Tactic for bower acquisition by male cichlids,Cyathopharynx furcifer,in Lake Tanganyika

A tactic for bower acquisition by male cichlids,Cyathopharynx furcifer, was studied in Lake Tanganyika. Males held crater-shaped bowers of sand within their territories, which were located adjacent to each other. Females visited bowers to spawn eggs, subsequently brooding the eggs in their mouths. Some individuals held territories without bowers near those of males with bowers. Although only the males with bowers succeeded in reproduction, they were apparently exhausted by bower maintenance and reproduction, and often deserted their bowers. These were soon occupied by males which had held nearby territories without bowers, such males then engaging in reproductive activity. Although the construction of new bowers by males was observed, such was unsuccessful, probably because too much energy was required and/or the optimal space for bowers was limited. Direct aggression by males without bowers against bower-holding males to deprive the bowers was not observed, possibly due to the high costs of such competition. Therefore, waiting for bower desertion by other males may be the best bower acquisition tactic for males without bowers.     

Female Mate Preference for Males Having Long and Symmetric Fins in the Bower-holding Cichlid Cyathopharynx furcifer

Female mate preference in a bower-holding cichlid, Cyathopharynx furcifer, was studied in Lake Tanganyika. Most males held territories with crater-shaped bowers in sand, but some males held territories without bowers. Territories were distributed adjacently and females visited them to spawn. After engaging in circling behaviour with the male, a female deposited eggs in the bower. Soon after spawning, the female picked the eggs up into her mouth and brooded them in places away from male territories. Female mate choice appeared to follow three steps: 1) females visited only bower-holding male territories, and more frequently visited territories of males that performed courtship displays at a higher frequency and had longer pelvic fins; 2) females preferred to start circling with males having longer and more symmetrical pelvic fins; 3) females chose males with more symmetrical pelvic fins as their mates. Less than 7% of females that visited male territories spawned eggs in the bowers. In contrast to other bower-holding species, bower size did not correlate with male reproductive success in C. furcifer. Bowers may therefore be essential as spawning sites or may function as a species recognition character for females. Female choice may be dependent instead on males having long and symmetrical pelvic fins apparent during the circling behaviour carried out in the bowers.     

Foraging behavior of the scale-eater Plecodus straeleni (Cichlidae,Teleostei) in Lake Tanganyika,Africa

Synopsis Sixty-nine individuals of Plecodus straeleni were followed for 1 h each in the field with the aid of SCUBA, and time budgets, hunting techniques and prey selection were investigated in relation to sex and body size. The time of cruising in midwater and on the substrate amounted to 3/4 of the total time. The rest of the time was mainly spent on five hunting techniques named pursuing, waiting, mingling, aiming and stealthy approaching. Pursuing (following a flying prey at high speed) was frequently used by adults, especially males, mainly to attack the spiny eel Afromastacembelus moorii. Waiting (keeping motionless on the substrate, waiting for a known prey) was used by some adult females when they tried to steal eggs of the mouthbrooder Cyathopharynx furcifer on the bower and by adult males when they targeted an eel having hidden under a rock. Mingling (mixing in a school of prey to attack school members) was a favorite tactic of subadults to attack plankton-feeders. Aiming (directing the head to a target fish for a moment) commonly occurred when both adults and subadults attacked solitary fishes. In stealthy approaching, the scale-eater approached an unwary prey from behind or sideway. Attacks by these hunting techniques amounted to 97% of the total attacks, which were made on 38 cichlid species and 7 non-cichlid species. Hunting techniques and prey preference varied not only with sex and size but even among consexuals of similar sizes. A number of individuals successively attacked only one or a few prey species in 1 h. Food specialization among individuals was attributed to their learning of the behavior and life style of preferred prey species.     

Effect of temperature on the respiration of an Antarctic freshwater anostracan, <Emphasis Type="Italic">Branchinecta gaini</Emphasis> Daday 1910, in field experiments

The Antarctic crustacean Branchinecta gaini (Branchiopoda, Anostraca) occurs in nine fresh water lakes near the Polish H. Arctowski Station. In one of the largest, Lake Wujka (Lake Uncle in English), we determined how temperatures affect its respiration and whether this is sex dependent. Experiments were carried out on males and females bearing eggs over a range of temperatures from 0.5 to 10°C. An ANOVA showed that while the amount of oxygen consumed increased with temperature (P < 0.001) males consumed more oxygen than similarly-sized females bearing eggs (P < 0.001).     

