Macropterous Males Research Articles

Identification and Functional Analysis of the fruitless Gene in a Hemimetabolous Insect, Nilaparvata lugens.

The fruitless (fru) gene functions as a crucial "tuner" in male insect courtship behavior through distinct expression patterns. In Nilaparvata lugens, our previous research showed doublesex (dsx) influencing male courtship songs, causing mating failures with virgin females. However, the impact of fru on N. lugens mating remains unexplored. In this study, the fru homolog (Nlfru) in N. lugens yielded four spliceosomes: Nlfru-374-a/b, Nlfru-377, and Nlfru-433, encoding proteins of 374aa, 377aa, and 433aa, respectively. Notably, only Nlfru-374b exhibited male bias, while the others were non-sex-specific. All NlFRU proteins featured the BTB conserved domain, with NlFRU-374 and NlFRU-377 possessing the ZnF domain with different sequences. RNAi-mediated Nlfru or its isoforms' knockdown in nymph stages blocked wing-flapping behavior in mating males, while embryonic knockdown via maternal RNAi resulted in over 80% of males losing wing-flapping ability, and female receptivity was reduced. Nlfru expression was Nldsx-regulated, and yet courtship signals and mating success were unaffected. Remarkably, RNAi-mediated Nlfru knockdown up-regulated the expression of flightin in macropterous males, which regulated muscle stiffness and delayed force response, suggesting Nlfru's involvement in muscle development regulation. Collectively, our results indicate that Nlfru functions in N. lugens exhibit a combination of conservation and species specificity, contributing insights into fru evolution, particularly in Hemiptera species.

Studies in Australian Tettigoniidae: New short-winged Agraeciini from Australia (Orthoptera: Tettigoniidae; Conocephalinae; Agraeciini).

Descriptions of seven new, short-winged Australian Agraeciine genera are presented with details of distribution, calling songs and karyotypes of several species. Photographs of the habitats of most species are included. A key to the known brachypterous and micropterous Australia agraeciines is presented. A new subtribe Australiagraeciina Rentz, Su, Ueshima is described to include species with small size of adults, macropterous males, apterous females and males with the stridulatory file positioned on a raised swelling. Included in the new subtribe are the following: Australiagraecia Rentz, Su and Ueshima Gen. et sp. nov. with the species A. spina Rentz, Su and Ueshima Gen. et sp. nov. (type species); A. minuta Rentz, Su and Ueshima Gen. et sp. nov.; A. helleri Rentz, Su and Ueshima Gen. et sp. nov.; A. torndirrupa Rentz, Su and Ueshima Gen. et sp. nov.; A. tagera Rentz, Su and Ueshima Gen. et sp. nov.; A. gladiator Rentz, Su and Ueshima Gen. et sp. nov.; A. curvata Rentz, Su and Ueshima Gen. et sp. nov. Ganiagraecia Rentz, Su and Ueshima Gen. nov.; G. karwinia Rentz, Su and Ueshima Gen. et sp. nov. (type species). Gwynnagraecia Rentz, Su and Ueshima Gen. nov.; G. viridis Rentz, Su and Ueshima Gen. et sp. nov. (type species).; G. perplexa Rentz, Su and Ueshima Gen. et sp. nov.; G. marandoo Rentz, Su and Ueshima Gen. et sp. nov. Latitatagraecia Rentz, Su and Ueshima Gen. nov.; L. kalamaya Rentz, Su and Ueshima Gen. et sp. nov. (type species); L. vulgivaga Rentz, Su and Ueshima Gen. et sp. nov. The following are placed in the subtribe Agraeciina Redtenbacher 1891: Cooloolagraecia Rentz, Su and Ueshima Gen. nov.; C. wallum Rentz, Su and Ueshima Gen. et sp. nov. (type species); C. gubbi Rentz, Su and Ueshima Gen. et sp. nov. Kokominiagraecia Rentz, Su and Ueshima Gen. nov.; K. dicra Rentz, Su and Ueshima Gen. et sp. nov. (type species). Timbarragraecia Rentz, Su and Ueshima Gen. nov.; T. samneilli Rentz, Su and Ueshima Gen. et sp. nov. (type species). A key to the Australiagraecia species is included.

