Temperature-related breakdowns in the coordination of mating in Enchenopa binotata treehoppers (Hemiptera: Membracidae)

Temperature influences the expression of a wide range of behavioral traits in ectotherms, including many involved in the initiation of pair formation and mating. Although opportunities to mate are thought to be greatest when male and female activity overlap, sex-specific behaviors and physiology could result in mismatched thermal optima for male and female courtship. Here, we investigate how conflicts in the thermal sensitivity of male and female courtship activity affect patterns of mating across temperatures in Enchenopa binotata treehoppers (Hemiptera: Membracidae). These plant-feeding insects coordinate mating with plant-borne vibrational signals exchanged in male–female duets prior to pair formation. We manipulated temperature across an ecologically relevant range (18–36ºC) and tested the likelihood of individual male and female E. binotata to engage in courtship activity using vibrational playbacks. We then staged male–female mating interactions across the same temperature range and quantified the thermal sensitivity of mating-related behaviors across stages of mating. Specifically, we measured the timing of duetting, the likelihood for key pre-copulatory behaviors to occur, whether the pair mated, and copulation duration. We found sex-specific thermal sensitivity in courtship activity: Males showed a clear peak of activity at intermediate temperatures (27–30ºC), while females showed highest activity at the hotter thermal extreme. Mating rates, courtship duets, and copulatory attempts were less likely to occur at thermal extremes. Also, duetting occurred earlier and copulation was shortest at higher temperatures. Overall, our data suggest that sexes differ in how temperature affects mating-related activity and some processes involved in mate coordination may be more sensitive than others across variable thermal environments.     

Local population density and group composition influence the signal‐preference relationship in Enchenopa treehoppers (Hemiptera: Membracidae)

Many animals exhibit social plasticity – changes in phenotype or behaviour in response to experience with conspecifics that change how evolutionary processes like sexual selection play out. Here, we asked whether social plasticity arising from variation in local population density in male advertisement signals and female mate preferences influences the form of sexual selection. We manipulated local density and determined whether this changed how the distribution of male signals overlapped with female preferences – the signal preference relationship. We specifically look at the shape of female mate preference functions, which, when compared to signal distributions, provide hypotheses about the form of sexual selection. We used Enchenopa binotata treehoppers, a group of plant‐feeding insects that exhibit natural variation in local densities across individual host plants, populations, species and years. We measured male signal frequency and female preference functions across the density treatments. We found that male signals varied across local social groups, but not according to local density. By contrast, female preferences varied with local density – favouring higher signal frequencies in denser environments. Thus, local density changes the signal–preference relationship and, consequently, the expected form of sexual selection. We found no influence of sex ratio on the signal–preference relationship. Our findings suggest that plasticity arising from variation in local group density and composition can alter the form of sexual selection with potentially important consequences both for the maintenance of variation and for speciation.     

Temperature coupling of mate attraction signals and female mate preferences in four populations of Enchenopa treehopper (Hemiptera: Membracidae)

Variation in temperature can affect the expression of a variety of important fitness‐related behaviours, including those involved with mate attraction and selection, with consequences for the coordination of mating across variable environments. We examined how temperature influences the expression of male mating signals and female mate preferences—as well as the relationship between how male signals and female mate preferences change across temperatures (signal–preference temperature coupling)—in Enchenopa binotata treehoppers. These small plant‐feeding insects communicate using plantborne vibrations, and our field surveys indicate they experience significant natural variation in temperature during the mating season. We tested for signal–preference temperature coupling in four populations of E. binotata by manipulating temperature in a controlled laboratory environment. We measured the frequency of male signals—the trait for which females show strongest preference—and female peak preference—the signal frequency most preferred by females—across a range of biologically relevant temperatures (18°C–36°C). We found a strong effect of temperature on both male signals and female preferences, which generated signal–preference temperature coupling within each population. Even in a population in which male signals mismatched female preferences, the temperature coupling reinforces predicted directional selection across all temperatures. Additionally, we found similar thermal sensitivity in signals and preferences across populations even though populations varied in the mean frequency of male signals and female peak preference. Together, these results suggest that temperature variation should not affect the action of sexual selection via female choice, but rather should reinforce stabilizing selection in populations with signal–preference matches, and directional selection in those with signal–preference mismatches. Finally, we do not predict that thermal variation will disrupt the coordination of mating in this species by generating signal–preference mismatches at thermal extremes.     

