Process generating the ditribution pattern of eggs of the common cabbage butterfly,Pieris rapae crucivora

The process generating the negative binomial in the distribution pattern of eggs of the common cabbage butterfly, Pieris rapae crucivora, was investigated by releasing the female adults in a net house where cabbages were planted. The distribution of butterflies visited and laid an egg or more per plant followed thePoisson series under the uniform light condition, while that of eggs laid per visit conformed to the logarithmic distribution. From these results, it may be concluded that the negative binomial arises from compounding of thePoisson and the logarithmic distribution. The observed frequency of eggs found per plant fitted to the negative binomial with parameter thus computed theoretically. The change in the degree of aggregation with the increase of the parental density was considered in connection with the above results.     

On the distribution of the common cabbage butterfly,Pieris rapae crucivora,in the field

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Contributions from the Department of Biology, Miyazaki University, No. 45.     

Pattern of spatial distribution of the common cabbage butterfly,Pieris rapae in a cabbage farm

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Contributions from the Entomological Laboratory, Kyoto University, No. 203.     

Dispersive behaviour of larvae of the common cabbage butterflyPieris rapae crucivora

To investigate the aggregative nature of the larvae of Pieris rapae crucivora, each 50 individuals of the 4th and 5th instar larvae collected from cabbage farms and reared under crowded and solitary conditions were released on an experimental arena and their dispersive behaviour was observed with the lapse of time. Both the 4th and 5th instar larvae showed the trend to approach toward random distribution when they were released under clumped condition, and they maintained random distribution when they were released at random. Therefore, it may be concluded that the larvae have not any aggregative nature caused by the mutual attraction among individuals. However, as the larvae reared in crowds sometimes showed the slight aggregative behaviour, it seems that the larval dispersal is different between densely and sparsely populated plants in field.     

Avoidance of maladaptive,precocious copulation in the cabbage white butterfly,Pieris rapae crucivora

In the cabbage white butterfly, Pieris rapae crucivora, copulation hinders normal expansion and hardening of the wings of newly emerged females. The resulting permanent wing deformation makes it impossible for females to fly and therefore, to find an oviposition site and nectar sources. An attempt was made to clarify whether the newly emerged female butterfly avoids copulation. Observation of wing expansion and hardening reveals that the wings are fully expanded and hard by 20–30 min after emergence. In the field, presentation of females with soft wings to males shows that males will attempt to copulate with these females. However, newly emerged females prevent successful completion of copulation by assuming the mate refusal posture, and thereby avoid a potentially maladaptive copulation. The discussion focusses on the question as to why females and not males avoid early copulation.     

Mate preference in males of the cabbage butterfly, Pieris rapae crucivora, changes seasonally with the change in female UV color

We initially investigated whether females of the cabbage butterfly, Pieris rapae crucivora, exhibit a seasonal change in ultraviolet wing color, which is a key stimulus for mate recognition by conspecific males, and whether and how a seasonal change affects the mating behavior of the males. We found that female UV wing color changes seasonally, the color being more pronounced in summer than in spring or autumn. We also demonstrated that male mate preference changes seasonally, concomitantly with the change in female UV color. Specifically, males appearing in summer exhibit a mating preference for summer-form females over spring- or autumn-form females, while those appearing in spring or autumn exhibit no seasonal preference, thereby facilitating more effective mate location. Our results suggest that this field of study will require more strictly controlled experimental investigation in which the seasonal change in UV color is considered when UV-influenced mating behaviors such as mate choice are investigated.     

Associative learning in the ovipositional behaviour of the cabbage butterfly, Pieris rapae

ABSTRACT. When tested with familiar and novel oviposition sites, gravid female Pieris rapae (L.) tended to land on sites of the same appearance as those they had experienced 24 h earlier. This acquired preference could be reversed by subsequent e xperience. An ovipositional preference, shown by groups of insects, paralleled the landing preferences of single insects. These influences of experience were shown with intact cabbage plants of different kinds, with discs cut from the leaves of different kinds of cabbage, and with discs of blotting paper of different shades of green and blue, wetted with sinigrin solution or water. A single landing by a gravid female on paper wetted with sinigrin solution induced a landing preference for the same colour of paper in a choice test made 24 h later. Gravid females thus associated a favourable chemical stimulus of oviposition with the appearance of the acceptable site. Such learning by trial and error would facilitate host-selection from a distance. In the laboratory it induced oviposition on 'neutral' sites of the same appearance as 'host' sites.     

