Field-collected Males Research Articles

The greening-causing agent alters the behavioral and electrophysiological responses of the Asian citrus psyllid to a putative sex pheromone

The Asian Citrus Psyllid (ACP), Diaphorina citri, is a vector of the pathological bacterium Candidatus Liberibacter asiaticus (CLas), which causes the most devastating disease to the citrus industry worldwide, known as greening or huanglongbing (HLB). Earlier field tests with an acetic acid-based lure in greening-free, ‘Valencia’ citrus orange groves in California showed promising results. The same type of lures tested in São Paulo, Brazil, showed unsettling results. During the unsuccessful trials, we noticed a relatively large proportion of females in the field, ultimately leading us to test field-collected males and females for Wolbachia and CLas. The results showed high rates of Wolbachia and CLas infection in field populations. We then compared the olfactory responses of laboratory-raised, CLas-free, and CLas-infected males to acetic acid. As previously reported, CLas-uninfected males responded to acetic acid at 1 µg. Surprisingly, CLas-infected males required 50 × higher doses of the putative sex pheromone, thus explaining the failure to capture CLas-infected males in the field. CLas infection was also manifested in electrophysiological responses. Electroantennogram responses from CLas-infected ACP males were significantly higher than those obtained with uninfected males. To the best of our knowledge, this is the first report of a pathogen infection affecting a vector’s response to a sex attractant.

Patterns of Gonadic Development and Operational Sex Ratio Promote Promiscuity ofEuxesta bilimeki(Diptera:Ulidiidae)

AbstractPromiscuous mating systems are widely distributed among animals and can be promoted by operational sex ratios (number of receptive adults; OSR). In populations where OSR is not biased towards any sex, the possibility that males and females mate with several individuals increases. For both sexes to synchronize in time and space for reproduction, adults should possess or simultaneously acquire nutrients required to reach sexual maturity. Among synovigenic (without a full complement of eggs at eclosion) species, nutrient acquisition, protein in particular, may influence the OSR. In the Agave fly Euxesta bilimeki (Hendel) (Diptera: Ulidiidae), both sexes engage in multiple mating and females frequently expel all or part of the ejaculate. Here, we assessed the effect of protein intake on gonadic development, and estimated OSR from field-collected individuals. Body protein content was compared between wild and laboratory individuals with access to different diets, and mating frequency and individual mating rate were analyzed for cohorts at a 1:1 sex ratio. Both sexes required protein ingestion for gonadic development, but there were no differences in protein content between field-collected males and males fed protein and sugar in the laboratory, despite the fact that males assigned 9.3% of their corporal weight to testicles. Euxesta bilimeki is a promiscuous species where both males and females mate multiply with one or several individuals in short periods of time; thus, large testes size may be linked to the need of voluminous ejaculate production, and might be further exacerbated by female ejaculate expulsion.

Latitudinal and altitudinal variation in ecologically important traits in a widespread butterfly

AbstractUnderstanding how organisms adapt to complex environments lies at the very heart of evolutionary biology and ecology, and is of particular concern in the current era of anthropogenic global change. Variation in ecologically important traits associated with environmental gradients is considered to be strong evidence for adaptive responses. Here, we study phenotypic variation along a latitudinal and an altitudinal cline in 968 field-collected males of the widespread European butterfly Pieris napi. In contrast to our expectations, body size decreased with increasing latitude and altitude, suggesting that warmer rather than cooler conditions may be more beneficial for individual development in this species. Higher altitudes but not latitudes seemed to be associated with increased flight performance, suggesting stronger challenges for flight activity in high-altitude environments (e.g. due to strong wind). Moreover, wing melanization increased while yellow reflectance decreased towards colder environments in both clines. Thus, increased melanization under thermally challenging conditions seems to compromise investment into a sexually selected trait, resulting in a trade-off. Our study, although exclusively based on field-collected males, revealed indications of adaptive patterns along geographical clines. It documents the usefulness of field-collected specimens, and the strength of comparing latitudinal and altitudinal clines to identify traits being potentially under thermal selection.

Gene expression signatures of mating system evolution.