Experiments inducing prospective polar body nuclei to participate in embryogenesis of the sawfly Athalia rosae (Hymenoptera)

Summary Mature eggs dissected from ovaries of unmated females of Athalia rosae (Hymenoptera: Tenthredinidae), if placed on a filter-paper soaked with distilled water, are activated and develop to haploid males. Occasionally, however, diploid females develop from these artificially activated eggs. Treatment of mature unfertilized eggs dissected from diploid females with ice-cold temperatures immediately before activation and with a high temperature (36° C) upon and immediately after activation resulted in the production of diploid males, diploid females, triploid females and gynandromorphs at high frequency. The same treatment of mature unfertilized eggs dissected from triploid females resulted in the production of only triploid survivors. These results, together with the results on the segregation of a marker mutation, yellow fatbody (yfb), appear to indicate that meiotic divisions were complete in the treated eggs, and that all four nuclei became potentially capable of participating in development with or without automictic fusion.Studies on the sawfly, Athalia rosae (Insecta, Hymenoptera, Tenthredinidae), part V     

Effect of Temperature on the Life History of Cirrospilus sp. near lyncus (Hymenoptera: Eulophidae), a Parasitoid of Phyllocnistis citrella (Lepidoptera: Gracillariidae)

The effect of four constant temperatures on the life history of Cirrospilus sp. near lyncus was examined in the laboratory. This species is one of the most abundant generalist indigenous parasitoids of the citrus leafminer, Phyllocnistis citrella Stainton, in Spain. Adult lifespan of C. sp. near lyncus decreased from 50.2 to 9.1 days as temperatures increased from 15 to 30°C, respectively. Both gross fecundity and host-feeding were highest at 20°C (170.48 eggs and 32.33 hosts). Oviposition rates were optimal at higher temperatures (5.22 eggs per day at 25°C and 4.79 eggs per day at 30°C) and were dependent on female age. In contrast, host-feeding rates for a given temperature did not depend on age. Generation time decreased with increasing temperatures from 68.05 days at 15°C to 12.19 days at 30°C. Net reproduction peaked at 20°C (68.86 viable females per female). Intrinsic rate of increase doubled from 15°C (0.059 females per female per day) to 20°C (0.127 females per female per day) and almost doubled again from 20 to 30°C (0.210 females per female per day). Given these parameters, C. sp. near lyncus could perform optimally in the area occupied by P. citrella in the Mediterranean region.     

Life-cycle of Suidasia medanensis (=pontifica) (Acari: Suidasiidae) under laboratory conditions in a tropical environment

The life cycle of Suidasia medanensis (= pontifica) was studied under laboratory conditions at 26°C and 86% relative humidity. Freshly laid eggs were observed until they developed into adults and the periods between stages were recorded. Production of eggs by mated females was monitored until they died. The eggs required an average of 12.6 ± 0.6 days to develop into adults. Mean longevity of mated females and males was similar (48.6 ± 13 and 49.1 ± 20 days, respectively). The conditions used in this study may be considered optimal for in vitro culture of S. medanensis.     

Mating systems of two midwater-spawning cichlids,Cyprichromis microlepidotus andParacyprichromis brieni,in Lake Tanganyika

The breeding habits of 2 maternal mouthbrooding cichlids,Cyprichromis microlepidotus andParacyprichromis brieni, were investigated in Lake Tanganyika. Although spawning on the substrate in the male's mating territory is prevalent in maternal mouthbrooders, bothC. microlepidotus andP. brieni spawned in the water column. MaleC. microlepidotus established their mating territories in the open water column, while maleP. brieni did so around fixed spawning sites near a vertical rock surface. In both species, females visited male mating territories, departing soon after spawning and collecting the eggs. Sneaking, which was observed only inP. brieni, may be attributed to the presence of refuges for sneakers in this species. FemaleC. microlepidotus deposited their entire clutch of about 9 eggs in one male territory. In contrast, femaleP. brieni divided their clutch of about 11 eggs among several males. After the final egg-release, femaleC. microlepidotus repeatedly approached their mate, with the mouth near the abdomen of the latter (nuzzling), but femaleP. brieni often departed without nuzzling. Males may eject sperm during nuzzling to fertilize eggs inside the female's mouth. However, maleP. brieni is also known to eject sperm near spawning females when the females are not nuzzling. Such behavior seems to be a male countermeasure against female mate infidelity, because males could not ensure paternity of eggs by ejecting sperm only during female nuzzling.     