Vibrational communication and reproductive isolation in the Enchenopa binotata species complex of treehoppers (Hemiptera: Membracidae)

Sexual communication can contribute to population divergence and speciation because of its effect on assortative mating. We examined the role of communication in assortative mating in the Enchenopa binotata species complex of treehoppers. These plant-feeding insects are a well studied case of sympatric speciation resulting from shifts to novel host-plant species. Shifting to hosts with different phenologies causes changes in life-history timing. In concert with high host fidelity, these changes reduce gene flow between populations on ancestral and novel hosts and facilitate a rapid response to divergent natural selection. However, some interbreeding can still occur because of partial overlap of mating periods. Additional behavioral mechanisms resulting in reproductive isolation may thus be important for divergence. In E. binotata, mating pairs form after an exchange of plant-borne vibrational signals. We used playback experiments to examine the relevance of inter- and intraspecific variation in male advertisement signals for female mate choice in a member of the E. binotata species complex. Female signals given in response to male signals provided a simple and reliable assay. Male species and male individual identity were important determinants of female responses. Females failed to respond to the signals of the two most closely related species in the complex, but they responded strongly to the signals of conspecific males, as well as to those of the most basal species in the complex. Communication systems in the E. binotata species complex can therefore play a role in reproductive isolation. Female responses were influenced by among-individual variation in male signals and females, suggesting the involvement of sexual selection in the evolution of these communication systems.     

Treehopper trees: phylogeny of Membracidae (Hemiptera: Cicadomorpha: Membracoidea) based on molecules and morphology

Abstract. Recent independent phylogenetic analyses of membracid relationships based on molecular and morphological data have identified monophyletic lineages within the family. However, the results of these studies have not fully resolved treehopper phylogeny, and relationships among some higher membracid lineages remain in doubt. Portions of three datasets (958 aligned nucleotides from elongation factor‐1α, 2363 aligned nucleotides from 28S ribosomal DNA, and eighty‐three morphological features of adults and nymphs) introduced in recent studies were reanalysed separately and in combination with two new molecular datasets (321 aligned nucleotides from wingless and 1829 aligned nucleotides from 18S ribosomal DNA). The results of the combined data analyses, contrary to previous analyses of morphological data alone, grouped membracids into two well‐supported lineages, one comprising Stegaspidinae and Centrotinae, the other comprising Membracinae, Darninae and Smiliinae. The analyses recovered Centrotinae, Membracinae and Darninae as monophyletic groups, but Stegaspidinae was paraphyletic with respect to Centrotinae, and Smiliinae was polyphyletic with Micrutalini placed as a sister group to the clade comprising Membracinae, Darninae and Smiliinae. These results are consistent with the following hypotheses, proposed previously based on an analysis of morphological data: (1) the posterior pronotal process was derived and lost multiple times during the evolution of Membracidae; (2) Membracidae originated in the New World and reached the Old World subsequently via dispersal; (3) maternal care evolved independently multiple times and may or may not have been preceded by the acquisition of ant mutualism.     