The diversity of mating systems among animals is astounding. Importantly, similar mating systems have evolved even across distantly related taxa. However, our understanding of the mechanisms underlying these convergently evolved phenotypes is limited. Here, we examine on a genomic scale the neuromolecular basis of social organization in cichlids of the tribe Ectodini from Lake Tanganyika. Using field-collected males and females of four closely related species representing two independent evolutionary transitions from polygyny to monogamy, we take a comparative transcriptomic approach to test the hypothesis that these independent transitions have recruited similar gene sets. Our results demonstrate that while lineage and species exert a strong influence on neural gene expression profiles, social phenotype can also drive gene expression evolution. Specifically, 331 genes (∼6% of those assayed) were associated with monogamous mating systems independent of species or sex. Among these genes, we find a strong bias (4:1 ratio) toward genes with increased expression in monogamous individuals. A highly conserved nonapeptide system known to be involved in the regulation of social behavior across animals was not associated with mating system in our analysis. Overall, our findings suggest deep molecular homologies underlying the convergent or parallel evolution of monogamy in different cichlid lineages of Ectodini.

Micronutrient consumption by female Argiope bruennichi affects offspring survival

Sexual cannibalism has long been hypothesized to be a foraging decision in which females consume males for the nutrients in their bodies. While few studies have documented fecundity benefits of sexual cannibalism, several recent studies have documented benefits of cannibalism to egg hatching success or offspring survival. We tested if small supplements of dietary essential nutrients fed to female spiders, Argiope bruennichi, would result in increases in offspring survival similar to those seen following sexual cannibalism. All female spiders were prevented from cannibalizing their mates and subsequently fed either: a dead male spider, or a similarly-sized dead fly with one of four nutrient supplements (water control, dietary essential fatty acids, dietary essential amino acids, or nonessential amino and fatty acids). Females that consumed a small supplement of dietary essential amino acids produced offspring that survived simulated overwintering conditions significantly longer than offspring of other treatments. While a previous study found a significant effect of cannibalism on offspring survival using field-collected males as prey, the current study, which used lab-reared males as prey, found no effect of sexual cannibalism on offspring survival. Hence, our results suggest that dietary essential amino acids, which may be sequestered by males from their diet, could be valuable supplements that increase the success of the offspring of cannibalistic females. Further work is needed to determine the source and identity of these dietary essential amino acids and if other essential nutrients (e.g., trace elements, vitamins, etc.) may also be limiting in female diets and affect offspring success.

Social structure of the polygynous ant, Crematogaster osakensis

The colony structures of social insects vary greatly among species. In ant societies, the number of queens within a colony is variable during colony maturation. We investigated the social structure of a polygynous ant Crematogaster osakensis in a series of field and laboratory experiments. First, the initial colonies headed by multiple queens were found in the field. In laboratory experiments, queens that were artificially cohabited after their nuptial flight harmoniously co-existed even in the presence of newly emerged workers, suggesting that mated queens of this species can establish their colony cooperatively as primary polygynous colonies. In addition, the mating frequency of a queen was typically more than one, estimated from the sperm number stored in field-collected males and queens, and from genetic relatedness among daughters of lab-reared monogynous colonies. Second, our assessment of genetic relatedness in a mature field colony of this species revealed that dealated queens, as well as workers and alates, were relatives. The number of developed oocytes identified reproductive skew in two of five field-collected nests. Moreover, under laboratory conditions, the most fertile egg layer altered over 3 months of observation. Based on these lines of evidence, we propose that in C. osakensis, polygynous foundresses might either be unrelated and subsequently be replaced by daughter queens of particular foundresses, or be related in the first place.

Insecticide resistance and diminished secondary kill performance of bait formulations against German cockroaches (Dictyoptera: Blattellidae).

Bait formulations are considered to be the most effective method for reducing German cockroach (Blattella germanica) infestations. An important property of some bait formulations is secondary kill, whereby active ingredient (AI) is translocated in insect-produced residues throughout the cockroach population, especially affecting relatively sedentary early-instar nymphs. B. germanica was collected from a location where baits containing hydramethylnon, fipronil or indoxacarb had become ineffective, and these AIs were topically applied to adult males. Results revealed the first evidence for hydramethylnon resistance, moderate resistance to fipronil and extremely high resistance to indoxacarb. Insecticide residues excreted by field-collected males that had ingested commercial baits effectively killed nymphs of an insecticide-susceptible laboratory strain of B. germanica but failed to kill most nymphs of the field-collected strain. We report three novel findings: (1) the first evidence for hydramethylnon resistance in any insect; (2) extremely high levels of indoxacarb resistance in a field population; (3) reduced secondary mortality in an insecticide-resistant field-collected strain of B. germanica. We suggest that, while secondary mortality is considered to be advantageous in cockroach interventions, the ingestion of sublethal doses of AI by nymphs may select for high insecticide resistance by increasing the frequency of AI resistance alleles within the population. © 2015 Society of Chemical Industry.

