Wing morph-related physiological differences in adults of temperate population of Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

The reproductive and diapausing adult females of brachypterous morph and macropterous females with reproductive arrest of non-diapause type, originating from the laboratory cultures of Pyrrhocoris apterus, were studied for their feeding and drinking behaviour, digestive enzyme activities, and carbohydrate and lipid contents. The highest feeding and drinking activities were observed in reproductive brachypters, the lowest in macropters. Macropters also differed from brachypters by lower activities of gut lipase, peptidase and protease, lower concentration of haemolymph sugars, and lower weight of fat body, which probably reflects their low feeding activity. The total content of fat body lipids was also lower in macropters (0.6 mg) than in reproductive and diapausing brachypters (4.6 and 7.5 mg, respectively) on day 14. A very high amount of glycogen was found in the fat body of diapausing brachypters, 363 μg on day 14, as opposed to 15 and 80 μg in macropterous and reproductive brachypterous females, respectively. The obtained data indicate that the most important difference between macropterous and brachypterous females with different types of reproductive arrest consists of an enhanced mobilization of lipids for dispersal in macropters and accumulation of energetic reserves for hibernation in brachypters.     

Differences in adipokinetic response of Pyrrhocoris apterus (Heteroptera) in relation to wing dimorphism and diapause

Three experimental groups of adult females (reproductive and diapausing brachypters, and macropters with reproductive arrest) of Pyrrhocoris apterus (Linnaeus) (Heteroptera: Pyrrhocoridae) from a temperate population were analysed for their adipokinetic responses. The adipokinetic response, expressed as an increase of haemolymph lipids after injection of adipokinetic hormone from Locusta migratoria (Lom-AKH-I), was assessed in relation to age, wing dimorphism and type of reproductive arrest. Two pmols of Lom-AKH-I were used for determination of adipokinetic responses. The increase of haemolymph lipids in all experimental groups of females induced by this dose of the hormone was comparable with that induced by crude extract of the bug’s own corpora cardiaca. The level of adipokinetic response after injection of 2 pmol of Lom-AKH-I was significantly higher in macropterous and diapausing brachypterous females than in reproductive brachypterous females. However, significantly higher contents of haemolymph lipids in control macropterous females than those found in the control reproductive and diapausing brachypterous females of the corresponding age revealed wing-morph-related differences in lipid metabolism. The observed wing morph- and diapause-related differences in the content of haemolymph lipids and adipokinetic response, respectively, are discussed in relation to the different roles of two wing morphs in the life history of this heteropteran.     

Temporal pattern of feeding activity in the firebug Pyrrhocoris apterus and its relation to sex, wing dimorphism and physiological state of adults

Abstract.  The present study tested whether the pattern of feeding activity in the firebug Pyrrhocoris apterus (L.) is sex- and wing morph-related, diurnal or nocturnal, as well as whether the feeding rhythm persists in constant darkness. Temporal patterns of feeding activity are analysed in macropterous and brachypterous adults reared under long-day (LD 18 : 6 h) and short-day (LD 12 : 12 h) photoperiods, and in adults transferred to constant darkness. In females, the total feeding activity is highest in long-day reproductively active brachypters, intermediate in short-day diapausing brachypters, and lowest in macropters; the differences among males are substantially smaller. Although the total feeding activity of macropterous males is higher than in macropterous females, no sex-related differences are found in feeding activity of diapausing and reproductively active brachypters. The frequency of feeding exhibits sex-related differences, with obviously higher values in males. Mean feeding periods of macropterous and reproductively active brachypterous males are shorter than in females of the same wing morph. Mean interfeeding periods are longest in macropters, intermediate in diapausing brachypters, and shortest in reproductively active brachypters, and always lower in males than in females. The study shows that the feeding activity of P. apterus adults is age-, sex- and wing morph-related, and exhibits a diurnal pattern, except in reproductively active brachypterous females. The latter do not express a clear diurnal rhythm of feeding, presumably because of interactions with cycles of egg development and oviposition. The persistence of diurnal rhythm of feeding activity in short-day brachypterous females transferred to constant darkness indicates an endogeneity of this rhythm in P. apterus .     