Fine structure of the stretch receptor in the bursa copulatrix of the butterfly,Pieris rapae crucivora

Summary A pair of multipolar stretch-receptive neurons were found in the bursa copulatrix of the female cabbage white butterfly, Pieris rapae crucivora. The cell body of each neuron, about 10 m in diameter, lies on the edge of the muscular region in the antero-lateral wall of the corpus bursae. No special accessory structure, such as a receptor muscle, is associated with the neuron. The several dendrites extend radially into the muscle layer. The dendrites are ensheathed except for their terminal tips, and, on their course, they anchor repeatedly on the epithelial cells or the muscle fibers in such a manner that their basement membranes fuse together. While the ensheathed dendrite is usually 0.1–0.2 m in diameter, it often forms 1–2 m varicosities especially at anchor sites, so that it looks like a varicose, or beaded, chain. The varicosities contain a number of mitochondria, but only microtubules are found in the fine interconnecting parts of the dendrite. The naked dendritic tips terminate in the basement membrane of the epithelial cell. The varicosities, as well as naked tips, seem to be important for stimulus transduction in the sensory cell of this type.     

Basic unit of population observed in the distribution of the rice-stem borer,Chilo simplex,in a paddy field. Pattern of the spatial distribution of insect. 4th report

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Contributions from the Entomological Laboratory, Kyoto University, No. 231.     

The learning abilities of the white cabbage butterfly,Pieris rapae,foraging for flowers

This study examines the role of learning and memory in the butterflyPieris rapae crucivora Boisduval during foraging for flowers. In an outdoor cage with 6 flower species,P. rapae showed various visiting patterns: some visited only one species, while others visited several species in a day. The foraging process for flowers ofErigeron annuus (L.) Pers. could be divided into two successive steps: (1) landing on the nectaring caputs, and (2) finding the source of nectar in the caput. Butterflies learned to proceed through the two steps more efficiently with successive attempts: they gradually decreased landings on nectarless caputs and probings on the nectarless petals of ligulate flowers respectively. As a result, handling time per unit caputs became shorter, and apparent rewards per unit time, i.e. the efficiency of collecting nectar, increased. In addition, once learned,P. rapae could remember a rewarding flower color for 3 days, which was not interfered with by learning another flower color. This indicates thatP. rapae keeps memory for a period longer than 3 days, and that they can remember at least two flower species as suitable flower resources. Furthermore, data indicated that they sometimes can apply the foraging skills obtained on other flower species to a novel one. These abilities could enable butterflies to easily switch flower species, or to enhance labile preference. It has been known thatP. rapae also shows flower constancy, which may be due to memory constraints. Therefore, they may appropriately use two foraging tactics: visit consistency and labile preference, to get enough nectar according to their circumstances.     

Constituents of host- and non-host plants deterring oviposition by the cabbage butterfly, Pieris rapae

Oviposition by Pieris rapae L. on cabbage was deterred by homogenized cabbage tissue sprayed onto intact plants. Ether extracts of cabbage also were deterrent, but water extracts were not. Hexane extracts of other host plants deterred oviposition and water extracts had little or no effect. Polar as well as non-polar extracts of non-host plants inhibited oviposition. Polar deterrents in the non-host crucifers, Erysimum cheiranthoides and Capsella bursa-pastoris may explain the avoidance of these plants by P. rapae. Chemical deterrents, as well as stimulants, apparently play a major role in the acceptance or rejection of plants as hosts by ovipositing female butterflies.

