Morphological Types Of Sensilla Research Articles

Morphological Characterization of the Antennal Sensilla of the Legume Pod Borer, Maruca vitrata (Fabricius) (Lepidoptera: Crambidae).

Maruca vitrata (Fabricius) is an important lepidopteran pest of legumes in the tropics and subtropics. Here, we studied the ultrastructural organization of its antennal sense organs using scanning electron microscopy. The antennae of both sexes of M. vitrata were filiform with the number of flagellar segments varying from 72 to 84. Nine major morphological types of sensilla were observed on male and female antennae: sensilla trichodea (ST), sensilla basiconica (SB), sensilla auricillica (SA), sensilla chaetica (SCh), sensilla coeloconica (SCoe), sensilla cylindrica (SCy), sensilla squamiformia (SSq), sensilla styloconica (SSt), and Böhm sensilla (BS). Three of these sensilla types (SB, SSq, and BS) are newly reported for M. vitrata. Morphological observations revealed that four types are multiporous (ST, SB, SA, and SCoe), two types are uniporous (SCh and SCy), and three types are aporous (SSq, SSt, and BS). The average length of male ST was longer than that of the female. Sensilla cylindrica were observed only on male antennae, indicating sexual dimorphism. This study aims to provide some basic evidence for further studies on the mechanism of insect-plant chemical communication and future semiochemical-based management strategies of the major legume pest M. vitrata.

Antennal sensory structures of Phenacoccus solenopsis (Hemiptera: Pseudococcidae)

BackgroundThe cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is one of the most devastating sap-sucking pests of cultivated plants. The success of P. solenopsis is attributable to its ecological resilience and insecticide resistance, making its control extremely difficult and expensive. Thus, alternative safe approaches are needed to prevent the pest population from reaching the economic threshold. One of these novel approaches is based on the fact that chemical communication via the olfactory system drives critical behaviors required for the survival and development of the species. This knowledge can be useful for controlling insect pests using traps based on semiochemicals. The antennae of insects are an invaluable model for studying the fundamentals of odor perception. Several efforts have been made to investigate the histological and ultrastructural organization of the olfactory organs, such as the antennae and maxillary palps, in many insect species. However, studies on the antennal sensory structures of Phenacoccus species are lacking. Furthermore, although enormous progress has been made in understanding the antennal structures of many mealybug species, the olfactory sensilla in the antennae of P. solenopsis have not yet been described. In this study, we describe, for the first time, the morphology and distribution of the antennal sensilla in male and female P. solenopsis using scanning electron microscopy.ResultsOur results revealed that the entire antennae length and the number of flagellar segments were different between the sexes. Eight morphological types of sensilla were identified on male antennae: trichoid sensilla, chaetic sensilla (three subtypes), basiconic sensilla (two subtypes), and campaniform sensilla (two subtypes). Six morphological types of sensilla were found on female antennae. Sensilla chaetica of subtype 2 and campaniform sensilla of subtype 1 were distributed only on male antennae, suggesting that these sensilla are involved in the recognition of female sex pheromones. The subtype 1 of sensilla chaetica was significantly more abundant on female antennae than on male ones, while subtype 3 was only located on the terminal flagellar segment of the antenna in both sexes.ConclusionsThis study provides insightful information for future electrophysiological and behavioral studies on chemical communication in insects, particularly the cotton mealybug, P. solenopsis that could help in developing new strategies for controlling this economically important insect species.

Morphological characterization and distribution of antennal sensilla of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) using scanning electron microscopy.

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a serious polyphagous pest of various field and horticultural crops. A complete knowledge on the morphological features of antennal sensory structures is essential for efficient semiochemical-based control methods. The external structure and distribution of antennal sensilla in male and female adults of H. armigera were investigated using scanning electron microscopy. Eight distinct morphological types of sensilla were identified in both sexes: sensilla trichodea, sensilla basiconica, sensilla auricillica, sensilla coeloconica (multiporous), sensilla chaetica (uniporous), sensilla styloconica, sensilla squamiformia, and Böhm sensilla (aporous) in varying numbers and distribution along the length of the antennae. Of these sensilla, the most widespread are sensilla trichodea and sensilla basiconica on the antennae of both sexes. Female antennae have comparatively greater number of sensilla trichodea than male antennae. Among eight types of sensilla, sensilla basiconica, auricillica, styloconica type II, squamiformia, and Böhm sensilla were identified and reported for the first time in H. armigera. Sexual dimorphism in H. armigera was mainly detected as the variations in sensilla shape, numbers, and distribution of each type of sensilla. The sexual difference was observed in the numbers of sensilla coeloconica, chaetica, styloconica, and squamiformia per flagellomere. The possible functions of these sensilla were discussed in view of previously reported lepidopteran insects. The findings provide fundamental information on the morphology and distribution of antennal sensory structures in H. armigera. It would be useful for further detailed studies on physiological and behavioral function of each sensillum type and helpful for formulating related pest control methods.