Two new species of Abelocephala (Heteroptera: Reduviidae) from Taiwan

The millipede assassin bug genus Abelocephala Maldonado, 1996 (Heteroptera: Reduviidae: Ectrichodiinae: Abelocephalini) is currently comprised of seven Oriental species. Two macropterous males, representing two new species, were recently collected from Taiwan in Malaise trap samples: A. baliensis sp. nov. and A. yilanensis sp. nov. Habitus and structural images are provided for each new species. A revised diagnosis of Abelocephala and an updated identification key to all species of the genus are given.

Expression Profiles and Biochemical Analysis of Chemosensory Protein 3 from Nilaparvata lugens (Hemiptera: Delphacidae).

Insects have evolved highly sensitive olfactory sensory systems to detect plant hosts and mates, with plant volatiles playing an important role in informing insect behavior. Chemosensory proteins (CSPs) are thought to play a key role in this process, but in this respect, there is limited information on brown planthopper Nilaparvata lugens, one of the most destructive pests of rice. To expand our understanding of CSP function in N. lugens we explored expression profiles and binding characteristics of NlugCSP3. The ligands with higher binding affinity were also validated by molecular docking and behavioral assays. NlugCSP3 mRNA was expressed at relatively higher levels in antennae and abdomen of 3-day-old unmated macropterous males as well as in antennae of 3-day mated macropterous and brachypterous females. Fluorescence competitive binding assays revealed that 5 out of 25 candidate volatiles are strong binders (Ki < 10μM). Behavioral assays revealed that nonadecane and 2-tridecanone, which have high binding affinities in fluorescence competition-binding assays, displayed strong attractiveness to N. lugens. Pursuing this further, molecular docking analysis identified key amino acid residues involved in binding volatile compounds. Overall, our data provide a base for further investigation of the potential physiological functions of CSP3 in Nilaparvata lugens, and extend the function of NlugCSP3 in chemoreception of N. lugens.

Establishment of a new genus, Brephallus Wang et al., gen. nov. (Blattodea, Blaberidae, Epilamprinae) based on two species from Pseudophoraspis, with details of polymorphism in species of Pseudophoraspis.

Brephallus Wang et al., gen. n. is established as a genus distinct from Pseudophoraspis Kirby, 1903 because of the lack of a well-developed apical outgrowth on sclerite L2D and substantial genetic differences. Two species are transferred to the new genus from Pseudophoraspis, i.e., Brephallusfruhstorferi (Shelford, 1910), comb. n. and Brephallustramlapensis (Anisyutkin, 1999), comb. n. We provide a detailed generic diagnosis of Brephallus Wang et al., gen. n. Based on COI data, males, females and nymphs of three Pseudophoraspis species (P.clavellata Wang et al., 2013, P.recurvata Wang et al., 2013 and P.kabakovi Anisyutkin, 1999) were successfully matched. The former two are sexually dimorphic with macropterous males and micropterous females. Photos of the species from China are presented.

Biased dispersal of Metrioptera bicolor, a wing dimorphic bush-cricket.

In the highly fragmented landscape of central Europe, dispersal is of particular importance as it determines the long-term survival of animal populations. Dispersal not only secures the recolonization of patches where populations went extinct, it may also rescue small populations and thus prevent local extinction events. As dispersal involves different individual fitness costs, the decision to disperse should not be random but context-dependent and often will be biased toward a certain group of individuals (e.g., sex- and wing morph-biased dispersal). Although biased dispersal has far-reaching consequences for animal populations, immediate studies of sex- and wing morph-biased dispersal in orthopterans are very rare. Here, we used a combined approach of morphological and genetic analyses to investigate biased dispersal of Metrioptera bicolor, a wing dimorphic bush-cricket. Our results clearly show wing morph-biased dispersal for both sexes of M. bicolor. In addition, we found sex-biased dispersal for macropterous individuals, but not for micropters. Both, morphological and genetic data, favor macropterous males as dispersal unit of this bush-cricket species. To get an idea of the flight ability of M. bicolor, we compared our morphological data with that of Locusta migratoria and Schistocerca gregaria, which are very good flyers. Based on our morphological data, we suggest a good flight ability for macropters of M. bicolor, although flying individuals of this species are seldom observed.

