Wing Length Measurements Research Articles

Increasing winter temperatures explain body size decrease in wintering bird populations of Northern Europe—But response patterns vary along the spatioclimatic gradient

AbstractAimRecent evidence has shown changes in body size and shape of individuals, which are suggested to be a result of global warming caused by climate change. Here, we explored the spatiotemporal changes in wing length and body mass of 24 wintering bird species in Northern Europe and how these relate to temperature anomaly.LocationFinland and Sweden, Europe.Time Period50 years, 1970 to 2020.Major Taxa StudiedBirds, 24 species.MethodsWe used site‐specific, long‐term winter ringing data containing wing length and body mass measurements from across Sweden and Finland for 24 bird species. We modelled wing length and body mass change over time, in relation to the spatioclimatic gradient and as response to temperature anomalies (of [i] the same winter as the ringing took place, [ii] the previous winter and [iii] the previous spring) by accounting for phylogenetic relatedness between species and their species‐specific responses to each predictor of interest.ResultsWe show that across all species, body size has decreased since the 1970s, with a negative relationship between wing length and temperature anomalies of previous winters, suggesting carry‐over effects likely linked to body size‐related survival or dispersal. Body mass was negatively related to the temperature anomaly of the same winter, indicating more immediate effects related to reduced fat reserves during mild winters.Main ConclusionsOur results highlight a climate‐driven decrease in body size across several species and its association with positive anomalies in winter temperature in the high latitudes. However, the responses are not spatially uniform and there is considerable species‐specific variation, emphasizing the importance of conducting multispecies studies when investigating responses to climate change. The mechanisms of decreasing wing length and body mass seem to differ and underline the immediate and carry‐over effects of temperature warming during the nonbreeding season.

Analysis of vocal communication in the genus Falco

Vocal learning occurs in three clades of birds: hummingbirds, parrots, and songbirds. Examining vocal communication within the Falconiformes (sister taxon to the parrot/songbird clade) may offer information in understanding the evolution of vocal learning. Falcons are considered non-vocal learners and variation in vocalization may only be the result of variation in anatomical structure, with size as the major factor. We measured syringes in seven Falco species in the collection at the American Museum of Natural History and compiled data on weight, wing length, and tail length. Audio recordings were downloaded from several libraries and the peak frequency and frequency slope per harmonic number, number of notes in each syllable, number of notes per second, duration of each note, and inter-note duration was measured. Mass, wing length, and syringeal measurements were strongly, positively correlated, and maximum frequency is strongly, negatively correlated with the size. Frequency slope also correlates with size, although not as strongly. Both note and inter-note length vary significantly among the seven species, and this variation is not correlated with size. Maximum frequency and frequency slope can be used to identify species, with the possibility that bird sounds could be used to identify species in the field in real time.

Phenotypic senescence in a natural insect population.

Senescence seems to be universal in living organisms and plays a major role in life-history strategies. Phenotypic senescence, the decline of body condition and/or performance with age, is a largely understudied component of senescence in natural insect populations, although it would be important to understand how and why insects age under natural conditions. We aimed (i) to investigate how body mass and thorax width change with age in a natural population of the univoltine Clouded Apollo butterfly (Parnassius mnemosyne, Lepidoptera: Papilionidae) and (ii) to assess the relationship of this change with sex and wing length. We studied a population between 2014 and 2020 using mark-recapture during the whole flight period each year. Repeated measurements of body mass and thorax width and single measurements of wing length were performed on marked individuals. We analyzed body mass and thorax width change with age (days since marking), wing length, and the date of the first capture. Both body mass and thorax width declined nonlinearly with age. Individuals appearing earlier in the flight period had significantly higher initial body mass and thorax width and their body mass declined faster than later ones. Initial body sizes of females were higher, but males' body sizes decreased slower. Initial thorax width showed higher annual variation than body mass. To our best knowledge, this is the first study that revealed phenotypic senescence in a natural butterfly population, using in vivo measurements. We found sexual differences in the rate of phenotypic senescence. Despite the annual variation of initial body sizes, the rate of senescence did not vary considerably across the years.

