A review of the pre-oviposition behaviour of small cabbage white butterfly, Pieris rapae(lepidoptera: Pieridae)

This paper reviews the literature concerning the ovipositional behaviour of Pieris rapae (small cabbage white butterfly) and where appropriate considers results from studies involving other butterflies. The paper considers searching behaviour, stimuli utilised in host plant finding and identification and concludes with a general section on the role of learning and prior experience in ovipositional behaviour.     

The functional morphology of the feeding appendages and gut of Hippolyte varians (Crustacea: Natantia)

The musculature of the feeding appendages are described and compared with those few early accounts of other Decapoda, particularly those of Pandalus danae and Astacus fluviatilis . While the musculature is very similar to that of the latter, the relative importance of the various muscles may differ markedly and a number of previously undescribed muscles have been found, while others present in Pandulus and Astacus are not present in Hippolyte . The alimentary canal is also described, together with its associated musculature. The function of the various appendages and the parts of the gut are described from observations of living specimens.     

The inheritance of preference for strains of Rhizobium trifolii by white clover (Trifolium repents)

The preference or selection of Rhizobium strains by both parental and F₁ white clover plants was studied using antibiotic resistant mutants of Rhizobium trifolii. Highly significant differences were found between crosses in their preference for 75 str. Progenies from crosses between plants in which the preference for 75 str was 90–100% had 85% of the nodules inhabited by that strain. Progenies of crosses between plants in which the preference for 75 str was less than 50% had only 13% of their nodules inhabited by 75 str. Intermediate values were found for progenies from other crosses. The inheritance for this particular character was clearly additive and without any dominance or maternal effect. The results are discussed from the point of view of improving symbiotic nitrogen fixation by breeding white clover for uniform preference for effective strains of R. trifolii.     

Primary feather lengths may not be important for inferring the flight styles of Mesozoic birds

Chan, N.R., Dyke, G.J. & Benton, M.J. 2013: Primary feather lengths may not be important for inferring the flight styles of Mesozoic birds. Lethaia, Vol. 46, pp. 146–152. Although many Mesozoic fossil birds have been found with primary feathers preserved, these structures have rarely been included in morphometric analyses. This is surprising because the flight feathers of modern birds can contribute approximately 50% of the total wing length, and so it would be assumed that their inclusion or exclusion would modify functional interpretations. Here we show, contrary to earlier work, that this may not be the case. Using forelimb measurements and primary feather lengths from Mesozoic birds, we constructed morphospaces for different clades, which we then compared with morphospaces constructed for extant taxa classified according to flight mode. Consistent with older work, our results indicate that among extant birds some functional flight groups can be distinguished on the basis of their body sizes and that variation in the relative proportions of the wing elements is conservative. Mesozoic birds, on the other hand, show variable proportions of wing bones, with primary feather length contribution to the wing reduced in the earlier diverging groups. We show that the diverse Mesozoic avian clade Enantiornithes overlaps substantially with extant taxa in both size and limb element proportions, confirming previous morphometric results based on skeletal elements alone. However, these measurements cannot be used to distinguish flight modes in extant birds, and so cannot be used to infer flight mode in fossil forms. Our analyses suggest that more data from fossil birds, combined with accurate functional determination of the flight styles of living forms is required if we are to be able to predict the flight modes of extinct birds. □Birds, flight, morphospace, Mesozoic, wing.     

Asymptotes of diseases caused by non-specialised fungal pathogens in intraspecific mixed stands of cereal cultivars

A model describing disease progress of non-specialised fungal pathogens in intraspecific mixed stands of cereal cultivars (Jeger, Griffiths & Jones, 1981b) has been extended beyond the logarithmic phase of disease development. The extended. logistic model indicates that whatever the outcome in the early stages (disease less than or more than the mean of disease in the pure stands), disease will eventually level off at a value equal to the mean of disease asymptotes in the pure stands. The time scale involved in such levelling-off, however, means that substantial benefit may still be expected from deployment of such mixtures. Analytical solutions for the model are obtained for the special case where the ratio of disease asymptote to initial disease is the same for each pure stand.     

Predisposition to Septoria nodorum as a result of take-all (Gaeumannomyces graminis) infection of wheat

In a series of experiments excised leaves from take-all infected wheat plants and from control plants were inoculated with Septoria nodorum. Larger lesions, more lesions/leaf and more pycnidia/unit area of lesion were produced from take-all plants. Significant effects of predisposition were demonstrated when only 3% of the area of the total root system was infected by take-all. Microscopical investigations revealed that germ-tubes of S. nodorum grew more rapidly on leaves from take-all plants, but the time of penetration was not affected. It is proposed that the observed effects of predisposition arose because more germ-tubes produced successful infections and host tissue was more rapidly colonised. The importance of these results for the epidemiology of glume blotch is discussed.     

Effects of powdery mildew at different growth stages on grain yield of barley

Pot-grown barley plants (cv. Proctor) were exposed to infection by powdery mildew during four stages of development, G.S. 2–6, G.S. 7–9, G.S. 10-10-5 and G.S. 11 (Feekes scale, Large, 1954). All combinations were examined (i.e. 2⁴ factorial). The numbers of fertile tillers at harvest were significantly reduced by mildew during periods G.S. 2–6 and G.S. 7–9. Numbers of grains per head and grain size (1000 grain weight) were significantly reduced by mildew only during G.S. 2–6. Effects, on components of yield, of the four mildew treatments were found to be almost entirely additive. The only significant interactions found were for grain size: in this instance there was some interaction between treatments at G.S. 2–6 and G.S. 10-10-5 and between treatments at G.S. 2–6, G.S. 7–9 and G.S. 10-10-5.