The phylogeny of the superfamily Coccoidea (Hemiptera: Sternorrhyncha) based on the morphology of extant and extinct macropterous males

AbstractCurrently, 49 families of scale insects are recognised, 33 of which are extant. Despite more than a decade of DNA sequence‐based phylogenetic studies of scales insects, little is known with confidence about relationships among scale insects families. Multiple lines of evidence support the monophyly of a group of 18 scale insect families informally referred to as the neococcoids. Among neococcoid families, published DNA sequence‐based estimates have supported Eriococcidae paraphyly with respect to Beesoniidae, Dactylopiidae, and Stictococcidae. No other neococcoid interfamily relationship has been strongly supported in a published study that includes exemplars of more than ten families. Likewise, no well‐supported relationships among the 15 extant scale insect families that are not neococcoids (usually referred to as ‘archaeococcoids’) have been published. We use a Bayesian approach to estimate the scale insect phylogeny from 162 adult male morphological characters, scored from 269 extant and 29 fossil species representing 43/49 families. The result is the most taxonomically comprehensive, most resolved and best supported estimate of phylogenetic relationships among scale insect families to date. Notable results include strong support for (i) Ortheziidae sister to Matsucoccidae, (ii) a clade comprising all scale insects except for Margarodidae s.s., Ortheziidae and Matsucoccidae, (iii) Coelostomidiidae paraphyletic with respect to Monophlebidae, (iv) Eriococcidae paraphyletic with respect to Stictococcidae and Beesoniidae, and (v) Aclerdidae sister to Coccidae. We recover strong support for a clade comprising Phenacoleachiidae, Pityococcidae, Putoidae, Steingeliidae and the neococcoids, along with a sister relationship between this clade and Coelostomidiidae + Monophlebidae. In addition, we recover strong support for Pityococcidae + Steingeliidae as sister to the neococcoids. Data from fossils were incomplete, and the inclusion of extinct taxa in the data matrix reduced support and phylogenetic structure. Nonetheless, these fossil data will be invaluable in DNA sequence‐based and total evidence estimates of phylogenetic divergence times.

Wing morph- and age-related differences in fertilization success of adult males of a flightless bug, Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae)

The aim of the present study was to test the hypothesis that short-winged (brachypterous) and long-winged (macropterous) adult males of a flightless bug Pyrrhocoris apterus differ in fertilization success. For this purpose, 5, 10 and 28 days old brachyp- terous and macropterous males were mated for the same period of time with reproductively active 5 days old brachypterous females. The average hatchability of five egg batches of these females was used as a measure of the fertilization success of the males. The results revealed significantly higher hatchability of the eggs laid by females that copulated with 5 or 10 days old brachypterous males than with same-aged macropterous males. In contrast, the average hatchability of eggs of females that copulated with 28 days old brachypterous males was significantly lower than of those mated with same-aged macropterous males. It is the first report of wing morph- and age-related differences in fertilization success of males in insects with a non-functional wing-polymorphism. The possible relationship between wing- and age-related differential fertilization and the mating success of P. apterus males, and differ- ences in the amount of secretion transferred from their accessory glands into the reproductive tract of females during copulation, is discussed.

Variation in Acquisition of Fiji Disease Virus by &lt;I&gt;Perkinsiella saccharicida&lt;/I&gt; (Hemiptera: Delphacidae)