Differences in haemolymph proteins in relation to diapause and wing dimorphism inPyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

Three different cultures of dimorphic bug,Pyrrhocoris apterus, were analyzed concerning diapause and its relation to wing morph pattern. The proportion of macropterous bugs was considerably higher (36%) in the Mediterranean culture from Israel than that (1.3%) in the temperate culture from the Czech Republic. The macropterous morph- and brachypterous morphrelated types of reproduction arrest, differing by the length of pre-oviposition period, were distinguished in cultures analyzed. The reproduction arrest with an average pre-oviposition period of 38.2 days in Mediterranean macropters and 18.5 days in macropters from selected macropterous strain, was found to be typical for macropterous morph. Two different photoperiodic conditions induced macropterous morph-related reproduction arrest, the long-day (18 h light-6 h dark) photoperiod in macropterous strain macropters and the short-day (12 h light-12 h dark) photoperiod in Mediterranean macropters. The brachypterous morph-related reproduction arrest, characterized by pre-oviposition period longer than 90 days, occurred predominantly in diapausing brachypterous bugs. While the hibernal diapause of brachypterous bugs was characterized by a very high level of the 78- and 82-kDa proteins in haemolymph, their content in haemolymph of macropters during macropterous morph-related reproduction arrest was almost as low as in the reproductive adults. The variation of reproduction arrest in relation to wing dimorphism represents an important feature in the life strategy ofP. apterus.     

Locomotor activity in adult Pyrrhocoris apterus (Heteroptera) in relation to sex, physiological status and wing dimorphism

The pattern of locomotor (walking) activity was studied in adult males and females of short‐winged (brachypterous) and long‐winged (macropterous) morph of the flightless bug Pyrrhocoris apterus (Linnaeus) (Heteroptera: Pyrrhocoridae) under constant laboratory conditions. Walking activity was measured with a computerized video system and analysed with respect to sex, physiological status (reproduction, diapause and reproductive arrest of non‐diapause type) and wing dimorphism of the bugs. The largest duration was observed in the macropterous females with reproductive arrest of non‐diapause type (average 6 h per day) and the shortest duration in diapausing brachypterous females and males (average less than 2 h per day). This was reflected also in the overall time spent by walking during the first 14 days after imaginal ecdysis. The time spent by walking significantly increased in the macropterous morph as the bugs aged, whereas in diapausing brachypters the time spent by walking decreased with age. No linear relationship between walking activity and age was found in reproductive brachypterous morph. The bugs of all experimental groups moved mostly during the photophase and were almost inactive during the scotophase. Thus, walking activity in P. apterus is diurnal, irrespective of the wing morph, physiological status, sex and age. Contrary to the macropterous morph, where the locomotor activity of females during photophase was significantly higher than in males, no significant differences were found between the locomotor activities of brachypterous males and females. The observed differences in locomotor activity are discussed in relation to different roles of two wing morphs in the life history of this heteropteran.     

Wing morph-specific differences in the metabolism and endocrine control of reserve mobilization in adult males of a flightless bug, <Emphasis Type="Italic">Pyrrhocoris apterus</Emphasis> (L.) (Heteroptera)

The differences in the metabolism and endocrine control of reserve mobilization in long-winged (macropterous) and short-winged (brachypterous) males of a flightless firebug (Pyrrhocoris apterus) were studied. We found that protein content in the gut was significantly lower in 5–10 day-old macropterous males due to their fasting and higher in 28 day-old ones than in the same aged brachypterous counterparts as the result of renewed food intake. Overall protease activity was significantly lower in 10–14 day-old macropters, while an abrupt increase in the activity starting on day 21 after adult ecdysis was also associated with renewal of the food intake. The levels of carbohydrates in haemolymph were only slightly lower in 1–10 day-old macropterous males than in the same aged brachypters. However, more than twofold higher lipid content in haemolymph of 7–10 day-old macropterous males than in the same aged brachypterous males was found. Higher mobilization of lipid reserves from the fat bodies in macropterous males was accompanied by more intensive adipokinetic response and higher levels of adipokinetic hormone in the body. It is the first report of endocrine regulation of wing morph-related differences in the lipid mobilization in males of wing-polymorphic insects.     