The role of social experience in eavesdropping by male wolf spiders (Lycosidae)

When reproductive success is limited by mate search costs, males can reduce costs by eavesdropping and initiating displays if conspecific courtship is detected. Here, we examine eavesdropping by male Schizocosa ocreata wolf spiders, with field studies, laboratory studies using video playback and live exposure studies. In field enclosure experiments, introduced males responded with increased courtship signalling behaviour in the presence of a courting male. In the laboratory, field-collected males spent more time engaged in interaction behaviours and performed more bouts of courtship activity in response to a courting video male stimulus than did laboratory-reared males, suggesting that eavesdropping might arise as a consequence of field experience. To explore this further, we conducted associative learning studies on naïve, laboratory-reared males, pairing video playback of male courtship with sensory cues indicating female presence. Results showed that males with no prior exposure learned to associate courtship of other males with cues indicating the presence of females. In subsequent video playback experiments, field-collected males recognized differences in male behaviour, responding with courtship more often and for longer periods to video stimuli of courting male spiders than to walking males or an empty leaf litter background (no spider). Additional studies showed that males spent significantly more time in courtship displays when presented with two to three live or video male stimuli simultaneously. Together, these findings confirm that male wolf spiders meet assumptions of eavesdropping behaviour, and suggest that social experience arising from exposure to courtship interactions of conspecifics may impact male eavesdropping and subsequent courtship behaviour. • We examined eavesdropping by male Schizocosa ocreata wolf spiders in the field and laboratory. • In the field, males showed more courtship signalling behaviour in the presence of a courting male. • Field-collected males were more responsive to videos of courting males than lab-reared males. • Naïve lab-reared males learned to associate courtship of other males with female presence. • Males courted longer when two to three live or video males were presented simultaneously.

Clinal variation explains taxonomic discrepancy in the calling songs of shield-back katydids (Orthoptera: Tettigoniidae: Tettigoniinae: Aglaothorax)

Understanding the relationship between mating trait evolution and speciation requires data from a variety of taxa. I analysed the calling songs of the shield-back katydid genus Aglaothorax, which represents a little-known lineage of acoustic insects. Field-collected males of all described species and most subspecies were recorded under controlled laboratory conditions. Discriminant analysis was 90.5% successful in separating song types, but the song types thus delineated did not correspond to currently recognized taxa as defined by morphology. The discrepancy is caused by two species, Aglaothorax morsei and Aglaothorax longipennis, the songs of which vary in a cline across the Transverse Ranges and the Los Angeles Basin of southern California. From west to east, pulse rate and duty cycle decrease and interpulse interval increases. Selection for species recognition at a contact zone, sexual selection and interactions between signals and the environment are considered as causes of the cline. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 910–921.

Relationships between relative size of sexual traits and male mating success in the Mediterranean killifish Aphanius fasciatus (Nardo, 1827)

Some relationships between the relative size of secondary sexual traits and male mating success were investigated in the killifish Aphanius fasciatus (Nardo, 1827). The relative ability of a male to compete with another male for access to a ripe female was related to the relative size of male sexual traits by means of a behavioural experiment under controlled laboratory conditions. Furthermore, the covariation in the expression of sexual traits was analysed from a sample of field-collected males. Results of the behavioural experiment showed that male dominance and success were positively related to the relative height of the dorsal fin, but not to the pattern of vertical bars along body sides. Within the analysed male population, males with larger fins tended to have thinner bars, whereas there was no statistically significant correlation with bar number or with bar asymmetry. The results were discussed in terms of advantages conferred by larger dorsal fins in killifish breeding systems, and developmental constraints defining a multiple set of traits correlated to male quality were also hypothesised.

The Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) voltage-gated sodium channel and mutations associated with pyrethroid resistance in field-collected adult males

Helicoverpa zea is one of the most costly insect pests of food and fiber crops throughout the Americas. Pyrethroid insecticides are widely applied for its control as they are effective and relatively inexpensive; however, resistance to pyrethroids threatens agricultural systems sustainability because alternative insecticides are often more expensive or less effective. Although pyrethroid resistance has been identified in this pest since 1990, the mechanisms of resistance have not yet been elucidated at the molecular level. Pyrethroids exert their toxicity by prolonging the open state of the voltage-gated sodium channel. Here we report the cDNA sequence of the H. zea sodium channel α-subunit homologous to the para gene from Drosophila melanogaster. In field-collected males which were resistant to cypermethrin as determined by the adult vial test, we identify known resistance-conferring mutations L1029H and V421M, along with two novel mutations at the V421 residue, V421A and V421G. An additional mutation, I951V, may be the first example of a pyrethroid resistance mutation caused by RNA editing. Identification of the sodium channel cDNA sequence will allow for testing hypotheses on target-site resistance for insecticides acting on this channel through modeling and expression studies. Understanding the mechanisms responsible for resistance will greatly improve our ability to identify and predict resistance, as well as preserve susceptibility to pyrethroid insecticides.

