Notes on the biological development of the darkling beetle Blaps nefrauensis nefrauensis Seidlitz, 1893 (Coleoptera: Tenebrionidae)

Several endemic species of Blaps occur in Tunisia, and the species Blaps nefrauensis nefrauensis has been reported in Moulares (urban zone in west-central Tunisia), where it lives and reproduces in home gardens and old buildings. The aim of this work is to study the life cycle of the darkling beetle, considering both field and laboratory rearing conditions. As a result, the beetle species has different developmental stages (egg, larva, prepupa, pupa, and adult) that last about 15 months. Each year during the same period, adults emerge (early summer) and expire (late autumn), larvae hatch (late summer) and pupate (early summer). There is only one generation per year. Females began laying eggs in late July. The eggs were ovoid, white, and about 2.7 mm in length and 1.5 mm in width. Embryogenesis took an average of nine days. The first instar larvae were at initially only 4.5 mm long and ivory white in color. A brief description of the newly egg hatched larva was provided; thus, the nerve fibers innervating the apical setae in the antennae and ligula were detected. Further light microscopic examination of the embryo before hatching from the egg pointed out that the antennal sensilla are protected during the embryogenesis stage.

Interpopulation Plasticity in a Darkling Beetle Life-History along a Whole Oceanic Island Altitudinal Gradient

Insects show remarkable phenotypic plasticity in response to changing environmental conditions. The abiotic factors that determine their phenotypes often vary in time and space, and oceanic islands harbour ideal environments for testing predictions on this matter. The ubiquitous beetle Pimelia laevigata costipennis Wollaston, 1864 (Tenebrionidae) is distributed over the entire altitudinal gradient of the island El Hierro (Canary archipelago), from 0 to 1501 m above sea level. Here, we examine how environmental factors (i.e., rainfall and temperature), associated with the altitudinal gradient, affect the body size, reproductive phenology, clutch size and egg volume, and population dynamics of this ectothermic flightless insect. Pimelia l. costipennis populations inhabiting upland localities, typified by lower temperatures, and greater precipitation and vegetation cover, were larger in body size and laid larger clutches with smaller eggs than those in the lowlands. Moreover, reproduction occurred earlier in the year at lower sites and later at higher sites, whereas activity density was highest in the uplands where it increases with temperature. This study first explores the changes in life history patterns along a whole insular altitudinal gradient, and finds interpopulation plasticity. It confirms that environmental factors associated with species spatial distribution act additively as drivers of phenological and phenotypic expression.

Therapeutic Effect of Darkling Beetle (Zophobas morio) Hemolymph on Skin Thermal Injury in Mice Infected by Staphylococcus haemolyticus

Staphylococci are the most common pathogens isolated from skin infections in livestock or companion animals. Antibiotic therapy is the best treatment for infections, but local or systemic use of antimicrobials increases the risk of bacterial resistance. Insects are rich in antimicrobial peptides, which can reduce bacterial resistance and can be used to treat bacterial infections after skin burns. We propose that the use of the darkling beetle (Z. morio) hemolymph to treat skin infections in mice by Staphylococcus haemolyticus is one of the alternatives. Z. morio hemolymph alleviated the increase in wound area temperature in mice with a skin infection, reduced the bacterial load of the wound, and accelerated the wound healing speed significantly. Pathological sections showed that Z. morio hemolymph can significantly reduce inflammatory cell infiltration, and promote skin tissue repair. Real-time fluorescent quantitative polymerase chain reaction (PCR) revealed that the Z. morio hemolymph can significantly reduce the levels of pro-inflammatory cytokines, including interleukin-1 beta (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and chemokine interleukin-8 (IL-8). Our findings suggest that Z. morio antibacterial hemolymph can promote wound contraction, relieve local inflammatory responses and promote wound healing in mice infected with a heat injury, which has a positive therapeutic effect and enormous potential for skin thermal injury.

Two new species and new records of lichen-feeding darkling beetles (Coleoptera: Tenebrionidae: Helopini) from Turkey with notes on bionomics and trophic relations

Turkonalassus mavi M. Nabozhenko & B. Keskin, sp. n. and Odocnemis rufocruralis M. Nabozhenko & B. Keskin, sp. n., two distinctive darkling beetle species of the tribe Helopini, are described from the Southeastern Anatolia region of Turkey, based on both their external morphology and genital structures. Turkonalassus mavi sp. n. differs from all congeners by the bluish dorsal surface of the body, the pronotum widest before middle, and wide merged baculi of the median lobe of the aedeagus. Odocnemis rufocruralis sp. n. belongs to the praelonga species-group. Odocnemis rufocruralis sp. n. is similar to O. torosica Nabozhenko & Keskin, 2016, O. terminassianae (Nabozhenko, 2011) and O. kakunini Nabozhenko & Keskin, 2016 but differs from all three taxa by the reddish-brown body with red legs, male apical maxillary palpomere wider than in female, elevate and narrowly separate male protrochanters, and the structure of the very long and narrow apical piece of the aedeagus. New data on distribution, bionomics, and trophic relations of several species of Helopini from Turkey are given. Host lichens are determined for nine species. The majority of studied adult beetles feed on lichens from the families Physciaceae and Parmeliaceae. Some examined taxa feed on Cladoniaceae. Feeding on crustose lichens is registered for the first time for Coleoptera, specifically Odocnemis rufocruralis sp. n. was observed to feed on Pertusaria sp. (on Prunus) in Mardin Province.