Fiji leaf gall, caused the Fiji disease virus (genus Fijivirus, family Reoviridae, FDV), is a serious disease of sugarcane, Saccharum officinarum L., in Australia and several other Asia-Pacific countries. In Australia FDV is transmitted only by the planthopper Perkinsiella saccharicida Kirkaldy (Hemiptera: Delphacidae), in a propagative manner. Successful transmission of FDV by single planthoppers confined to individual virus free plants is highly variable, even under controlled conditions. The research reported here addresses two possible sources of this variation: (1) gender, wing form, and life stage of the planthopper; and (2) genotype of the source plant. The acquisition of FDV by macropterous males, macropterous females, brachypterous females, and nymphs of P. saccharicida from infected plants was investigated using reverse transcription-polymerase chain reaction to diagnose FDV infection in the vector. The proportion of individuals infected with FDV was not statistically related to life stage, gender, or adult wing form of the vector. The acquisition of FDV by P. saccharicida from four cultivars of sugarcane was compared to assess the influence of plant genotype on acquisition. Those planthopper populations reared on diseased 'NCo310' plants had twice as many infected planthoppers as those reared on 'Q110', 'WD1', and 'WD2'. Therefore, variation in FDV acquisition in this system is not the result of variation in the gender, wing form and life stage of the P. saccharicida vectors. The cultivar used as the source plant to rear vector populations does affect the proportion of infected planthoppers in a population.

Differential allocation of protein resources to flight muscles and reproductive organs in the flightless wing-polymorphic bug, Pyrrhocoris apterus (L.) (Heteroptera)

Differences in the growth of dorsolongitudinal flight muscles and gonads in 1-28 days old long-winged (macropterous) and short-winged (brachypterous) adults of the firebug (Pyrrhocoris apterus L.) and the resource allocation to these organs were studied by means of total protein analysis. We found predominant allocation of food resources to flight muscles compared to reproductive organs in both macropterous males and females during the first 5 days of adult life. Subsequent histolysis of developed flight muscles coincided with increased total protein content in some reproductive organs. Initiation of intensive food intake after starvation or application of higher dose of methoprene on macropterous adults changed the resource allocation in favour of growth of reproductive organs and induced precocious histolysis of flight muscles. It indicates an involvement of juvenile hormone in wing morph-related differential allocation of resources in the bug. Increased total protein contents in the ovaries and accessory glands of starved macropterous females and males treated with methoprene, respectively, indicate that proteins derived from the methoprene-induced histolysis of the flight muscles are re-utilized for the growth of the reproductive organs. It is the first report of persistence of differential resource allocation to flight muscles and reproductive organs in the wing-polymorphic insects with non-functional macropterism.

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.

Endocrine control of wing morph-related differences in mating success and accessory gland size in male firebugs

Endocrine regulation has long been suspected to be a primary physiological cause of correlations between life history traits in insects. However, data showing hormonal control of wing morph-related differences in mating success of macropterous and brachypterous males are lacking. I investigated the relation between male mating success and the size of the accessory glands in the flightless firebug, Pyrrhocoris apterus (L.). Differential mating success of macropterous and brachypterous adult males depended on age. Brachypterous males had an early mating advantage (on days 3–14 after adult ecdysis), but macropterous males later gained this advantage (days 21–28 after ecdysis). The developmental patterns of mating success of the two wing morphs and the size of their accessory glands were positively related. The accessory glands were smaller and mating success lower in food-deprived brachypterous males than in normally feeding brachypterous males. Allatectomy of brachypterous males led to the accessory glands shrinking, whereas methoprene increased the size of the accessory glands of these males to that observed in same-aged controls. Mating success and the size of the accessory glands in macropterous males were also increased after methoprene treatment. This is the first report of endocrine control of a wing morph-related difference in mating success and its relation to the maturation rate of the accessory glands in wing-polymorphic insects.

Energy Allocation in Brachypterous versus Macropterous Morphs of the Pygmy Grasshopper Tetrix subulata (Orthoptera: Tetrigidae)

In wing dimorphic insects, there exists a trade-off between dispersal and reproduction. The brachypterous or short-winged morph reproduces faster while the macropterous or long-winged morph is better able to colonize new habitats. In the present study, energy reserves (carbohydrates, proteins and lipids) and energy consumption (derived from the electron transport activity) were quantified in brachypterous and macropterous males and females of the pygmy grasshopper Tetrix subulata (Linnaeus 1758). It was found that the macropterous morph consumes significantly more energy and has a significantly higher protein content in comparison with the brachypterous morph. Both parameters are probably related to better developed wing muscles in the macropterous morphs. No differences were found in carbohydrate and lipid content. It was also observed that energy consumption and protein content were significantly higher in males compared to females. These findings are probably related to the higher activity of males, which spend most of the time searching for females.

