Non-host plant odor (Tanacetum vulgare; Asteracea) affects the reproductive behavior ofLobesia botrana Den. et Schiff (Lepidoptera: Tortricidae)

Females ofLobesia botrana Den. et Schiff. (Lepidoptera Tortricidae) are attracted in natural conditions by volatiles released by a nonhost plant: tansy (Tanacetum vulgare L.; Asteracea). We have shown that both tansy flowers and their odor inhibit oviposition behavior and mating behavior and reduce adult longevity. The mean number of eggs laid per female isolated with tansy flowers was reduced by up to 50% every 2 days during the 6 days of exposure. This reduction was maintained after the tansy was removed. In the presence of tansy essential oil, the egg-laying reduction ranged from about 30 to 80% according to the odor concentration. The number of spermatophores found in females isolated with tansy flowers was also reduced twofold compared to the control treatment, indicating that the presence of tansy reduced mating activity. This mating activity is strongly reduced, by two-thirds, when adults face the highest dose of essential oil compared to controls. The number of eggs laid by the controls cannot be explained by the number of spermatophores. Therefore, the reduction in oviposition has been attributed to the presence of tansy flowers or to the tansy odor. Tansy flowers and tansy odor increased male mortality during the exposure (10% in the control, 50% in the tansy treatment, and up to 98% in the odor treatment). The highest rates of male mortality occurred during the 4- to 6-day period of exposure to flowers or odor. Repellence resulting in sustained locomotor activity is a possible cause of such a mortality. Female mortality was increased only in response to the highest dose of odor. This increase might be due to egg retention, and not directly to a plant effect. We discuss the effects of tansy flower odor on different patterns relative to the reproductive behavior ofL. botrana and, especially, on oviposition behavior in the ecological context of plant selection and polyphagy.     

Olfactory Associative Learning of the Pupal Parasitoid Pimpla luctuosa Smith (Hymenoptera: Ichneumonidae)

Laboratory experiments were conducted to determine the role of learning in olfactory host searching by the ichneumonid pupal parasitoid, Pimpla luctuosa Smith. Females learned to associate novel odors such as vanilla and strawberry with hosts when they oviposited in at least several hosts with the odors. Repeated experiences of hosts with an odor increased the response of the experienced odor, and females that had experienced host odor seven times responded to the experienced odors 90% of the time. Although the response by females to a learned odor gradually decreased with increasing host-deprivation time, 60% of the females that had experienced host odor 7 days earlier still responded to the experienced odor. Females also learned two separate odors associated with hosts at a time and responded to both odors without a preference for one odor over the other. When trained two separate odors with hosts, females learned the second odor more quickly than the first odor. After females experienced several stings in simulated hosts with the previously learned odor, they ceased to respond to the learned odor, suggesting that repeated unrewarding experiences cause females to cease to respond to the learned odors.     

Plasticity in the egg-spacing behavior of a seed beetle: Effects of host deprivation and seed patchiness (Coleoptera: Bruchidae)

Egg-laying females of the seed beetle Callosobruchus maculatusdiscriminate between egg-free and egg-laden seeds and produce a nearly uniform distribution of eggs among seeds. We examined plasticity in this trait in response to both an internal factor (level of host deprivation) and an environmental one (the spatial configuration of available seeds). Responses to each factor were measured in genetically divergent strains that show a relatively strong (S strain) or weak (B strain) tendency to spread eggs evenly among seeds. Following a modest (10-h) period of host deprivation, S-strain females distributed their eggs less uniformly among seeds; the proportion of females committing at least one oviposition mistake increased from 20 to 50%. Similarly, S-strain females distributed their eggs less uniformly if seeds were presented in multiple, discrete patches instead of in a single, large patch. The higher frequency of oviposition mistakes in the multiple-patch arena was caused in part by females maintaining a uniform distribution of eggs within patches but not among patches. In contrast, females from the sloppier B strain were unaffected by either host deprivation or resource dispersion. Responses to seed patchiness are discussed in relation to the role of learning in the egg-spacing behavior of C. maculatus.     

