Life cycle and host specificity of the heliotrope weevil,Pachycerus cordiger (=Madidus auct.) [Col.: Curculionidae]

Pachycerus cordiger Germar (Curculionidae: Cleonini) is a potential agent for the biological control ofHeliotropium europaeum L. (Boraginaceae) in Australia. Adults feed on the leaves and larvae feed on the main roots of the weed within an earthen cell. These is one generation per year. Adults overwinter in the cells before emerging in late spring when they begin to feed, mate and oviposit on their host plants from late May until late July. Seven Boraginaceae and 31 economically important crop species were tested using adults and 1^st instar larvae.P. cordiger was found to be specific to the Boraginaceae. Field observations strongly suggested that the weevil is restricted to summer-annualHeliotropium species. A widespread egg parasite,Caenocrepis? bothynoderi Gromakov [Hymenoptera: Pteromalidae], caused up to 18% mortality.     

Feeding behavior ofLemur catta andLemur fulvus

The feeding behavior of two sympatric species of lemurs, Lemur cattaand Lemur fulvus,was studied in an enclosure simulating a natural habitat at the Duke University Primate Center. L. fulvusspent less time feeding during the day than L. catta.But the former species ate more fruit and had longer feeding bouts on preferred food items than L. catta.They also had a shorter food passage time than L. cattaand their choice of resting places was more influenced by food distribution. Furthermore, the two lemur species ate parts of different plant species and showed different reactions to chemical plant components. According to these results, L. fulvusis a more conservative feeder than L. catta.These interspecific differences in feeding behavior may be one of a number of differences that allow the two species to coexist. In allopatry, however, L. fulvusmay also adopt feeding patterns similar to those of L. catta.But L. cattawas never found to change its feeding strategies in different areas. It may be this option of L. fulvusto adopt different feeding strategies in different situations that allows this species to have the widest range of all Malagasy lemurs. Duke University Primate Center Publication No. 259.     

Allozymic and morphological relationships amongAndrocymbium gramineum,A. europaeum,andA. psammophilum (Colchicaceae)

Levels of allozymic and morphological diversity amongAndrocymbium gramineum, A. europaeum, andA. psammophilum have been assessed using data on 17 allozyme loci and 18 morphological characters. No apparent pattern of geographic or ecological variation was found. Our results also suggest thatA. gramineum andA. europaeum should be considered members of a single species and that the insular speciesA. psammophilum can no longer be thought of as the result of a founder effect fromA. gramineum. Intrapopulational variability was greater than inter-populational variability at both levels studied, which is of strategic interest for the ex-situ conservation of these threatened endemic species.     

Hybridisation,genomic constitution and generic delimitation inElymus s. l. (Poaceae: Triticeae)

Intergeneric crosses were made between representatives of the genomically-defined generaElymus, Agropyron, Elytrigia, Pseudoroegneria, andThinopyrum. The genomic constitution ofElytrigia repens, the type species ofElytrigia, is shown to be SSH, a genomic combination otherwise found only inElymus. The S genome ofPseudoroegneria has almost always a dominant influence on the morphology of the taxa of which it is a component.Wang (1989) showed that the J genome inThinopyrum and the S genome have considerable homoeology, with a mean c-value of 0.35 in diploid SJ hybrids. A genetic coherence from S to SJ^e, J^e, J^eJ^b, and J^b can be expected, agreeing with the continuous morphologic variation pattern observed. Because of the absence of morphological discontinuities between the taxa,Pseudoroegneria (S),Elymus (SH, SY, sometimes with additional genomes),Elytrigia (SSH, SSHX), andThinopyrum (SJ, SJJ, J) are best treated as a single genus,Elymus, following the generic concept ofMelderis in Flora Europaea and Flora of Turkey. The basic genomic constituents ofElymus will then be the S and/or J genomes.Agropyron, with diploids, tetraploids, and hexaploids based on the P genome is morphologically distinct from other genera inTriticeae. In a few species ofElymus andPseudoroegneria, a P genome is an additional constituent. In these cases the P genome has a negligible morphological influence. Therefore, it seems reasonable to maintainAgropyron as a separate genus.     

