Types Of Trichoid Sensilla Research Articles

Functional Characterization of Peripheral Neurons and a Receptor Recognizing Sex Pheromones in Hyphantria cunea (Erebidae).

Hyphantria cunea (Lepidoptera: Erebidae) is difficult and costly to control as a quarantine pest found globally. Sex pheromone trapping is an effective measure for its population monitoring and control; however, the peripheral neural mechanism of sex pheromone recognition in H. cunea remains unclear. An electrophysiological analysis showed that both male and female moths of H. cunea responded to four components of sex pheromones and the responses of male moths were stronger than those of the female moths. We identified three types of trichoid sensilla (ST) responsive to sex pheromones using the single sensillum recording technique. Each type was involved in recognizing 9R, 10S-epoxy-1, Z3, Z6-heneicosatriene (1, Z3, Z6-9S, 10R-epoxy-21Hy). Four peripheral neurons involved in the olfactory encoding of sex pheromones were identified. Four candidate pheromone receptor (PR) genes, HcunPR1a, HcunPR1b, HcunPR3, and HcunPR4, were screened by transcriptome sequencing. All of them were highly expressed in the antennae of males, except for HcunPR4, which was highly expressed in the antennae of females. Functional identification showed that HcunPR1a responded to sex pheromone. Other HcunPRs were not functionally identified. In summary, neurons involved in sex pheromone recognition of H. cunea were located in the ST, and HcunPR1a recognized secondary pheromone components 1, Z3, Z6-9S, 10R-epoxy-21Hy. Interestingly, PRs that recognize the main components of the sex pheromone may be located in an unknown branch of the olfactory receptor and merit further study. Our findings provide a better understanding of the peripheral neural coding mechanism of type II sex pheromones, and HcunPR1a may provide a target for the subsequent development of highly effective and specific biopesticides for H. cunea.

Functional Morphology and Ultrastructure of the Peripheral Antennal Sensillar System of Graphosoma italicum (Müller, 1766) (Insecta: Hemiptera: Pentatomidae).

The antennae of the shield bug Graphosoma italicum (Müller, 1766) were examined through scanning and transmission electron microscopy to reveal their general morphology, as well as the antennal sensilla's distribution, size, and ultrastructure of their dendrites and function. The antennae comprise five antennomeres (one scape, two pedicels, and two flagellomeres). Different lengths of chaetic mechanosensilla (Ch1-Ch4) exist on all antennomeres, and several highly sensitive campaniform sensilla are embedded in the exoskeleton and measure cuticular strain. One pair of peg sensilla, the typical proprioceptive, is only on the proximal edge of the first pedicel and directed to the distal edge of the scapus. The antennal flagellum possesses two subtypes of trichoid and basiconic sensilla, each with one type of coeloconic olfactory sensilla. The distinctive characteristics of G. italicum are also apparent in two subtypes of coeloconic sensilla embedded in different cavities on both antennomeres of the flagellum, probably with a thermo-hypersensitive function. All studied morphological types of the sensilla and their function were supported by ultrastructural elements. The long and thin trichoid sensilla type 2 (TrS2) with an olfactive function was the most abundant sensilla localized on both flagellomeres. The peripheral antennal sensilla system consists of six main types of sensilla divided into twelve subtypes.

Sexual dimorphism of antennal and ovipositor sensilla of Tetrastichus sp. (Hymenoptera: Eulophidae)

• Sensilla on antenna and ovipositor of Tetrastichus sp. were investigated. • Tetrastichus sp. has eight types of antennal sensilla and four types of ovipositor sensilla. • Types and distribution of antennal and ovipositor sensilla were discussed. • Tetrastichus sp. exhibits sexual dimorphism in the profiles of the antennal sensilla. Tetrastichus sp. (Hymenoptera: Eulophidae) is a primary parasitoid of the Metisa plana (Lepidoptera: Psychidae), an oil palm bagworm. The sensilla on the surface of the antenna and ovipositor of Tetrastichus sp. were examined using a scanning electron microscope. The antennae of both male and female Tetrastichus sp. are geniculate in shape and hinged at the scape-pedicel joint. The female antenna is about 200 µm longer than the male antenna. However, the male antenna has an additional flagellomere compared to the female antenna. In total, eight different types of antennal sensilla were observed on the antenna of Tetrastichus sp.: trichoid sensilla type 1, 2, 3, 4, placoid sensilla type 1 and 2, basiconic sensilla, and campaniform sensilla. The antenna of the female Tetrastichus sp. lacks placoid sensilla type 2 and campaniform sensilla. The distribution and abundance of the antennal sensilla were compared between the male and female Tetrastichus sp. and discussed. On the ovipositor stylet of Tetrastichus sp., coeloconic sensilla, styloconic sensilla and campaniform sensilla were observed. Trichoid sensilla were observed at the medial part of the distal extremity of the ovipositor.

