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Preliminary data on Stegobium paniceum (L.) larval head sensilla
No full textSensory structures of Stegobium paniceum (L.) head have been investigated under Scanning and Transmission Electron Microscopes and described. Their possible function is hypothesized
Ultrastructural and functional aspects of the spermatheca in the american harlequin bug, Murgantia histrionica (Hemiptera: Pentatomidae)
No full textThe spermatheca of Murgantia histrionica (Hahn) was investigated using fluorescence, scanning and transmission electron microscopy. The aim of the study was to elucidate the structure of this organ, pointing out differences between mated and unmated females. Results have shown an elaborated cuticular structure associated with muscular and glandular tissues. The spermatheca is joined with the common oviduct by the spermathecal duct, forming a thin saccular dilation through two consecutive invaginations. The distal part of the organ is formed by a series of two communicating cuticular chambers. The first cylindrical-shaped chamber, corresponding to the coiled region, is wrapped by longitudinal muscular fibers suspended between two cuticular flanges. The contractions of these fibers compress a deformable zone of the cylinder, pumping the sperm toward the spermathecal duct. Without contractions the cylinder results to be isolated from the proximal part of the spermatheca by means of a valve. The second chamber, corresponding to the spermatheca, is made of two parts: a truncated-conical sub chamber, with a constant cuticular thickness, bearing on itself the distal flange, where muscular fibers are attached. The second part is a bulb-like structure wrapped in a glandular epithelium. The secretory units are composed by two cells: a secretory cell and an associated duct cell. Every evacuating duct shows a little reservoir just after the terminal apparatus, and converge inside the distal bulb after a tortuous path. The functional implications of this structure in the reproductive biology of M. histrionica are discussed
Antennal sensory structures in Scaphoideus titanus ball (Hemiptera: Cicadellidae)
No full textScaphoideus titanus Ball (Hemiptera: Cicadomorpha) is a leafhopper vector of a
phytoplasma disease, the Flavescence dore ́e (FD), belonging to the vine yellows group. A scanning
and transmission electron microscope study has been carried out to investigate the antennal sensory
structures. The first two segments, the scape and the pedicel, are short, covered by cuticular
scales and devoid of sensilla, with exception of some scattered hairs on the pedicel. The flagellum
consists of a unique, elongated segment in which numerous subunits can be recognized, being separated
by a sort of cuticular crown. The proximal five subunits bear most of the sensilla. We discovered
the presence of single- and double-walled coeloconic sensilla, campaniform sensilla, basiconic
sensilla, and trichoid sensilla. A scolopidium is located within the proximal region of the flagellum.
Ultrastructural investigations suggest that the antennal sensilla could be involved in the perception
of air-borne vibrations, temperature, and humidity variations. The most relevant feature is
the extreme reduction of the olfactory sensilla, both in terms of number of sensory structures and
sensory neurons per sensillum. The strong reduction in antennal olfactory sensilla to which this
specie has undergone is discussed as possible consequence of the specificity toward the host plant
Risposte olfattive di adulti di Hyalesthes obsoletus ai composti volatili di alcune piante ospiti
No full textFine structure of the antennal glands of the ant nest beetle Paussus favieri (Coleoptera, Carabidae, Paussini)
No full textThe antennae of the ant nest beetle Paussus favieri are studied by using both SEM and TEM. In the
myrmecophilous genus Paussus, these structures are composed of three joints: scape, pedicel and a wide
third joint, the ‘‘antennal club’’, resulting from the fusion of antennomeres A3–A11 (flagellum). The
antennal club shows an exceptional glandular activity, with the presence of pores mostly crowded in
special hairless cuticular areas, surrounding the base of single setae, grouped at the base of tufts of setae,
or positioned inside deep pockets that store the secretions, with filiform material arising from them. The
surface of A1 and A3 are covered by mechanoreceptors, modified to spread the glandular exudates, while
the chemoreceptors are restricted to the apex of the club. The fine structural analysis shows a great
number of antennal glands, that can be referred to three main typologies: type A (GhA) bi-cellular,
composed of a large secretory cell and a small duct cell, positioned close to the antennal surface; type B
(GhB), tri-cellular, composed of two secretory cells and one duct cell, less frequent and positioned deep
inside the antennal club; type C (GhC), rare, located deeply within the antennal lumen, in the vicinity of
the trophocytes. This complexity indicates that more than one substance could be released from the
antennae. Possible functional aspects of the secretions dealing with symbiotic interaction with the host
ants are discussed
Potential use of vibrational signals to manage the Brown Marmorated Stink Bug, Halyomorpha halys, a new invasive agricultural pest
No full textThe Brown Marmorated Stink Bug (BMSB), Halyomorpha halys (Hemiptera: Pentatomidae) is a polyphagous insect that can cause severe economic damage on different crops. In Italy this species was first recorded in the region Emilia Romagna in 2012 and in few years it spread in most of the Northern and part of the Central Italian regions. As well as in other stink bugs the mid-short range mating communication is based on the exchange of vibrational signals (duet) between sexes that is the key of pair formation, courtship and copula. During the duet females are stationary and males actively search on the plant. In other pentatomids the directionality of the searching in males, given by female attractive signals, has been demonstrated. We hypothesize that the same principle works also in BMSB and thus it would be possible to use the female calling signal to attract males towards precise source sites (i.e. artificial shakers). If confirmed, this would represent a potential implementation to the traps commonly used for BMSB monitoring, by providing an additional stimulus to enlarge the amount of captured bugs.
To assess whether the female calling signal could be employed to capture males we performed different bioassays with males stimulated with either natural and synthetic vibrational signals, in different scenarios (i.e., net cages, round arenas, potted plants). Vibrational signals were recorded with laser vibrometer and a video analysis software was used to study the behavioural responses.
Our experiments demonstrated the attractive effect of the female signal in all performed tests. On average, more than 50% of the tested males were attracted to vibrating sources. In addition, we also found a significant increase of walking speed, walked distance and time spent in stimulated areas. These results show promise for developing more efficient trapping techniques against H. halys in both agricultural and urban environments
Olfactory responses and sensilla morphology of Hyalesthes obsoletus Signoret (Hemiptera: Fulgoromorpha: Cixiidae)
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