Size and Partner Choice in Dysdercus maurus Distant (Hemiptera: Pyrrhocoridae)

This study investigates whether females of Dysdercus maurus (Hemiptera) are considering male’s sizes in order to make their reproductive partner choice. Morphometric and biomass measurements were obtained from single males and copulating pairs. Positive correlations were identified for both sizes and weights between males and females in copula. The average ratios established between the couples sizes/weight were around 1.66. Female choice may operate in such a way that each female has her own optimal male size for mating, resulting from a trade-off between the negative influence of large partner size in female fecundity and the advantages of large male size for offspring fitness. Thus, the best choice for a D. maurus female may be a male of average size in relation with her own size.     

Repetitive mating and female fitness in Dysdercus cardinalis (Hemiptera: Pyrrhocoridae)

Using three mating-treatment groups–pairing with a male for life, pairing with a male from adult emergence to first oviposition, and no pairing (virgin)–of Dysdercus cardinalis females in a laboratory study, the following results were obtained. Most of the virgin females did not lay eggs; those that did oviposited for the first time at a considerably older age than females in the other two groups. In a lifetime, females pairing with a male for life and those pairing with a male up to first oviposition produced essentially the same number of eggs, and this was more than 3.5 times the number of eggs laid by a virgin female. Virgin females produced an average of 1.3 clutches in a lifetime, compared with about 4.5 clutches produced by females in the other two groups. Reproductive span was significantly shorter, and fecundity per day of reproductive span significantly greater, for females pairing with males for life than for those pairing with a male up to first oviposition. Age at death was significantly different amongst females in different mating-treatment groups. Virgin females had the longest life, followed by females pairing with a male up to first oviposition and females pairing with a male for life, in that order. There was a positive correlation between lifetime gross reproduction and age at death for females pairing with a male for life. There was no relationship between these two characters for females pairing with a male up to first oviposition. Both females pairing with a male for life and those pairing with a male to first oviposition exhibited a significant inverse relationship between fecundity per day and age at death. The results obtained indicate that (1) mating is a prerequisite for normal gonadal activity in Dysdercus cardinalis , and (2) repetitive mating increases the rate of reproduction. This would reduce the mean age of parenthood which is inversely related to the intrinsic rate of increase.     

Evolution of mimicry in the New World Dysdercus (Hemiptera: Pyrrhocoridae)

Evolution of mimicry rings is reconstructed for the New World species of cotton-stainer bugs (Dysdercus, Hemiptera: Pyrrhocoridae). Using a cladistic analysis of 43 species (including D. silaceus Doesburg, 1968 stat. nov . and D. modestus Doesburg, 1968 stat. nov .), evolution of colour patterns and biogeographical history of the clade are hypothesized. Three probable mimicry rings are obtained from the analysis, together with data about their possible model–mimic or comimic–comimic structures: (a) ‘Yellow’ species in north-western South America and in the Andes (several possible models, D. rusticus, D. mimus part., D. imitator part., and D. collaris part. as mimics); (b) ‘Median Yellow–Black’ species with a median-forewing black pattern in north-western South America and Central America (several possible models, D. basialbus as a mimic); (c) ‘Median Red–Black’ species with a median-forewing black pattern in the Caribbean islands (D. andreae, D. discolor, D. neglectus–D. sanguinarius clade, and D. jamaicensis–D. fervidus–D. ocreatus clade as comimics). A few additional, less supported rings are also identified. Two highly polymorphic species (D. obscuratus, D. mimus) seem to enter different mimicry rings in different regions.     

