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20 pages, 5447 KiB

Open AccessArticle

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

by Milos Sevarika, Paolo Giannotti, Andrea Lucchi and Roberto Romani

Insects 2022, 13(12), 1138; https://0-doi-org.brum.beds.ac.uk/10.3390/insects13121138 - 10 Dec 2022

Cited by 1 | Viewed by 1619

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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22 pages, 22003 KiB

Open AccessArticle

Antennal Morphology and Fine Structure of Flagellar Sensilla in Hippoboscid Flies with Special Reference to Lipoptena fortisetosa (Diptera: Hippoboscidae)

by Annalisa Andreani, Antonio Belcari, Patrizia Sacchetti and Roberto Romani

Insects 2022, 13(3), 236; https://0-doi-org.brum.beds.ac.uk/10.3390/insects13030236 - 27 Feb 2022

Cited by 3 | Viewed by 2719

Abstract

Lipoptena cervi (Linnaeus), Lipoptena fortisetosa Maa, Hippobosca equina Linnaeus, and Pseudolynchia canariensis (Macquart) are hematophagous ectoparasites that infest different animal species and occasionally bite humans. Hosts are located by a complex process involving different kinds of stimuli perceived mainly by specific sensory structures [...] Read more.

Lipoptena cervi (Linnaeus), Lipoptena fortisetosa Maa, Hippobosca equina Linnaeus, and Pseudolynchia canariensis (Macquart) are hematophagous ectoparasites that infest different animal species and occasionally bite humans. Hosts are located by a complex process involving different kinds of stimuli perceived mainly by specific sensory structures on the antennae, which are the essential olfactory organs. General antennal morphology, together with distribution and ultrastructure of sensilla, have been studied in detail with scanning and transmission electron microscopy approaches. Observations have revealed some common features among the four studied hippoboscids: (a) typical concealment of the flagellum inside the other two segments; (b) characteristic trabecular surface of the flagellum; (c) peculiar external microtrichia; (d) presence on the flagellum of basiconic sensilla and grooved peg coeloconic sensilla; (e) unarticulated arista. The ultrastructure of L. fortisetosa revealed that microtrichia and the flagellar reticulated cuticle are not innervated. Different roles have been hypothesized for the described antennal structures. Microtrichia and the reticulated cuticle could convey volatile compounds towards the flagellar sensory area. Peculiar sensory neurons characterize the unarticulated arista which could be able to detect temperature variations. Coeloconic sensilla could be involved in thermoreception, hygroreception, and carbon dioxide reception at long distances, while the poorly porous basiconic sensilla could play a role in the host odour perception at medium–short distances. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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27 pages, 23252 KiB

Open AccessArticle

Male Accessory Glands of Blister Beetles and Cantharidin Release: A Comparative Ultrastructural Analysis

by Maurizio Muzzi, Emiliano Mancini, Emiliano Fratini, Manuela Cervelli, Tecla Gasperi, Paolo Mariottini, Tiziana Persichini, Marco Alberto Bologna and Andrea Di Giulio

Insects 2022, 13(2), 132; https://0-doi-org.brum.beds.ac.uk/10.3390/insects13020132 - 26 Jan 2022

Cited by 2 | Viewed by 2897

Abstract

Members of the family Meloidae are known to produce cantharidin, a highly toxic monoterpene found in their hemolymph and exuded as droplets capable of deterring many predators. As a nuptial gift, males transfer large amounts of cantharidin to females via a spermatophore, which [...] Read more.

Members of the family Meloidae are known to produce cantharidin, a highly toxic monoterpene found in their hemolymph and exuded as droplets capable of deterring many predators. As a nuptial gift, males transfer large amounts of cantharidin to females via a spermatophore, which is formed by specific accessory glands containing high concentrations of this terpene. Using light, electron and ion beam microscopy, the ultrastructural features of the three pairs of male accessory glands as well as the glandular part of the vasa deferentia were comparatively investigated in seven species of blister beetles belonging to five different tribes and two subfamilies. All gland pairs examined share common features such as mesodermal derivation, the presence of muscle sheath, a developed rough endoplasmic reticulum, abundant mitochondria, secretory vesicles, and microvillated apical membranes. Within the same species, glands exhibit distinctive features, suggesting that each pair is responsible for the formation of a specific substance. The vasa deferentia, while showing many similarities within the family, often exhibit features unique to each of the individual species investigated, whereas the accessory glands of the first and second pairs display the highest degree of ultrastructural variability. A comparison across the species shows an interesting constancy limited to ultrastructural features in the third pair of accessory glands. The similarities and differences among the species are discussed in the light of the available literature and in relation to the potential role that blister beetles’ male accessory glands could play in the storage and management of cantharidin. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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8 pages, 1797 KiB

Open AccessArticle

Echoentomography for Assessing Braconid Parasitization on Soft-Bodied Tephritid Hosts

by Renato Ricciardi, Rossana Izzetti, Marco Romanelli, Davide Caramella, Andrea Lucchi and Giovanni Benelli

Insects 2021, 12(11), 980; https://doi.org/10.3390/insects12110980 - 29 Oct 2021

Viewed by 2529

Abstract

Entomological approaches currently available for assessing host parasitization require dissection, polymerase chain reaction (PCR), or waiting for adult emergence. The first two methods are relatively fast but destructive, whereas the third one allows the emergence of the parasitoid but it is time consuming. [...] Read more.

