Flight fuel related differences between solitary and gregarious locusts (Locusta migratoria migratorioides)

Abstract. Flight fuel relations of crowded and isolated Locusta migratoria migratorioides were investigated in younger (12–16 days after fledging) and older (27–30 or 27–32 days after fledging) adult males.No phase polymorphism dependent differences were found in resting haemolymph carbohydrate levels of the younger locusts.In the older age group, resting haemolymph carbohydrate levels were slightly though significantly higher in the isolated than in the crowded locusts.Injection of various doses of synthetic adipokinetic hormones (AKHs) did not induce marked changes in haemolymph carbohydrate levels and no differences were found between crowded and isolated locusts.A 30 min flight led to the same decrease in haemolymph carbohydrate levels of isolated and crowded locusts, 43.3% and 44.6% of the resting levels, respectively.We concluded, therefore, that the results do not seem to indicate that isolated locusts rely more heavily on carbohydrates as flight fuel than crowded locusts.Hyperlipaemic responses to flight were less intense in isolated than in crowded locusts, but phase polymorphism dependent differences in flight-induced increase of haemolymph lipid levels were not parallel in 12–16-day-old and 27–32-day-old males.In the younger age group the difference was mainly in the duration of flight needed to induce full response which appeared already after 20 min of flight in the crowded locusts, but only after 45 or 60 min of flight in the isolated ones.In contrast, the older isolated locusts showed markedly lower haemolymph lipid elevations than the crowded locusts even after 30, 45 or 60 min of flight.The hypothesis is forwarded that isolated locusts have a rather coarse adipokinetic strategy focused on a single long-distance migratory flight, whereas gregarious locusts possess a fine adipokinetic balance for reiterative migratory flights and saving fuel reserves for unpredictable long-distance migrations.     

Occurrence of immunoreactive estradiol-positive material in the haemolymph and ovary of the tasar silkworm,Antheraea mylitta

Summary

Estradiol from the haemolymph and ovaries of tasar silkworm, Antheraea mylitta, was assayed using radio immunoassay. The estimated concentration of estradiol was 143 pg/mg in the ovaries and 102 pg/ml in the haemolymph.     

How does an eclosing fly deal with obstacles?

ABSTRACT. Stereotyped eclosion behaviour of Sarcophaga bullata Parker (Diptera, Sarcophagidae) consists of two different repetitive sequences of movements. One, which is instrumental for making forward progress in extricating the body from the puparium or for digging through the soil, is called the programme for forward movement (PFM). The other, which is performed as a response to an obstruction, is called the programme for obstruction removal (POR). The initial and final phases of each repetitive sequence are identical in both programmes, the sequences differing only in the middle portion. In the POR, the locomotor elements of the PFM sequence (peristalsis) are substituted by a train of repetitive expansions of the ptilinum, which are caused by simultaneous contractions of the abdominal and thoracic muscles. These ptilinal movements function as an air hammer against the obstruction. Switching from the PFM to POR can be experimentally induced by a rough mechanical stimulation of the head (squeezing, pushing against a barrier) but not by gentle tactile stimulation of the ptilinum or antennae. The critical period for induction of the POR is in the phase of the PFM sequence at which the two programmes diverge. A constant mechanical stimulus is necessary for a sustained performance of the whole POR. A hypothetical scheme of the neural basis of this behaviour is suggested.     

Ice nucleation and freezing tolerance in New Zealand alpine and lowland weta, Hemideina spp. (Orthoptera; Stenopelmatidae)

Abstract.The alpine tree weta Hemidiena maori Pictet et Saussure (Orthoptera: Stenopelmatidae) is a large, flightless insect found above the treeline on many of the mountain ranges of the South Island of New Zealand. The population found on the Rock and Pillar Range, Central Otago has been identified as freezing tolerant with a haemolymph ice nucleating agent. The ability of H. maori to survive freezing is compared to the lowland weta Hemideina thoracica Walker and H. crassidens Blanchard, both of which are able to survive the formation of some ice in their bodies. Mortality is associated with time spent frozen in H. thoracica , and it is hypothesized that this species is killed when a critical proportion of its body water is frozen. All five subalpine and alpine populations of H. maori surveyed were found to be freezing tolerant.
Comparison of temperatures of first nucleation and mean supercooling point of haemolymph droplets suggest that haemolymph ice nucleating activity varies between populations of H. maori. Hemideina maori collected from the Mt Cook region appear to lack a haemolymph ice nucleator. This population is nevertheless freezing tolerant, suggesting that the haemolymph ice nucleating agent described in H. maori is not essential for freezing tolerance. Hemideina crassidens and H. ricta Hutton, both of which are found in lowland habitats, also had high mean supercooling point and temperatures of first nucleation of haemolymph droplets, suggesting that these species also have a haemolymph ice nucleator.
Comparison of ice nucleation characteristics of haemolymph and faecal material (representing gut contents) suggests that gut nucleators in H. maori may be at least as efficient as the haemolymph nucleator. It is concluded that freezing tolerance is probably not an adaptation to the alpine environment. This highlights the need for inter- and intraspecific comparative studies if physiological data are to be used to draw evolutionary conclusions.     

