Ultrastructural Organization and Metal Elemental Composition of the Mandibles in Two Ladybird Species.

The mandibles are among the most important appendages of insects' mouthparts. Their morpho-functional organization is correlated with the variation in dietary preferences. In this study, we investigated the ultrastructural organization and metal composition of the mandibles of two ladybird species with different dietary habits: Harmonia axyridis (an entomophagous species) and Subcoccinella vigintiquatuorpunctata (a phytophagous species). The ultrastructural organization was studied using Scanning and Transmission Electron Microscopy, whereas the metal composition was investigated using Energy-Dispersive X-ray spectroscopy (EDX). Significant differences were observed in the general organization and metal enrichment pattern between the two species. The mandibles of H. axyridis are large and present a molar part with two teeth, with the apical one showing a bifid apex. In contrast, S. vigintiquatuorpunctata exhibited a molar region with several teeth on its apical part. The study revealed significant differences in metal content between the teeth and the prostheca of H. axyridis. Mn was the most abundant element in teeth, whereas Cl was more abundant in the prostheca. In the case of S. vigintiquatuorpunctata, Si was the most abundant element in the prostheca, while Mn was more present in the teeth. A comparison between the two species revealed that both teeth and prostheca showed significant variation in the elemental composition. These findings underscore the role of dietary preferences in shaping the structural and metal composition variations in the mandibles of these two ladybird species.

Effect of the mycotoxins enniatin B and deoxynivalenol on the wheat aphid Sitobion avenae and on the predatory lacewing Chrysoperla carnea.

BACKGROUND: Fusarium species are responsible for Fusarium head blight (FHB) in wheat, resulting in yield losses and mycotoxin contamination. Deoxynivalenol (DON) and enniatins (ENNs) are common mycotoxins produced by Fusarium, affecting plant, animal and human health. Although DON's effects have been widely studied, limited research has explored the impact of ENNs on insects. This study examines the influence of DON and enniatin B (ENB), both singularly and in combination, on the wheat aphid Sitobion avenae and one of its predators, the lacewing Chrysoperla carnea. RESULTS: When exposed to DON (100 mg L-1) or DON + ENB (100 mg L-1), S. avenae exhibited significantly increased mortality compared to the negative control. ENB (100 mg L-1) had no significant effect on aphid mortality. DON-treated aphids showed increasing mortality from 48 to 96 h. A dose-response relationship with DON revealed significant cumulative mortality starting at 25 mg L-1. By contrast, C. carnea larvae exposed to mycotoxins via cuticular application did not show significant differences in mortality when mycotoxins were dissolved in water but exhibited increased mortality with acetone-solubilized DON + ENB (100 mg L-1). Feeding C. carnea with aphids exposed to mycotoxins (indirect exposure) did not impact their survival or predatory activity. Additionally, the impact of mycotoxins on C. carnea was observed only with acetone-solubilized DON + ENB. CONCLUSIONS: These findings shed light on the complex interactions involving mycotoxins, aphids and their predators, offering valuable insights for integrated pest management strategies. Further research should explore broader ecological consequences of mycotoxin contamination in agroecosystems. © 2024 Society of Chemical Industry.

Impact of Enniatin and Deoxynivalenol Co-Occurrence on Plant, Microbial, Insect, Animal and Human Systems: Current Knowledge and Future Perspectives.

Fusarium mycotoxins commonly contaminate agricultural products resulting in a serious threat to both animal and human health. The co-occurrence of different mycotoxins in the same cereal field is very common, so the risks as well as the functional and ecological effects of mycotoxins cannot always be predicted by focusing only on the effect of the single contaminants. Enniatins (ENNs) are among the most frequently detected emerging mycotoxins, while deoxynivalenol (DON) is probably the most common contaminant of cereal grains worldwide. The purpose of this review is to provide an overview of the simultaneous exposure to these mycotoxins, with emphasis on the combined effects in multiple organisms. Our literature analysis shows that just a few studies on ENN-DON toxicity are available, suggesting the complexity of mycotoxin interactions, which include synergistic, antagonistic, and additive effects. Both ENNs and DON modulate drug efflux transporters, therefore this specific ability deserves to be explored to better understand their complex biological role. Additionally, future studies should investigate the interaction mechanisms of mycotoxin co-occurrence on different model organisms, using concentrations closer to real exposures.

Human ectoparasitosis by mites of the genus Pyemotes Amerling 1861 (Acarina: Pyemotidae).

The mites of the family Pyemotidae Berlese (1897) are a large family of ectoparasitoids arthropods, known as pathogen for humans since the 18th century and responsible for the so-called "straw itch" or "grain itch" in granary and dock workers. The identified species of the genus Pyemotes are divided into two groups: the scolyti group (P. scolyti, P. parviscolyti and P. dimorphus) and the ventricosus group (P. tritici and P. ventricosus). The first group is characterized by nonvenomous mites usually parasitizing bark beetles; the ventricosus group includes species associated with a large number of hosts (Coleoptera, Lepidoptera, Hymenoptera, Diptera and Rhynchota), parasitizing all host stages, often highly poisonous and responsible for itchy skin lesions for humans. Several species of Pyemotes mites can be pathogenic to humans, especially in spring and summer and in indoor environments, where worm-eaten wood or infested foodstuffs are present. The most frequent clinical feature is the "strophulus," characterized by small erythematous, edematous, and papular lesions centered by a tiny vescicle evolving into a small erosion covered by crust, or by a central hemorrhagic punctum. Other less frequently observed clinical features are urticaria-like lesions, erythematous excoriated papular and pustular lesions, and rarely scabies-like eruptions. The parasitological diagnosis together with the environmental disinfestation and removing of each substrate infested by insects parasitized by Pyemotidae is mandatory to definitely solve Pyemotes dermatitis.