Biphasic perimicrovillar membrane production following feeding by previously starved Dysdercus peruvianus (Hemiptera: Pyrrhocoridae)

The development of perimicrovillar membranes (PMM) from midgut cells of starved and fed Dysdercus peruvianus was studied by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and assays for specific enzymatic markers of the perimicrovillar membranes (alpha-glucosidase), perimicrovillar space (aminopeptidase) and microvillar membranes (beta-glucosidase). High activities of these enzymes were observed 6h post-feeding and significant production of membranes was observed at 30 h post-feeding. In the gut cells of starved insects, the rough endoplasmic reticulum was organized in concentric bundles, with a greater number of mitochondria in the cellular apex. The presence of electron dense double-membrane vesicles and the production of PMM were not observed in this condition. Thirty hours post-feeding, a disorganization of the rough endoplasmic reticulum was observed, and it was possible to see double-membrane vesicles close to the cell apex. The membrane system formation was evident with a significant development of PMM in the midgut lumen. The luminal surface of the midgut during starvation and up to 48 h post-feeding was monitored using SEM. It was demonstrated that in the starved condition, the PMM was virtually absent from gut cells, except at the base of the microvilli. At 6h post-feeding, the microvilli were already completely covered with PMM, but with a maximum of PMM formation seen at 30 h post-feeding. Signals of PMM degradation were observed 48 h after pulse feeding.     

Egg size increases with maternal age in the cotton stainer bugs Dysdercus fasciatus and D.cardinalis (Hemiptera: Pyrrhocoridae)

Abstract.

• 1 Egg-size variation over the reproductive span of laboratory-reared females is described in two species of cotton stainers: Dysdercus fasciatus Sign. from woody Malvales and D.cardinalis Gerst. from herbaceous Malvales.
• 2 Egg size increases with maternal age due to a decrease in clutch size as maternal age advances in both species.
• 3 The two species are similar in size, but egg size is about 28% larger and clutch size about 19% smaller in D.fasciatus than in D.cardinalis. These contrasts may be related to the host-plant biology which differs between the two species.

     

Effect of short-term cold temperature stress on development,survival and reproduction of Dysdercus koenigii (Hemiptera: Pyrrhocoridae)

Red cotton bug Dysdercus koenigii F. (Hemiptera: Pyrrhocoridae), is found destructive pest in various cotton growing areas. Under natural conditions insects are highly subjected to thermal stresses. In present work the developmental duration and survival rate of all immature stages, adult longevity and reproduction of D. koenigii by exposed to rapid changes in very low temperatures were studied. When 3 h short-stress of low temperatures (12–0 °C) was given to different stages of D. koenigii, the results revealed that survival rate of all stages were significantly reduced. Survival rate of female was significantly higher than male after exposed to cold temperature stress. Mating percentage, fecundity and hatching percentage were decreased significantly with the decrease of short-term cold temperature stress. Based on these results, we concluded that the developmental duration, survival rate and reproduction of D. koenigii significantly affected when they exposed to short term cold temperature stress.     

Phylogeny of the New World Dysdercus (Insecta: Hemiptera: Pyrrhocoridae) and Evolution of their Colour Patterns

Evolution of colour patterns is reconstructed in the case of the New World species of Dysdercus (Hemiptera: Pyrrhocoridae). The phylogenetic species concept was applied to this group, elevating five subspecific taxa to specific rank (D. capitatus, D. discolor, D. fervidus, D. luteus, and D. neglectus), and the resulting 41 phylogenetic species were analysed cladistically. Using optimization methods, evolution of colour patterns of the group is hypothesized, and possible developmental mechanisms of colour-pattern evolutionary changes are inferred.     

A comparison of the reproductive strategies of three species of Dysdercus from Africa (Hemiptera,Pyrrhocoridae)

Summary Reproductive strategies have been investigated for three species of Dysdercus from Africa, D. intermedius, D. cardinalis and D. nigrofasciatus. Reproductive parameters were measured for each species on individuals cultured in the laboratory. D. cardinalis is associated more with herbaceous than with arboreal host plants and is intermediate in body size. It tended to have the least age at first reproduction, reproduced most frequently, and layed the smallest clutches on average, spreading relatively high amounts of parental investment in more clutches than the other two species. It also laid the greatest number of clutches and eggs in a lifetime. D. intermedius specializes on arboreal host plants, and is the largest of the three species. It had the greatest age at first reproduction, reproduced less frequently than D. cardinalis, and layed the largest clutches. Its parental investment over time declined earlier than that of D. cardinalis. D. intermedius layed the least number of clutches in a lifetime, but its lifetime gross reproduction was intermediate in magnitude. D. nigrofasciatus has the widest diet breadth, and is the smallest in body size. Its age at first reproduction was similar to that of D. cardinalis, but D. nigrofasciatus reproduced least frequently, laying relatively large clutches. It was similar to D. intermedius in its pattern of parental investment over time, and essentially layed the same number of clutches in a lifetime as the latter species, although its lifetime gross reproduction was the smallest.It is suggested that the reproductive strategies of the three species might have evolved as adaptations to selection events in the niches of the immature stages.     