Characterization of Antennal Sensilla and Immunolocalization of Odorant-Binding Proteins on Spotted Alfalfa Aphid, Therioaphis trifolii (Monell).

The spotted alfalfa aphid [Therioaphis trifolii (Monell), Homoptera, Drepanosiphidae] is a well-known destructive pest that can significantly reduce alfalfa yields. Herein, the morphology of antennal sensilla of T. trifolii has been examined by using scanning electron microscopy and the ultrastructure of sensilla stellate and placoidea was described by transmission electron microscopy. Stellate sensilla, placoid sensilla, and coeloconic sensilla were found on the 6th segment, and a single sensillum placoidea was located on the 5th segment. Placoid sensilla were also present on the 3rd antennal segment of alate and apterous aphids, and the number was similar between two morphs. Two types of trichoid sensilla and coeloconic sensilla were found on the antennae, respectively. The results of ultrastructure showed that stellate sensilla are innervated by three neurons, while placoid sensilla present three groups of neurons, equipped with 2–3 dendrites in each neuron group. Immunocytochemical localization of odorant-binding proteins (OBPs) was performed on ultrathin sections of sensilla stellate and placoidea, and we observed that the antiserum against OBP6 intensively labeled all placoid sensilla from both primary and secondary rhinaria. OBP7 and OBP8 could also be detected in placoid sensilla, but less strongly than OBP6. In addition, OBP6, OBP7, and OBP8 were densely labeled in stellate sensilla, suggesting OBP6, OBP7, and OBP8 may sense alarm pheromone germacrene A in T. trifolii.

Scanning Electron Microscopy of Sand Flies of the Chagasi Series, Psychodopygus (Diptera: Psychodidae) Genus, Focusing on the Genitalia.

Males of cryptic or closely related species present great morphological variation in their genitalia, whereas females, such as those of the Chagasi Series of the Psychodopygus Mangabeira, 1941 genus, are more similar. Therefore, our aim was to study the fine structure of the male genitalia of five species of the Chagasi Series to better understand the variation in their morphology and its influence on the copulatory process. The sand fly species were captured in the following Brazilian states: Psychodopygus chagasi (Costa Lima, 1941) (Rondônia), Psychodopygus complexus (Mangabeira, 1941) (Tocantins), Psychodopygus squamiventris maripaensis (Floch & Abonnenc, 1946) (Amapá), Psychodopygus squamiventris squamiventris (Lutz & Neiva, 1912) (Amazonas), and Psychodopygus wellcomei Fraiha, Shaw & Lainson, 1971 (Pará and Ceará). Insects were stored in ethanol 70% (then dehydrated) and dry after they were sputtered with gold. The samples were observed under a scanning electron microscope. Microtrichiae, two types of trichoid sensilla, coeloconic and chaetic sensillae, were observed on the antenna of all species, with no difference between them. Only on the anepimeron of P. squamiventris squamiventris a modified 'racket'-like scale was observed. As for the male genitalia, the setae and structures of each species were fully described, such as the small setae on the paramere apex of the P. squamiventris subspecies, and the grooves present in this region and on the paramere lobe of P. complexus and P. wellcomei, which are impossible to observe with optic microscopy. New information is thus provided on the male genitalia, which can contribute to future bionomic studies of these species.

Antennal and ovipositor sensilla of Pseudoligosita yasumatsui (Hymenoptera: Trichogrammatidae)

Abstract Pseudoligosita yasumatsui Viggiani and Subba Rao 1978 (Hymenoptera: Trichogrammatidae) is a common egg parasitoid of rice insect pests. The surface morphology of the antenna and ovipositor on P. yasumatsui was examined using scanning electron microscopy. The antenna of P. yasumatsui is geniculate in shape, hinged at the scape-pedicel joint, approximately 190 μm in length and consists of seven antennomeres. In total, the male and female antennae have ten different types of sensilla: trichoid sensilla type 1, 2, 3, 4, 5, 6, campaniform sensilla, basiconic sensilla, and placoid sensilla type 1 and 2. The flagellum of the female antenna is covered with cuticular pores, which are absent on the male antennal flagellum. The distal extremity of its ovipositor stylet has campaniform sensilla and styloconic sensilla. Trichoid sensilla found on its apical abdomen part may play a role in the host detection and egg placement. The types and distribution of antennal and ovipositor sensilla on the parasitoid were discussed.