Feeding behaviour, digestive physiology and lipid content in macropterous females of Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae)

Abstract. Macropterous females of Pyrrhocoris apterus (L.) reared under short-day conditions (LD 12:12 h) were analysed for temporal patterns of feeding and drinking behaviour, activities of digestive enzymes in the gut, and lipid and glycogen content in the haemolymph and fat body. Peaks of drinking activity were recorded at days 3, 7 and 10 during the first 14 days after imaginal ecdysis. Feeding activity peaked on the third day, ceasing completely after the fourth day of adult life. Esterase, protease, amylase and aminopeptidase activities exhibited the highest overall activity in the first days after imaginal emergence; then enzyme activities decreased. In the fat body, the content of lipids was highest on day 5, then a decrease of about 40% was observed at day 14; the amount of glycogen was highest on day 1 at 11 μg of glucose equivalents/mg of fat body, then decreased to 2 μg at day 14 after the imaginal moult. In the haemolymph, the lipid content rose until day 8 when it reached almost 0.3 μmol/μl; at day 14 the value was slightly lower. The association of fasting with reproductive arrest in macropterous females of P. apterus, accompanied by a decrease in digestive enzyme activities and a mobilization of lipid reserves from the fat body, was demonstrated.     

Ecological significance of the wing polymorphism of the oriental chinch bug,Cavelerius saccharivorus Okajima (Heteroptera: Lygaeidae)

The wing polymorphism of the oriental chinch bug, Cavelerius saccharivorus, was studied in relation to its reproductive strategy. The frequency distribution of wing form in terms of the relative wing length (R.W.L.) changed with increase in the population density from a single modality biased toward the brachypterous form to bimodality with both macropterous and more extreme brachypterous forms. Since some evidences in the field showed that fliers are limited to macropters, such a bimodality of wing form indicated that C. saccharivorus employs a mixed strategy with some portion of adults staying on in the same habitat, whereas the rest disperse. Moreover, macropters were larger in body size than brachypters emerging in high density populations, although smaller than brachypters emerging in low density populations. Larger body size as well as the delay of ovarian maturation in macropters was considered to be a beneficial trait for migratory behaviour.     

Adaptive significance of wing dimorphism in males ofNilaparvata lugens

The trade-offs associated with macroptery in males were investigated in a wing-dimorphic planthopper, Nilaparvata lugens (Stål) (Delphacidae, Hemiptera). Developmental time of brachypters was significantly shorter than that of macropters across a wide range of population densities, while no within-population differences between wing morphs in body weight were found. In mating experiments, brachypterous males 12 to 24 h old were almost three times more successful in competition for females than macropterous males of the same age, while in five days old males, macropters were twice as successful as brachypters. In competition for females involving direct body contact between males, brachypterous and macropterous males were equally successful. It is suggested that macroptery and delayed peak in sexual activity in males may both be influenced by the titre of juvenile hormone, as is known from females. The combination of prolonged development and delayed maximum competitive ability for mates, associated with macroptery, is likely to be disad vantageous, representing probably a penalty associated with macroptery in males in undisturbed habitats.     

Developmental and diel changes of adipokinetic hormone in CNS and haemolymph of the flightless wing-polymorphic bug,Pyrrhocoris apterus (L.)