Corpus allatum volume-dependent differences in accessory gland maturation in long- and short-winged males of Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae)

In the present study the temporal changes in the volume of the corpus allatum in three experimental groups of adult males (macropterous, reproductive brachypterous and diapausing brachypterous) of the flightless bug Pyrrhocoris apterus were determined and related to the size of male accessory glands. The results revealed wing morph- and age-dependent differences in the corpus allatum volume in males of this bug. In 4-14 day old males, the volumes of the corpus allatum and accessory glands were largest in long-day reproductive brachypters, intermediate in long-day macropters, and smallest in short-day diapausing brachypters. The smaller corpus allatum in young macropterous males than in same aged reproductive brachypterous males was due to the sponta- neous fasting of the former. Later, starting on day 18 after adult emergence, i.e. when macropterous males were feeding normally, there were no significant differences in the volumes of the corpus allatum between long-day brachypterous and macropterous males. On the other hand, the corpus allatum of 18-28 day old diapausing brachypterous males was significantly smaller than that of same aged long-day macropterous and reproductive brachypterous males. The sizes of the corpus allatum and accessory glands were sig- nificantly positively correlated in macropterous and diapausing brachypterous males. This is the first report of corpus allatum volume-dependent wing morph-related differences in the rate of accessory gland maturation in males of insects with a non-functional macropterism. The role of differential activity of the corpus allatum in the different life history strategies of males of the two wing morphs in this wing-polymorphic insect is discussed.

Wing dimorphism in three carabid species living in the grasslands of Mt. Omuro, Shizuoka, Japan

A 3 y study on the wing polymorphism of carabid beetles living in various habitats was conducted in Ito, Shizuoka, Japan. The survey covered grasslands, copses and farmlands. Seven species were grassland specialists, four were woodland or copse specialists, one was found only in fallow paddies and six species were identified as generalists being caught irrespective of the kind of habitat. Wing dimorphism was found in Hemicarabus tuberculosus (Dejean et Boisduval), Cymindis daimio Bates and Pterostichus samurai (Lutshnik), all of which were grassland inhabitants. Macropterous forms of H. tuberculosus were found at a low proportion of 0.022 in the population, giving an estimate of 0.15 for the frequency of a presumed recessive allele determining macroptery. There was a tendency for macropterous males to be larger in body size compared with brachypterous ones. Three and one macropterous specimens were found in the 39 and 35 sampled specimens of C. daimio and P. samurai, respectively. The three dimorphic species were found mainly in volcanic grassland, which is burned every February. It was suggested that they are the inhabitants of unstable harsh habitats.

Wing morph-specific differences in the metabolism and endocrine control of reserve mobilization in adult males of a flightless bug, Pyrrhocoris apterus (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.

Decreased mating propensity of macropterous morph in a flightless wing-polymorphic insect, Pyrrhocoris apterus (Heteroptera)

The effect of wing length (brachyptery and macroptery) on mating activity was investigated in adult males and females of a flightless wing-polymorphic insect, Pyrrhocoris apterus (L.). Mating activity of the brachypterous and macropterous adult bugs was assessed according to 14 different parameters. The competition tests revealed higher numbers of copulations and greater dura- tion of mating activity in brachypterous than in macropterous males. Brachypterous males are between two to four times more suc- cessful in competition for females than their macropterous counterparts, depending on the wing morph and physiological status of the females. Decreased mating success of macropterous males is associated with the smaller size of their accessory glands. Lowered competitive ability for mates is a likely penalty associated with macroptery. Receptivity tests showed the highest tendency to mate in reproductive brachypterous females, lower in macropterous females and the least in diapausing brachypterous females. This is the first report of decreased mating propensity of macropterous morphs in insects with non-functional wing polymorphism. The associa- tion of lowered mating success with the higher dispersal activity of the macropterous morph in this bug and a trade-off between the ability to reproduce and to disperse in the flightless wing-polymorphic insects is discussed.