Flight behavior of the bean bug, Riptortus clavatus (Thunberg) (Hemiptera: Alydidae), relative to adult age, sex and season

Studies related to the flight behavior of the bean bug, Riptortus clavatus, an insect pest of soybean, provide information, which can aid the development of management tactics. R. clavatus flight activities were determined using the tethered flight technique in the laboratory and a field study. We compared the flight parameters (flight distance, duration, speed and frequency) of laboratory-reared mated or unmated females and males of different adult age groups, and field-collected females and males from different seasons in a year. Mating effect was only significant for flight frequency, which was higher for unmated adults. Only the flight frequency was different between females and males. Among age groups, 25 d old individuals were shown to have higher flight parameters while the 35 or 45 d old groups showed the lower flight. Among the season, flight activities decreased as the season progressed. The flight distance of R. clavatus in a day was estimated to be 1.6–5.1 km with an average speed of 0.8 m/s from the laboratory data. However, from the field study, it was shown that bean bugs flew a 45–54 m distance with a flight speed of 3.0–3.6 m/s for the first single flight. The second flight was much shorter and slower. We discuss the possible difference of flight parameters between the laboratory and field studies with features of flight mill, variable field conditions and host plant finding behaviors. Further study on flight behavior may provide a better understanding of R. clavatus biology which may guide proper management.

A Modified F1 Screening Method for Detecting Resistance Gene Alleles to Bt Cotton in Helicoverpa armigera (Lepidoptera: Noctuidae)

Large-scale cultivation of Bt cotton places high selection pressure on target insects and, consequently, may prompt resistance evolution in pest populations. To better monitor Bt-resistance allele frequency in field populations, a modification of the F1 screen was developed to screen F1 progeny derived from single pair mating between field-collected males and laboratory resistant females (designated as F1 screen). This method was used to survey a field population of Heliocoverpa armigera (Hübner) for resistance alleles at the same loci in the resistant strain. After treatment of the F1 progeny derived from more than 260 single pair mating lines with Bt cotton, there was no clear separation of resistant genotypes from susceptible genotypes based on survival rates which demonstrated a linear distribution within a certain range. We further analyzed larval growth data of the F1 progeny and found a correlation between larval body weight and survival rate. The maximum correlation was obtained when F1 larval body weight reached ≥0.7 mg. To avoid underestimation, body weight ≥0.6 mg was used to initially separate potential positive lines (resistant genotype). After that, a corrected survival rate of >21.3% (the minimal theoretical rate of >25% for F0 males to carry sr and rr genotypes) was used as the criterion to examine F2 progeny derived from single sib-mating of F1 adults and to verify whether the potential positive lines carried resistant alleles.

Resistance Allele Frequency to Bt Cotton in Field Populations of Helicoverpa armigera (Lepidoptera: Noctuidae) in China

Resistance evolution in target insects to Bacillus thurningiensis (Bt) cotton, Gossypium hirsutum L., is a main threat to Bt cotton technology. An increasing trend of population density of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) has been observed since 2001 in Qiuxian County (Hebei, China), where Bt cotton has been planted dominantly since 1998. This region was selected in 2006 and 2007 for estimating frequency of gene alleles conferring resistance to Bt cotton by screening the F1 progeny from single-pair cross between field-collected male and laboratory female of the Bt-resistant strain of H. armigera (F1 screen). F1 offspring from each single-pair line were screened for resistance alleles based on larval growth, development, and survival on Bt cotton leaves for 5 d. Two-year results indicated that ≈20% of field-collected males carried resistance alleles. The conservative estimate of the resistance allele frequency was 0.094 (95% CI, 0.044–0.145) for 2006 and 0.107 (95% CI, 0.055–0.159) for 2007. This is the first report of resistance allele frequency increase to such a high level in the field in China. Long-term adoption of Bt sprays, dominant planting of single-toxin–producing Bt cotton, and lack of conventional cotton refuge system might accelerate the resistance evolution in the region.