Morphological Effect of Gamma Radiation on the Antennal Sensory Structure of Peach Fruit Fly, Bactrocera zonata, Using Electron Microscopy

External morphology of antennal sensilla of both sexes of irradiated with sterilizing and substerilizing doses and unirradiated peach fruit fly, Bactrocera zonata were studied with scanning electron microscopy. The antenna of this fly consists of 3 segments: Basal scape, pedicel and funiculus. The antennal segments of males tended to be longer and more elongated than those of females. Eight distinct morphological types of sensilla belong to four groups. These sensilla are: trichoid sensilla type I and II, chaetica sensilla type I and II, basiconic sensilla type I, II, III and campaniform sensilla (in the pedicel of female). The changes which occurred to the antennae and their associated sensilla due to the sterilizing dose (90Gy for male and 50Gy for female) were investigated; distribution, size and position are also described.

Morphological changes induced by thermal treatment and gamma irradiation on the males' hind legs of Spodoptera littoralis (Noctuidae; Lepidoptera)

External morphology of males' hind legs of Spodoptera littoralis subjected to thermal treatment (33 °C and 37 °C) or/and irradiated with substerilizing doses of gamma radiation (75, 100 and 150 Gy) were studied using scanning electron microscopy (SEM) in the parental generation. Five types of sensilla have been distinguished; three types of trichoid sensilla (T1,T2 and T3), sensilla basiconica and sensilla auricillica, which are considered as olfactory chemoreceptors. Moreover, sensilla chaetica are contact chemoreceptors, whereas sensilla styloconica are thermo–hygro/gustatory mechanoreceptors. The impact of thermal treatment or/and gamma irradiation reflect a clear morphological change in S. littoralis legs'sensilla, claws, spurs and scales. Otherwise, the degree of deformity was thermal and dose dependent, as it increased with an increase of the degree of temperature and dose of irradiation applied. Substerilizing doses 75 and 100 Gy, either alone or combined with thermal treatment 33 °C, have low undesirable effects on the hind legs with successful mobility or courtship behavior. Consequently, synergistic effect of gamma radiation and thermal stress induced successful application in the integrated pest management program for controlling S. littoralis.

Immunolocalization of Odorant-Binding Proteins on Antennal Chemosensilla of the Peach Aphid Myzus persicae (Sulzer)

The antennal sensilla of Myzus persicae were mapped using scanning and transmission electron microscopy. Placoid sensilla and coeloconic sensilla were found on the 6th segments, whereas 2 types of trichoid sensilla were present all through the length of the antenna. A single sensillum placoideum was located on the 5th segment, whereas alate aphids also presented placoid sensilla on the 3rd antennal segment. Immunocytochemical localization of odorant-binding proteins (OBPs) was performed on ultrathin sections of antennal chemosensilla. The antiserum against OBP7 intensively labeled all placoid sensilla from both primary and secondary rhinaria, with gold granules concentrated in the lymph surrounding the dendrite. OBP6 and OBP3 could also be detected in placoid sensilla, but less strongly than OBP7. Barely significant reaction or no reaction was observed with antibodies against OBP8.

External morphology of Trichogramma dendrolimi matsumura (hymenoptera: Trichogrammatidae) organ and ultrastructure of the sensilla