Wing morph-related differences in the pattern of mating activity in a flightless bug, Pyrrhocoris apterus (L.) (Heteroptera)

Summary The mating activity of the long-winged (macropterous) and short-winged (brachypterous) adult males and females from a temperate population (Czech Republic) of the firebug Pyrrhocoris apterus (L.) was studied during the first 14 days of adult life under constant laboratory conditions. The study showed that macropterous pairs copulated almost three times less frequently than the brachypterous pairs. The mean inter-copulation period was significantly longer in macropterous females than in brachypterous ones. Despite the fact that there was no significant difference between the total courtship frequencies of macropterous and brachypterous males, the mean duration of the inter-mating period was significantly shorter in brachypterous males than in macropterous ones, which indicates higher mating vigour of the former. Thus, the lower mating propensity of macropterous pairs was mainly due to lowered receptivity of females and in some extent to lowered mating vigour of males. The courtships of males and copulations of pairs of both wing morphs occurred predominantly throughout the photophase. The mean (peak) time of courtship and copulation activities of brachypterous pairs occurred at about 17:30 MET and 19:00 MET before the onset of the scotophase, respectively. In macropterous pairs the mean peak time of courtship and copulation occurred 2 h earlier. The study showed that the wing morph-related differences in mating activity characteristic for many flying wing-polymorphic insects are maintained also in insects whose all macropterous specimens have evolved flightlessness.

Wing morph-related differences in developmental pattern of accessory gland proteins in adult males of Pyrrhocoris apterus (L.) and their endocrine control

The study showed that the amounts of the total proteins and 53kDa protein in male accessory glands (AGs) of the firebug Pyrrhocoris apterus (L.) increased with age of the adult life. The 53kDa protein, the most abundant polypeptide detected in the secretion of the AGs, and some other smaller peptides were identified as glycoproteins. Changes in the amounts of the total proteins and 53kDa protein in AGs were found to be wing morph-dependent and their levels were significantly higher in 1–10 days old brachypterous males than in macropterous males of the same age. Macropterous males were characterized by delayed growth of the AGs. Treatment of adult macropterous males with methoprene significantly increased the amounts of total proteins and 53kDa protein in their AGs when compared to acetone-treated macropterous controls of the same age. Allatectomy of brachypterous males decreased the levels of the total proteins and 53kDa protein in their AGs, while application of methoprene enhanced the quantity of allatectomy-suppressed proteins in these tissues. This is the first report of juvenile hormone-dependent wing morph-related differences in the synthesis of AG proteins and their endocrine control in wing-polymorphic insects.

The evolution of trade-offs: geographic variation in call duration and flight ability in the sand cricket, Gryllus firmus.

Quantitative genetic theory assumes that trade-offs are best represented by bivariate normal distributions. This theory predicts that selection will shift the trade-off function itself and not just move the mean trait values along a fixed trade-off line, as is generally assumed in optimality models. As a consequence, quantitative genetic theory predicts that the trade-off function will vary among populations in which at least one of the component traits itself varies. This prediction is tested using the trade-off between call duration and flight capability, as indexed by the mass of the dorsolateral flight muscles, in the macropterous morph of the sand cricket. We use four different populations of crickets that vary in the proportion of macropterous males (Lab = 33%, Florida = 29%, Bermuda = 72%, South Carolina = 80%). We find, as predicted, that there is significant variation in the intercept of the trade-off function but not the slope, supporting the hypothesis that trade-off functions are better represented as bivariate normal distributions rather than single lines. We also test the prediction from a quantitative genetical model of the evolution of wing dimorphism that the mean call duration of macropterous males will increase with the percentage of macropterous males in the population. This prediction is also supported. Finally, we estimate the probability of a macropterous male attracting a female, P, as a function of the relative time spent calling (P = time spent calling by macropterous male/(total time spent calling by both micropterous and macropterous male). We find that in the Lab and Florida populations the probability of a female selecting the macropterous male is equal to P, indicating that preference is due simply to relative call duration. But in the Bermuda and South Carolina populations the probability of a female selecting a macropterous male is less than P, indicating a preference for the micropterous male even after differences in call duration are accounted for.