α-galactosidase activity in ingested seeds and in the midgut of Dysdercus peruvianus (Hemiptera: Pyrrhocoridae)

The midgut of Dysdercus peruvianus is divided into three main sections (V₁-V₃) and is linked through V₄ to the hindgut. The distribution of α-galactosidase activity in the different gut segments of D. peruvianus females was studied. α-galactosidase hydrolyzes the trisaccharide raffinose, the major carbohydrate of cotton seeds, on which the insects live. In D. peruvianus midgut, α-galactosidase activity is mainly found in soluble fractions of V₁ contents. However, a comparison between specific activities using different α-galactosidase substrates in cotton seed extracts, V₁ tissue homogenate, and midgut contents suggested that the contribution of the enzymes from seeds may be very significant. Gel filtration on Sephacryl S-200 of samples from seed extracts, V₁ tissue, and V₁ contents revealed that in all samples raffinose hydrolysis is accomplished by α-galactosidases with similar M_r (30,000 ± 3,000) and does not involve the activity of a β-fructosidase. Thermal inactivation studies of extracts from the three sources suggested that there was only one molecular form of the insect α-galactosidase and that the activity found in V₁ contents includes enzymes derived from the seed kernel. In insects fed with cotton seeds, the α-galactosidase activity increased in parallel with diet ingestion. In starved insects fed with tablets of sucrose plus raffinose, an increase in α-galactosidase activity was also observed, confirming that the insect is able to synthesize part of the gut enzyme. The results indicated that raffinose digestion starts in V₁ utilizing α-galactosidases derived from the seed kernel and by an additional α-galactosidase synthesized by insect tissues. The action of α-galactosidases liberates galactose and sucrose, which are sequentially hydrolyzed by the major membrane-bound α-galactosidase releasing glucose and fructose in V₁ and V₂ lumina. Arch. Insect Biochem. Physiol. 34:443–460, 1997. © 1997 Wiley-Liss, Inc.     

Vitellins and vitellogenins of Dysdercus koenigii (Heteroptera: Pyrrhocoridae)--identification, purification and temporal pattern

Two vitellins, VtA and VtB, were purified from the eggs of Dysdercus koenigii by gel filtration and ion exchange chromatography. VtA and VtB have molecular weights of 290 and 260 kDa, respectively. Both Vts are glycolipoproteinaceous in nature. VtA is composed of three polypeptides of M(r) 116, 92 and 62 kDa while VtB contained an additional subunit of M(r) 40 kDa. All subunits except the 116-kDa subunit are glycolipopolypeptides. Polyclonal antibody raised against VtA (anti-VtA antibody) cross-reacted with VtB and also with vitellogenic haemolymph and ovaries and pre-vitellogenic fat bodies, but not with haemolymph from either adult male, fifth instar female, or pre-vitellogenic females demonstrating sex and stage specificity of the Vts. Immunoblots in the presence of anti-VtA revealed two proteins (of 290 and 260 kDa) in both vitellogenic haemolymph and pre-vitellogenic fat bodies that are recognised as D. koenigii Vgs. In newly emerged females, Vgs appeared on day 1 in fat bodies and on day 3 in haemolymph and ovaries. Vg concentration was maximum on day 2 in fat body, day 4 in haemolymph and day 7 in ovary. Although the biochemical and temporal characteristics of these proteins show similarity to some hemipterans, they are strikingly dissimilar with those of a very closely related species.     