Cyclops heberti n.sp. and Cyclops singularis n.sp., two new species within the genus Cyclops (‘strenuus-subgroup’) (Crust. Copepoda) from ephemeral ponds in southern Germany

Some of the species within the genus Cyclops O. F. Müller, 1785 can only be determined exactly by combining different methods and techniques. Based on the comprehensive analysis of morphometrical data, some populations in periodical ponds near Lake Constance were examined for their pattern of chromatin diminution and were compared by enzyme electrophoresis. These studies provided evidence of two new species. Together with C. furcifer Claus, 1857 and C. vicinus Uljanin, 1875 one of the ponds (‘Litzelsee’) was inhabited by four Cyclops species. In addition to morphological differences and distinct electrophoretic characteristics, C. furcifer and the new species differ in the timing of their chromatin diminution: C. singularis in the fourth, C. heberti in the fifth, and C. furcifer in the sixth cleavage. The qualitative course of chromatin diminution is rather similar in all three species. The same combination of three Cyclops species (without C. vicinus) was also found in an older sample (1990) from another ephemeral pond near Lake Constance. A close genetical relationship between the three species seems probable.     

Comparative histology of the testes of the spined loach Cobitis taenia L. and natural allotetraploids of Cobitis (Pisces, Cobitidae)

The spined loach Cobitis taenia L. creates exclusively diploid and mixed diploid–polyploid populations. Allotriploid females, which co-exist with C. taenia or C. elongatoides and a few tetraploid males and females dominate in most Cobitis mixed populations. They reproduce gynogenetically and produce triploid eggs that are stimulated to development by sperm from Cobitis males. Some of these eggs are fertilized, which leads to the production of bisexual tetraploids. Males of C. taenia (2n = 48) from a diploid population in Lake Klawój, Northern Poland (46 individuals) and from a mixed Cobitis population in the Bug River, Eastern Poland (7 individuals), and three tetraploid males (4n = 98) from the same mixed population were examined. All the fish were analyzed karyologically and histologically. Tubules with cysts of the testes of C. taenia from both populations were filled with germ cells at various developmental stages. Among fishes from Lake Klawój sperm maturation in batches simultaneous with the batch spawning of C. taenia females was found. The testes of the loach C. taenia, from a mixed population in the Bug River, were filled with spermatozoa over the entire reproductive season. Sperm maturation in batches was not observed. Sperm maturation in batches seems to be only connected with a few diploid males in this population. So, a continuous process of spermatogenesis in their testes is required. Only in the testes of all tetraploid Cobitis males were cells characteristic of the early stages of spermatogenesis observed, i.e. without spermatids and spermatozoa. Furthermore, the histological sections of the testis of a male captured in August, revealed fragments with connective tissue between the germ cells. However the participation of tetraploid, infertile Cobitis males in the process of reproduction in the investigated mixed population remains controversial. The results obtained so far, reveal that even the infertile sperm of tetraploid males may induce gynogenesis in Cobitis triploid females.     

Mating behavior and thermoregulation of the reindeer warble fly,Hypoderma tarandi L. (Diptera: Oestridae)