Transmission of Bacterial Symbionts With and Without Genome Erosion Between a Beetle Host and the Plant Environment

Many phytophagous insects harbor symbiotic bacteria that can be transmitted vertically from parents to offspring, or acquired horizontally from unrelated hosts or the environment. In the latter case, plants are a potential route for symbiont transfer and can thus foster a tripartite interaction between microbe, insect, and plant. Here, we focus on two bacterial symbionts of the darkling beetle Lagria villosa that belong to the genus Burkholderia; the culturable strain B. gladioli Lv-StA and the reduced-genome strain Burkholderia Lv-StB. The strains can be transmitted vertically and confer protection to the beetle’s eggs, but Lv-StA can also proliferate in plants, and both symbiont strains have presumably evolved from plant pathogens. Notably, little is known about the role of the environment for the transmission dynamics and the maintenance of the symbionts. Through manipulative assays, we demonstrate the transfer of the symbionts from the beetle to wheat, rice and soybean plants, as well as leaf litter. In addition, we confirm that aposymbiotic larvae can pick up Lv-StA from dry leaves and the symbiont can successfully establish in the beetle’s symbiotic organs. Also, we show that the presence of plants and soil in the environment improves symbiont maintenance. These results indicate that the symbionts of L. villosa beetles are still capable of interacting with plants despite signatures of genome erosion and suggest that a mixed-mode of bacterial transmission is likely key for the persistence of the symbiosis.

The first described darkling beetle of the tribe Metaclisini (Coleoptera: Tenebrionidae) from Eocene Baltic amber

The description of an extinct species of Metaclisa Jacquelin du Val, 1861 (Tenebrionidae) is presented. This genus and the tribe Metaclisini are recorded as fossils for the first time, from Eocene Baltic amber. The new species Metaclisa ottoi sp. nov. belongs to the subgenus Trichometaclisa subgen. nov. and differs from all other Metaclisini in possessing short, fine recumbent setation on the pronotum and elytra; in addition, the prosternal process in Metaclisa ottoi sp. nov. is roundly bent down and weakly projected behind the procoxae, which differs from extant species.

Insects use lubricants to minimize friction and wear in leg joints

A protein-based lubricating substance is discovered in the femoro-tibial joint of the darkling beetle Zophobas morio (Insecta). The substance extrudes to the contacting areas within the joint and appears in a form of filiform flows and short cylindrical fragments. The extruded lubricating substance effectively reduces the coefficient of sliding friction to the value of 0.13 in the tribosystem glass/lubricant/glass . This value is significantly lower than 0.35 in the control tribosystem glass/glass and comparable to the value of 0.14 for the tribosystem glass/dry PTFE (polytetrafluoroethylene or Teflon). The study shows for the first time that the friction-reducing mechanism found in Z. morio femoro-tibial joints is based on the lubricant spreading over the contacting surfaces rolling or moving at low loads and deforming at higher loads, preventing direct contact of joint counterparts. Besides Z. morio , the lubricant has been found in the leg joints of the Argentinian wood roach Blaptica dubia .

Novel Extract from Beetle Ulomoides dermestoides: A Study of Composition and Antioxidant Activity

A biologically active extract from the darkling beetle Ulomoides dermestoides was obtained using the electro-pulse plasma dynamic extraction method. The beetle water extract contained a complex of antioxidant substances such as antioxidant enzymes and nonprotein antioxidants, as well as a complex of heat shock antistress proteins. This determines the rather high antioxidant activity of the aqueous extract of the beetle, i.e., 1 mg of dry matter/mL of the extract has an equivalent antioxidant activity to 0.2 mM Trolox (a water-soluble analog of vitamin E). It was shown that the beetle extract can lead to a 25–30% increase in the average lifespan of nematode Caenorhabditiselegans, under normal conditions, and a 12–17% increase under conditions of oxidative stress (with paraquat), and significantly inhibits the fructosylation reaction of serum albumin. Therefore, the beetle aqueous extract shows promise as a biologically active complex exhibiting antioxidant activity.

Preventive Activity of the Extract of the Darkling Beetle Ulomoides Dermestoides in the Diet of C57Bl/6JSTO Mice in a Neurotoxic Model of Parkinson's Disease

The effect of aqueous extracts of the biomass of the adult Ulomoides dermestoides beetle on the delayed effects of the defoliant paraquat causing parkinsonism in experimental mice was evaluated. The motor activity of the animals was analyzed in behavioral tests using a rotarod and a vertical pole. The number of tyrosine hydroxylase-immunopositive neurons in the ventral part of the substantia nigra of the midbrains of experimental and control mice was studied by immunohistochemistry. In the model in vitro system with SH-SY5Y human neuroblastoma, the effect of the extracts on cell proliferation was examined in the absence and presence of the neurotoxin MPP+. The isolation of biologically active substances from raw biomass using cavitation effects made it possible to obtain extracts with protective properties in the model of an early stage of Parkinson's disease used in this study.

Preventive Activity of the Extract of the Darkling Beetle Ulomoides Dermestoides in the Diet of C57Bl/6JSTO Mice in a Neurotoxic Model of Parkinson's Disease

The effect of aqueous extracts of the biomass of the adult beetle Ulomoides dermestoides on the delayed effects of defoliant paraquat causing parkinsonism in experimental mice was evaluated. The motor activity of the animals was analyzed in behavioral tests using a rotarod and a vertical pole. The number of tyrosine hydroxylase-immunopositive neurons in the ventral part of the substantia nigra of the midbrain of experimental and control mice were studied by immunohistochemistry. In the model in vitro system with SH-SY5Y–human neuroblastoma, the effect of the extracts on cell proliferation was examined in the absence and in the presence of the neurotoxin MPP+. The isolation of biologically active substances from raw biomass using cavitation effects made it possible to obtain extracts with protective properties in the model of an early stage of Parkinson's disease used.