Morphology and distribution of sensilla on the antennae and ovipositor of the Hymenopteran parasitoid Pseudotorymus jaapiellae Yang et Chen

Pseudotorymus jaapiellae is an important ectoparasitoid of the larvae of Gephyraulus lycantha, a serious gall-forming pest that devastates wolfberry, Lycium barbarum, in Northwest China. To provide requisite background for our ongoing research on the mechanisms of P. jaapiellae's host location and subsequent oviposition, we used scanning electron microscopy to describe the external morphologies and distributions of sensilla on their antennae and ovipositors. The geniculate antennae of both male and female P. jaapiellae were each composed of a scape with a basal radiculum, a pedicel, an anellum and a flagellum. We identified nine morphological sensilla types on the antennae of both sexes, including three sensilla trichodea (ST), one sensillum basiconicum (SB), two sensilla chaetica (SCh), one sensillum placodeum (SP), one sensillum coeloconicum (SCo), and one sensillum campaniformia (SCa). Females had significantly more ST I and SP than males had, but males had more ST III than did females. We observed six types of sensilla on the ovipositor, including three ST, one SB, and two SCa. ST II, ST IV and SB II were on the sheath, whereas ST V and the SCa were on the stylus. Finally, the possible biological functions of these sensilla were discussed according to their morphology and ultrastructure. These results provide an important basis for further study on chemical communication between P. jaapiellae and their host, and contribute to the development of a biological control program for G. lycantha, using the parasitoid, P. jaapiellae.

Sensation of the tiniest kind: the antennal sensilla of the smallest free-living insect Scydosella musawasensis (Coleoptera: Ptiliidae).

Miniaturization is a major evolutionary trend prominent in insects, which has resulted in the existence of insects comparable in size to some unicellular protists. The adaptation of the complex antennal multisensory systems to extreme miniaturization is a fascinating problem, which remains almost unexplored. We studied the antennal sensilla of Scydosella musawasensis Hall, 1999 (Coleoptera: Ptiliidae), the smallest free-living insect, using scanning electron microscopy. The antenna of S. musawasensis bears 131 sensilla; no intraspecific variation in the number or position of the sensilla has been revealed. Nine different morphological types of sensilla are described according to their external morphological features and distribution: four types of sensilla trichodea, one type of sensilla chaetica, two types of sensilla styloconica, and two types of sensilla basiconica. Morphometric analysis of the sensilla of S. musawasensis, based on measurements of the lengths and diameters of sensilla and their location and number, showed the absence of significant differences between females and males. Comparative allometric analysis of S. musawasensis and larger Coleoptera showed that the number of sensilla and the size of sensilla chaetica decrease with decreasing body size. However, the number of the types of sensilla and the length and diameter of the multiporous sensilla basiconica revealed no correlation with the body size. Comparison of the acquired data with the results of our earlier study of the antennal sensilla of some of the smallest parasitic wasps is used to put forward hypotheses on the common principles of miniaturization of the antennal sensory systems of insects.

Mouthpart sensory structures of the human head louse Pediculus humanus capitis

Head lice are exclusive human parasitic blood-sucking insects. Distributed worldwide among school-age children, this parasitosis generates scalp irritation and sometimes social prejudice. Understanding how head lice detect and perceive their human hosts is crucial to control transmission. Here, we describe the sensory structures present on the mouthparts of Pediculus humanus capitis and their possible contribution to the feeding decision-making process. On the anterior zone of the clypeus around the haustellum two morphological types of sensilla, invariable in location and number, were identified: fourteen short clypeus bristles (SCB) and six long clypeus bristles (LCB). During feeding these structures contact the host skin but not its blood. Located antero-dorsally on the everted haustellum and between the epipharyngeal teeth, a third sensillar type was identified: about four short peg epipharyngeal (SPE) sensilla. These structures are bathed with the incoming blood, when head lice feed, so may have a gustatory role. In behavioural experiments antennectomy of lice did not interfere with feeding behaviour, suggesting that the sensory structures on the mouthparts could be involved in host assessment.