Development of imaginal competence to adipokinetic hormone in Locusta: lipid and carbohydrate levels, and glycogen phosphorylase activity in precocene-induced adultiforms

Abstract. Adipokinetic responses to injection of synthetic adipokinetic hormone I (sAKH) were investigated in precocene-induced fifth-instar adultiforms and in chemically allatectomized but morphogenetically normal adults of Locusta migratoria (L.). The results were compared with data on normal fifth (=last)-instar nymphs and normal adults. Chemical allatectomy did not affect the resting level of lipid in the haemolymph, nor the slight decrease of haemolymph carbohydrate concentration induced by sAKH. The effects of chemical allatectomy on sAKH-induced hyperlipaemia, the resting level of haemolymph carbohydrate, total glycogen phosphorylase specific activity, as well as sAKH-induced phosphorylase activation in the fat body, were mostly minor and probably indirect. The concentrations of lipid and carbohydrate in the haemolymph, and sAKH-induced activation of fat body glycogen phosphorylase were more or less similar in normal fifth-instar nymphs, normal adults and fifth-instar adultiforms. Thus, precocious metamorphosis did not affect markedly those parameters which show no or slight changes during normal metamorphosis. In contrast, parameters which change substantially during normal metamorphosis (sAKH-induced hyperlipaemia, sAKH-induced changes in haemolymph carbohydrate level and total glycogen phosphorylase activity) showed similar changes in the course of precocious metamorphosis; the values for fifth-instar adultiforms were similar to those obtained for normal adults, but differed markedly from those found in normal fifth-instar nymphs. Thus, accelerated (precocious) morphological adult development is strongly correlated with accelerated imaginal target competence to AKH and with relevant physiological development.     

Radioimmunological Quantification of C21, C19 and C18 Steroids in Haemolymph of the Insect Locusta migratoria

Summary

Titers of pregnenolone, progesterone, testosterone, 5α-dihydrotestosterone, estrone and estradiol were measured by radioimmunoassay in purified haemolymph extracts of larval and adult male and female Locusta migratoria. They varied between following values (in pg/ml): pregnenolone: 467–757; progesterone: 37–119; testosterone: 11–54; 5α-dihydrotestosterone: 13–41; estrone: 25–1392; estradiol: 12–26. Titers of pregnenolone progesterone, testosterone, 5α-dihydrotestosterone and estradiol did not substantially fluctuate among the developmental stages we examined. Peaks of estrone were found in males and females in the middle of the fifth larval instar and in 3 week old adult males. The titers of most of the above six steroids are about 5 to 10 times lower than the concentrations found in purified extracts of several tissues of this insect.     

High-molecular-weight serum proteins from Locusta migratoria: identification of a protein specifically binding juvenile hormone III

ABSTRACT. Tritiated 10,11-epoxyfarnesyl diazoacetate (EFDA), a photoaffinity label, can be covalently attached to the binding site of a JH-III-specific binding protein in the haemolymph of Locusta migratoria migratorioides (R & F). The specificity of the binding of EFDA to the binding protein is verified by displacement with excess unlabelled JH-III, and EFDA can be used to identify the binding protein in native pore-limiting gradient poly(acrylamide) gel electrophoresis (PAGE) and sodium dodecyl sulphate-PAGE. The native binding protein has a molecular weight of 575,000 and is composed of seemingly identical subunits of molecular weight 81,000.
Three other high-molecular weight serum proteins are identified by native PAGE: a lipophorin, composed of two kinds of apolipophorins, a larval storage protein and a cyanoprotein. The molecular weights and subunit structures of these proteins are investigated, but none of these other high-molecular weight proteins bind JH-III to an appreciable extent.     

Influence of temperature and carbon dioxide concentration on juvenile hormone titre and dependent parameters of adult worker honey bees (Apis mellifera L.)

It is known that juvenile hormone plays an important role in the regulation of labour division and of the different life spans, and that the microclimate of the bee hive is characterized by its high CO₂ concentration and its varying temperature depending on the presence of brood.We have investigated the influence of microclimates characteristic of breeding and broodless areas on the juvenile hormone titre in the haemolymph and whole body extracts, on the corpora allata in vitro activity, on the degradation of juvenile hormone and on the dry weight of the hypopharyngeal glands using bees of known ages. A microclimate of 35°C and 1.5% CO₂, as observed in the breeding area, induces a rapid and pronounced increase in the juvenile hormone titre. On the other hand, this titre remains low in bees kept at 27°C and 1.5% CO₂, a microclimate associated with broodless combs. Rates of juvenile hormone synthesis by corpora allata in vitro were found to be extremely low, even in the presence of farnesenic acid, and not related to the juvenile hormone titre. In vitro incubation of juvenile hormone in haemolymph revealed no degradation while injected juvenile hormone was found to be degraded and taken up by the gut at rates only weakly correlated with the juvenile hormone titre.We propose a hypothetical model for the regulation of the juvenile hormone titre as well as the course of labour division by the varying microclimates observed in the bee hive.     

The sandfly Lutzomyia longipalpis shows specific humoral responses to bacterial challenge

Abstract The presence of immune molecules induced by microorganisms in the haemolymph of Lutzomyia longipalpis sandflies has been investigated. Injections of Escherichia coli and Micrococcus luteus into female sandflies induced anti-bacterial activity in the haemolymph. Inhibition zone assays showed that haemolymph from E.coli and M.luteus injected sandflies differentially inhibited M.luteus growth. This differential effect was specific to M. luteus infection since anti-Zs. coli activity was similar in haemolymph from both E.coli oxM.luteus injected sandflies. Haemolymph following injection of either bacteria showed the induction of a 4kDa peptide. Haemolymph from M.luteus injected sandflies also contained a 33 kDa polypeptide which was absent in haemolymph from E.coli and control uninfected insects. Sandflies, in common with other insects, were shown to possess general and specific humoral immune responses to the presence of microorganisms.