Intraspecific variation in the egg-spacing behavior of the seed beetleCallosobruchus maculatus

Females of Callosobruchus maculatustend to distribute their eggs uniformly among host seeds and, thereby, reduce competition among larvae within seeds. We investigated variability in this behavior by assaying beetles from seven geographic strains on each of three host species. To quantify egg-spacing behavior,we devised an index (U)that estimates the uniformity of the egg distribution but is independent of the number of eggs laid. Egg-spacing behavior was highly variable among beetle strains and legume hosts. Females from an Indian strain frequently achieved the most uniform distribution possible (maximum hyperdispersion), whereas females from two Brazilian strains frequently deposited eggs randomly. Differences among strains were evident throughout the period of oviposition;some strains were sloppy when even egg densities were low. Variation in egg-spacing behavior appears to be influenced by prior host associations and by host size. The most well-developed spacing behavior was observed in a strain associated with the smallest host, which supports only one or two larvae per seed. Realized fecundity also varied significantly among beetle strains. We found no evidence, however, of a predicted tradeoff between the number of eggs laid and the uniformity of the egg dispersion.     

Responses of Two Potential Host Species (Formica gnava and Formica occulta) to Pupae of the Obligatory Slave-Making Ant, Polyergus breviceps (Hymenoptera: Formicidae)

Queens of the slave-making ant, Polyergus breviceps, take over nests of adult Formica workers when establishing new colonies. Although naïve to slave-maker brood, the usurped Formica rear Polyergus offspring and nests containing both host and parasite species forms. Host worker acceptance of parasite brood has been attributed to the similarity of brood tending signals between these closely related taxa and/or the presence of an attractive pheromone in the slave-maker brood. By presenting single-species groups of Formica occulta and Formica gnava (two host species of P. breviceps) with a choice of Formica pupae of both species or with a choice of P. breviceps pupae from both types of mixed-species nests, it seems that neither close phylogenetic relatedness nor an attractive brood odor alone can account for the propensity of host workers to adopt slave-maker pupae. Significantly greater numbers of P. breviceps pupae were adopted by enslaved workers than by free-living workers, and within the enslaved groups and the free-living F. gnava group, greater numbers of P. breviceps pupae were adopted if they were from nests where the host species was conspecific to workers used in tests. When presented with F. gnava and F. occulta pupae, Formica workers adopted conspecific pupae almost exclusively and ignored or consumed pupae of the other host species. Taken together, these results imply that P. breviceps pupae have both a species-specific odor and a general brood-tending pheromone, upon which a host odor may be imposed. The disparate requirements of immatures at different stages of development for cue specificity or generality in maintaining nest exclusivity and maximizing inclusive fitness are discussed.     

Fine structure of the flagellar apparatus of gametesin situ and motile zygotes of the green algaUlothrix flacca var.Roscoffensis (Ulotrichales) (Chlorophyta)