We have used an enzyme-linked immunoassay (ELISA) for determination of the AKH content in CNS (brain + corpora cardiaca + corpora allata) and haemolymph of adult macropterous and brachypterous females of the bug Pyrrhocoris apterus. The tests revealed that the AKH content fluctuates between 1 and almost 4 pmol/CNS during the first 14 days of adult life and significantly increased in order diapausing brachypters相似文献   

Reproductive cost of flight capability: a comparison of life history traits in wing dimorphic planthoppers

Abstract. 1. Reproductive costs associated with flight capability were evaluated in the wing dimorphic planthopper, Prokelisia dolus Wilson, by comparing the life history of traits of winged (macropterous) and flightless (brachypterous) females under controlled laboratory conditions.
2. Macropters with large thoraces and fully developed wings maintain a greater investment in flight apparatus than brachypters with small thoraces and reduced wings.
3. Associated with greater flight capability in the macropter of P.dolus are shorter adult life, decreased total fecundity, and delayed age at first reproduction compared to brachypterous females.
4. Under field conditions where mortality is high, the difference in realized fecundity between the two wing forms living on similar resources is further exaggerated with the brachypter having the greater advantage.
5. When the life history traits of the wing forms of P. dolus are compared with traits for nine other species of planthoppers, two similarities emerge. First, the preoviposition period of the macropterous wing form is always longer than that for the brachypter resulting in a reproductive delay. Second, most studies show that macropters are less fecund than brachypters.
6. There is no general tendency among planthopper species for macropterous adults to live fewer days or develop more slowly as nymphs compared to their flightless counterparts.
7. The reproductive delay and reduced fecundity of the volent wing form of planthoppers supports the notion that flight capability is costly and that phenotypic trade-offs between flight and reproduction exist.     

Wing and flight muscle polymorphism in a lygaeid bug, Horvathiolus gibbicollis: determinants and life history consequences

ABSTRACT.

• 1 Horvathiolus gibbicollis (Costa), a ground-living seed-feeding bug of the mediterranean region, has two wing morphs. In macrop-terous bugs both pairs of wings are fully developed. In brachypterous ones forewings are reduced to about two-thirds and hindwings to less than a third of their length in macropters.
• 2 Each morph bred true with regard to wing length when reared under variable density, food and temperature conditions for several generations.
• 3 All F₁ offspring between crosses of the two morphs were brachypterous. In F₂ approximately 25% were macropters and 75% brachypters implying monogenic control of wingform.
• 4 Flight muscles in macropters vary from fully developed to totally reduced. This variation is determined by environmental conditions during adult life. Most young adult bugs have flight muscles, and totally starved or unmated bugs retain their flight muscles. Fed and mated females histolyse flight muscles as they start laying eggs, while most males of the same group retain their muscles.
• 5 Brachypterous bugs have a smaller thorax and larger abdomen than macropterous ones.
• 6 Brachypterous bugs reach adulthood slightly before macropterous ones, and they have a distinctly shorter adult preoviposition period.
• 7 Lifetime egg production does not differ significantly between the two wing morphs. However, the temporal pattern of egg laying is different in the two morphs. The m_x-curve of macropters starts later, then attains a higher peak and finally decreases faster than that of brachypters.
• 8 Initially, macropters lay smaller eggs than brachypters, but egg volume increases with age in macropters and eventually approaches that of brachypters.
• 9 The initial increase in reproductive effort (egg volumexegg number) of macropters is concomitant with wing muscle histolysis and the mobilization of thorax space for reproduction.
• 10 Adult survival rate does not differ between the morphs.