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Zusammenfassung Die Eiablage von Pieris rapae auf Kohl wurde gehemmt von einem Homogenisat aus Kohlblättern, das auf intakte Pflanzen gesprüht wurde. Ether-Extrakte der Kohlblätter wirkten im Gegensatz zu Wasserextrakten abschreckend. Ebenso zeigten Hexanextrakte anderer Wirtspflanzen eine hemmende Wirkung auf die Eiablage, während Wasserextrakte anderer Wirtspflanzen keine Wirkung aufwiesen. Dagegen aber verhinderten sowohl polare als auch unpolare Extrakte von Nicht-Wirtspflanzen die Eiablagen. Polare, abschreckende Substanzen in den Nicht-Wirtspflanzen Erysimum cheiranthoides und Capsella bursa-pastoris (Cruciferae) könnten Ursache dafür sein, dass P. rapae diese Pflanzen meidet. Chemische Substanzen mit sowohl abschreckender als auch stimulierender Wirkung spielen offensichtlich eine bedeutende Rolle für legebereite Schmetterlingsweibchen bei der Auswahl von Pflanzen als geeigneten Eiablageplatz.

     

Purification,characterization, and synthesis of vitellin from the cabbage butterfly Pieris rapae L.

Vitellin from the cabbage butterfly Pieris rapae L. was purified and characterized by electrophoresis. Vitellin from P. rapae is a phosphorylated glycolipoprotein of 380,000 ± 10,000 molecular weight as determined by nondenaturing polyacrylamide gel electrophoresis. Two subunits with an M_r of 150,000 and 40,000 were obtained from vitellin. The native molecule is thought to be a tetramer composed of two molecules of each of these subunits. The isoelectric point, as determined by isoelectric focusing on polyacrylamide gels, is 6.10. Vitellin and vitellogenin were indistinguishable by immunological methods such as double diffusion and tandem-crossed immunoelectrophoresis. Vitellogenin from the hemolymph and vitellin from the ovary were quantified by rocket immunoelectrophoresis. Vitellogenin and vitellin were first detected in 6-day-old pupae, and their levels increased continuously during ovarian development. Vitellogenin synthesis by the fat body in 4-day-old female pupae could be induced by juvenile hormone I.     

The spatial distribution of the wheat-bulb fly,Leptohylemyia coarctata (fall.) (Diptera: Anthomyiidae)

The spatial distribution of the eggs, larvae, pupae and adults of the wheat-bulb fly was investigated by fitting 42 sets of data comprising 1334 samples to the Poisson and negative binomial distributions, and by using the power law (S²=am^b). In general, the tests indicated that all stages were aggregated and fitted the negative binomial model.     

Female size and age-specific fecundity in the small white butterfly,Pieris rapae crucivora Boisduval (Lepidoptera: Pieridae)

Individual differences in several reproductive parameters of female Pieris rapae were investigated in a controlled laboratory condition. Lifetime and age-specific fecundity showed considerable variability between individuals. Larger females began oviposition at an earlier age than smaller ones, and larger females were more fecund than smaller ones. Larger females laid a larger proportion of their eggs in the early stages of their reproductive lifetime, whilst smaller females laid the larger proportion of their eggs later in their reproductive lifetime. The significance of the variance in age-specific fecundity associated with female size is discussed with respect to the seasonal change in size and habitat utilization of this species.     

Long-term changes in the oviposition behaviour of the cabbage butterfly, Pieris rapae, induced by contact with plants

ABSTRACT. Contact between the tarsi and cabbage foliage was found to have important influences on the oviposition behaviour of Pieris rapae , whereas contact between the ovipositor tip and cabbage foliage showed no influence. Oviposition on a leaf disc was not influenced by the presence of previously laid eggs. Gravid female P.rapae showed an increased tendency to approach and land on host or non-host foliage, or on yellow or green cards, after tarsal contact with cabbage foliage. This effect persisted for at least 72h. It was accompanied by an increased tendency to oviposit on non-host plants, most obviously within seconds of contact with cabbage, but with some persistence after 72h. Contact with a non-host leaf (lettuce) reduced the tendency of females to land on plants, but this effect was less pronounced than the one induced by contact with cabbage. These behavioural changes were immediate as well as long-term and were not associated with changes in the ovaries, so they probably result from the direct effects of sensory input on the CNS. Such behaviour probably increased the likelihood that gravid females would locate host-plants for oviposition in the field. For tests of host-plant specificity, the implications are that the behaviour of gravid females towards an array of plants might differ according to the presence or absence of hosts, not only during the test, but also during the preceding several days.