Summary This fine structural study ofUlothrix flacca (Dillw.) ThuretRoscoffensis variety (Berger-Perrot), a marineUlothrix, describes in detail the flagellar apparatus configuration of gametesin situ in the gametangia and in motile zygotes. The gametes's flagellar apparatus shows two basal bodies overlapping at their proximal end at a 30° angle, in an 11/5 o'clock configuration or with a counterclockwise absolute orientation. The basal bodies are interconnected by a non-striated band or capping plate. They are wrapped in their proximal part by an electron-dense sheath and obtured by a bilobed terminal cap. A cruciate microtubular root system having a 4-2-4-2 alternation pattern is present. A striated microtubule associated component (S.M.A.C.) or system I fibres accompany the two membered root R₂. The system II fibres or rhizoplasts along with striated bands associated to the microtubular roots, were not observed and are presumed to be absent.In the motile zygotes, the basal bodies are paired in a cruciate pattern. During the fusion process, two basal bodies, one of each pair, slide in a face to face position with a slight displacement into the 11/5 o'clock direction; the other two make a 30° counterclockwise rotation, thus making a 60° angle between the two basal bodies of each pair instead of 30° in the gamete.After comparison with the flagellar apparatus of other green alga gametes, it is concluded that the taxonomic affinities ofUlothrix flacca var.Roscoffensis, lie with theUlvophyceae sensuStewart andMattox 1978.Abbreviations CP capping plate - ER endoplasmic reticulum - G Golgi body - LG lipid globule - M mitochondria - MS presumed mating structure - N nucleus - R ₂,R ₄ microtubular roots - SH sheath - SMAC striated microtubule associated component - TC terminal cap - V vacuole - Ve vesicles in the anterior papilla - 1, 2, 1, 2 basal bodies numerotation     

The Influence of Oviposition Experience on Response to Host Pheromone in Trichogramma sibericum (Hymenoptera: Trichogrammatidae)

Searching times and residence times of Trichogramma sibericum Sorokina were measured in the laboratory on individual cranberry leaves that had been treated with the sex pheromone of blackheaded fireworm [Rhopobota naevana (Hübner)] and on leaves that were left untreated. Mean searching time was higher on leaves treated by passive diffusion with either 50 or 100 g of the main component of fireworm pheromone, (Z)-11-tetradecen-1-ol acetate (Z11-14: Ac), than on control leaves. Mean residence times were also higher on leaves treated by passive diffusion with 50 g of Z11-14: Ac than on leaves untreated with pheromone. Pretrial oviposition experience in either the presence or the absence of host pheromone did not influence variation in searching time or residence time. This indicates that neither associative learning of the odor of host pheromone nor a more generalized increase in response to chemical stimuli after oviposition (priming) affects retention responses of T. sibericum to pheromone. Results are discussed in the context of current theories on the evolution of learning in insect parasitoids and as they relate to the concurrent use of pheromone-based mating disruption and releases of T. sibericum for pest management of the blackheaded fireworm.     

Eusynaptomyces benjaminii,spec. nova, (Ascomycetes,Laboulbeniales) und seine Anpassungen an das Fortpflanzungsverhalten seines WirtesEnochrus testaceus (Coleoptera,Hydrophilidae)

Eusynaptomyces benjaminii is described as a new species of the ectoparasiticLaboulbeniales (Ascomycetes). It exists only on two very restricted areas of the body (= position specifity) of its hostEnochrus testaceus (F.) (Coleoptera, Hydrophilidae): on the claws of the right fore-leg and on the lower side of the frontal border of the pronotum. In these two habitatsEu. benjaminii develops two extremely different growth-forms. Male and female hosts are parasitized on somewhat different parts of their body. This can be explained by their mating behaviour. The growth-forms ofEu. benjaminii are so different that one ignorant of the biology of hosts and parasites, might regard them as members of different species or even genera. They are to be interpreted as adaptations of one species to growth positions and mating behaviour of the host. There is no sex-of-host specifity as assumed by certain authors for several species of theLaboulbeniales.

     

Meiotic studies ofElymus nutans andE. jacquemontii (Poaceae,Triticeae) and their hybrids withPseudoroegneria spicata and seventeenElymus species

Hybridizations ofElymus nutans andE. jacquemontii were carried out with one species ofPseudoroegneria (S genome), and 20Elymus species, each containing either of the SH, SY, SYH, or SYW genomes. Chromosome configurations were analysed at metaphase I of the two target taxa and their interspecific hybrids. It is concluded that (i)E. nutans is an allohexaploid containing the SYH genomes, andE. jacquemontii is an allotetraploid having the SY genomes; (ii) the genomic affinity is associated with the geographic distance between the species studied; (iii) minor genomic structural rearrangements have occurred within the hexaploid taxon ofE. nutans.     