Size variation in wild Bactrocera tryoni (Diptera: Tephritidae): only a small amount is related to the host fruit

AbstractBody size is an indicator of fitness in fruit flies (Diptera: Tephritidae), with larger males and females having increased mating success and egg production, respectively. Based on laboratory studies, the larval diet and its nutritional composition are considered the most important factors influencing juvenile growth and subsequent adult body size. However, a very limited literature is less clear on the importance of larval diet as an adult size modifier of wild fruit flies. Bactrocera tryoni (Froggatt) is a polyphagous species with larvae feeding within the fruit of over 200 plant species. To test the impact of larval host on adult size in wild individuals of this species, we collected naturally infested fruit from the field and then reared out adults in the laboratory. The wing length and dry body weight of emergent flies were measured. Linear mixed models were used to analyse the difference in size depending on fruit type, larval density, sex and their interactions. Separate measurements of body size, wing length and dry body weight were significantly influenced by the larval host fruit collected from the field. However, only 7% and 24% of the variation of the wing discal–medial cell length and dry body weight, respectively, could be explained by larval host fruit type with high individual body size variation both within and between host fruit types. Fruit protein content was positively correlated, and water content negatively correlated, to wing discal–medial cell length. Unexpectedly, the parameters of wing length and dry body weight were only weakly correlated with each other. The results support the large body of laboratory‐based fruit fly diet work, which identifies protein as a key component of the larval diet, but do not support a general assumption that larval host is the key driver of adult body size variation in wild frugivorous tephritids. Rather, and in agreement with a small number of laboratory‐based trials, the importance of larval diet to adult fitness appears to become less important as the larval feeding environment becomes more complex.

Colonization and Authentication of the Pyrethroid-Resistant Anophelesgambiae s.s. Muleba-Kis Strain; an Important Test System for Laboratory Screening of New Insecticides.

Simple SummaryMalaria control and prevention have traditionally relied on the use of insecticides in the form of treated bed nets or residual spraying in households. However, scaling up of these interventions—based on few available insecticide classes—resulted in the development and spread of insecticide resistance in malaria-transmitting mosquitoes. There is therefore an urgent need for introducing and applying new insecticides that are effective against these mosquitoes. Laboratories tasked with evaluating the efficacy of novel insecticides need to establish a large colony of resistant mosquitoes. In this study, we report the procedures used and challenges faced during the establishment and maintenance of a resistant mosquito strain in the laboratory which reflects the characteristics of the wild-resistant mosquito populations found in East Africa.Background: The emergence and spread of insecticide resistance in malaria vectors to major classes of insecticides call for urgent innovation and application of insecticides with novel modes of action. When evaluating new insecticides for public health, potential candidates need to be screened against both susceptible and resistant mosquitoes to determine efficacy and to identify potential cross-resistance to insecticides currently used for mosquito control. The challenges and lessons learned from establishing, maintaining, and authenticating the pyrethroid-resistant An. gambiae s.s. Muleba-Kis strain at the KCMUCo-PAMVERC Test Facility are described in this paper. Methods: Male mosquitoes from the F1 generation of wild-pyrethroid resistant mosquitoes were cross-bred with susceptible female An. gambiae s.s. Kisumu laboratory strain followed by larval selection using a pyrethroid insecticide solution. Periodic screening for phenotypic and genotypic resistance was done. WHO susceptibility tests and bottle bioassays were used to assess the phenotypic resistance, while Taqman™ assays were used to screen for known target-site resistance alleles (kdr and ace-1). Additionally, the strains were periodically assessed for quality control by monitoring adult weight and wing length. Results: By out-crossing the wild mosquitoes with an established lab strain, a successful resistant insectary colony was established. Intermittent selection pressure using alphacypermethrin has maintained high kdr mutation (leucine-serine) frequencies in the selected colony. There was consistency in the wing length and weight measurements from the year 2016 to 2020, with the exception that one out of four years was significantly different. Mean annual wing length varied between 0.0142–0.0028 mm compared to values obtained in 2016, except in 2019 where it varied by 0.0901 mm. Weight only varied by approximately 0.001 g across four years, except in 2017 where it differed by 0.005 g. Routine phenotypic characterization on Muleba-Kis against pyrethroids using the WHO susceptibility test indicated high susceptibility when type I pyrethroids were used compared to type II pyrethroids. Dynamics on susceptibility status also depended on the lapse time when the selection was last done. Conclusions: This study described the procedure for introducing, colonizing, and maintaining a resistant An. gambiae s.s. strain in the laboratory with leucine to serine substitution kdr allele which reflects the features of the wild-resistant population in East Africa. Challenges in colonizing a wild-resistant mosquito strain were overcome by out-crossing between mosquito strains of desired traits followed by intermittent insecticide selection at the larval stage to select for the resistant phenotype.