Hypoderma (=Oedemagena) tarandi L. (Diptera: Oestridae) is characterized by a mating strategy in which both sexes meet and mate at two types of distinct topographical landmarks. In the expansive, treeless vidda (= tundra-like) biome, mating places are unique, rocky areas located along rivers and streams or in rocky areas of drying river and stream beds. In wooded valleys below the vidda, flies mated at certain topographical areas along dirt road tracks/paths. Thermoregulatory activities of males occupying perches at mating places included selection of substratum at perch site, orientation of body to sun's rays, crouching, stilting, and flights into upper cooler air. On warm sunny days males perched for just 1–2 min before flying up into cooler air to promote cooling. Laboratory and field studies revealed that flies could not metabolically cool down when held at 25–38°C. Time spent at mating places depended on temperature, duration of sunshine, and wind velocity. Males were very aggressive in pursuing allHypoderma-sized objects that passed by them or that landed near them, but they did not defend specific perch sites. Males either pursued and caught females in flight, or they hopped onto females that landed near them. During 5 years, 74 males and 14 females were seen at mating places. Dissection of six females caught at mating places revealed them to be recently eclosed flies full of fat body and with all eggs intact; two not paired with males were non-inseminated. Three experimentally paired females remainedin copulo for 10, 13, and 19.5 min.     

Mating and fecundity of Dermatophagoides farinae

Studies of the life cycle of cultured Dermatophagoides farinae found that after an initial mating D. farinae females lived for 63.3 ± 64.6 (SD) dafter their egg production period ended .The long period after cessation of egg production for D. farinae suggested D. farinae females could mate multiple times and produce eggs continuously for a longer period. The purpose of this study was to determine if female D. farinae could mate at least two times, and subsequently increase the production of viable eggs over a longer period of time compared to a single mating. Female D. farinae were randomly selected from thriving cultures and isolated in cages. When the females had ceased to lay eggs a male was added to the cage. Fifty-seven percent of the isolated females mated again and produced a second batch of viable eggs. In natural or culture populations, females have continuous availability of males. Therefore, in another experiment, females that emerged from the tritonymphal stages were continuously exposed to fresh males and fecundity and lengths of the reproductive and post reproductive periods were determined. These females had a 11 d longer reproductive period and produced 30.7% more eggs compared to females that only mated one time after they emerged from the tritonymphal stage. However, the post reproductive period was still long (58.6 ± 11.4 [SE] d) the significance of which is not clear. In conclusion, this study revealed that D. farinae females are capable of more than one successful mating that results in increased egg production compared to that of a single mating. It is likely that females mate multiple times in natural and culture populations. It was observed that females actively attract males during the reproductive period but not afterward even though she continues to live a long time. This revised version was published online in July 2006 with corrections to the Cover Date.     

Functional response of the predator <Emphasis Type="Italic">Scolothrips takahashii</Emphasis> to hawthorn spider mite, <Emphasis Type="Italic">Tetranychus viennensis</Emphasis>: effect of age and temperature

A leaf disc bioassay was employed to examine the effects of temperature and predator age on functional response of an acarophagous thrips, Scolothrips takahashii Priesner, to hawthorn spider mite, Tetranychus viennensis Zacher, in the laboratory. The results indicated that the predatory thrips exhibited type-II functional responses against the mites under various temperatures, and that females are more voracious than males. Analysis showed that temperature had significant effects on the predatory capacity of adult thrips over the range of 20–35 °C. Attack rate in females linearly increased with temperature while in males it was independent of temperature. Handling times in both males and females decreased linearly with increasing temperature. Extended response models describing the functional response with temperature incorporated as a parameter were developed, yielding an estimated maximum numbers of prey attacked at four temperatures were 38.38, 55.06, 71.74 and 88.42 eggs per day for females, and 15.11, 26.11, 37.11 and 48.01 eggs per day for males, respectively. The age of predator affected both the type of the functional response shown and the magnitude of predation by S.␣takahashii on the spider mite. Females of various ages exhibited Type-II functional responses with similar attack rates, but handling time prolonged linearly as age increased: the handling times in 15- and 18-d-old females were significantly longer than in 6-d-old thrips. However, Type-I functional responses were determined for males aged 12 d or more; the maximum number of prey eaten in 24 h decreased as age increased. The implications of the results for the management of hawthorn spider mite are discussed.     