     

Enhancement of short wing formation and ovarian growth in the genetically defined macropterous strain of the brown planthopper,Nilaparvata lugens

When JH II, III or methoprene was applied in the nymphal stages to two different strains of the brown planthopper which were selected to produce long (macropterous) or short (brachypterous) wing forms, no effect was observed on the molting profile or metamorphosis. Brachypterization of a majority of the presumptive macropters was, however, observed by application of these chemicals, although there was no effect on wing form in the presumptive brachypters. The results show that the sensitive periods for the brachypterization of the presumptive macropters falls between early antepenultimate instar and within 1 or 2days of the penultimate instar, and that the chemicals were effective, in the following order of potency: methoprene>JH III>JH II. Ovarian growth was greatly enhanced in the presumptive macropters when JH III or methoprene was applied twice, within 12h of the 3rd or 4th nymphal instar and 6h before adult emergence. JH II on the other hand had no effect on ovarian growth when applied to the presumptive macropters at any of the nymphal stages. None of the chemicals had any effect on ovarian growth in the presumptive brachypters.     

Relation between temporal persistence of host plants and wing length in leafhoppers (Hemiptera: Auchenorrhyncha)

Abstract.

• 1 Wing form frequencies in 255 populations of 101 species of leafhoppers (Auchenorrhyncha) in temporary and permanent habitats were documented.
• 2 The proportion of brachypterous specimens in the leafhopper assemblages on ruderal host plants in temporary habitats (median 2%, range 0–8%) was significantly lower than that on permanent host plants in undisturbed habitats (median 22%, range 0–94%).
• 3 Leafhopper species typical of temporary habitats were either monomorphic, macropterous, or wing-dimorphic with macropterous forms prevailing in both sexes.
• 4 Among the eighty-nine species recorded in permanent habitats, forty-five species were wing dimorphic. In forty-one dimorphic species, a brachypterous form prevailed. This prevalence was found for both sexes in thirty-one species, for only females in nine species and for only males in one species.
• 5 The prevalence of brachypters in males, but not in females, found in Anoscopus flavostriatus, is probably the first such documented case in Auchenorrhyncha.
• 6 The hypothesis is proposed that in temporary habitats, density-dependent production of macropters in wing dimorphic species is an adaptation to frequent habitat deterioration caused by factors independent of the density of the species.
• 7 The predominance of brachypters in permanent habitats indicates that a density-dependent decrease in fitness usually does not offset the potential decrease in fitness connected with macroptery and dispersal. Because of this inability of leafhopper populations to decrease significantly the quality of their resources, a high population density cannot be used as a predictor of future quality of these resources, which is information essential for efficient dispersal behaviour.

     

Reproduction and egg diapause of the oriental chinch bug,Cavelerius saccharivorus okajima (Heteroptera: Lygaeidae), in the subtropical winter season in relation to its wing polymorphism

Reproduction and egg diapause of the oriental chinch bug, Cavelerius saccharivorus, in the subtropical winter season were investigated in relation to its wing polymorphism. Macropterous females collected from the southern part of Okinawa Is. in the autumn season delayed their oviposition and were less fecund early in the adult life period, but survived much longer than brachypterous females collected from the same locality. The total fecundity was not significantly different between wing morphs. The diapause of eggs laid by brachypters tended to be terminated more easily at a high temperature than that of eggs laid by macropters. This indicated that the eggs laid by macropters were more intense in their diapause than those laid by brachypters. However, irrespective of the parental wing form, diapause showed considerable variation in its intensity within and between clutches.     

Feeding,reproductive and locomotor activities in diapausing and non-diapausing adults ofDrosophila

Feeding, reproductive and locomotor activities of fourDrosophila species were studied under short and long daylengths at 15°C. A short daylength induced firm reproductive diapause in experimental strains ofD. subauraria andD. triauraria from northern Japan, but very shallow diapause in those ofD. lutescens andD. rufa from southern Japan. A subtropical strain ofD. triauraria had no diapause. The influence of diapause on feeding activity was detected only in aged (> 12 day old) females; that is, the feeding activity was lower in diapausing females than in non-diapausing ones. Females that do not produce eggs would not require so much energy. On the other hand, young adults of the study species exhibited a high feeding activity and rapidly increased bodyweight irrespective of sex and the diapause state. They would need nutrition to build up their adult body. In males, the feeding activity decreased with age irrespective of the diapause state. Males would not require so much energy for reproductive activity. Diapausing males became heavier than non-diapausing males, perhaps because they accumulated triacylglycerols in fat bodies. However, female bodyweight did not differ by the diapause state, perhaps because diapausing females accumulated triacylglycerols and reproducing females had eggs in their ovaries. InD. triauraria, diapausing individuals exhibited somewhat lower locomotor activity than non-diapausing ones.     