In this article, we described the ultrastructure of the sensilla on the antenna, eyes, mouthparts, wings, legs, and external genitalia of female and male Trichogramma dendrolimi using scanning electron microscopy (SEM). The antenna possessed the most sensilla types. We found 13 types of sensilla on female antenna, which were trichoid sensilla (TS) type 1-4, chaetica sensilla (ChS) type 1-2, campaniform sensilla (CaS), falcate sensilla, placoid sensilla (PS) type 1-2, basiconic capitate peg sensilla (BCPS) type 1, coeloconic sensilla (CoS), and styloconic sensilla. Ten types of sensilla were found on the male antenna, some were the same as that on female T. dendrolimi antenna, such as TS types 1 and 3, CaS, PS type 1, BCPS type 1, and CoS, but TS types 5 and 6, ChS type 3, and BCPS 2 were specific to male T. dendrolimi antenna. The leg possesses eight types of sensilla and a kind of tympana structure. Four types of TSs were found on the wings. On the mouthparts, sensilla on the maxillary and labial palps were unique, including two TSs and one ChS. The ovipositor possesses three types of sensilla, and the copulatory organ possesses two types. The eyes had only one kind of TS. Furthermore, external morphology of antenna and external genitalia revealed distinct sexual dimorphisms. According to their morphology, the possible functions of these sensilla were discussed. These results may further our understanding of the sensory mechanisms of T. dendrolimi in response to infochemicals within the environment.

Morphology and Distribution of Sensilla on Tarsi and Ovipositors of Six Fruit Flies (Diptera: Tephritidae)

Abstract Fruit flies (Diptera: Tephritidae) are among the most important pests of fruits and vegetables. In this study, the typology, number, size, and distribution pattern of sensilla on tarsi and ovipositors of six fruit fly species, including Bactrocera Cucurbitae Coquillett, Bactrocera diaphora (Hendel), Bactrocera dorsalis Hendel, Bactrocera minax (Enderlein), Bactrocera scutellata (Hendel), and Bactrocera tau (Walker), were analyzed by scanning electron microscopy techniques. The tarsi of these six fruit fly species are equipped with three types of trichoid sensilla (1, 2, and 3), chaetica sensilla, and basiconic sensilla. Two types of sensilla, trichoid sensilla (4 and 5) and campaniform sensilla, are identified on the ovipositors of the female fruit files. In addition, the possible functions of these sensilla are discussed in light of previously published literature, and the trichoid sensilla (1, 2, and 3) on the tarsi, and trichoid sensilla (4 and 5), as well as campaniform sensilla on the ovipositors are considered as mechanoreceptor. The basiconic sensilla might have an olfactory function, and the chaetica sensilla were suggested as a mechano- or olfactory / gustatory neurons. Future functional tarsi and ovipositors morphology and electrophysiological of tarsi and ovipositors studies are needed to confirm these proposed functions.

Ultrastructure of sensory receptors on the antennae of Oryctes elegans Prell (Coloeptera: Scarabidae)

Oryctes elegans is one of the economically important pest of palm trees in Saudi Arabia. Chemoreceptors are very important organs for mating, feeding or oviposition in insects. We described the morphology ultra structure and description of antennae among males and females using scanning electron microscopy. Observation have been described determined that the antennae of O. elegans were lamellate type and composed of nine segments. There were three types of trichoid sensilla found on the antennae. These were elongated, curved and articulate, respectively. Fourth type was placoid sensillae concentrated on the lateral segments of antennae. These sensillae were abundant distributed on pedicle and the 1st flagellomeres. Sensillae found on females and males antennae were similar but the antennal segments of males were thinner than females.

Sensillary morphology on the rostral apex and their possible role in prey location behaviour of the carnivorous stinkbug, Eocanthecona furcellata (Wolff) (Heteroptera: Pentatomidae)

Abstract Eocanthecona furcellata (Wolff), the carnivorous heteropteran, demonstrates interesting feeding mechanisms that suggest the involvement of the antennal and labial tip sensilla. This study was conducted to identify the morphology of various sensilla present on the labial tip of this insect using scanning electron microscopy. Four morphologically different types of trichoid sensilla comprise the largest and most numerous sensilla and occur throughout the surface of the labial tip. Three new and unique types of sensilla were discovered. Long hairs with profusely branched shafts are present at the entrance of the rostral groove. An oval‐shaped peg surrounded by sensory hairs with branched shafts and a short, stout peg encircled by a group of long hair‐like sensilla was found among the sensilla population of two lobes. The morphology of the new sensilla is given and possible functions of individual receptors are suggested on morphological grounds.