The Antennal Sensory Structures of Female Anagyrus vladimiri (Hymenoptera: Encyrtidae).

The Encyrtidae (Hymenoptera) encompasses a large group of parasitic wasps widely used in biocontrol programs of scale insects (Hemiptera: Coccoidea). Anagyrus vladimiri is a solitary parasitoid that attacks and develops on several mealybugs of economic importance. Thus, this species is widely used as a biocontrol agent of Planococcus spp. and Pseudococcus spp. A. vladimiri males and females show sexual dimorphism with regard to the antennal organization, in terms of shape and the development of antennomeres. Ultrastructural investigations of female antennae, carried out with scanning (SEM) and transmission (TEM) electron microscopy, revealed the presence of nine distinct antennomeres. The scape was enlarged and paddle-like, compared to the other antennomeres. The club (the apical antennomere) was mono-segmented and housed the highest number of sensilla. Eight morphologically different types of sensilla were described; sensilla trichoidea I, trichoidea II, chaetica I, chaetica II, grooved peg sensilla, campaniform sensilla, multiporous plate sensilla and multiporous basiconic sensilla. Ultrastructural investigations allowed for us to assign a specific function to each type of sensilla. The most abundant type of sensilla were sensilla trichoidea I and multiporous plate sensilla. We also found two types of sensilla (multiporous basiconic sensilla and sensilla chaetica II) that were present only on the females.

Morpho-functional Analysis of the Head Glands in Three Auchenorrhyncha Species and Their Possible Biological Significance.

The Cicadomorpha Philaenus spumarius, Neophilaenus campestris, and Cicadella viridis are known transmitters of the bacterium Xylella fastidiosa. Here, we studied the ultrastructural organization of their cephalic glands. Our investigations with scanning, transmission, focused ion beam-scanning electron microscopes and light microscope revealed for the first time in Auchenorrhyncha the presence of two types of cephalic glands. Both belonged to the Class III epidermal glands, according to the Noirot and Quennedey classification. Type A glands were the most common, being mainly located around antennae, lorum, and gena. Moreover, these glands were observed also on the abdomen and thorax, always in association with sensilla trichoidea. The second type of glands (type B) were located exclusively at the apical part of the postclypeus in P. spumarius and N. campestris. The ultrastructural organization was similar in both types, being composed of a secretory cell and a conducting canal. Differences were observed in the width of the cuticular opening, being smaller in the type II glands. In addition, we have recorded the presence of a maxillary sensory pit in all species and described sensilla trichoidea ultrastructural organization. Finally, we discussed the ultrastructural organization of the glands and their potential biological role.

Behavioural and electrophysiological responses of Philaenus spumarius to odours from conspecifics.

The meadow spittlebug, Philaenus spumarius L. (Hemiptera: Auchenorrhyncha: Aphrophoridae), is the main vector of Xylella fastidiosa subsp. pauca strain ST53, the causal agent of the Olive Quick Decline Syndrome. Philaenus spumarius and other Auchenorrhyncha are known to communicate via vibrations, whereas the possible occurrence of semiochemical communication has been poorly investigated so far. Through a chemical ecology approach, we provide evidence of intraspecific chemical communication in P. spumarius. In Y-tube olfactometer bioassays, males were attracted to unmated females as well as toward the headspace volatile extracts collected from unmated females. Conversely, females did not respond to unmated male volatiles or their extracts, nor did males and females respond to volatiles from individuals of the same sex. Electroantennography assays of unmated male and female headspace extracts elicited measurable responses in the antennae of both sexes. Male responses to body wash extracts from both sexes were stronger compared to female responses. Thus, suggesting the presence of compounds that are highly detected by the male's olfactory system. The female head seemed to be the source of such compounds. This is the first record of intraspecific chemical communication in P. spumarius and one of the very few records in Auchenorrhyncha. Possible biological roles are under investigation.

Fine Morphology of Antennal and Ovipositor Sensory Structures of the Gall Chestnut Wasp, Dryocosmus kuriphilus.

Dryocosmus kuriphilus is a gall-inducing insect, which can cause significant damage on plants of the genus Castanea Mill., 1754. Antennae and ovipositor are the main sensory organs involved in the location of suitable oviposition sites. Antennal sensilla are involved in the host plant location, while ovipositor sensilla assess the suitability of the ovipositional bud. On both organs, diverse sensillar organs are present. Here, the distribution and ultrastructural organization of the sensilla were investigated by scanning and transmission electron microscopy. The antennae of D. kuriphilus are filiform and composed of 14 antennomeres, with the distal flagellomere bearing the highest number of sensilla. On the antennae, 6 sensilla types were found; sensilla chaetica, campaniformia, coeloconica-I, coeloconica-II, trichoidea and placoidea. The sensilla placoidea and trichoidea were the most abundant types. On the external walls of the ovipositor, gustatory and mechanoreceptive sensilla were observed. Internally, the egg channel hosted two additional sensory structures. The putative functional role of each sensilla in the context of insect's ecology is discussed as well as the ovipositional mechanism used by this insect.