Patterns of painting in satin bowerbirds Ptilonorhynchus violaceus and males’ responses to changes in their paint

Satin bowerbirds Ptilonorhynchus violaceus have an elaborate multi‐component sexual display, some components of which have been extensively studied. We describe a relatively unstudied component of this display, bower painting, and birds’ responses to manipulations of their paint. Males of this species focus their display around a stick bower constructed on the forest floor which they decorate with a variety of objects and paint. Painting involves a male masticating plant material and wiping the plant‐saliva mixture onto the inside walls of the bower; during courtship visits to bowers, females nibble at this paint. We found that 93% of 53 males painted their bowers at our study site and the time males spent painting their bowers accounted for 24% of their time at the bower. We experimentally removed and added paint to bowers to test whether males respond to these changes in their paint. Males gave more advertisement calls and spent less time manipulating sticks at the bower when we added fresh wet paint to their bowers compared to older dried paint or a control treatment. They did not respond to the removal of paint from their bowers, perhaps because it was primarily older dried paint that was removed. We also found that males painted more frequently when there was measurable wind in their bowers, which could have degraded the quality of the signal. Our findings indicate that fresh wet paint is more important to males than older dried paint and, together with previous work at this site, suggest that paint may act as a signal to females. Given that females nibble bower sticks during courtship, we suggest that bower paint may function as a chemical sexual signal rather than a visual signal.     

Sneaky copulations by subordinate males suggest direct fitness benefits from male–male associations in spotted bowerbirds (Ptilonorhynchus maculatus)

Male spotted bowerbirds (Ptilonorhynchus maculatus) build and defend a structure of sticks and straw—the bower—decorated with colourful objects to attract mates during the breeding season. Specific non-territorial, subordinate males are tolerated by resident males at bowers over multiple breeding seasons. Prior research showed that these male–male associations exhibit attributes of coalitionary behaviour and that subordinate males gain delayed benefits from associating with bower owners, namely future bower inheritance. Yet, it remained unclear whether subordinate males may additionally gain direct fitness benefits from attending established bowers. Here, we report on four separate instances of sneaky copulations (or attempts of copulating) by subordinate males at resident males' bowers. Multiple non-resident males disrupted the ongoing copulations between the bower owner and a receptive female, and these events were followed by violent aggressive interactions. These observations shed new light on same-sex social dynamics in spotted bowerbirds and support the hypothesis that subordinate males are sexually mature individuals that occasionally obtain access to females while attending established bowers. We discuss these findings in light of the literature on male courtship coalitions and agonistic behaviour in bowerbirds, and highlight further aspects of subordinate behaviour that require empirical investigation.     

Trichogramma platneri (Hym.: Trichogrammatidae): Host choices between viable and nonviable codling moth,Cydia pomonella,and three-lined leafroller,Pandemis limitata (Lep.: Tortricidae) eggs

In laboratory host-preference studies,Trichogramma platneri Nagarkatti (Hym.: Trichogrammatidae) females, reared on viable codling moth,Cydia pomonella (L.) (Lep.: Tortricidae) eggs, parasitized significantly more viable than nonviable codling moth eggs produced by cobalt 60 irradiated adults. This ovipositional preference was maintained when competition increased per host egg. Similarly, one, three and fiveT. platneri females consistently oviposited more eggs into viable versus nonviable host eggs. A single femaleT. platneri parasitized a similar number of viableC. pomonella and three-lined leafroller,Pandemis limitata (Robinson) (Lep.: Tortricidae) eggs. However, as the number of females per host eggs increased, a significantly larger number of codling moth versus leafroller eggs were parasitized. One, three and fiveTrichogramma females parasitized significantly moreP. limitata versus nonviableC. pomonella eggs. NonviableC. pomonella eggs deflated to less than 25% of their original volume in four and ten days when held under dry and humid conditions respectively. The blackened prepupal stage of the parasitoid generally occurred in the nonviableC. pomonella eggs four days post-parasitization whereas the parasitized viable eggs blackened zero to one day earlier. Incubation under dry or humid conditions did not appear to influence the number of parasitized eggs that were able to blacken and show evidence of parasitism. Summerland Research Centre Contribution No. 938.     