Reverse and Conventional Chemical Ecology Approaches for the Development of Oviposition Attractants for Culex Mosquitoes

Synthetic mosquito oviposition attractants are sorely needed for surveillance and control programs for Culex species, which are major vectors of pathogens causing various human diseases, including filariasis, encephalitis, and West Nile encephalomyelitis. We employed novel and conventional chemical ecology approaches to identify potential attractants, which were demonstrated in field tests to be effective for monitoring populations of Cx. p. quinquefasciatus in human dwellings. Immunohistochemistry studies showed that an odorant-binding protein from this species, CquiOBP1, is expressed in trichoid sensilla on the antennae, including short, sharp-tipped trichoid sensilla type, which house an olfactory receptor neuron sensitive to a previously identified mosquito oviposition pheromone (MOP), 6-acetoxy-5-hexadecanolide. CquiOBP1 exists in monomeric and dimeric forms. Monomeric CquiOBP1 bound MOP in a pH-dependent manner, with a change in secondary structure apparently related to the loss of binding at low pH. The pheromone antipode showed higher affinity than the natural stereoisomer. By using both CquiOBP1 as a molecular target in binding assays and gas chromatography-electroantennographic detection (GC-EAD), we identified nonanal, trimethylamine (TMA), and skatole as test compounds. Extensive field evaluations in Recife, Brazil, a region with high populations of Cx. p. quinquefasciatus, showed that a combination of TMA (0.9 µg/l) and nonanal (0.15 ng/µl) is equivalent in attraction to the currently used infusion-based lure, and superior in that the offensive smell of infusions was eliminated in the newly developed synthetic mixture.

Olfactory Coding in Antennal Neurons of the Malaria Mosquito, Anopheles gambiae

Olfactory receptor neurons (ORNs) in the antenna of insects serve to encode odors in action potential activity conducted to the olfactory lobe of the deuterocerebrum. We performed an analysis of the electrophysiological responses of olfactory neurons in the antennae of the female malaria mosquito Anopheles gambiae s.s. and investigated the effect of blood feeding on responsiveness. Forty-four chemicals that are known to be present in human volatile emanations were used as odor stimuli. We identified 6 functional types of trichoid sensilla and 5 functional types of grooved-peg sensilla (GP) based on a hierarchical cluster analysis. Generalist ORNs, tuned to a broad range of odors, moderate specialist ORNs and 2 ORNs tuned to only one odor were identified in different sensilla types. Neurons in GP were tuned to more polar compounds including the important behavioral attractant ammonia and its synergist L-lactic acid, responses to which were found only in GP. Combinatorial coding is the most plausible principle operating in the olfactory system of this mosquito species. We document for the first time both up- and downregulation of ORN responsiveness after blood feeding. Modulation of host-seeking and oviposition behavior is associated with both qualitative and quantitative changes in the peripheral sensory system.

Scanning electron microscopy studies of sensilla and other structures of adult Dermatobia hominis (L. Jr., 1781) (Diptera: Cuterebridae).

The surfaces of the body segments and appendages of male and female Dermatobia hominis (L. Jr., 1781) were studied by scanning electron microscopy with the objective of contributing to the current knowledge of the morphology of this insect. The image analyses were done with consideration of the scientific literature on morphology, ultrastructure, and insect sensory structures. A new criterion for distinguishing the sexes of this fly was observed as well as a new setiform empodium type associated with other smaller setae. Different types of trichoid sensilla were observed, as well as spinules, a type of cuticular setiform projection and a scale-like structure. The possible function of the sensilla was discussed, and sensilla with mechanosensory and chemosensory functions were found. Pilose regions that could be involved in the production and/or liberation of pheromones were encountered in the intersegmental spaces of the female abdomen. The current study of the ultrastructure of the body surface of D. hominis contributes to current knowledge of morphology, taxonomy, and sensory structures of this species.

Structure, distribution, and innervation of sensilla on the ovipositor of the spruce budworm,Choristoneura fumiferana, and evidence of a gustatory function for type II sensilla

Four types of trichoid sensilla were described on the ovipositor of the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae). Types I and III sensilla were short and long multiporous hairs, respectively. Type IV sensilla were long and aporous. Each was innervated by a single dendrite. Type II sensilla were multiporous and also had a single terminal pore. They were innervated by four dendrites. Electrophysiological responses were obtained from these type II sensilla to a range of chemical stimuli.