Neurosecretory cells in Dysdercus similis (Hemiptera)

The neurosecretory cells of Dysdercus similis have been described. "A", "B", "C" and "D" types of neurosecretory cells are present. The "A" type of cells of the pars-intercerebralis show cyclical secretion. When these cells show secretory activity during one to three days of emergence, they have scattered granules. The cells are seen packed with clumps of neurosecretory material when they are not secreting, and this is interpreted as a storage stage. The axons of these cells supply the corpora cardiaca and some neurosecretory material also reaches the corpus allatum. The release of this neurosecretory material can be correlated both with moulting in the young stages and later with reproduction in the adults.     

The exocrine glands of Dysdercus cingulatus (Heteroptera,Pyrrhocoridae): Morphology and function of nymphal glands

The exocrine glandular system of the nymphs and the adults of Dysdercus cingulatus were studied. The D. cingulatus nymphs present 3 dorso-abdominal glands (lying under the 3rd, 4th, and 5th abdominal terga) and a pair of dorso-lateral pygidial glands on the pygidium (tergum 8). Histological and ultrastructural studies show that the upper and lower walls of the dorso-abdominal glands differ in structure; 3 types of cells were described: epidermal cells, unicellular secretory cells, and multicellular secretory units. Each of these exocrine glands plays an important part in the behavior of the nymphs (gregariousness, alarm, defense). The morphology of the various glands is discussed, and the chemistry of their secretions and their biological functions are considered.     

Behavioral response and relative toxicity for the active compounds of Caulerpavera veravalensis (Thivy and Chauhan) against nymph of Dysdercus cingulatus (Fab.) (Hemiptera: Pyrrhocoridae)

Outburst of harmful insects in the agricultural environment cause potential risk to farmers and it makes an alarm to scientific communities for the development of effective pest management strategies. Prevalent usage of synthetic pesticides results in the development of insect resistance and make higher toxicity to non-target organisms. Phytochemicals derived from seaweeds offers an alternative solution for controlling the agricultural pest. The growth and development of Dysdercus cingulatus was affected by the chloroform extract of sea weed Caulerpa veravalensis at various concentrations (25, 50, 75 and 100 μg/mL). Similarly, relative growth rate (RGR) and oviposition also significantly decreased compared to control. The crude extract of C. veravalensis was further eluted through the column chromatography and partially purified fractions were tested to find toxicity against third instar nymph of D. cingulatus. The active fraction FVI illustrates higher mortality hence it was subjected to GC–MS analysis to find the active chemical constituents. The GC–MS results revealed that nine major compounds with nymphicidal activity against D. cingulatus. Probit analysis of 95% confidential level showing a LC₅₀ value of 183.307 μg/mL against the third instar nymph of D. cingulatus. Our findings suggest that Tetradecanoic acid, 10, 13-dimethyl-, methyl ester from fraction FVI shows highest peak area percentage of 89.2% and it may be one of the insecticidal compounds affecting the behavior of D. cingulatus.     

Body Colouration Related to the Deposition of Pteridines in the Epidermis and Other Organs of Dysdercus Species (Insecta; Heteroptera: Pyrrhocoridae)