Wing length of tsetse caught by stationary and mobile sampling methods

IntroductionA variety of techniques have been used to control tsetse with varying degrees of success. In a study on the population structure of Glossina fuscipes fuscipes that recovered after a previous vector control trial on two Kenyan islands, it was reported that the average fly size on the intervention islands was significantly smaller than on the none intervention islands and also compared to the size before the intervention. The conclusion was that vector control using tiny targets exerted size selection pressure on the population. The study recommended for further studies and suggested that this phenomenon could be among the reasons why targets used as a sole control method have rare reports of successful elimination of tsetse populations. Therefore, in this paper we report on a study of body size of tsetse flies caught in epsilon traps (as a stationary device) and black screen fly rounds (as a mobile trapping device). Materials and methodsThe study was carried out in eastern Zambia to test the hypothesis that the body size (measured as wing length) of G. m. morsitans males or females, captured by epsilon traps and fly rounds is the same. ResultsA total of 1442 (489 females and 953 males) wing length measurements of G. m. morsitans were used in the analysis. It was established that tsetse flies caught by epsilon traps are on average larger than those caught by fly rounds. The likelihood of a large female or male fly being caught by traps, relative to a small one, significantly increased by 5.088 times (95% CI: 3.138–8.429) and by 2.563 times (95% CI: 1.584–4.148), respectively, p < 0.0001, compared with being caught by fly rounds. The hypothesis was rejected. ConclusionThis study showed that epsilon traps capture significantly larger G. m. morsitans than fly rounds do. Therefore, further research is recommended to verify i) whether the predilection of traps to capture larger flies has an effect on the process of tsetse elimination when targets are used e.g. targets may take longer to reach elimination than if the predilection was not there, ii) whether different results can be obtained on ecogeographic distribution of different sizes of the species if fly rounds are used for sampling instead of epsilon traps. The results from such studies could influence the strategies used in future control operations.

Long-term declines in winter body mass of tits throughout Britain and Ireland correlate with climate change.

The optimum body mass of passerine birds typically represents a trade‐off between starvation risk, which promotes fat gain, and predation pressure, which promotes fat loss to maintain maneuvrability. Changes in ecological factors that affect either of these variables will therefore change the optimum body masses of populations of passerine birds. This study sought to identify and quantify the effects of changing temperatures and predation pressures on the body masses and wing lengths of populations of passerine birds throughout Britain and Ireland over the last 50 years. We analyzed over 900,000 individual measurements of body mass and wing length of blue tits Cyanistes caeruleus, coal tits Periparus ater, and great tits Parus major collected by licenced bird ringers throughout Britain and Ireland from 1965 to 2017 and correlated these with publicly available temperature data and published, UK‐wide data on the abundance of a key predator, the sparrowhawk Accipiter nisus. We found highly significant, long‐term, UK‐wide decreases in winter body masses of adults and juveniles of all three species. We also found highly significant negative correlations between winter body mass and winter temperature, and between winter body mass and sparrowhawk abundance. Independent of these effects, body mass further correlated negatively with calendar year, suggesting that less well understood dynamic factors, such as supplementary feeding levels, may play a major role in determining population optimum body masses. Wing lengths of these birds also decreased, suggesting a hitherto unobserved large‐scale evolutionary adjustment of wing loading to the lower body mass. These findings provide crucial evidence of the ways in which species are adapting to climate change and other anthropogenic factors throughout Britain and Ireland. Such processes are likely to have widespread implications as the equilibria controlling evolutionary optima in species worldwide are upset by rapid, anthropogenic ecological changes.