Evolution of a protein superfamily: Relationships between vertebrate lens crystallins and microorganism dormancy proteins

Summary A search of sequence databases shows that spherulin 3a, an encystment-specific protein ofPhysarum polycephalum, is probably structurally related to the - and -crystallins, vertebrate ocular lens proteins, and to Protein S, a sporulation-specific protein ofMyxococcus xanthus. The - and -crystallins have two similar domains thought to have arisen by two successive gene duplication and fusion events. Molecular modeling confirms that spherulin 3a has all the characteristics required to adopt the tertiary structure of a single -crystallin domain. The structure of spherulin 3a thus illustrates an earlier stage in the evolution of this protein superfamily. The relationship of - and -crystallins to spherulin 3a and Protein S suggests that the lens proteins were derived from an ancestor with a role in stressresponse, perhaps a response to osmotic stress.     

Karyotypes and sex determination in two species of laelapid mites (Acari: Gamasida)

The chromosome number and morphology of two species of the family Laelapidae have been determined: Hypoaspis aculeifer Canestrini, 1887 has 9() and 18() chromosomes and Cosmolaelaps miles Berlese, 1914 7() and 14(). Both karyotypes have monokinetic chromosomes and show obvious similarity. The longest chromosome of both species consists of a normal and a heterochromatic arm. The two laelapid mites prove to be arrhenotokous, as unfertilized females lay eggs from which only males arise. A theory has been postulated that within the Gamasida an evolutionary line towards arrhenotoky is present.Arguments supporting an independent evolution of sex determining system in the two acarine taxa Actinotrichida and Anactinotrichida are discussed.     

Adult experience modifies attraction of the leafminer parasitoidOpius dissitus (Hymenoptera: Braconidae) to volatile semiochemicals

Oviposition-experienced females of Opius dissitus Muesebeck, a braconid parasitoid of Liriomyza sativaeBlanchard, preferentially landed on leafminer-infested rather than uninfested lima bean (Phaseolus lunatus L.) plants in a flight tunnel assay. Both naive and oviposition-experiencedparasitoids responded strongly to odors of infested lima bean plants in a four-arm olfactometer in comparison with odors of uninfested plants, suggesting that volatile semiochemicals are used in host location. Parasitoids with an oviposition experience on lima bean (lima-experienced) spent significantly more time in the infested odor than naive individuals, however, eggplant-experienced wasps did not spend significantly more time in the infested odor field than naive wasps. When parasitoids reared on leafminers in lima bean were provided a choice between the odor of infested lima bean and the odor of infested eggplant or cotton, naive and lima-experienced wasps preferred infested lima odor. An oviposition experience on the other plant species resulted in a dramatic shift in preference. It was concluded that the experience effect was due, at least in part, to associative learning, as has been reported for other parasitoids. The parasitoids may perceive unconditioned stimuli during host contact and oviposition on an infested leaf and may associate those stimuli with volatile semiochemicals emanating from the leaf or host. Subsequently, the volatiles associated with the presence of hosts are used in directing the search for hosts.     

Pheromone puffs suppress mating by Plodia interpunctella and Sitotroga cerealella in an infested corn store