Resistance Allele Frequency to Bt Cotton in Field Populations of <I>Helicoverpa armigera</I> (Lepidoptera: Noctuidae) in China

Resistance evolution in target insects to Bacillus thurningiensis (Bt) cotton, Gossypium hirsutum L., is a main threat to Bt cotton technology. An increasing trend of population density of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) has been observed since 2001 in Qiuxian County (Hebei, China), where Bt cotton has been planted dominantly since 1998. This region was selected in 2006 and 2007 for estimating frequency of gene alleles conferring resistance to Bt cotton by screening the F1 progeny from single-pair cross between field-collected male and laboratory female of the Bt-resistant strain of H. armigera (F1 screen). F1 offspring from each single-pair line were screened for resistance alleles based on larval growth, development, and survival on Bt cotton leaves for 5 d. Two-year results indicated that approximately equal to 20% of field-collected males carried resistance alleles. The conservative estimate of the resistance allele frequency was 0.094 (95% CI, 0.044-0.145) for 2006 and 0.107 (95% CI, 0.055-0.159) for 2007. This is the first report of resistance allele frequency increase to such a high level in the field in China. Long-term adoption of Bt sprays, dominant planting of single-toxin-producing Bt cotton, and lack of conventional cotton refuge system might accelerate the resistance evolution in the region.

Towards a sterile insect technique field release of Anopheles arabiensis mosquitoes in Sudan: Irradiation, transportation, and field cage experimentation

BackgroundThe work described in this article forms part of a study to suppress a population of the malaria vector Anopheles arabiensis in Northern State, Sudan, with the Sterile Insect Technique. No data have previously been collected on the irradiation and transportation of anopheline mosquitoes in Africa, and the first series of attempts to do this in Sudan are reported here. In addition, experiments in a large field cage under near-natural conditions are described.MethodsMosquitoes were irradiated in Khartoum and transported as adults by air to the field site earmarked for future releases (400 km from the laboratory). The field cage was prepared for experiments by creating resting sites with favourable conditions. The mating and survival of (irradiated) laboratory males and field-collected males was studied in the field cage, and two small-scale competition experiments were performed.ResultsMinor problems were experienced with the irradiation of insects, mostly associated with the absence of a rearing facility in close proximity to the irradiation source. The small-scale transportation of adult mosquitoes to the release site resulted in minimal mortality (< 6%). Experiments in the field cage showed that mating occurred in high frequencies (i.e. an average of 60% insemination of females after one or two nights of mating), and laboratory reared males (i.e. sixty generations) were able to inseminate wild females at rates comparable to wild males. Based on wing length data, there was no size preference of males for mates. Survival of mosquitoes from the cage, based on recapture after mating, was satisfactory and approximately 60% of the insects were recaptured after one night. Only limited information on male competitiveness was obtained due to problems associated with individual egg laying of small numbers of wild females.ConclusionIt is concluded that although conditions are challenging, there are no major obstacles associated with the small-scale irradiation and transportation of insects in the current setting. The field cage is suitable for experiments and studies to test the competitiveness of irradiated males can be pursued. The scaling up of procedures to accommodate much larger numbers of insects needed for a release is the next challenge and recommendations to further implementation of this genetic control strategy are presented.

Effects of nickel and temperature on the ground beetle Pterostichus oblongopunctatus (Coleoptera: Carabidae)

In natural ecosystems it is not unusual for an organism to be exposed both to chemical and physical stressful factors at the same time. Herein we present results of the study on nickel toxicity to the carabid beetle, Pterostichus oblongopunctatus, and effect of Ni and temperature on the beetles respiration rates. In the first part of the study (Experiment I) we measured the survival, respiration rates and internal Ni concentrations in animals exposed for 245 d at constant temperature (20 degrees C) to food contaminated with Ni at nominal concentrations 0; 600; 1,200; 2,400; 4,800; and 9,600 mg kg(-1) dry weigh (dw). The LC(50) was estimated at 8,351 mg Ni kg(-1), with no effect on fertility. We found a significant positive correlation between Ni concentration in food and internal body concentration of Ni, and a negative correlation between Ni exposure and the respiration rate. Based on these results, the concentration of 2,400 mg kg(-1) (LOEC for the respiration rate) was selected for the second part of the study (Experiment II) in which field-collected males of P. oblongopunctatus were exposed to Ni-contaminated food for 64 d and then to uncontaminated food for the next 64 d at three temperatures: 10, 15 and 20 degrees C. In this part of the study we found that the temperature under which the beetles were kept affected their respiration rates, and that effect of Ni on the respiration was significant only in animals originating from 20 degrees C. The results from both experiments indicate that negative effects of nickel appear only after relatively long exposure.