Fit is fat: winter body mass of Atlantic Puffins Fratercula arctica

ABSTRACTCapsule: Atlantic Puffins Fratercula arctica from Scottish and Norwegian populations were significantly heavier in winter than when rearing chicks.Aims: To compare body masses of Atlantic Puffins on their wintering grounds off the Faroe Islands with those of birds rearing chicks at colonies in Scotland and Norway.Methods: We took standardized measurements of wing length and body mass of Atlantic Puffins during the summer chick-rearing period and on the wintering grounds near the Faroe Islands. These measurements were used to estimate seasonal changes in body mass for the two breeding populations. In three cases data were available for individuals weighed both at the colony and on the wintering grounds.Results: On average, Atlantic Puffins breeding in Scotland and Norway increased their body mass by 20–30% between the chick-rearing period and winter. The very limited individual level data accorded well with the population level estimates.Conclusions: Our results provide the first estimates of the order of magnitude in mass change between two key life history stages in this species. They indicate that gains in body mass between chick-rearing and winter are at least double the decline in mass previously recorded between incubation and chick-rearing. Given the Atlantic Puffin’s deteriorating conservation status, improved information on seasonal changes in body condition should help determine the underlying causes of die-offs in major wreck incidents such as those reported in recent years.

A morphometric sexing approach for the Ring-necked Parakeet Psittacula krameri in Italy

ABSTRACTOnly one fact is certain when sexing the Ring-necked Parakeet visually: adult males have a rose-coloured ring and a black bib that is fully developed by their third year. Sexually immature males (those <3 years old) and females are considered impossible to separate without using biometric measures, some additional to those in previous literature. While the biometrics of males and females overlap broadly in value, males tend to be slightly larger than females in all measurements. We tested the possibility of sexing individuals of this species using a series of biometric measurements. A total of 97 parakeets were captured and measured in 2016–17. Measurements of wing length, tail length, bill length, height and thickness, tarsus length, mass, third-primary length and number of yellow underwing coverts were recorded for these individuals. In addition, photographs of the head and wing were taken. Feather samples were taken from all individuals for DNA extraction and 45 of these birds (26 females and 19 males) have been sexed. The measurements from these known-sex individuals were pooled with the measurements for adult males and a logistic regression of the known sexes was performed to verify whether the mean value of the biometric variables was statistically different between females and males. We found that it is possible to separate the sexes using morphological measures of wing, tail, bill length and thickness, tarsus and the number of yellow underwing coverts.

Influences of feather wear and age on wing lengths of Blue Tits Cyanistes caeruleus

ABSTRACTAlthough studies of wing length in many bird species show longer wings in adults than in juveniles, and increases in wing length among immature age classes of long-lived birds, evidence for an increase in wing length among adult small passerines is very limited. Previous studies of Blue Tits Cyanistes caeruleus have concluded that adults have longer wing lengths than juveniles but that there is no change in wing length with age of adults, yet the latter conclusion has been based on very limited data. Here we examine wing-length data from a large number of retraps of Blue Tits over a 30-year period at a single site in west Scotland. We found very little evidence for feather wear affecting wing-length measurements during the non-breeding season and, as expected, adults had longer wing lengths than juveniles. However, when comparing individuals caught as both one- and two-year-olds, wing lengths were significantly more likely to increase than decrease. This result has implications for studies of evolutionary biology of Blue Tits, such as survival of individuals in relation to biometrics. It would be interesting to determine whether such age-related increases in wing length are widespread in passerines.