Ultrastructure of Antennal Morphology and Sensilla of Teak Skeletonizer, Eutectona machaeralis Walker (Lepidoptera: Crambidae).

The leaf skeletonizer, Eutectona machaeralis (Walker) (Lepidoptera: Crambidae), is a severe insect pest of teak trees (Tectona grandis L.f.) in China. To provide some basic evidence for future semiochemical-based management strategies of E. machaeralis, the morphology, ultrastructure, and distribution of antennal sensilla of adults were observed under scanning and transmission electron microscopy. The shape and structure of antenna were similar between males and females, both being filiform. However, the antennal length of males was significantly longer than that of females. Eight morphological sensilla types were observed in both sexes: Böhm's bristles, sensilla trichodea, sensilla basiconica, sensilla chaetica, sensilla styloconica, sensilla coeloconica, sensilla auricillica, and sensilla squamiformia. Significant sexual dimorphism of the sensilla dimensions was found, especially in sensillar length. The putative and potential functions of the different sensilla types are discussed based on the fine structures of the cuticular walls and dendrites of the different sensilla types. We expect these results to help lay a solid foundation for future functional research and develop further investigations of E. machaeralis.

Morphological characterization of antennae and antennal sensilla of Diaphorina citri Kuwayama (Hemiptera: Liviidae) nymphs.

Diaphorina citri Kuwayama is the most economically important citrus pest which is the primary vector of Candidatus Liberibacter spp. causing citrus greening (huanglongbing, HLB) disease. To better understand the developmental and structural changes of antennae and antennal sensilla in D. citri nymphs, we investigated the antennal morphology, structure and sensilla distribution of the five nymphal stages of D. citri using scanning electron microscopy. The antennae of the five different nymphal stages of D. citri were filiform in shape, which consisted of two segments in the first-, second- and third-instar nymphs; three segments in the fourth- and fifth-instar nymphs. The length of their antennae was significantly increased with the increase of the nymphal instar, as well as the total number of antennal sensilla. Ten morphological sensilla types were recorded altogether. They were the long terminal hair (TH1), short terminal hair (TH2), sensilla trichoidea (ST), cavity sensillum 1 (CvS1), cavity sensillum 2 (CvS2), sensilla basiconica 1-3 (SB1-3), sensilla campaniform (SCA) and partitioned sensory organ (PSO). Also, the distribution of antennal sensilla in each nymphal stage of D. citri was asymmetrical. The SBs only occurred on the antennae of the third-, fourth- and fifth-instar nymphs. Only one CvS2 was found in the third- and fifth-instar nymphs, and one SCA in the fourth- and fifth-instar nymphs, respectively. The possible roles of the nymphal antennal sensilla in D. citri were discussed. The results could contribute to a better understanding of the development of the sensory system, and facilitate future studies on the antennal functions in D. citri nymphs.

Morphological, chemical and electrophysiological investigations of Telchin licus (Lepidoptera: Castniidae).

The giant sugarcane borer Telchin licus (Drury, 1773) (Lepidoptera: Castniidae) is a day-flying moth pest of sugarcane, pineapples and bananas. To better understand the chemical communication in this species, we examined the morphology of its olfactory system and the chemical composition of its body parts. The ventral surface of the clubbed antennae of T. licus has six morphological types of sensilla: sensilla trichodea, basiconica, chaetica, squamiforma, coeloconica, and auricillica. The telescopic ovipositor shows no evidence of a sexual gland, or female-specific compounds. On the other hand, the midleg basitarsus of males releases (E,Z)-2,13-octadecadienol and (Z,E)-2,13-octadecadienol, which are electroantennographically active in both sexes. These compounds are known female sex pheromones in the Sesiidae family and are male-specific compounds in another castniid moth, although further investigations are necessary to elucidate their ecological role in the Castniidae family.