Mating behavior of Psammotettix alienus (Hemiptera: Cicadellidae)

The Wheat dwarf virus, the causal agent of the wheat dwarf disease, is transmitted by leafhoppers from the genus Psammotettix and currently the main protection strategy is based on the use of insecticide treatments. Sustainable management strategies for insect vectors should include methods that are targeted to disrupt reproductive behavior and here we investigated the mating behavior of Psammotettix alineus (Dahlbom 1850) in order to determine the role of vibrational signals in intra‐specific communication and pair formation. Both genders spontaneously emit species‐ and sex‐specific calling songs that consisted of regularly repeated pulse trains and differ primarily in pulse train duration and pulse repetition time. Females preferred the conspecific male calling song. After a coordinated exchange of pulse trains, the male approached the stationary female. During the close range courtship and also immediately prior to copulatory attempts distinct male vibrational signals associated with wing flapping and wing vibrations were recorded from the substrate. In the presence of a receptive female, competing males emitted vibrational signals most likely aimed to interfere with male‐female interaction. Mated females regained sexual receptivity after they laid eggs. Although results suggest that the viruliferous status of insects may have an effect on vibrational songs, our current results did not reveal a significant effect of virus on leafhopper performance in mating behavior. However, this study also suggests, that detailed understanding of plant–vector–virus interactions relevant for vector mating behavior is essential for trying new approaches in developing future control practices against plant viruses transmitted by insect vectors.     

First Immature of the New World Treehopper tribe Thuridini (Hemiptera,Membracidae, Smiliinae) with a new synonym,a new combination,and a new country record

The species Thuris depressus Sakakibara (1975) is proposed as a syn. n. of Thuris binodosus (Goding 1926), comb. n. The distribution of the genus is expanded from Brazil and Peru to include Ecuador and Venezuela, and the immature is described based on 75 characters.     

Labial gland disease in the genusFormica (Formicidae,Hymenoptera)

Summary Labial gland disease causes swelling of the labial glands in the pupal stage inFormica species. The resulting adults have enlarged thoraces and are called secretergates (Wasmann's pseudogynes). They infect the younger larvae, probably during feeding. The agent of the disease is unknown. It soon becomes non-infectious outside the labial glands. Diseased females were not seen to feed larvae. Yet their offspring contained secretergates. The discrepancy remains unexplained.     

Phylogenetic patterns of mimicry strategies in Darnini (Hemiptera: Membracidae)

A phylogenetic analysis based on 58 morphological characters including 18 species representing 14 genera over the 15 currently known in Darnini (Hemiptera: Membracidae) confirms the monophyly of this tribe. This result is particularly supported by the presence of cucullate setae on the ventral side of the femora. Two sister clades are inferred: the clade Funkhouseriana+ which groups four genera (Aspona, Cyphotes, Funkhouseriana, Taunaya) and exhibits a ‘bird dropping’ habitus and all other genera which exhibit a ‘dewdrop’ like habitus (Alobia, Darnis, Dectonura, Hebetica, Hebeticoides, Leptosticta, Ochrolomia, Stictopelta) or a ‘thorny’ habitus (Alcmeone, Sundarion). In the ‘dewdrop’ habitus, only the clade Ochrolomia+ is retained as a monophyletic unit. According to these results, pronotal shapes and habitus have evolved independently in each monophyletic unit and each one seems correlated with a particular type of mimicry strategy. According to the strategy, characters involved are different, a priori independent; moreover, they look coordinated regarding to the mimicry function they serve. The various evolutionary scenarios are discussed in relation to the phylogeny, and particularly in correlation with the non-gregarious behavior of these membracids, also coherent with their mimicry strategy.     

Pathogenicity of fungal isolates (Ascomycota: Hypocreales) against Peregrinus maidis, Delphacodes kuscheli (Hemiptera: Delphacidae), and Dalbulus maidis (Hemiptera: Cicadellidae), vectors of corn diseases

Preliminary screening assays were carried out on 17 isolates from five fungal species Beauveria bassiana, Lecanicillium muscarium, Metarhizium anisopliae, Isaria farinosa, and I. fumosorosea. The three most effective isolates against Peregrinus maidis (Hemiptera: Delphacidae) were B. bassiana CEP 147, CEP 150, and CEP 189. There were no consistent differences found in males and females regarding fungal susceptibility. However, more females than males were proportionally infected. There was not a correlation between the percentage of conidial germination and the percentage of mortality caused by fungal infection in any of the treatments. Only B. bassiana CEP 147, which caused a cumulative mortality of 69.8 ± 6.4% after 7 days post-inoculation, was selected to be assayed against adults of P. maidis, Delphacodes kuscheli (Hemiptera: Delphacidae), and Dalbulus maidis (Hemiptera: Cicadellidae). In pathogenicity tests significant differences were observed among treatments. After 2 weeks post-inoculation, both D. kuscheli (cumulative mortality of 73.3 ± 9.0%) and P. maidis (cumulative mortality of 68.6 ± 6.7%) were significantly more susceptible than D. maidis (cumulative mortality of 49.9 ± 9.7%) to the selected isolate.     