The efficacy of pheromone mating disruption was investigated in a 7×6×3 m corn storage room harboring a high population density of Indian meal moth, Plodia interpunctella (Hübner) and Angoumois grain moth, Sitotroga cerealella (Olivier). Pheromones were released from a controlled release dispenser, the metered semiochemical timed release system (MSTRS^TM) at emission rates of 0.6 g min^–1 (Z9,E12:14:Ac for Indian meal moth) and 0.2 g min^–1 (Z7,E11-16:Ac for Angouimois grain moth). Mating disruption efficacy was evaluated using three parameters: male capture in pheromone traps, visual examination of mating behavior, and the incidence and frequency of mating as measured by spermatophores. In three trials, comparisons were made between data collected before pheromone treatment and during treatment. Disruption of pheromone source location by males averaged 70% and 40% for P. interpunctella and S. cerealella, respectively, in the three trials. In addition, reduced levels of copulation by both species were recorded during pheromone treatment. More importantly, significant reductions were recorded in the incidence and frequency of mating by females of both species collected during the treatment period. While 85% of P. interpunctella females collected before pheromone treatment in three trials had mated at least once, only 50% of the females collected during treatment had mated. The mean number of matings, as measured by spermatophores, ranged between 0.8–1.1 and 0.5–0.7 before and during pheromone treatment, respectively. Similarly, a 20–30% reduction in the proportion of mated S. cerealella females was recorded during pheromone treatment. In the three trials, mean number of spermatophores per S. cerealella female averaged 1.0 and 0.7 during the pretreatment and treatment periods, respectively. Additional tests conducted in small boxes also recorded significant mating disruption of both species.     

Intraspecific classification of melons (Cucumis melo L.) in view of their phenotypic and molecular variation

Cucumis melo L. (melon) genotypes differ widely in morphological and biochemical traits. Intraspecific classification of such variability has been difficult, and most taxonomists still rely on the work of Naudin (1859). A collection of 54 accessions representing diverse genotypes from 23 countries was surveyed. Morphological traits related to the vegetative and flowering stages and mature fruit morphology and quality parameters, e.g., taste, aroma, sugar composition and pH, were scored. These were used to construct a botanical-morphological dendrogram that generally reflected the classification ofCucumis melo into several horticultural varieties. DNA polymorphism among the accessions was assessed using the Inter-SSR-PCR and RAPD techniques that detected abundant DNA polymorphism among melon genotypes. Cluster analysis indicated that the largest divergence was between North American and Europeancantalupensis andinodorus cultivars as one group, and the more exotic varieties:conomon, chito, dudaim, agrestis andmomordica, as a second group. The molecular phylogeny agreed, broadly, with the classification of melon into two subspecies, and did not contradict the division into horticultural varieties. It was apparent, however, that the infra-specific division is rather loose, molecular variation being distributed continuously between and within cultivar groups. We suggest that despite the morphological diversity, separation between varietal-groups may be based on a too small number of genes to enable unambiguous infra-specific classification based on DNA diversity.     

The influence of environmental factors on dormancy and duration of egg development in Metrioptera roeseli (Orthoptera: Tettigoniidae)

Summary Developing eggs of Metrioptera roeseli HGB. have an obligate embryonic diapause in stage 23 and a facultative initial diapause in stage 4. Initial diapause is lacking when the ovipositing females are kept at long day photoperiod (LD 16/8), but is induced at LD 14/10 and LD 8/16. When natural light conditions are given in the laboratory, the females mostly lay diapausing eggs from the end of August onwards. In eggs without initial diapause, a larger number of embryos reach a stage, in which the embryonic diapause can be broken by chilling, only at favorable temperature (4 weeks at 24°C or 8 at 18°C) and in contact with water before the first winter. Thus, some individuals of a given population of M. roeseli have an annual, others a biennial life cycle. The variability in the duration of egg development is due to a photoperiodically induced, facultative initial diapause and to a possible quiescence caused by insufficient temperature and/or moisture.     

Population Biology of Maculinea rebeli (Lepidoptera: Lycaenidae) on the Chalk Grasslands of Eastern Westphalia (Germany) and Implications for Conservation