Morphology and Distribution of the Antennal Sensilla of Two Species, Megalurothrips usitatus and Thrips palmi (Thysanoptera: Thripidae).

The morphology and distribution of the antennal sensilla of Megalurothrips usitatus Bagnall and Thrips palmi Karny were examined using scanning electron microscopy (SEM). These are serious pests of various economically important crops, and their antennae are important in chemical communication. The antennae of both species consist of a scape, pedicel, and flagellum, but the flagellum of M. usitatus is made up of six sub-segments, whereas that of T. palmi consists of five sub-segments. Seven morphological sensilla types, including Böhm bristle (BB), sensilla campaniformia (Sca), three types of sensilla basiconica (Sb1, Sb2 and Sb3), two types of sensilla chaetica (Sch1 and Sch2), sensilla styloconica (Sst), sensilla trichodea (St), and sensilla cavity (Scav), were recorded in both species. The scape and pedicels exhibited Sch1, BB and Sca. The flagellum exhibited two types of Sch, three types of Sb, St, Sst and Scav. Based on these results, the putative function of the sensilla of M. usitatus and T. palmi are also discussed.

Antennal sensory structures in water bugs of Nepoidea (Insecta: Hemiptera: Nepomorpha), their morphology and function

The Nepoidea superfamily belongs to the water bugs’ infraorder (Nepomorpha) and consists of two families—Belostomatidae and Nepidae. Species from those families are the largest of all nepomorphans and are considered to be top predators in aquatic ecosystems. A characteristic feature of the group is the existence of short antennae concealed in grooves behind the eyes, which is an adaptation to the water habitat. The antennae bear many types of sensillar structures, which receive signals from the environment. Among such structures, mechanosensilla were of the greatest diversity. The antennal sensilla of species from both families were examined under the scanning electron microscope. 11 essential morphological types of sensilla were distinguished, including 5 new mechanosensilla types (sensilla paddle-like, cone-like, squamiformia, brush-like and club-like). Basal types of mechanosensilla such as trichodea, chaetica, basiconica (subtype 1) and campaniformia occur in Nepoidea and other Heteroptera. In some representatives of both families, sensilla paddle-like and sensilla basiconica type 1 were observed. Moreover, sensilla chaetica and cone-like were found in some species of Belostomatidae, whereas in Nepidae sensilla squamiformia, brush-like and club-like were observed. Apart from mechanosensilla, one type of thermo-hygrosensilla (ampullacea) and two different shaped olfactory sensilla basiconica (subtypes 2, 3) and coeloconica (subtypes 1, 2, 3) were found. It could indicate sensilla use in the identification of the water reservoirs and locating prey.

Ultrastructure observations on antennal sensilla of Heortia vitessoides the most serious pest of Aquilaria sinensis

Heortia vitessoides is the most serious pest of Aquilaria sinensis,which is an economically important evergreen tree native to China and is the principal source of Chinese agarwood. In severe infestations,the insects completely eat up the leaves of A. sinensis,causing severe economic losses. In a more recent study,we found that the antennal sensilla of adult play important roles in the host location,mating and oviposition of H. vitessoides. Here,the external morphology of the antennal sensilla of H. vitessoides were examined using scanning electron microscopy. The result showed that the antennae of both sexes of H. vitessoides were filiform in shape,which consist of the scape,pedicel and about 64 segments of flagellomeres. Eight morphological sensilla types were recorded in both sexes,including sensilla trichodea,sensilla chaetica,sensilla basiconica,sensilla coeloconica,sensilla styloconica,sensilla auricillica,sensilla squamiformia and böhm bristle. Major differences were recorded in the distribution and quantity of different sensilla types in each segment of antenna. The sensillas are almost confined to the ventral and lateral surfaces rather than the back side of antennae. Antennal flagella contained the most sensilla while the scape and pedicel segments only contained böhm bristles and sensilla squamiformias. Sensilla trichodea Ⅲ were only found on male antennae. These results are discussed in relation to the possible roles of the sensilla types in the host location,mating and oviposition selection behavior of H. vitessoides.

