Comments on flower evolution and beetle pollination in the generaAnnona andRollinia (Annonaceae)

Dynastid scarab beetle pollination appears basic within the genusAnnona. Those species ofAnnona which are more morphologically derived, as well as allRollinia spp. possess reduced floral chambers and attract small beetles likeNitidulidae orStaphylinidae. Pollination of the primitive species ofAnnona byDynastinae would imply that the genus had not evolved before the Tertiary. The fossil record is in congruence with this hypothesis. Once again it is stressed that the cantharophilous syndrome, as it is found in theAnnonaceae, Magnoliaceae, Eupomatiaceae andCalycanthaceae, with beetles being exclusive pollinators, is a secondary and derived condition and obviously different from the expected basic entomophily of the original angiosperms.     

The value of certain plant parameters as an index for salt tolerance in Indian mustard (Brassica juncea L.)

In a micro-plot study of 6 cultivars of Indian mustard (Brassica juncea L.) it was observed that germination of seeds and seed yield per plot decreased linearly with rising salinity levels. On the contrary, seed yield per plant increased with the salinity until at a critical salinity level it fell abruptly. Compared to the cultivars of the sensitive group the tolerant ones exhibited a higher magnitude of reduction in number of leaf stomata per unit area (stomatal frequency of leaf) at the critical salinities (12 mmhos/cm and above) of irrigation water, whereas the decrease in leaf water potential (-leaf) was not so marked at the same salinity levels. Tolerant cultivars were also notable for having a wider K/Na ratio (1.63 and 1.28) and a higher accumulation of free proline (2.10 and 2.30 mole/g) at EC irrigation water of 12 and 16 mmhos/cm respectively. Reductions in yield at these salinities were rather lower being 27.0 and 79.8% respectively in tolerant cultivars compared with 59.0 and 94.2% respectively in sensitive ones.     

The allocation process and between-tree survival probabilities inDendroctonus frontalis infestations

Conclusion We have presented two transfer functions for allocating populations ofD. frontals adults in spots: a fixed probabilityTF and a time-temperature dependentTF. Both procedures produced essentially equivalent results when applied to actual population measurements taken from spots. The time-temperatureTF was more realistic than the constant probabilityTF, but introduced an added source of variation into the transfer. Temperature was demonstrated to have a significant effect on adult longevity. The time-temperature dependentTF provides a means of incorporating this important variable. TheF1 andF2 values obtained from this time-temperature dependentTF were also judged to be superior to the values obtained from the constant probabilityTF. Survival of reemerged and emerged beetles were shown to be cyclic and compensatory. Texas Agricultural Experiment Station Paper No. TA 15523.     

Three new asexual arthroconidial yeasts, Geotrichum carabidarum sp. nov., Geotrichum histeridarum sp. nov., and Geotrichum cucujoidarum sp. nov., isolated from the gut of insects

Twenty arthroconidial yeasts were isolated from the digestive tract of basidiome-feeding beetles and lepidopteran larvae. All of the yeasts reproduced only asexually by arthroconidia and some by endo- or blastoconidia as well. Based on the comparisons of sequences in ribosomal RNA genes and other taxonomic characteristics, the yeasts were identified as three unknown Geotrichum species. The three new species are described as Geotrichum carabidarum (NRRL Y-27727^T), G. histeridarum (NRRL Y-27729^T), and G. cucujoidarum (NRRL Y-27731^T). Phylogenetic analyses from ribosomal DNA sequences showed that members of the genus Geotrichum and related arthroconidial yeast taxa were divided into two major clades: (1) Dipodascus and Galactomyces with Geotrichum anamorphs including all the new species; and (2) Magnusiomyces with Saprochaete anamorphs. G. cucujoidarum formed a subclade with G. fermentans and Geotrichum sp. Y-5419, while the two closely related species, G. carabidarum and G. histeridarum, represent a new basal subclade in the clade of Geotrichum and its teleomorphs.     

Endozoochory by beetles: a novel seed dispersal mechanism

Background and Aims

Due in part to biophysical sized-related constraints, insects unlike vertebrates are seldom expected to act as primary seed dispersers via ingestion of fruits and seeds (endozoochory). The Mediterranean parasitic plant Cytinus hypocistis, however, possesses some characteristics that may facilitate endozoochory by beetles. By combining a long-term field study with experimental manipulation, we tested whether C. hypocistis seeds are endozoochorously dispersed by beetles.

Methods

Field studies were carried out over 4 years on six populations in southern Spain. We recorded the rate of natural fruit consumption by beetles, the extent of beetle movement, beetle behaviour and the relative importance of C. hypocistis fruits in beetle diet.