In epidermal cells of Dysdercus species, two types of pigment granules were detected using both light and electron microscopic methods; the granules differed in colour, size, distribution and osmiophily. Red (D. intermedius) and yellow (D. nigrofasciatus) epidermal cells contained both types of granules, but in white cells only one type was present. Chromatographic analyses showed that the larger granules were more transparent to electrons, and contained uric acid, while the smaller ones contained erythropterin, became coloured later, and were osmiophilic. In accordance with these findings, in the testes of D. intermedius both granule types were present, but in the testes of D. nigrofasciatus only those containing erythropterin. The number of granules per cell varied with the species and developmental stage. Epidermal cells of D. intermedius contained more erythropterin granules than those of D. nigrofasciatus, the reverse occurring in the testes. This pattern corresponded to the visible colouration of the insects. As the development progressed, a decrease of the red and an increase of the white granules took place in the coloured epidermal cells. The main amount of pteridines, except isoxanthopterin, was accumulated in the integument of the insects studied. Chemical and histological data showed the influence of pterins on insect colouration. Orange, yellow and red colours were caused by different amounts of erythropterin containing special granules in the epidermal cells, and the white colour only by uric acid containing granules. A partial melanization of the cuticle resulted in dark spots below which pteridines were deposited additionally in the epidermal cells. Considering erythropterin, the quantitative chemical data are in accordance with the histological ones and also with the colouration externally visible. Intensively red coloured stages had a higher concentration of erythropterin and more corresponding granules than the light-red coloured ones; the lowest amount was found in yellow coloured insects. Therefore, the pigmentation effect of erythropterin, which reached from yellow to orange and red, depended on its concentration and played the most important role in the colouration of the Dysdercus species studied, uric acid was responsible for the colouration of the white parts of the integument.     

Effect of actinomycin-D on the fat body RNA content in Dysdercus koenigii (Heteroptera: Pyrrhocoridae)

The effect of actinomycin-D on the RNA content of the total fat body was studied on day 3, 4, 5 and 6 of the first reproductive cycle in the females. Actinomycin-D exhibited its highest inhibitory effect in insects injected on day 4 and a lower degree of the effect was seen in insects injected on day 5. These results suggest that by the end of day 4, a major quantity of DNA-dependent RNA, necessary for vitellogenin synthesis, has already been synthesised and accumulated.     

The larval development of the telotrophic meroistic ovary in the bug Dysdercus intermedius (Heteroptera, Pyrrhocoridae)

Bug ovaries are of the telotrophic meroistic type. Nurse cells are restricted to the anterior tropharium and are in syncytial connection with the oocytes via the acellular trophic core region into which cytoplasmic projections of oocytes and nurse cells open. The origin of intercellular connections in bug ovaries is not well understood. In order to elucidate the cellular processes underlying the emergence of the syncytium, we analysed the development of the ovary of Dysdercus intermedius throughout the five larval instars. Up to the third instar, the germ cell population of an ovariole anlage forms a single, tight rosette. In the center of the rosette, phosphotyrosine containing proteins and f-actin accumulate. This center is filled with fusomal cytoplasm and closely interdigitating cell membranes known as the membrane labyrinth. With the molt to the fourth instar germ cells enhance their mitotic activity considerably. As a rule, germ cells divide asynchronously. Simultaneously, the membrane labyrinth expands and establishes a central column within the growing tropharium. In the fifth instar the membrane labyrinth retracts to an apical position, where it is maintained even in ovarioles of adult females. The former membrane labyrinth in middle and posterior regions of the tropharium is replaced by the central core to which nurse cells and oocytes are syncytially connected. Germ cells in the most anterior part of the tropharium, i.e. those in close proximity to the membrane labyrinth remain proliferative. The posterior-most germ cells enter meiosis and become oocytes. The majority of the ovarioles' germ cells, located in between these two populations, endopolyploidize and function as nurse cells. We conclude that the extensive multiplication of germ cells and their syncytial assembly during larval development is achieved by incomplete cytokineses followed by massive membrane production. Membranes are degraded as soon as the trophic core develops. For comparative reasons, we also undertook a cursory examination of early germ cell development in Dysdercus intermedius males. All results were compatible with the known basic patterns of early insect spermatogenesis. Germ cells run through mitotic and meiotic divisions in synchronous clusters emerging from incomplete cytokineses. During the division phase, the germ cells of an individual cluster are connected by a polyfusome rich in f-actin.     

Peculiarities of the epidermal gland system of the cotton stainer Dysdercus fasciatus Signoret (Heteroptera: Pyrrhocoridae)

The epidermal gland system of adult Dysdercus fasciatus, which shows conspicuous sexual dimorphism, is described. Observations on the development of the glands and a discussion of their possible functions are included.     