Comparative Study of the Antennal Phenotype in Species of the Belminus (Hemiptera: Triatominae) Genus Using Optical and Scanning Electron Microscopy.

The genus Belminus Stål, 1859 is distinguished by markedly entomophagous species. This genus is a poorly studied group of the Triatominae (Jeannel, 1919), which includes hematophagous species that are vectors of Trypanosoma cruzi (Chagas, 1909), the etiological agent of Chagas disease. This study reports for the first time the description of the antennal sensilla of Belminus corredori (Galvão & Angulo, 2003), Belminus herreri (Lent & Wygodzinsky, 1979), and Belminus ferroae (Sandoval, Pabón, Jurberg & Galvão, 2007) nymphs and adults throughout scanning electron microscopy and optical microscopy. Nine morphological types of sensilla were identified in the three species, including bristles I and II, trichobothria, tapered hairs, thin-walled trichoid, thick-walled trichoid, basiconic, campaniform, and coeloconica sensilla. The analysis of the most abundant types of sensilla and their distribution in nymphs and adults shows similarities with the antennal phenotypes described in other Triatominae. Quantitative differences showed the important phenotypic plasticity of this morphological trait in the genus and allowed for the separation of the species in both sexes. These differences were associated with sexual dimorphism and wing condition (macropterous and brachypterous). The role of the antennal phenotype in sexual behavior, its usefulness as a taxonomic tool, and its relationship with the dispersal capacity of these species are 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.

Between extreme simplification and ideal optimization: antennal sensilla morphology of miniaturized Megaphragma wasps (Hymenoptera: Trichogrammatidae).

One of the major trends in the evolution of parasitoid wasps is miniaturization, which has produced the smallest known insects. Megaphragma spp. (Hymenoptera: Trichogrammatidae) are smaller than some unicellular organisms, with an adult body length of the smallest only 170 µm. Their parasitoid lifestyle depends on retention of a high level of sensory reception comparable to that in parasitoid wasps that may have antennae hundreds of times larger. Antennal sensilla of males and females of Megaphragma amalphitanum and M. caribea and females of the parthenogenetic M. mymaripenne are described, including sensillum size, external morphology, and distribution. Eight different morphological types of sensilla were discovered, two of them appearing exclusively on female antennae. Two of the types, sensilla styloconica and aporous placoid sensilla, have not been described previously. Regression analyses were performed to detect and evaluate possible miniaturization trends by comparing available data for species of larger parasitoid wasps. The number of antennal sensilla was found to decrease with the body size; M. amalphitanum males have only 39 sensilla per antenna. The number of antennal sensilla types and sizes of the sensilla, however, show little to no correlation with the body size. Our findings on the effects of miniaturization on the antennal sensilla of Megaphragma provide material for discussion on the limits to the reduction of insect antenna.

Antennal Morphology and Localization of a Pheromone-Binding Protein of Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae).

In the sensory system of insects, olfactory sensilla constitute important functional elements for discriminating odors. Therefore, we used light microscopy and scanning electron microscopy to investigate the morphology and distribution of sensilla in the antennae of Lobesia botrana (Denis & Schiffermüller). In addition, we studied the expression of the gene encoding for pheromone-binding protein 1 (LbotPBP1) by in situ hybridization. Lobesia botrana antennae are filiform and are subdivided into three segments: scape, pedicel, and flagellum. The number of flagellum and their overall length were significantly higher and longer in males than in females. Six morphological types of sensilla (trichodea, chaetica, coeloconica, auricillica, basiconica, and styloconica) were identified on the antennae of both sexes. Trichodea sensilla were the most abundant on the antennae of L. botrana, and three subtypes, discerned by their lengths, were observed. However, sensilla trichodea subtype III was only present in male antennae. Moreover, LbotPBP1 expression was restricted to this type of sensilla, thus confirming its olfactory role, specifically under the context of sexual pheromone perception.