Antennal sensilla of the click beetle, Melanotus villosus (Geoffroy) (Coleoptera: Elateridae)

The typology, number and placement of antennal sensilla of the click beetle Melanotus villosus (Geoffroy) (Coleoptera: Elateridae) were studied using scanning electron microscopy. On both the males and females the antennae are made up of the scape, pedicel and nine flagellomeres. Two types of basiconic sensilla, three types of trichoid sensilla, one type of styloconic sensilla, one type of chetoid sensilla, dome-shaped sensilla, grooved pegs, and Böhm sensilla all appear on the antennae of the beetles of both sexes, with the exception of trichoid sensilla type II, whose large number (average of 1635 hairs per antenna) was found only in male beetles. Sensilla trichodea type II evidently respond to the sex pheromone produced by the female beetle. Unlike the other two click beetles, studied up till now, Agriotes obscurus and Limonius aeruginosus, the trichoid and basiconic sensilla of M. villosus, whose proven or assumed function is olfactory, are located predominantly on the flagellomeres ventral extensions. It is assumed that the placement of the olfactory sensilla, mainly on the ventral side of M. villosuss antennae, and their more or less even distribution on the flagellomeres, can be seen as morphological adaptation of this species of insect, whose specific behavioural reaction of olfactory searching is flying, both before and after contact with an odour plume.

Mouthpart sensilla of cave species of australian paratemnopteryx cockroaches (BLATTARIA : BLATTELLIDAE)

The external morphology and distribution of sensilla on maxillary and labial palpi are described for 3 Australian cave-dwelling cockroach species, Paratemnopteryx stonei, P. howarthi, and P. sp. nov (Blattaria : Blattellidae), using scanning electron microscopy. The apex of the maxillary palpus expands ventrally into a flexible pad with a distinct sensillar field. The total number of sensilla ranges from 1045 (males)–1486 (females). Sensillar fields of females are larger and contain more sensilla than those of the males, although the density of sensilla is usually equal or greater for males. Papilla-like groove-and-slit chemoreceptors comprise 93–97% of the sensilla. Two types of trichoid sensilla occur along with bifurcuted sensilla and rare basiconic sensilla that are poreless and have an inflexible socket. Chaetic sensilla occur on all species and several thousand pectinate scales, with bulbous bases, and spicules are present in large fields on each side of the sensillar field. The apex of the labial palpus is only slightly expanded into a sensillar field. Sensillar diversity is similar to the maxillary palpus but there are only 5–29% as many sensilla, the number ranging from 97 (males)–346 (females). Sensillar fields of females are slightly to much larger than those of males but the sensillar density is equal between the sexes or greater on males. Two types of trichoid and one or two types of basiconic sensilla occur on each species. Chaetic chemoreceptors are present along with three types of non-socket spines. Sensilla varied moderately in morphology and gender-related abundance from those on epigean cockroach species.

STRUCTURE, SENSORY EQUIPMENT, AND SECRETIONS OF THE OVIPOSITOR IN A GIANT SPECIES OF HYMENOPTERA: MEGARHYSSA ATRATA F. (ICHNEUMONIDAE, PIMPLINAE)

AbstractMegarhyssa atrata F., the largest hymenopteran parasitoid known, is found in the holarctic. The stylus of its ovipositor can reach a length of 142 mm, the longest of all known genitalia in Arthropoda. This pimpline parasitizes its host, Tremex columba L., at a great depth in wood. Valvulae 3, which are always shorter than the stylus, are characterized on their outer side by abundant trichoid sensilla of three different types, and on their inner side by a dense layer of cuticular spines probably used in cleaning and shielding the stylus while at rest. The joint region between stylus and abdominal segments is richly equipped with mechanoreceptive trichoid and campaniform sensilla. The ovipositor canal is located between the two valvulae 1 which are separate for their entire length and supported proximally by the two valvulae 2 which are joined to each other from the base. The distal end of the stylus, shaped like an indented lancet, has secretory pores, the first such to be observed in Hymenoptera, from which accessory gland secretions flow. These secretions reach the end of the stylus by intravalvular canals in valvulae 1 and 2. These substances, which may cause cell lysis and also act as lubricants, can accumulate among the tens of thousands of cuticular formations distributed along the stylus which are thought to be surface storage cavities for the secretions. The sensory equipment of the stylus consists of six rows of approximately 200 mechanoreceptive campaniform sensilla. The ovipositor of M. atrata is thus characterized by almost exclusively mechanoreceptive sensory equipment; chemical stimuli appear to be monitored by two types of trichoid sensilla on valvulae 3. The finding that secretory pores occupy exactly the same sites as chemoreceptors in Ichneumonidae, Chalcidoidea, and Proctotrupoidea demonstrates the importance of studying the ovipositor of this parasitoid adapted to withstanding extreme pressures as it penetrates deep into wood.