Key Results

The tenebrionid beetle Pimelia costata was an important disperser of C. hypocistis seeds, consuming up to 17·5 % of fruits per population. Forty-six per cent of beetles captured in the field consumed C. hypocistis fruits, with up to 31 seeds found in individual beetle frass. An assessment of seeds following passage through the gut of beetles indicated that seeds remained intact and viable and that the proportion of viable seeds from beetle frass was not significantly different from that of seeds collected directly from fruits.

Conclusions

A novel plant–animal interaction is revealed; endozoochory by beetles may facilitate the dispersal of viable seeds after passage through the gut away from the parent plant to potentially favourable underground sites offering a high probability of germination and establishment success. Such an ecological role has until now been attributed only to vertebrates. Future studies should consider more widely the putative role of fruit and seed ingestion by invertebrates as a dispersal mechanism, particularly for those plant species that possess small seeds.     

Beetle visitations,and associations with quantitative variation of attractants in floral odors of <Emphasis Type="Italic">Homalomena propinqua</Emphasis> (Araceae)

This study investigated floral visitations of two beetles, Parastasia bimaculata (Scarabaeidae) and Chaloenus schawalleri (Chrysomelidae), and examined associations between beetle visitations and variation in attractant traits, such as quantitative variations of attractants in floral odors and heat generation of spadices in Homalomena propinqua (Araceae). Observations showed P. bimaculata visited pistillate-phase inflorescences most frequently during heat generation, whereas C. schawalleri visited regardless of floral stages and heat generation. Chemical analyses of five dominant components of floral odors showed quantities of 2-butanol, veratrole, and α-pinene during the pistillate phase were the most abundant during all floral stages, and increased during heat generation. When testing combinations of these five authentic chemicals, some mixtures including 2-butanol or veratrole or both attracted both beetles, and veratrole attracted C. schawalleri. These results strongly suggested that the increased emission of floral odor attractants which accompanied heat generation influences floral visitations by P. bimaculata, but not by C. schawalleri. We therefore hypothesize that P. bimaculataaculata is a reliable pollinator, and that variation in attractant traits is a honest signal for P. bimaculata to seek rewards. In contrast, C. schawalleri can detect the signal even at low levels, and so visits inflorescences steadily during all floral stages.     

Oviposition schedules,survivorship curves,and mortality factors within trees of two cerambycid beetles (Coleoptera: Cerambycidae), the Japanese pine sawyer,Monochamus alternatus hope,and sugi bark borer,Semanotus japonicus lacordaire

Summary Oviposition schedules under laboratory conditions, survivorship curves, and mortality factors within trees of two cerambycid beetles, Japanese pine sawyer (JPS),Monochamus alternatus Hope, and sugi bark borer (SBB),Semanotus japonicus Lacordaire, were investigated. Average longevities of reared adults of JPS were 38.1 days for males and 42.3 days for females; those of SBB were 15.7 days for males and 23.8 days for females. It was confirmed that the JPS must feed on the pine branches for full maturation after emergence, but SBB need not; they are able to lay eggs soon after emergence. The average fecundities of JPS and SBB were 32.9 and 90.5, respectively. Thus, the JPS lay fewer eggs for a long time with continuous maturation feeding, whereas the SBB lay more eggs for short time without maturation feeding. Average survivorship curves of JPS within dead pine trees in 8 pine forests were theDeevey's B type, showing a constant mortality through the pre-imaginal stages in the trees. On the other hand those of SBB in 4 cedar stands approached theDeevey's type, suggesting that the high mortality occurred at an early stage in the trees. Average mortalities of JPS between the appearance of oviposition scars and adult emergence in 8 forests ranged from 62.3% to 95.2%. Intraspecific ompetition of JPS resulting from overcrowding in dead pine trees appeared to be main mortality factor. For SBB, as most larvae were killed by resin flow in living trees, this appeared to be the main mortality factor for this species.     

Hymenolepis diminuta: membrane transport of glucose and beta-methylglucoside

Absorption kinetics of [¹⁴C]glucose and [β-methyl-¹⁴C]glucoside in Hymenolepis diminuta are reported. β-Methylglucoside (βMG) is a pure competitive inhibitor of [¹⁴C]glucose transport and has kinetic parameters, V_max and K_t, for transport similar to those reported for glucose. While absorbed ¹⁴C-βMG is not metabolized, transport of this glucose analog retains the general characteristics which have been established for glucose transport including: (1) Na⁺ dependence, (2) inhibition by K⁺, (3) sensitivity to phlorizin and various hexoses, (4) transport against an apparent concentration gradient, and (5) increase in worm water during accumulation. It is concluded that glucose and βMG are transported by the same system. The value of using βMG to study the mechanism of hexose transport and accumulation in H. diminuta is suggested.