Evolution of Pair-Living in <Emphasis Type="Italic">Phaner furcifer</Emphasis>

Pair-living evolved several times independently in the primate lineage and most likely for more than one reason. Currently, there are 7 hypotheses regarding the evolution of pair-living in primates. They may explain several but not all cases. I investigated the applicability of the explanations to fork-marked lemurs Phaner furcifer. I used information from a long-term study on 8 fork-marked lemur families in Kirindy Forest to evaluate the hypotheses. Fork-marked lemurs live in uniform dispersed pairs, which share and defend a territory but spend three-quarters of their activity time apart from each other. Unconditional female dominance and lack of permanent close association between pair-partners disqualify most hypotheses. Lack of male parental care and long travel distances in small home ranges disqualify other explanations. I conclude that there is no support a priori for any current pair-living hypothesis and that the newly formulated intersexual-feeding-competition hypothesis best explains the evolution of pair-living in fork-marked lemurs. Accordingly, female range exclusivity evolved first as a consequence of intense feeding competition. Subsequently, indirect feeding competition drove females to accept a single male to share their territory as a defense against feeding competition from males whose ranges unsystematically overlap those of several females. This situation led to pair-living because formation of dispersed one-male-multifemale-units was too costly for males in terms of reduced foraging efficiency.     

Rearing ofChaetorellia australis (Dipt., Tephritidae) on an artificial diet

Larvae of the tephritid flyChaetorellia australis Hering, which infests flowerheads of the yellow starthistleCentaurea solstitialis L. (Asteraceae), and which is a candidate species for biological control, of that weed, were reared for the first time and for two consecutive generations on an artificial diet. At a density of 0.5 eggs per g diet a yield of 18.5% F₁ adults (over hatched eggs), was obtained. When the density of eggs per g diet increased, the yield decreased. At 25°C the duration of development from egg to adult was 20–25 days for both generations. F₁ adults reared on artificial diet had an average longevity of 32.0 days for males and 34.9 days for females. The fecundity was 53.3 eggs per female and the egg hatchability 88.8%. These and other biological parameters are similar to those of wild flies.      

Life history and demography of the predatory mite,Amblyseius longispinosus Evans

The life history and demography of Amblyseius longispinosus Evans were studied under laboratory conditions 25–28°C and 65–85% RH using the red form of the twospotted spider mite, Tetranychus urticae Koch complex as prey. The entire development from egg to adult averaged 102.5 h for both sexes with a survival rate of 90.0%. Immature females consumed more prey eggs than males, averaging 7.9 and 6.4 eggs/day, respectively. The embryonic development time for male eggs was longer (average 45.2 h) than for female eggs (average 42.6 h). The average duration of succeeding stages did not differ between the sexes: larva, 15.7; protonymph, 21.1; and deutonymph, 23.0 h. Larvae were not observed to feed. Statistically significant differences between sexes were noted with respect to consumption of the deutonymphs (female, average 4.0±0.2; male, average 2.9±0.3 eggs/day) but not of the protonymphs. Mating occurred on the same day as adult emergence and was repeated several times during the reproductive life. Egg laying started on the second day after emergence. Parameters relating to oviposition were: fecundity, gross (50.7) and net (43.3) eggs/female; hatchability, 99.6% (gross) and 99.5% (net); the oviposition lasted at most 28 days and showed a peak in the first week. Net reproductive rate (R₀) was 36.7 female offspring/female/generation time (T) of 9.0 days. The sex ratio was biased toward the females (71.9%), while the intrinsic rate of increase (r_m) was 0.4 with a doubling time (DT) of 1.7 days. Males lived longer (36 days) than females (30 days) with a LT₅₀ for males of 26 days and for females of 22 days.     

Dissemination of entomopathogenic fungi using Busseola fusca male as vector

The stem borer, Busseola fusca (Fuller), is an important pest of maize Zea mays L. and sorghum Sorghum bicolor (L.) in eastern and southern Africa. To control this pest, biological control methods including the use of entomopathogenic fungi are being considered. The pathogenicity of one isolate of Metarhizium anisopliae (Metsch.) Sorok. and one isolate of Beauveria bassiana Bals. (Vuill.) were first tested on different developmental stages of B. fusca including eggs, neonate, 2nd and 3rd-instar larvae. Both fungal isolates were pathogenic to all the stages tested. However, differences in mortality were observed among larvae that hatched from treated egg masses. Experiments were conducted thereafter to test whether B. fusca males could serve as a vector for fungal conidia to contaminate B. fusca females and subsequently eggs and larvae. Results demonstrated that B. fusca males successfully transferred inoculum to females during copulation, which in turn transmitted it to the eggs they laid on maize plants, resulting in the decrease of leaf damages.