penetration assay that we had developed recently (Wang et al, 2017a; Wang et al, 2016). Incubation of wild-type, slf and alas mutant ready-to-hatch embryos with bromophenol blue does not result in dye uptake, while snurstorr snarlik ( snsl ) mutant animals with a defective envelope (Zuber et al, 2018) do so (Fig.…”