Evolution of a complex behavior: the origin and initial diversification of foliar galling by Permian insects.

A central notion of the early evolution of insect galling is that this unique behavior was uncommon to rare before the diversification of angiosperms 135 to 125m.yr. ago. However, evidence accumulated during recent years shows that foliar galls were diverse and locally abundant as early as the Permian Period, 299 to 252m.yr. ago. In particular, a diversity of leaf galling during the Early Permian has recently been documented by the plant-damage record of foliar galls and, now, our interpretation of the body-fossil record of culprit insect gallers. Small size is a prerequisite for gallers. Wing-length measurements of Permian insects indicate that several small-bodied hemipteroid lineages originated early during the Permian, some descendant lineages of which gall the leaves of seed plants to the present day. The earliest foliar gallers likely were Protopsyllidiidae (Hemiptera) and Lophioneuridae (Thripida). Much of the Early Permian was a xeric interval, and modern galls are most common in dry, extra-tropical habitats such as scrubland and deserts. Plant-damage, insect body fossils, and the paleoclimate record collectively support the ecological expansion of foliar galling during the Early Permian and its continued expansion through the Late Permian.

Relationship between Body Weight and Linear Body Measurements in Japanese Quail (&lt;i&gt;Coturnix coturnix japonica&lt;/i&gt;)

A total of 108 two-weeks-old Japanese quail chicks were used to study the relationship between body weight and linear measurements and to predict body weight from linear measurements of body length (BL), body girth (BG), wing length (WL), shank length (SL), shank diameter (SD) and drum stick (DS).The results showed that the mean quail birds’ body weights were 35.23g and 143.78g, at 2nd and 8th weeks, respectively. Body weight gain was increased between 2 and 6 weeks of age and thereafter decreased with advancing age. Female birds were significantly (P&lt; 0.05) heavier than those of male counterpart at 6th and 8th weeks of age. Significantly positive correlations (P&lt;0.01) were obtained between body weight and body measurements at 2nd, 4th and 8th weeks. The best correlation was obtained between body weight and body girth at the 2nd week of age (0.70). The estimates of coefficient of determination and predictive equations show that body weight in Japanese quail is linearly related to body measurements especially with body girth and body length. The study shows that it is possible for breeders to use BG and BL as criteria for assessment and early selection of Japanese quail for body weight. Keywords: Japanese quail; Body weight; Linear measurements; Correlation © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i1.16368 J. Sci. Res. 6 (1), 175-183 (2014)

Comparability of Wing Length Measurements Based on Data Collected at two Twin Stations during Migration

Abstract Zaniewicz G. 2012. Comparability of wing length measurements based on data collected at two twin stations during migration. Ring 34: 37-43. Data collected during bird migration include measurements taken during ringing. The variety and quality of information, which these measurements can potentially provide, depend strongly on their accuracy and comparability. The analysis of the comparability was made based on the measurements of wing length taken by different ringers during autumn migratory seasons at the southern Baltic coast. An experiment was run with the measurements taken from six passerine species during several (from 8 to 10, depending on the species) migratory seasons at two twin sites belonging to Mierzeja Wioelana station. Pearson’s correlation coefficient was used to evaluate how strongly the habits of different measurers influence the measurements taken. The results of this experiment show that correlations between the measurements collected at these two sites are strong and statistically significant for the Blackcap (Sylvia atricapilla), Garden Warbler (Sylvia borin), Robin (Erithacus rubecula) and Song Thrush (Turdus philomelos). However, for the Goldcrest (Regulus regulus) and Willow Warbler (Phylloscopus trochilus) the relations were not significant. The last species allow to consider other causes, independent from human factor, which are possibly responsible for the average wing length local variability. In such species, we still need to look closer at the potential sources of their differentiation, such as the preferences of habitat selection between sexes, populations, etc.

Sexual dimorphism in Sturnira lilium (Chiroptera, Phyllostomidae): can pregnancy and pup carrying be responsible for differences in wing shape?