The population biology of Maculinea rebeli Hirschke, 1904, on dry grassland biotypes in different successional stages was investigated in the summers of 1990 and 1991 in the district of Höxter (North Rhine–Westphalia, Germany). The population characteristics of M. rebeli were studied by mark-recapture and eggshell counts on the larval host plant Gentiana cruciata. Pitfall traps, ant baits, excavating and counting of ant nests were used to examine the Formicidae community and the nest density of Myrmica sabuleti. In 1990, the total population of M. rebeli was estimated as 528 individuals, with subpopulations varying from 2 to 273 individuals. Populations existed in areas differing in size and vegetation structure. However, the limiting factor for population size was the density of the host ant population. The differences in population size did not depend on the size of the habitat or the density of the larval food plant. The butterflies can switch their host. In the absence of M. schenki, the colonies of M. sabuleti can maintain M. rebeli populations. Adult males and females have a maximum life expectancy of 13 days. The females prefer to oviposit on G. cruciata plants of 10–30cm height. Only plants which stuck out of the surrounding vegetation were oviposited on. The average number of eggs deposited per female was 100–150. Low density populations are probably most threatened. Therefore, future protective measures should work towards further maintaining and optimizing the habitats of the small populations, as well as creating the prerequisites so that dense stable populations of M. rebeli can develop.     

Raiding behavior of the dulotic antChalepoxenus muellerianus (Finzi) in the field (Hymenoptera: Formicidae,Myrmicinae)

Summary Little information is available regarding the raiding behavior in nature of dulotic ants belonging to the tribeLeptothoracini. Between July 17 and 24, 1991, several raids ofChalepoxenus muellerianus (Finzi) were observed in nature near Tignale/Lago di Garda, Italy. Apparently, this species raids frequently during its summer raiding season (5 raids were observed during 7 days spent observing 8 colonies). A singleChalepoxenus colony sometimes raids more than one host colony more or less simultaneously. Observations during which oneChalepoxenus colony raided another and captured slavemaker brood indicate that intraspecific raids can occur either accidentally, or as a result of competition or territoriality when there is a sufficient dense slavemaker population.     

Development and parasitism in the genus Hemileia (uredinales)

Seventeen species ofHemileia were studied with emphasis on these characters: extent of colonization, specialization of parasitic mycelium, haustorial development, pathologic histology, soral morphology and sporulation capacity. An attempt was made to trace the varying degree of development and parasitism in this rust genus comprising of just over 40 reported species. It was noted that theGopalkrishnan's Subepidermal type more advanced than his Superstomal — B type.Fourth part of my thesis submitted to the University of Poona, India, accepted in 1968 for Ph.D. Not published.     

Ultrastructure of carpospores inGastroclonium clavatum (Roth)Ardissone (Rhodymeniales)

Summary Carpospores ofG. clavatum have been studied under the light and electron microscopes. They are wedge-shaped cells of 80–100 m at their longest diameters. The nucleus is an uncondensed structure provided with a regular outline and a large nucleolus. The plastids constitute heterogeneous populations of organelles differing in size and shape as well as in number and arrangement of the thylakoids. Multiplicating plastids are also present. The mitochondria are small but have well developed cristae. The Golgi apparatus consists of very numerous active dictyosomes. Starch is the main storage substance but some large lipid bodies are also present. Labyrinthine polysaccharide aggregations are present in the carposporial cytoplasm. Multilayered bodies constitute a sui generis very conspicuous cell component.     

Variability of the inflorescence ofMicroseris laciniata (Compositae: Cichorieae)

Quantitative characters of the flowering head of a garden population ofMicroseris laciniata were scored during the second, third, and fourth season of growth. Number of achenes per head, number of phyllaries per head and the average number of pappus parts per achene in single heads show significant plant to plant variation. Achenes per head and pappus parts per achene were scored in identical plants in two subsequent seasons. The number of pappus parts per achene varies freely between five and ten. This contrasts with annual species ofMicroseris in which either five or ten pappus parts are found, depending on the species. In spite of a clear plant-specific average of pappus parts, both high and low pappus part determination can be demonstrated in all specimens. The number of pappus parts depends on the position of an achene on the receptacle, marginal achenes usually having fewer pappus parts than central ones. This gradient is not closely correlated with the position of an achene on the genetic spiral.