Species- and sex-specific distribution of antennal olfactory sensilla in two tortricid moths, Epiphyas postvittana and Planotortrix octo

We investigated the morphology and distribution of antennal sensilla in males and females of two tortricid moths, Epiphyas postvittana and Planotortrix octo, by scanning electron microscopy. The number and overall length of flagellomeres were significantly greater in females than in males in both species. The antennae of each species bearing six morphological types of sensilla (trichodea, basiconica, coeloconica, auricillica, chaetica, and styloconica), with different numbers and distributions along the antennae. Among these sensilla, four types (trichodea, basiconica, coeloconica, and auricillica) displayed multi-porous cuticular surfaces, indicating that their primary sensory function is olfactory. Each of these four types of sensilla could be further classified into subtypes according to their size, shape, and surface structure. Both E. postvittana and P. octo exhibited sexual dimorphism of the profiles of antennal olfactory sensilla. Trichoid sensilla were the most abundant type in both species. Subtype I trichoid sensilla were male-specific in both species, indicating that they are responsible for the perception of conspecific female sex pheromone. By contrast, subtype II trichoid sensilla were more abundant in female antennae in both species, suggesting that some subtype II trichoid sensilla are involved in female-specific behaviors, such as oviposition. Chaetic and styloconic sensilla displayed relatively even distributions along the antennae. Our results indicate that the antennae of E. postvittana and P. octo have species-specific and sex-specific profiles of olfactory sensilla. The morphological information obtained in our study provides a basis for electrophysiological and behavioral studies of the olfactory sensory function of each morphological type of sensilla.

Structure and distribution of the sensilla on the antennae of Tuta absoluta (Lepidoptera: Gelechiidae)

The tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), is a widespread devastating pest that develops on tomato and other economically important solanaceous crops. Current semiochemically-based management strategies still fail to significantly reduce damages and need to be improved. Here we describe under scanning and transmission electron microscopy the structure and distribution of the sensilla that are displayed on adult antennae. These were similar in size between males (3424.4±135.3μm) and females (3292.1±111.5μm), being segmented into a scape, a pedicel, and a distal filiform flagellum. Eight morphological sensilla types were observed on both sexes: Böhm’s bristles, sensilla squamiformia, sensilla trichodea, sensilla basiconica (two subtypes), sensilla chaetica, sensilla coeloconica, sensilla auricillica, and sensilla styloconica. The main sexual dimorphism was related to the higher abundance of sensilla trichodea in males, twice as abundant as in females. The putative functional significance of the different sensilla types regarding the insect ecology is discussed based on the available literature. This work provides descriptions of the antennae and related sensory structures. We expect these results to help develop further electrophysiological investigations aiming to a better understanding of T. absoluta olfaction.

Scanning Electron Microscopy Study of the Antennal Sensilla of Monema flavescens Walker (Lepidoptera: Limacodidae).

Monema flavescens Walker (Lepidoptera: Limacodidae) is a serious polyphagous defoliator. Using scanning electron microscopy, the external morphology of the antennal sensilla of this pest was examined for a better understanding of the mechanisms of insect-insect and insect-plant chemical communications. The antennae of M. flavescens were filiform in shape, and 11 morphological types of sensilla were found in both sexes. Six types of likely chemosensory sensilla were identified: uniporous sensilla chaetica, multiporous sensilla trichodea, and four types of multiporous sensilla basiconica. The sensilla identified as likely mechanoreceptors included two subtypes of aporous sensilla chaetica, aporous sensilla coeloconica, aporous sensilla styloconica, and Böhm's bristles, whereas the position of the antennae was monitored by Böhm's bristles.

Antennal Sensillum Morphology and Electrophysiological Responses of Olfactory Receptor Neurons in Trichoid Sensilla of the Diamondback Moth (Lepidoptera: Plutellidae)

Abstract Plant chemical signals are important olfactory cues for the survival and reproduction of phytophagous insects. The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) is a Brassica spp. (Brassicales: Brassicaceae) specialist pest, with most of its life events occurring on Brassica spp. hosts. We conducted a scanning electron microscopy study on the morphology and distribution of antennal sensilla of male and female P. xylostella. Seven morphological types of sensilla were identified in the antennae of P. xylostella: 3 types of sensilla trichodea (Tr I, Tr II and Tr III), sensilla chaetica, sensilla coeloconica, sensilla auricillica and sensilla styloconica. One particular type of trichoid sensillum (Tr III) was present only in the males. The presence of numerous pores or deep longitudinal grooves on the surfaces of 5 morphological types of sensilla indicated that their major function is olfactory. Single sensillum recordings were also carried out on the trichoid sensilla of the fe...