Tropomyosin is co-localized with the actin filaments of the scolopale in insect sensilla

Summary Immuno-electron microscopy confirms that the scolopale, a characteristically prominent cytoskeletal element of insect scolopidia, is composed mainly of actin filaments. Immunohistochemistry reveals that these filaments are co-localized with tropomyosin. Myosin S1-decoration shows that their polarity is unidirectional. Antibodies to -actinin do not bind within the scolopale. The association of these actin filaments with tropomyosin in the absence of myosin, together with their uniform polarity, strongly suggests that, in the scolopale, they have a stabilizing rather than contractile function. Filament elasticity would appear to be important for stimulation. The degree of elasticity may well be governed by the extent of tropomyosin binding.     

Deriving ecological relationships from geographical correlations between host and parasitic species: an example with orchid bees

Aim  To investigate biogeographical patterns of cleptoparasitic Exaerete bee species and their orchid bee hosts.
Location  Neotropical region, from Central America to southern Brazil.
Methods  Correlations between relative frequencies of cleptoparasitic Exaerete species and their host Eulaema species were employed to investigate the geographical association between such species pairs.
Results  Our data support the current proposition that the Eulaema meriana / Eulaema flavescens complex is the main host for Exaerete frontalis . Contrary to current belief, however, Eulaema nigrita apparently is not the only and, in some regions, not the most important host for Exaerete smaragdina .
Main conclusions  Current knowledge on cleptoparasite host associations among orchid bees is based on fortuitous observations, and in some instances generalizations from such observations are not corroborated by the frequencies and distributions of the bees involved. Our data suggest that cleptoparasitic pressure, rather than other features of the forest environment, may be responsible for the low abundance of E. nigrita in the Amazonian forests.     

Innervation pattern of suboesophageal ventral unpaired median neurones in the honeybee brain

In honeybees (Apis mellifera), the biogenic amine octopamine has been shown to play a role in associative and non-associative learning and in the division of labour in the hive. Immunohistochemical studies indicate that the ventral unpaired median (VUM) neurones in the suboesophageal ganglion (SOG) are putatively octopaminergic and therefore might be involved in the octopaminergic modulation of behaviour. In contrast to our knowledge about the behavioural effects of octopamine, only one neurone (VUMmx1) has been related to a behavioural effect (the reward function during olfactory learning). In this study, we have investigated suboesophageal VUM neurones with fluorescent dye-tracing techniques and intracellular recordings combined with intracellular staining. Ten different VUM neurones have been found including six VUM neurones innervating neuropile regions of the brain and the SOG exclusively (central VUM neurones) and four VUM neurones with axons in peripheral nerves (peripheral VUM neurones). The central VUM neurones innervate the antennal lobes, the protocerebral lobes (including the lateral horn) and the mushroom body calyces. Of these, a novel mandibular VUM neurone, VUMmd1, exhibits the same branching pattern in the brain as VUMmx1 and responds to sucrose and odours in a similar way. The peripheral VUM neurones innervate the antennal and the mandibular nerves. In addition, we describe one labial unpaired median neurone with a dorsal cell body, DUMlb1. The possible homology between the honeybee VUM neurones and the unpaired median neurones in other insects is discussed. This work was supported by the DFG ME 365/24-2.     

Characterization of the nicotinic acetylcholine receptor subunit gene Mdalpha2 from the house fly, Musca domestica

A nicotinic acetylcholine receptor (nAChR) subunit gene, Mdalpha2, was isolated and characterized from the house fly, Musca domestica. This is the first nAChR family member cloned from house flies. Mdalpha2 had a cDNA of 2,607 bp, which included a 696 bp 5'-untranslated region (UTR), an open reading frame of 1,692 bp, and a 219 bp 3'-UTR. Its deduced amino acid sequence possesses the typical characteristics of nAChRs. Mdalpha2 genomic sequence was 11.2 kb in length in the aabys strain and 10.9 kb in the OCR strain, including eight exons and seven introns. Based on the deduced amino acid sequence, Mdalpha2 had the closest phylogenetic relationship to the Drosophila melanogaster Dalpha2 and Anopheles gambiae Agamalpha2, and a similar genomic structure to Dalpha2. Quantitative real-time PCR analysis showed that Mdalpha2 is expressed in the head and the thorax at 150- and 8.5-fold higher levels than in the abdomen. Linkage analysis of a Mdalpha2 polymorphism indicates this gene is on autosome 2. The importance of these results in understanding the diversity and phylogenetic relationships of insect nAChRs, the physiology of nAChRs in the house fly, and the utility of nAChR sequences in resistance detection/monitoring is discussed.     

On the systematic position of Baltimartyria Skalski, 1995 and description of a new species from Baltic amber (Lepidoptera, Micropterigidae)

This paper describes a rare case of a male moth in Baltic amber in an excellent position for establishing a species. The moth represents the second species of the genus Baltimartyria Skalski, 1995, described herein as Baltimartyria rasnitsynisp. n. The detection of this new species prompts research on the systematic position of the genus within the family Micropterigidae. The genus was found to provide none of the apomorphic characters that would allow placement in one of the monophyletic lineages within the family. The genus is provisionally assigned to the "southern sabatincoid group", a weakly supported assemblage of Southern Hemisphere genera. The sister genus has still to be determined. Baltimartyria is the first North Hemisphere representative in this group. Some general aspects of historical biogeography relevant for the group are briefly discussed.     