Reproductive properties of the oriental chinch bug,Cavelerius saccharivorus Okajima (Heteroptera: Lygaeidae), in relation to its wing polymorphism

Reproductive properties of the oriental chinch bug, Cavelerius saccharivorus, were investigated for three types of female adults: brachypters produced in both high and low density populations and macropters produced in high density populations. With respect to egg-laying potential in terms of clutch size, clutch number, and total fecundity, macropters were superior to brachypters produced in the same high density population, although inferior to brachypters produced in the low density population. The mean fecundity of female adults in each type was positively correlated with mean body length. Macropterous females markedly prolonged their initiation of both copulation and oviposition and had a much longer life span compared with both types of brachypters. However, there was no fundamental difference in reproductive schedules between the two types of brachypters.     

Temperature-dependent wing dimorphism in a Japanese strain of tobacco thrips, Frankliniella fusca (Thysanoptera: Thripidae)

A Japanese strain of Frankliniella fusca (Hinds) was reared under 4 temperature and two photoperiodic conditions on leaves of green bean. On the basis of the ratio of fore wing length to head width (RWL) of adult thrips we defined individuals with RWL above 3.7 as macropterous forms and those with RWL below 3.5 as brachypterous forms. Percentages of macropterous individuals among females were 0 % at 18 °C, 10.6 % at 22.5 °C, 21.8 % at 25 °C, and 77.5 % at 27.5 °C, under 15L–9D. The proportion of macropters among females developing under 15L–9D was no different from that among those developing under 10L–14D. These results indicate that photoperiod does not affect wing form, and suggest that the proportion of macropterous females increases with temperature. Although development time from hatching to adult eclosion, adult pre-oviposition period, adult head width, adult longevity, total fecundity, and fecundity schedule were compared between macropterous and brachypterous females developing at 25 °C and 15L–9D, these traits were not significantly different between the wing forms. Males of this experimental strain were all brachypterous.     

Flight muscles polymorphism in a flightless bug, Pyrrhocoris apterus (L.): developmental pattern, biochemical profile and endocrine control

The flightless bug Pyrrhocoris apterus (L.) is polymorphic for both wing length and flight muscle development. The developed flight muscles of macropterous adults of both sexes first enlarge their volume during the first 5 days after adult emergence, but are then histolyzed in all males and females older than 10 and 14 days, respectively. The flight muscles of brachypterous adult males and females are underdeveloped due to their arrested growth. The total protein content of histolyzed dorsolongitudinal flight muscles from 21-day-old macropterous adults of both sexes is lower than that of developed dorsolongitudinal flight muscles in 5-10-days-old macropterous bugs, but substantially higher than the protein content of underdeveloped dorsolongitudinal flight muscles from adult brachypters. Histolyzed dorsolongitudinal flight muscles differ from the developed ones by decreased quantities of 18 electrophoretically separated proteins. Histolysis of developed dorsolongitudinal flight muscles is accompanied by significant decreases in citrate synthase, glyceraldehyde-3-phosphate dehydrogenase and β-hydroxyacyl-CoA dehydrogenase enzyme activities and an increase in alanine aminotransferase activity, and can be precociously induced by application of a juvenile hormone analogue. This is the first report of flight muscle polymorphism, histolysis of developed flight muscles and its endocrine control in insects displaying non-functional wing polymorphism.