Competition is one of the most cited mechanisms to explain secondary sexual dimorphism in animals. Nonetheless, it has been proposed that sexual dimorphism in bat wings is also a result of adaptive pressures to compensate additional weight caused by fetus or pup carrying during the reproductive period of females. The main objective of this study is to verify the existence of sexual dimorphism in Sturnira lilium wings. We employed geometric morphometrics techniques using anatomical landmarks superimposition to obtain size (Centroid Size) and shape variables of wings, which were reduced by Linear Discriminant Analysis (LDA). We also employed classical morphometrics using wing length measurements to compare efficiency between these two morphometric approaches and make comparisons using wing area measurements. LDA indicated significant differences between wing shapes of males and females, with 91% (stepwise classification) and 80% (leave-one-out cross validation) of correct classification. However, the size variable obtained did not contribute to such classifications. We have observed larger areas in female wings, but we found no differences in wing length measurements and no allometric effects in wing length, shape and area measurements. Interestingly, our study has provided evidences of morphological differences where classical morphometrics have failed. LDA and area measurements analyses revealed that females have a different area distribution in distinct portions of the wing, with wider dactylopatagia and plagiopatagia, and wingtips more triangular than males. No differences in body length or relative wing length were observed between the sexes, but pregnant females have more body weight than non-pregnant females and males. Our findings suggest that sexual dimorphism in the wing shape of S. lilium is probably related to the increase in flight efficiency of females during reproductive period. It decreases wing loading in specific portions of the wing and reduces energy cost to maintain a faster and maneuverable flight.

Quantifying the effect of feather abrasion on wing and tail lengths measurements

Wing and tail length measurements are important tools in ornithology. Amongst linear measurements, wing length has been considered to be the best indicator for body size for taxonomy and ecomorphology, as well as for studies about the impact of climate change on morphology. As feathers are dead tissue, abrasion will lead to a reduction in wing and tail length within a moult cycle. The aim of our study was to analyse the effect of feather abrasion on wing and tail length in the Stonechat Saxicola torquata. Generalized additive models revealed that wing lengths and tail lengths decrease significantly between the termination of feather growth and the next moult. The decrease in wing length was faster with increasing feather age. The decrease in tail length was nearly linear through time. Multiple measurements of recaptured individuals revealed a similar decrease in wing length to that observed in analyses based on single measurements of multiple individuals. An analysis of the length of the third outermost primary revealed the same pattern. Hence, the decrease in wing and tail length over time was caused by within-bird changes and not by mortality, emigration or immigration associated with wing and tail length. We found that feather abrasion was more pronounced in females compared to males at least during the breeding season, but there were no strong indications that feather abrasion was more pronounced in birds before their first complete moult compared to older individuals. A review of previous studies showed that a reduction in wing length of about 0.2–0.5 %/month is a common phenomenon. Our study shows that feather abrasion must be taken into account when analysing time-series of wing and tail length measurements to avoid spurious conclusions.

Biometrics, sexing and moulting of Snow Finch Montifringilla nivalis in Central Italy

As a small passerine typical of several Palaearctic mountain ranges, the Snow Finch Montifringilla nivalis is susceptible to climate change and studies into its ecology are badly needed. Data on biometric measurements and moult parameters are essential to underpin ecological studies and the aim of this study was to provide such data for a central Italian breeding population. Between 2003 and 2009, 404 individuals were ringed and measured. In the majority of morphometric measurements (wing length, eighth primary length [P8], bill depth, bill length, mass) adults were significantly larger than juveniles. Adult males had longer wings than females, but the sexes were similar for all other size parameters. Differences in wing length could be used to sex safely 88% of all adult individuals. Wing and P8 length measurements were influenced by feather abrasion, which was more pronounced in females and reduced wing measurements by 2 mm in summer compared to winter. The duration of primary moult was estimated to be 85 days in juveniles, 80 days in adult males and 67 days in adult females. In general, adults started moulting earlier than juveniles and males earlier than females. As usual among passerines, secondary moult started later than primary moult in both juveniles and adults and was accomplished in 50 and 65 days, respectively.