Breeding systems and hybridization inPetrorhagia sect.Kohlrauschia (Caryophyllaceae)

In the diploid speciesP. prolifera, the evolution of autogamy has resulted in the presence of distinct selfing and outcrossing races. The change in breeding system toward autogamy is associated with a reduction in the size of floral features and a lower pollen production. The outbreeding populations have only been found in Greece, while the selfing populations have colonized much of Europe. The two races appear to be reproductively isolated from one another. —Petrorhagia sect.Kohlrauschia contains four species.P. glumacea is outbreeding and shows unilateral incompatibility with the small-flowered race ofP. prolifera and interfertility with the large-flowered race; althoughP. glumacea is sympatric with the large-flowered race, they do not appear to hybridize in the wild. Amongst the allopatric species, internal breeding barriers are also found. These may take the form of hybrid sterility or seed incompatibility.P. velutina is autogamous and reproductively isolated from all the other species of the section regardless of whether they are sympatric or allopatric. It is suggested that the evolution of autogamy has been an important factor in the spread ofP. velutina, the tetraploidP. nanteuilii, and the small-flowered race ofP. prolifera in Europe.     

Chromosome banding patterns in Lettuce species (Lactuca sect.Lactuca,Compositae)

Chromosome banding patterns obtained with C- and N- banding, and AgNO₃ staining were studied in somatic metaphase complements of fourLactuca species.L. sativa andL. serriola have almost identical chromosome morphology, andL. saligna differs only slightly from them, butL. virosa is quite distinct from the other species. A gross comparison of the banded karyotypes suggests a closer relationship ofL. saligna toL. sativa/serriola than toL. virosa. Our data agree with the results of previous crossing experiments in these species but conflict partly with recent RFLP data which indicate a closer phenetic relationship ofL. saligna toL. virosa than toL. sativa/serriola. Such a discrepancy may be explained assuming that domestication ofL. sativa/serriola resulted in an increased selection pressure on unique DNA sequences as demonstrated by the RFLP data. Differential evolution of specific heterochromatin classes (and presumably of highly repetitive DNA classes), as revealed by chromosome banding techniques was not linked to domestication. Thus the disparity in conclusions about relationship (in terms of genetic similarity) as based on the different experimental approaches reflects a non-parallel evolution of highly repetitive vs. unique DNA classes.     

Crossing experiments of lettuce cultivars and species (Lactuca sect.Lactuca,Compositae)

The degree of relationships withinLactuca sativa and three wild relativesL. serriola, L. saligna, andL. virosa was studied by observing the performance, vigour and fertility of the F 1 hybrids obtained from crosses made in and between the four species. The crosses ofL. saligna ×L. virosa and the reciprocal crosses produced no hybrids.L. saligna andL. virosa are the least related of the four species.L. sativa ×L. serriola and the reciprocal crosses were successful and produced fertile hybrids These two species are genetically very closely related.L. saligna is known to produce, as a female parent, hybrids withL. sativa andL. serriola. Now the reciprocal cross was successful for the first time, so the unability to obtain hybrids in the past was based on the choice of accessions and not caused by unilateral incompatibility.L. virosa ×L. sativa and the reciprocal combination produced hybrids. The combinationL. serriola ×L. virosa produced hybrids with very limited fertility. In contrast to earlier reports (sterile hybrids) one combination of the reciprocal cross too produced hybrids with very limited fertility.—Some of theL. saligna ×L. sativa (and reciprocal) hybrids were found to look strikingly likeL. serriola. This adds evidence for the descent ofL. serriola andL. sativa:L. saligna also made part of the ancestral complex of the cultivated lettuce.     

Life history ofSmicronyx guineanus andSm. Umbrinus (Col.: Curculionidae) onStriga hermonthica (Scrophulariaceae)

The life history ofSmicronyx guineanus andSm. umbrinus, weevils attackingStriga hermonthica, was studied in Burkina Faso, West Africa. Field experiments were conducted in 1992 and 1993 at Kaya, in fields of sorghum (Sorghum bicolor (L.) Moench and pearl millet (Pennisetum americanum (L.) K. Schum. (syn.P. typhoides (Burm.) Stapf &; Hubb). The weevils are univoltine; the adults emerge in late August, mate and eggs are laid in the ovary ofStriga inflorescence. Larval feeding in the ovary causes galling and prevents seed production. The main damage toStriga seed capsule is caused by the larvae of at least twoSmicronyx species. Last-instar larvae drop to the soil and bury themselves to a depth of 1–15 cm, pupate and enter into dormancy. Most pupae are found in the upper 5–10 cm of the soil. The pupal period lasts from late October to late July. In May, we found 75.6% of pupae against 24.4% of adults in dormancy.     

The genusPicris (Asteraceae,Lactuceae) in Tropical Africa

Three species of the genusPicris L. are native in Tropical Africa:P. abyssinica Sch. Bip. (Ethiopia),P. xylopoda Lack, spec. nova (Nigeria, Ethiopia) andP. humilis DC. (Senegal, Mali). There are indications that the two perennial species,P. abyssinica andP. xylopoda, are related to and have evolved from a primitive Central Asiatic stock in a manner parallel to many African species ofCrepis L.P. humilis, on the other hand, is a small annual plant with a high number of derived characters. The introduced species of European origin growing south of the Sahara are briefly mentioned.     