Entomological approaches currently available for assessing host parasitization require dissection, polymerase chain reaction (PCR), or waiting for adult emergence. The first two methods are relatively fast but destructive, whereas the third one allows the emergence of the parasitoid but it is time consuming. In this framework, new diagnostic imaging tools may contribute to solve the lack of an accurate, rapid, and non-invasive approach to evaluate the parasitization of soft-bodied insects by their endoparasitoids. In this study, ultra-high frequency ultrasound (UHFUS) technology, which is currently used in medical and preclinical fields, was adopted to assess the parasitization of the invasive polyphagous Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), testing 2nd and 3rd instar larvae. Parasitization assays were carried out with the solitary koinobiont endophagous parasitoid Psyttalia concolor (Hymenoptera: Braconidae: Opiinae). The efficacy of UHFUS-based echoentomography was compared with the classical method of dissecting the larval host under a stereomicroscope. Our results showed that the UHFUS diagnostic capability was statistically comparable with that of dissection, both on C. capitata 2nd and 3rd larvae. Overall, UHFUS-based echoentomography may be further considered as a fast, non-invasive, and effective approach to evaluate the parasitoid’s ability to successfully oviposit in soft-bodied hosts. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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17 pages, 5146 KiB

Open AccessArticle

Entangling the Enemy: Ecological, Systematic, and Medical Implications of Dermestid Beetle Hastisetae

by Enrico Ruzzier, Marcin Kadej, Andrea Di Giulio and Andrea Battisti

Insects 2021, 12(5), 436; https://0-doi-org.brum.beds.ac.uk/10.3390/insects12050436 - 12 May 2021

Cited by 5 | Viewed by 2450

Abstract

Hastisetae are modified setae typical of Dermestidae Megatominae and are a primary defensive tool of both larvae and pupae against invertebrates and possibly vertebrates. Given their unique morphological features, hastisetae have recently been suggested as an additional character useful for larvae identification and [...] Read more.

Hastisetae are modified setae typical of Dermestidae Megatominae and are a primary defensive tool of both larvae and pupae against invertebrates and possibly vertebrates. Given their unique morphological features, hastisetae have recently been suggested as an additional character useful for larvae identification and possible source of information to clarify the systematics of Megatominae. Hastisetae are also recognized as important contaminants of stored products, work and living environment; in particular, the exposure to hastisetae seems to cause allergic reactions and the insurgence of skin rashes, asthma, conjunctivitis, and digestive system inflammation in humans. Starting from these basic concepts, the present paper provides a detailed description of the hastisetae of some Megatominae. Fine morphology of external and internal microstructures of the hastisetae is shown and compared at the genus level. The insertion on integument, the pedicel, the shaft, and the apical head are illustrated in detail, and the first observations of active defensive behavior based on hastisetae are recorded and presented. Possible implications to the systematics of skin beetles are proposed based on the results of the study. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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18 pages, 16910 KiB

Open AccessArticle

Morphological Characterisation of Haemocytes in the Mealworm Beetle Tenebrio molitor (Coleoptera, Tenebrionidae)

by Maria Luigia Vommaro, Joachim Kurtz and Anita Giglio

Insects 2021, 12(5), 423; https://doi.org/10.3390/insects12050423 - 08 May 2021

Cited by 13 | Viewed by 6308

Abstract

The immunocompetence of the mealworm beetle Tenebrio molitor has been well investigated at molecular and physiological levels, but information on morphological and functional characteristics of its immune cells (haemocytes) is still scarce and fragmentary. This study provides an updated overview of the morphology [...] Read more.

The immunocompetence of the mealworm beetle Tenebrio molitor has been well investigated at molecular and physiological levels, but information on morphological and functional characteristics of its immune cells (haemocytes) is still scarce and fragmentary. This study provides an updated overview of the morphology of circulating immune cells from mealworm beetle adults, using light and transmission electron microscopy. Based on their affinities for May–Grünwald Giemsa stain, haemocytes were defined as either eosinophilic, basophilic or neutral. Ultrastructural descriptions allowed to detect four main cell types in the haemolymph: prohaemocytes, plasmatocytes, granular cells and oenocytoids. The morphological plasticity of haemocytes and the evidence of mitotic circulating cells, intermediate cell stages, as well as autophagic activities suggest haemocyte proliferation, turnover and transdifferentiation as constantly active processes in the haemolymph. Cytochemical tests revealed differences in the distribution of carbohydrates among cell types underling the great plasticity of the immune response and the direct involvement of circulating immune cells in the resource allocation. In addition, our results provide a detailed morphological description of vesicle trafficking, macro- and microautophagy, apoptotic and necrotic processes, confirming the suitability of T. molitor haemocytes as a model for studying evolutionarily conserved cellular mechanisms. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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19 pages, 9531 KiB