Immatures of the New World treehopper tribe Amastrini (Hemiptera,Membracidae, Smiliinae) with a key to genera

The immatures stages of 8 of the 11 genera (Amastris Stål, Bajulata Ball, Erosne Stål, Harmonides Kirkaldy, Idioderma Van Duzee, Neotynelia Creão-Duarte & Sakakibara, Tynelia Stål, and Vanduzea Goding) of the tribe Amastrini are described for the first time along with brief diagnoses of Membracidae and the subfamily Smiliinae. A key to genera and notes on biology are provided. Multiple species of most genera are illustrated. Based on its distinct nymphal morphology, Vanduzea laeta nolina Ball is elevated to specific rank as Vanduzea nolina stat. n., and Bajulata, despite the superficial similarity of its adults to those of Vanduzea, is confirmed as warranting generic rank based on its unique nymphal morphology. Colombia is a new country record for Tynelia.     

Female mate choice of male signals is unlikely to promote ecological adaptation in Enchenopa treehoppers (Hemiptera: Membracidae)

A key question in speciation research is how ecological and sexual divergence arise and interact. We tested the hypothesis that mate choice causes local adaptation and ecological divergence using the rationale that the performance~signal trait relationship should parallel the attractiveness~signal trait relationship. We used female fecundity as a measure of ecological performance. We used a species in the Enchenopa binotata treehopper complex, wherein speciation involves adaptation to novel environments and divergence in sexual communication. We used a full‐sibling, split‐family rearing design to estimate genetic correlations (r_G) between fecundity and signal traits, and compared those relationships against population‐level mate preferences for the signal traits. Animal model estimates for r_G between female fecundity and male signal traits overlapped zero—rejecting the hypothesis—but could reflect sample size limitations. The magnitude of r_G correlated with the strength of the mate preferences for the corresponding signal traits, especially for signal frequency, which has the strongest mate preference and the most divergence in the complex. However, signal frequencies favored by the population‐level mate preference are not associated with high fecundity. Therefore, mate preferences do not appear to have been selected to favor high‐performance genotypes. Our findings suggest that ecological and sexual divergence may arise separately, but reinforce each other, during speciation.     

Social behavior and brood decline in reproductive-phase colonies ofBelonogaster petiolata (Degeer) (Hymenoptera: Vespidae)

Colonies ofBelonogaster petiolata in Gauteng (South Africa) produced reproductive offspring (gynes and males) in late January and early February of each nesting season; their appearance was associated with a decline in worker and brood numbers. Brood decline could commence in the presence of a dominant, reproductively active queen, and loss or removal of the queen was not followed directly by cessation of nest growth and brood care. An older worker usually took over the α-position in queenless colonies. Several factors appear to contribute to brood decline and, ultimately, termination of the colony cycle in this species. These include (1) cessation of the supply of solid food to colonies (and particularly their larvae) during the reproductive phase, (2) a decrease in the worker/larva ratio during the latter phase due to the progressive loss of workers, (3) increasing number of gynes and males, and (4) an adult priority over food reception from foragers.     