Sero-systematics ofCytisus sect.Trianthocytisus (Fabaceae)

The serological reaction of seed proteins provides evidence for a partly new systematic arrangement ofCytisus sect.Trianthocytisus and ofCytisus s.l. Proposed modifications agree with recent advances in morphological taxonomy. Sect.Trianthocytisus includes only two species,C. villosus andC. aeolicus. Its position is central within the genus, and this fact agrees with the proposed retypification ofCytisus (type species:C. villosus).C. emeriflorus, formerly included in the same section, constitutes the monospecific sect.Emeroides, which is intermediate towards the genusLembotropis. This is serologically isolated and includes onlyL. nigricans. It is confirmed thatC. sessilifolius should be removed from the genusCytisus as a monospecific genus:Cytisophyllum Lang which is closely allied toHesperolaburnum and toPodocytisus, the most primitive genera ofGenisteae.     

Comparative capitular morphology and anatomy of Coreopsis L. and bidens L. (compositae), including a review of generic boundaries

The capitular and floral morphology and anatomy ofBidens L. andCoreopsis L. were studied. All the North American species ofCoreopsis were studied. Selected species ofBidens from North and South America andCoreopsis from South America were included. The results were compared with previous observations on African species ofBidens (incl.Coreopsis). Emphasis was given to character states of the ray florets, paleae, stylearm apices, outer phyllaries, achenes, and pollen grains. Some of the character states are unique features ofCoreopsis, e.g., globular and elongately conical receptacles, deltoid outer phyllaries, truncate and indistinctly 3–5-dentate, 3–4-lobed ray florets, narrowly spathulate paleae, subulate paleae with linear-filiform upper half, hairy and apically 3-cleft paleae, truncate, convex or shallowly conical stylearm apices with the sweeping hairs limited to the area above the stigmatic surfaces and the orbicular to circular achenes. The cylindric setaceous pappus bristles so commonly encountered inBidens are unknown inCoreopsis. The pappus bristles inCoreopsis are paleaceous but similar, though thicker ones are also found in African species ofBidens (incl.Coreopsis) with winged achenes. Twin-celled hairs (setulae) with differing degrees of wall thickness are found on the achenes ofCoreopsis sect.Pseudoagarista (Mexico and South America),Coreopsis sect.Pugiopappus (California), AfricanBidens with winged achenes (e.g.,B. prestinaria, B. macroptera) and some North AmericanBidens (e.g.,B. aristosa). Similar sclerotic parenchyma make up the achenial wings of species in both genera. These may be interpreted as homologous structures, indicating the underlying similarity of these taxa and their derivation from a common ancestral stock.     

Responses of four arid zone grass species from varying habitats to drought stress

The effects of 4 or 8 drought cycles on four grass species,Cenchrus pennisetiformis, Leptochloa fusca, Panicum turgidum, andPennisetum divisum were assessed in a pot experiment. There were significant differences between the species in biomass production under water stress.C. pennisetiformis andP. turgidum produced significantly greater fresh and dry matter thanP. divisum and especially thanL. fusca. L. fusca had the lowest andP. divisum highest osmotic potentials compared with the other species after the completion of 4 or 8 drought cycles. Osmotic adjustment (difference between osmotic potential of droughted/rehydrated plants and control plants) was highest inL. fusca. The stomatal conductance was significantly decreased with increased drought stress inC. pennisetiformis. The elasticity ofC. pennisetiformis, P. turgidum andP. divisum increased with increase in number of drought cycles, whereas that ofL. fusca remained unchanged.L. fusca andP. turgidum had the lowest leaf hydration of all species after 8 drought cycles. The chlorophyllsa andb in all species remained unaffected by drought treatments. The proline content ofC. pennisetiformis andL. fusca increased significantly with increased drought stress, whereas that ofP. turgidum remained unaffected after 4 or 8 drought cycles.L. fusca synthesized great amount of leaf soluble proteins during 8 drought cycles, whereasP. divisum had low protein content after 4 drought cycles. The protein contents ofC. pennisetiformis andP. turgidum remained unaffected after 8 drought cycles. The leaf epicuticular wax ofL. fusca increased consistently with increased drought stress, but leaf wax ofP. divisum increased only at the highest drought stress and that ofC. pennisetiformis andP. turgidum increased after 4 drought cycles. On the basis of these results it was established thatC. pennisetiformis andP. turgidum were the most tolerant,P. divisum intermediate, andL. fusca the most sensitive to drought stress. The osmotic adjustment did not positively correlate with the degree of drought resistance.     