A graphical method for dating chicks using bivariate body measurements

Jones et al. (2005, J. Agric. Biol. Environ. Stat., 10, 306–320) developed a bivariate, nonlinear, mixed, growth curve model in order to estimate the ages of tern chicks from paired measurements of wing length and body weight. They found that age estimates obtained from a pair of measurements were much more precise than using either one alone. We present a graphical method for obtaining approximate answers to the same problem, but invoking fewer modeling assumptions. We obtain fiducial limits for dates by assessing whether pairs of measurements fall within confidence ellipses in the predicted morphological spaces of chicks of given ages. However, our conclusions differ markedly from those obtained by Jones et al.: we found that the precision of date estimates obtained using wing lengths alone were similar to those using both body measures. Supplemental materials including R-code and full illustration of the graphical method are available online.

Sex differences in body size and body condition in breeding Temminck’s Stints Calidris temminckii

There have been very few reports of body size measurements of live Temminck’s Stints, but earlier studies have shown sex differences in body mass and tarsus length. Here we use molecular techniques to determine the sex of Temminck’s Stints from a Norwegian breeding population. In total, we report measurements of body weight, wing length, tarsus length, bill length, skull length and keel length from 17 males and 30 females. We found significant sex differences in all of these variables, with the exception of tarsus length. The differences in skull length disappeared after the bill lengths had been subtracted from the measurements. A discriminant function analysis based on wing length and bill length correctly classified 86% of the cases (12/16 males, 25/27 females). Female Temminck’s Stints are known to regularly lay more than one clutch of eggs per season and could therefore be expected to be physiologically deprived of bodily energy stores. Nevertheless, we found females to be in better body condition than males.

MorphometIics of a Field Population. of Zonocerus variegatus L. (Orthoptera : Pyrgomorphidae).

Adults from natural populations of Zonocerus variegatus L. wen; collected with sweep net at seven locations in the campus of Obafemi Awolowo University, Ile-Ife, Nigeria. They were used for studies on morphometries based on wing, head, leg, pronotum and body length measurements. The relative fore wing length and relative hind wing length were normally distributed in both sexes but wider in females: The normal distribution of relative wing lengths indicates the existence of wing polymorphism in field-population of Z. veriegatus. The use of stepwise discriminant analysis, including canonical variables, showed that the insects from the different locations were a homogeneous population. The best discriminant characters which distinctly separate the two sexes were the fore- and hindwing widths for male population and forewing lengths for female population. There were significant differences in the body lengths and weights of males and females at all locations.

Investigations of dengue‐2 susceptibility and body size among Aedes aegypti populations

The mosquito Aedes aegypti (L.) (Diptera: Culicidae) is the primary global vector for dengue virus (DENV), yet considerable genetic variation exists among populations in terms of its competence to vector DENV. Variability in adult body size has also been observed among various mosquito populations and several studies have reported a relationship between body size and arbovirus dissemination, although most of these relied on artificially derived variation in body size. Here we examine the relationship between body size and disseminated DENV infection among 10 Ae. aegypti populations reared under optimum laboratory conditions. Body size variability was inferred from wing length measurements and DENV competence was evaluated as the proportion of individuals with disseminated infections following exposure to the dengue-2 JAM1409 strain. There were significant differences in mean wing lengths among populations (anova, F(9,22)= 7.10, P < 0.0001), ranging from 2.16 mm (Bangkok population) to 2.79 mm (MOYO-S [susceptible] population). We also observed significant differences among some populations in mean DENV infection rates (Waller-Duncan K-ratio t-test), ranging from 19.54% (MOYO-R [refractory] population) to 56.60% (MOYO-S population). However, we did not observe evidence for significant interactions between body size and DENV dissemination. We suggest that either the two traits are genetically independent or that our ability to detect interactions between them was limited by their respective inheritances as quantitative traits.