Social communication among captive stump-tailed macaques (Macaca arctoides)

I compared the frequency of occurrence, contextual usage, and meaning of some of the most prominent gestural signals in stump-tailed macaques. I recorded the occurrence of 15 visual and tactile behavior patterns in a multimale multifemale captive group of stump-tailed macaques with the behavior sampling method in 100 hr of observation and analyzed the data via factor analysis and analyis of variance. The hindquarter presentation was the most frequent gesture. It was displayed by subordinates to appease dominants even in the absence of impending risk of aggression. Bared-teeth, lip-smack, teeth-chatter, and present-arm are submissive signals as well, but they differ from the presentation and from one another in their contextual usage. Nonthrusting mount, hip-touch, hip-clasp, and genital manipulation are directed down the hierarchy and appear to reflect dominance, reassurance, protection, or bonding. Mock-bite is a ritualized aggressive behavior pattern, often used to resolve uncertain dominance relationships. Ventroventral embrace occurs as a female bonding pattern. Overall, most gestural signals in stump-tailed macaques relate to dominance and submission and, to a lesser extent, social bonding.     

Ant-Homoptera Interactions in a Neotropical Savanna: The Honeydew-Producing Treehopper,Guayaquila xiphias (Membracidae), and its Associated Ant Fauna on Didymopanax vinosum (Araliaceae)1

We investigate the ant fauna associated with the Neotropical treehopper, Guayaquila xiphias, on shrubs of Didymopanax vinosum in the cerrado (savanna) of SE Brazil. Treehoppers infested plants at the border of the cerrado almost exclusively and preferably fed near the apical meristem. During the reproductive phase of the host plant, however, the vast majority of the treehoppers aggregated on the inflorescences. We found 21 ant species harvesting honeydew at G. xiphias aggregations, the most frequent being Camponotus rufipes, Ectatomma edentatum, C. crassus, and C. renggeri. Such a taxonomic diversity of ants tending G. xiphias aggregations in the cerrado is far greater than that reported for any other ant-homopteran system. Daily turnover of ant species at a given treehopper aggregation was observed on 29 percent (64 out of 222) of the G. xiphias aggregations recorded on D. vinosum shrubs. Species replacements probably reflect distinct humidity and temperature ranges tolerated by the species, and may ultimately reduce interspecific competition at homopteran aggregations. Since predation and parasitism on G. xiphias can be severe, and tending ants protect the homopterans against predators and parasitoids, the round-the-clock activity by ants at G. xiphias aggregations is regarded as crucial for the survival of these treehoppers in the cerrado.     

Entomopathogenic fungi (Hypocreales) for control of potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) in an area endemic for zebra chip disease of potato

Potato psyllid, Bactericera cockerelli, is a serious pest of potato and other solanaceous vegetables in the United States, Mexico, Central America, and New Zealand and is responsible for transmission of Candidatus Liberibacter solanacearum which causes a disease known as “zebra chip” (ZC). Entomopathogenic fungi could provide a viable component for an integrated pest management strategy for control of B. cockerelli and other potato pest insects. Three field trials of commercial formulations of Metarhizium anisopliae (F 52®, Novozymes Biologicals) and Isaria fumosorosea (Pfr 97®, Certis USA) and abamectin (Agri-Mek®, Syngenta, USA) were conducted in Weslaco, Texas. Rates are expressed in quantity of product delivered in 375–470 l of water/ha. F 52 applied at 0.51, 1.1, and 2.2 l/ha and Agri-Mek applied at 584 ml/ha produced reductions of B. cockerelli eggs and nymphs of 45%, 59%, 67%, and 63%, respectively. Only Agri-Mek significantly reduced plant damage. Pfr 97 at 1.1 kg/ha with and without 1% Trilogy® (neem oil, Certis, USA), and Agri-Mek at 584 ml/ha resulted in psyllid reductions of 78%, 76%, and 84%, respectively. Significantly decreased plant damage and ZC symptoms were observed for all treatments. Tuber yields for Pfr plus Trilogy and Agri-Mek were significantly higher than the control. F 52 applied at 1.1 and 2.2 l/ha and Pfr 97 at 1.1 and 2.2 kg/ha produced 62%, 62%, 66%, and 65% reduction, respectively. Tuber yield for both rates of Pfr and the high rate of F 52 were significantly higher than the control. All fungal treatments significantly reduced plant damage and ZC symptoms.     