Chlorogenic acid as an antiherbivore defence of willows against leaf beetles

In the leaves of 13 Finnish willow species, the content of a phenolic, chlorogenic acid, was found to vary from 0 up to 18 mg g^–1 D.W. Effects of pure chlorogenic acid on insect feeding behaviour were tested using four common leaf beetle species which are in the field mainly found on willows with low-chlorogenic acid leaves. One species, Lochmaea capreae L., was invariably deterred by pure chlorogenic acid applied in naturally occurring concentrations on the willow leaves. Accordingly, in 2-choice laboratory feeding trials L. capreae was found to prefer low-chlorogenic acid leaves of four willow species over high-chlorogenic acid leaves of Salix pentandra L. and S. myrsinifolia Salisb. When presented on the leaves of S. phylicifolia L, pure chlorogenic acid inhibited also the feeding by Phratora polaris Sp.-Schn. Instead, chlorogenic acid had no significant effect on Ph. polaris when it was presented on the leaves of another willow S. cinerea L. In laboratory, Ph. polaris did not show general preference for willow species with low chlorogenic acid content in their leaves. Thus, the response of Ph. polaris to chlorogenic acid seems to depend on the plant species. Apparently variation in other traits such as leaf hairyness may easily override the potential effect of chlorogenic acid content on Ph. polaris. To two other leaf beetle species, Galerucella lineola F. and Plagiodera versicolora Laich., chlorogenic acid is an ineffective deterrent even at unnaturally high concentrations. In laboratory, G. lineola and P. versicolora did not prefer willows with low chlorogenic acid content in their leaves. Thus, among four studied leaf beetle species, only L. capreae seems to be clearly affected by this phenolic. Therefore, overall importance of chlorogenic acid as a defence against willow-feeding leaf beetles appears to be very limited.     

Microfungi on the Pandanaceae:Polytretophora macrospora sp. nov.

Polytretophora macrospora is introduced based on specimens from two species ofPandanus in Seychelles. The new species is compared with currently accepted species. A key and a comparative synopsis toPolytetophora species are provided. Numerous specimens ofP. calcarata, collected on members of the Pandanaceae from Australia, Fiji, Hong Kong, Malaysia, New Caledonia, Palau, Philippines, Seychelles and Solomon Islands are also reported, along withP. dendroidea onPandanus sp. from Malaysia.     

Pollination of sevenPlectranthus spp. (Lamiaceae) in southern Natal, South Africa

The genusPlectranthus (Lamiaceae) shows remarkable radiation on the sandstones of southern Natal and northern Transkei in South Africa, where six endemic species occur. Two of these endemic species,P. hilliardiae andP. oribiensis, are included in this study, as well asP. reflexus, for which only limited data are available. The other species that were studied areP. ambiguus, P. ciliatus, P. ecklonii, P. madagascariensis andP. zuluensis. Four of these taxa,P. ambiguus, P. hilliardiae, P. reflexus andP. saccatus var.longitubus, have uniquely long corolla-tubes (20–30mm) and this is related to pollination by nemestrinid flies of the genusStenobasipteron that have proboscides of similar length. Other nemestrinid species of the genusProsoeca have shorter proboscides and pollinate two species ofPlectranthus with shorter corolla-tube lengths (6–15mm). Acrocerid flies, tabanid flies and anthophorid bees are also important visitors to these species. This study on the pollination of seven species of varying corolla-tube lengths shows a correlation between floral tube length and proboscis length of insect visitors, many of which are recorded for the first time as pollinators ofPlectranthus.     

Puccinia kraussiana (Uredinales) onHeterosmilax gaudichaudiana,A new record of rust in Eastern Asia

Puccinia kraussiana, a rust fungus of Africa, was found in Taiwan for the first time in eastern Asia. It was parasiting on leaves ofHeterosmilax gaudichaudiana, on which all four stages were characteristically found. The host species,H. gaudichaudiana, newly added to the host range ofP. kraussiana, constitutes also a new entry to the phanerogamic flora of Taiwan.     