Open AccessArticle

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

by Milos Sevarika, Marco Valerio Rossi Stacconi and Roberto Romani

Insects 2021, 12(3), 231; https://0-doi-org.brum.beds.ac.uk/10.3390/insects12030231 - 09 Mar 2021

Cited by 13 | Viewed by 2646

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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10 pages, 3584 KiB

Open AccessArticle

Morphology of the Novel Basimandibular Gland in the Ant Genus Strumigenys (Hymenoptera, Formicidae)

by Chu Wang, Michael Steenhuyse-Vandevelde, Chung-Chi Lin and Johan Billen

Insects 2021, 12(1), 50; https://0-doi-org.brum.beds.ac.uk/10.3390/insects12010050 - 10 Jan 2021

Cited by 12 | Viewed by 2410

Abstract

In 1999, Barry Bolton postulated the presence of a basimandibular gland in the mandibles in all species of the ant genus Strumigenys, solely based on scanning microscopy observations. We now confirm the presence of this putative gland in the proximal outer part [...] Read more.

In 1999, Barry Bolton postulated the presence of a basimandibular gland in the mandibles in all species of the ant genus Strumigenys, solely based on scanning microscopy observations. We now confirm the presence of this putative gland in the proximal outer part of the mandibles of 22 investigated species by histological and ultrastructural examination, including 10 short- and 12 long-mandibulate species. All species have a basimandibular gland, that is formed by 15–25 µm thick epithelial cells and belongs to class-1 following the standard classification of insect exocrine glands. We consider it a novel gland because of its peculiar bowl-shape and special arrangement of the microvilli that are confined to large vacuolar spaces instead of reaching the cuticle. The gland is most pronounced in S. mutica, particularly in the queen. In addition to this gland, we also found scattered class-3 intramandibular gland cells in the mandibles. Queens of S. mutica are peculiar in having a cluster of these cells in the distal tip of their mandibles. As this species is a social parasite, further research is required to determine whether the development of these mandibular glands is related to its parasitic lifestyle. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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23 pages, 11557 KiB

Open AccessArticle

Comparative Morphology of the Mouthparts in Three Predatory Stink Bugs (Heteroptera: Asopinae) Reveals Feeding Specialization of Stylets and Sensilla

by Yan Wang, Jolanta Brożek and Wu Dai

Insects 2020, 11(11), 762; https://0-doi-org.brum.beds.ac.uk/10.3390/insects11110762 - 05 Nov 2020

Cited by 9 | Viewed by 3599

Abstract

Mouthpart structures were observed in three species of Asopinae using scanning electron microscopy to investigate their morphological disparity. The examined species attack mainly slow-moving, soft-bodied insects, primarily larval forms of the Lepidoptera, and are the natural enemies of many pests. This is the [...] Read more.

Mouthpart structures were observed in three species of Asopinae using scanning electron microscopy to investigate their morphological disparity. The examined species attack mainly slow-moving, soft-bodied insects, primarily larval forms of the Lepidoptera, and are the natural enemies of many pests. This is the first detailed description of their external mouthparts. The triangular and elongated labrum and four-segmented tube-like labium are longer in Picromerus species (Picromerus bidens (Linnaeus, 1758) and Picromerus lewisi Scott, 1874 than in Cazira bhoutanica Schouteden, 1907. The labrum of P. lewisi and C. bhoutanica appear to be equipped with olfactory sensilla basiconica Sb3, a special type of sensilla with nanopores. The labium surface in all studied species bears 14 types of sensilla (St1–St4, Sb1–7, Sst, Sca1–2). A new characteristic of sensilla trichodea is represented in sensillum St1; in both Picromerus species, it is classified as an olfactory sensillum with nanopores. The tripartite apex of the labium consists of two lateral lobes and a central membranous lobe having microtrichial extensions. Each lobe has one sensory field, including sensilla basiconica (Sb7), sensilla styloconica (Sst), and sensilla trichodea (St4). In the three studied predatory stink bugs, each mandibular stylet tip has five irregular teeth and three long, pointed hooks. The two opposing maxillae, which are held together by a tongue-and-groove system, form a food canal and a salivary canal. The apices of the right maxilla have small teeth and few short barbs along the edge of the food canal. In P. bidens and P. lewisi, there are 5 teeth, while in C. bhoutanica there are 2. Based on structural differences, we inferred that the hook-shaped mandibular teeth, right maxilla with small teeth, and few short barbs along edge of the food canal are more adapted for a predatory lifestyle. Predatory stink bugs use sharp recurved hooks and irregular teeth penetrating, tearing, or filing devices that aid in the mechanical disruption of host tissue. Stiff bristles in the food canal may indicate their possible adaptation to feeding on insect larvae. The evolution of mouthpart morphology and the putative functional significance of sensilla are discussed, providing insight into the sensory mechanism. Full article

(This article belongs to the Special Issue Novel Findings in Insect Functional Morphology and Anatomy)

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