Host colony usurpation by the queen of the Japanese pirate ant, Polyergus samurai (hymenoptera: formicidae)

Colony usurpations by newly mated queens of Polyergus samurai were observed under artificial conditions. Newly mated queens of P. samurai were introduced into three kinds of Formica japonica host colonies: queenright, queenless (artificially orphaned), and workerless (only a queen remaining) colonies. In the queenright condition, the P. samurai queen intruded into the host nest and killed the host queen, and was subsequently adopted by the host workers. In all queenright and queenless host colonies, seven of 13 queens of P. samurai succeeded in colony usurpation, although the starting time of grooming, a nestmate behavior, by host workers in the queenright condition occurred earlier than in the queenless condition. In workerless conditions, four of five P. samurai queens ignored the F. japonica queen. The results suggest that while host-queen killing is not necessary, it is important to win acceptance by host workers.     

中国新入侵害虫——桉梳木虱(半翅目:木虱科)

2018年5月,在云南省昆明市金殿森林公园种植的蓝桉树苗上采集到了一种密集发生的木虱,其成虫和若虫均严重危害桉树叶片。经鉴定为桉梳木虱,该种木虱原产于澳大利亚,此前已入侵欧洲、非洲、北美洲、南美洲和亚洲的一些国家,危害桉树。本文提供了桉梳木虱的危害情况和形态鉴别特征,提出了防范扩散危害的措施建议。     

The western jewel butterfly (Hypochrysops halyaetus: Lycaenidae) II: factors affecting oviposition within native Banksia bushland in an urban setting

Oviposition by western jewel butterflies (Hypochrysops halyaetus Hewitson) was studied in the urban Koondoola regional bushland reserve, Western Australia in 1999. Observations were made in a small (70 × 120 m) localised breeding area the ‘microdistribution study area’, and in 14 paired 20 × 20 m quadrats randomly placed along established tracks in the interior of the northern half of the reserve. The principal host plant was Jacksonia sternbergiana with the secondary host being Daviesia divaricata. More Jacksonia were used for oviposition and attended by ants (40 and 71%, respectively) in the microdistribution study than plants in the ‘quadrat’ study (8 and 25%, respectively). Jacksonia stems with basal diameters below 5 mm were less likely to have eggs. PCA showed Jacksonia to be associated with disturbed conditions with a high proportion of bare ground whereas Daviesia was associated with more mature vegetation. Jacksonia density was principally correlated with the proportion of bare ground and time since the last fire. Host ant (Crematogaster perthensis) presence and proportion of bare ground were the most important factors influencing oviposition. The presence of ants was closely associated with bare ground conditions and the presence of coccids. Conservation management for floristic diversity and maturity of vegetation in reserves is likely to be a widespread phenomenon, and may negatively affect the persistence of species requiring ephemeral patches of early successional vegetation. For H. halyaetus, a species dependent on disturbed/ephemeral habitat conditions, this conflict may threaten its survival, especially in small reserves, and as a result its conservation status may be underestimated. Management options are discussed.     

Isolation of Paecilomyces lilacinus (Thom) Samson (Ascomycota: Hypocreales) from the Chagas disease vector, Triatoma infestans Klug (Hemiptera: Reduviidae) in an endemic area in Argentina

A survey for entomopathogenic fungi of the Chagas disease vector Triatoma infestans was conducted in two provinces of Argentina from March–December 2003. Field-collected insects that died in the laboratory were individually maintained in moist chamber and incubated at 22 °C. Triatominae adults infected with the fungus Paecilomyces lilacinus were found at El Quebracho (27°34′S–64°31′W), Santiago del Estero province, Argentina, in December 2003. Paecilomyces lilacinus was cultured and isolated from infected insects in SDAY, PYG and MEA media. Pathogenicity tests were conducted and positive results were recorded. The median survival time (MST) of T. infestans exposed to a P. lilacinus conidial suspension was 12.8 days, and 100% mortality occurred at 30 days post-treatment. This is the first record of natural infection caused by P. lilacinus in T. infestans in the world.