Amino acid requirements of the cotton stainer, Dysdercus fasciatus (Pyrrhocoridae, Hemiptera)

L-glutamic acid-¹⁴C (U.L.) injection provided a convenient means for the study in vivo of the amino acid requirements of Dysdercus fasciatus. The production of ¹⁴CO₂ by the injected insects indicated that glutamic acid was metabolized by the Dysdercus system.Out of the 16 amino acids extracted from the treated insects, arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophane and valine carried a negligible amount of radioactivity, while alanine, aspartic acid, glycine, proline, serine and tyrosine had a very high level of radioactivity.On the basis of these studies, it would appear that the amino acids which had low radioactivity levels are essential, while those carrying high amounts of radioactivity are not essential for the normal growth of Dysdercus.

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Résumé L'injection de l'acide glutamique 14 C (U. L.) a constitué un moyen satisfaisant pour l'étude in vivo des besoins en acides aminés de Dysdercus fasciatus. La production de ¹⁴CO² par les insectes injectés a montré que l'acide glutamique était métabolisé par Dysdercus.Parmi les 16 acides aminés extraits des insectes traités, l'arginine, l'histidine, l'isoleucine, la leucine, la lysine, la méthionine, la phénylalanine, la thréonine, le tryptophane et la valine ont présenté un taux négligeable de radioactivité; tandis que l'alanine, l'acide aspartique, la glycine, la proline, la sérine et la tyrosine ont un très haut degré de radioactivité.Sur la base de ces études il apparaîtrait que les acides aminés qui ont des taux de radioactivité faibles sont essentiels à la croissance normale de Dysdercus, tandis que ceux qui présentent des taux élevés de radioactivité ne sont pas essentiels.

     

Absence of phytosterol dealkylation and identification of the major ecdysteroid as makisterone A in Dysdercus fasciatus (Heteroptera,Pyrrhocoridae)

The absence of phytosterol dealkylation in the cotton stainer bug, Dysdercus fasciatus, has been established and the major ecdysteroid in the fifth-stage larvae identified. The demonstration that the free and esterified sterols in D fasciatus consisted of 95–96% sitosterol and 4–5% campesterol, a similar composition to the cottonseed diet, together with the lack of conversion of [¹⁴C]sitosterol into cholesterol, establishes that phytosterol dealkylation does not occur in this insect species. The ecdysteroid titer determined by radioimmunoassay in the fifth instar of D fasciatus shows a distinct peak at day 6, the instar lasting for 7 days. Makisterone A was purified by HPLC from insects at a time of high ecdysteroid titer and identified as a major component by both fast atom bombardment and electron impact mass spectrometry. Gas-liquid chromatography/mass spectrometry (selected ion monitoring) confirmed the occurrence of makisterone A and revealed the presence of two unidentified compounds. One of these occurs in a similar amount to makisterone A and may be 26-hydroxymakisterone A, whereas only a minute amount of the other compound, which may be 20-deoxymakisterone A, was present; further identification of the latter compounds is necessary. C₂₇ ecdysteroids (eg, ecdysone and 20-hydroxyecdysone) and C₂₉ ecdysteroids (eg, podecdysone A) were undetectable. The specificity of the enzymes of ecdysteroid biosynthesis is discussed.     

Genus Carvaka Distant in Australia (Hemiptera: Cicadellidae: Selenocephalinae)

Abstract  The leafhopper genus Carvaka Distant (Hemiptera: Cicadellidae: Selenocephalinae) in Australia is reviewed in light of recent publications on the subfamily Selenocephalinae in the Oriental region. The genus Exitianellus Evans is transferred from the subfamily Deltocephalinae to the Paraboloponini and synonymised with Carvaka . Carvaka elegantula (Evans) comb. nov. is redescribed and three new species, C. mouldsorum , C. maculata and C. flava are added to the genus. A key for the separation of the Australian species of Carvaka is provided. The Australian fauna represents all three recognised species groups of the genus. The significance of this to the biogeographical origins of the Australian fauna is discussed.