Investigations of the host feeding preferences ofSitona weevils found commonly on white clover (Trifolium repens) in the UK

A series of laboratory and field studies were done to evaluate a range of leguminous plant species for their feeding potential by adult weevils of the genusSitona Germar. (Coleoptera: Curculionidae). Three species ofSitona, S. lineatus L.,S. flavescens Marsh. andS. hispidulus F. all of which are found commonly on white clover (Trifolium repens L.) in the UK were offered a range of 11 legume species,T. repens (white clover, cv. Olwen),T. pratense L. (red clover, cv. Marcom),T. fragiferum L. (strawberry clover, cv. Palestine),T. hybridum L. (hybrid clover, cv. Tetra),T. incarnatum L (crimson clover),T. dubium Sibth. (lesser yellow trefoil),Lotus corniculatus L. (birdsfoot-trefoil, cv. Leo),L. uliginosus Schkuhr. (large birdsfoot-trefoil),Melilotus alba Desr. (white melilot),Medicago sativa L. (lucerne, cv. Europe) andM. lupulina L. (black medick) in two laboratory experiments. The weevils were offered a choice of these legumes in one experiment whilst in the other they did not have a choice of food material. These legumes were also sown in the field and a number of measurements of damage, together with counts ofSitona spp., were made. In the laboratoryS. lineatus andS. hispidulus favoured some of the legumes to a greater or lesser extent than white clover.S. flavescens was more restricted in its feeding than the other two weevil species. In the field studyS. lineatus invaded the experimental area quickly and tended to favourMedicago spp. andMelilotus spp. Later in the yearS. flavescens dominated the sitona fauna on the experiment, with the exception of aggregations ofS. lineatus onM. sativa andM. alba. In a separate screen of 5 varieties of white clover (cvs Donna, Menna, Kersey, Olwen and Grasslands Huia), cv. Olwen appeared to be the most susceptible to sitona attack.     

Restriction fragment length polymorphisms of the phytohemagglutinin genes inPhaseolus andVigna (Leguminosae)

Restriction fragment length polymorphisms at the phytohemagglutinin (PHA) locus were determined among 21 genotypes ofPhaseolus vulgaris, P. coccineus, P. acutifolius, P. lunatus, and threeVigna species, using five restriction enzymes and one double digestion, in order to provide molecular evidence for their genetic relatedness. The dissimilarity between genotypes was estimated from binary RFLP data. The dissimilarity was high among species (from 0.75 to 0.95), and of variable extent among genotypes of the same species (0.33–0.89). InP. vulgaris, two different DNA hybridization patterns were found, giving further evidence for two major gene pools in that species. The restriction patterns ofP. vulgaris var.aborigineus, the putative ancestral form ofP. vulgaris, exhibit clear homology toP. vulgaris genotypes. An undefined landrace from Taiwan could be identified as aP. vulgaris genotype. RFLP-based trees for the phytohemagglutinin genes of the species studied were computed with several distance matrix and parsimony methods.     

A new species ofLentinula (Agaricales) from Central America

Lentinula aciculospora sp. nov. is described from a single Province in Costa Rica. Stature and habit of basidiomata of this species are similar to some otherLentinula taxa (i.e.L. edodes), but the elongate-cylindrical shape of basidiospores is a distinctive character ofL. aciculospora. The mating system ofL. aciculospora is tetrapolar as also found in other species of the genus, but this species is genetically isolated fromL. boryana, and all morphological variants ofL. edodes.     

Facilitated predation through interaction between life stages in the stinkbug predatorperillus bioculatus (Hemiptera: Pentatomidae)

Competitive interactions in arthropod predators are well-known, but positive interactions have received less attention. The two-spotted stinkbugPerillus bioculatus often feeds gregariously on leaf beetle larvae and caterpillar prey. Consequences of prey sharing amongP. bioculatus conspecifics of dissimilar size (instar) was studied using Colorado potato beetle (CPB) prey. Rearing second-instar (N2) nymphs ofP. bioculatus with an N5 conspecific facilitated early feeding on L4 CPB larvae (a difficult prey to handle by N2 nymphs but not by N5’s), thus increasing survival and accelerating development. One in every 20 cases ofP. bioculatus foraging in the field was accounted for by pairs or small groups of mostly feeding individuals. CPB egg masses and L4’s represented a disproportionate number of cases of aggregated feeding byP. bioculatus, compared to feeding singly. Small CPB larvae decreased in the diet of aggregated stinkbugs compared to L4 larvae and egg masses, suggesting that sharing these prey may be favorable or unavoidable. In a field test measuring residence/survival of N2’s limited to L4 prey, the N2’s rate of residence/survival increased significantly when large nymphs acting as food providers were also present. The function of communal feeding inP. bioculatus is discussed, as well as the potential for greater impact on prey density that may be expected from tolerance to opportunistic feeding by conspecifics in slightly gregarious predators.