Colonization of a Hybrid Strain to Restore Male &lt;I&gt;Anastrepha ludens&lt;/I&gt; (Diptera: Tephritidae) Mating Competitiveness for Sterile Insect Technique Programs

To restore male mating competitiveness of Mexican fruit flies, Anastrepha ludens (Loew) (Diptera: Tephritidae), reared for sterile insect releases by the Mexican Fruit fly Eradication Campaign, two strain replacement techniques were evaluated. Field cage male competitiveness tests revealed that laboratory males of the Metapa strain mated 3 times less often with wild females than field-collected wild males. A strain developed from the cross of wild males and laboratory females (hybrid strain) was similar to a strain developed from the cross of laboratory males and females (laboratory strain) in that its females produced similar amounts of eggs and the eggs displayed similar levels of hatch and egg-to-pupa transformation in artificial diet. By contrast, a strain developed from the cross of wild males and females (wild strain), forced into artificial rearing, experienced a series of bottlenecks involving reduced egg laying and extremely poor development in diet. The male F1 progeny of the hybrid strain and field-collected wild males outcompeted Fl laboratory males in field cage tests for matings with field-collected wild females. In conclusion, we found that strains developed from the cross of wild males and laboratory females allowed us to restore male mating competitiveness of F1 Mexican fruit flies without compromising mass-rearing production.

Corematal function in Utetheisa ornatrix: interpretation in the light of data from field-collected males

Males of the moth Utetheisa ornatrix produce a pheromone, hydroxydanaidal, contained in two brush-like organs, the coremata, which they evert during courtship. Hydroxydanaidal is derived chemically by the males from pyrrolizidine alkaloids that they sequester from their larval food plants. It had been shown previously that the amount of hydroxydanaidal in the coremata correlates positively with a number of male parameters that are a measure of the male’s “worth.” Hydroxydanaidal could thus be used by the female as a basis for discrimination in courtship. Experiments carried out with virgin Utetheisa had shown that females do indeed mate selectively with males of high corematal hydroxydanaidal content, thereby accruing the multiple benefits that are the consequence of such selectivity. Unresolved was the question whether corematal hydroxydanaidal could still provide a basis for female appraisal of suitors when these had previously mated. Given the proven promiscuity of the female, male Utetheisa could be expected to be promiscuous as well. Evidence we present here shows that field-collected males, which could be expected to be mostly non-virginal, are of reduced acceptability to females. They are also, on average, in possession of lower quantities of hydroxydanaidal, explaining possibly why they should be held in lesser regard. At low levels, however, hydroxydanaidal does not lend itself for precise assessment of male worth, because as we show herein, at such levels, the compound does not correlate with any of the criteria of male quality (male size, spermatophore mass, male pyrrolizidine alkaloid content, amount of pyrrolizidine alkaloid transmitted to the female). Males that have mated beforehand are therefore likely not to be classed into subcategories by the females, but simply as belonging to one category of “less desirables”. The significance of these findings to our understanding of the mating strategy of Utetheisa is discussed.

Female preference for male courtship flashes in Photinus ignitus fireflies

In Photinus fireflies, males produce spontaneous bioluminescent courtship flashes. Females preferentially respond to particular male flashes with flashes of their own. This study explored variation in female flash responsiveness as a function of male flash duration, female condition, lantern size, and lantern distance, as well as the relationship between male characteristics and spermatophore mass in Photinus ignitus fireflies. We determined female preference by scoring female flash response to simulated male flashes and determined variation in overall female flash responsiveness for laboratory-mated, laboratory-fed, and control P. ignitus females. Flash duration, lantern size, and body mass were recorded for field-collected males. Males were then mated to determine spermatophore mass. Females exhibited greater preference for artificial flashes representing the upper range of conspecific male flash duration and lantern size as well as flashes produced at a closer distance. Both laboratory-mated and laboratory-fed P. ignitus females showed lower overall responsiveness across all flash durations relative to control females that did not mate or feed in the laboratory. Male flash duration predicted a significant proportion of the variation in spermatophore mass for early-season males. These results suggest that female Photinus ignitus may prefer long flashes in order to obtain the direct benefit of larger spermatophores and may adjust their overall flash responsiveness as the relative importance of this benefit varieswith changing female condition. Copyright 2003.