Types of geographical distribution of leaf beetles (Chrysomelidae) in Central Europe

A comparison of the geographical distribution patterns of 647 species of Chrysomelidae in Central Europe revealed 13 types of distribution: (1) widely distributed, (2) southern, (3) southeastern, (4) southwestern, (5) northern, (6) eastern, (7) south east quarter, (8) south west quarter, (9) fragmented, (10) montane, (11) subalpine & alpine, (12) scattered, (13) unusual, and irregular patterns produced by insufficient data. Some of these distributions are trivial (e. g. northern, eastern, etc., alpine) but others are surprising. Some cannot be explained, e. g. the remarkable gaps in the distribution of Chrysolina limbata (Fabricius, 1775) and in Aphthona nonstriata (Goeze, 1777). Although our 63.000 records are necessarily tentative, we found that the distribution maps from these data reflect in many cases the common knowledge on the occurrence of leaf beetles in specific areas.     

New species of the genus Glaesotropis (Insecta: Coleoptera: Anthribidae) from Rovno amber

A new species of the fungus weevil genus Glaesotropis is described from the Late Eocene Rovno amber. G. diadiasashai sp. nov. differs from G. weitschati and G. minor described from Baltic amber in having a longer rostrum and in the structure of its antennae, with the third and fourth antennomeres being longer than the first and second ones. Additionally, the new species differs from G. weitschati in being smaller, in having unswollen frons, and weakly and smoothly concave elytral margin near hind coxae. The new species also differs from G. minor in having an uninterrupted posterior transverse carina on the pronotum, elytra less convex longitudinally, and a slightly broadened rostrum at the attachment of antennae.     

Regulatory peptides in fruit fly midgut

Regulatory peptides were immunolocalized in the midgut of the fruit fly Drosophila melanogaster. Endocrine cells were found to produce six different peptides: allatostatins A, B and C, neuropeptide F, diuretic hormone 31, and the tachykinins. Small neuropeptide-F (sNPF) was found in neurons in the hypocerebral ganglion innervating the anterior midgut, whereas pigment-dispersing factor was found in nerves on the most posterior part of the posterior midgut. Neuropeptide-F (NPF)-producing endocrine cells were located in the anterior and middle midgut and in the very first part of the posterior midgut. All NPF endocrine cells also produced tachykinins. Endocrine cells containing diuretic hormone 31 were found in the caudal half of the posterior midgut; these cells also produced tachykinins. Other endocrine cells produced exclusively tachykinins in the anterior and posterior extemities of the midgut. Allatostatin-immunoreactive endocrine cells were present throughout the midgut. Those in the caudal half of the posterior midgut produced allatostatins A, whereas those in the anterior, middle, and first half of the posterior midgut produced allatostatin C. In the middle of the posterior midgut, some endocrine cells produced both allatostatins A and C. Allatostatin-C-immunoreactive endocrine cells were particularly prominent in the first half of the posterior midgut. Allatostatin B/MIP-immunoreactive cells were not consistently found and, when present, were only weakly immunoreactive, forming a subgroup of the allatostatin-C-immunoreactive cells in the posterior midgut. Previous work on Drosophila and other insect species suggested that (FM)RFamide-immunoreactive endocrine cells in the insect midgut could produce NPF, sNPF, myosuppressin, and/or sulfakinins. Using a combination of specific antisera to these peptides and transgenic fly models, we showed that the endocrine cells in the adult Drosophila midgut produced exclusively NPF. Although the Drosophila insulin gene Ilp3 was abundantly expressed in the midgut, Ilp3 was not expressed in endocrine cells, but in midgut muscle.     

Expression of UV-, blue-, long-wavelength-sensitive opsins and melatonin in extraretinal photoreceptors of the optic lobes of hawkmoths

Lepidopterans display biological rhythms associated with egg laying, eclosion and flight activity but the photoreceptors that mediate these behavioural patterns are largely unknown. To further our progress in identifying candidate light-input channels for the lepidopteran circadian system, we have developed polyclonal antibodies against ultraviolet (UV)-, blue- and extraretinal long-wavelength (LW)-sensitive opsins and examined opsin immunoreactivity in the adult optic lobes of four hawkmoths, Manduca sexta, Acherontia atropos, Agrius convolvuli and Hippotion celerio. Outside the retina, UV and blue opsin protein expression is restricted to the adult stemmata, with no apparent expression elsewhere in the brain. Melatonin, which is known to have a seasonal influence on reproduction and behaviour, is expressed with opsins in adult stemmata together with visual arrestin and chaoptin. By contrast, the LW opsin protein is not expressed in the retina or stemmata but rather exhibits a distinct and widespread distribution in dorsal and ventral neurons of the optic lobes. The lamina, medulla, lobula and lobula plate, accessory medulla and adjacent neurons innervating this structure also exhibit strong LW opsin immunoreactivity. Together with the adult stemmata, these neurons appear to be functional photoreceptors, as visual arrestin, chaoptin and melatonin are also co-expressed with LW opsin. These findings are the first to suggest a role for three spectrally distinct classes of opsin in the extraretinal detection of changes in ambient light and to show melatonin-mediated neuroendocrine output in the entrainment of sphingid moth circadian and/or photoperiodic rhythms.This work was partially supported by the Canadian Institute for Advanced Research (A.D.B.) and the National Science Foundation (grant nos. IBN-0082700 and IBN-0346765; A.D.B.).