Adult reproductive behaviour in Asolus basalis (Hymenoptera: Scelionidae)

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ANIMAL BEHAVIOUR, X, 3-4

OVIPOSITION BEHAVIOUR OF THE YELLOW FEVER MOSQUITO, i.e. Aedes aegypta L. IN WEST AFRICA . By G . SURTEES, Pest Infestation Laboratory, Slough .

During 1955/58 the ecology and breeding behaviour of Aedes aegypte L . was studied in a southern Nigeria village. The village clearing was about half a mile in diameter and surrounded by secondary forest. It was found that breeding was restricted to water pots within the village and was more intense inside than outside houses . Breeding was almost totally absent from the abundant natural sites in the area . With the succession from village to forest conditions, certain changes in the nature of the potential breeding sites were observed . Those in the village were free from vegetable contamination and presented large, exposed surface areas of water . The reverse was true of forest sites . With regard to the intensity of breeding within houses, temperature and light intensity were regarded as important limiting factors . The importance of these factors as they influenced breeding behaviour was investigated in the laboratory.

When females were given a choice of ovipositing in water which varied in the degree of water contamination, relatively more eggs were laid in the purest water, even though a high degree of contamination had no deliterious effect on developing larvae . Oviposition was also more intense in dishes with relatively large surface areas and high water levels . The number of eggs laid in a series of dishes in a temperature gradient which ranged from 26 to 44°C . declined with increasing temperature . When oviposition was allowed in aa series of dishes placed in a light gradient ranging from 55 foot candles to less than one foot candle, more eggs were laid at the darker end . It was concluded, that in the case of this population, breeding was restricted to the immediate vicinity of the village by water contamination and to the insides of houses by temperature and light intensity.

THE LARVIPOSITION BEHAVIOUR OF APHIDS . By B . JOHNSON, Waite Agricultural Research Institute, Adelaide .

It is well known that the central nervous ments to the environment particularly with system of animals can produce effector stimuli respect to the control by the parent of the form of its progeny . Essentially the same general conof two principal kinds : those leading to muscular contraction and relaxation and producing what ditions favour reproductive as opposed to locoare known as behavioural responses, and those motory behaviour as favour the production of the apterous as opposed to the alate form . leading to physiological adjustments such as From an analysis of the factors involved in the through the production and release of neurosecretory substances . The types of neural responses it is clear that, despite the relatively small number of neurones in their central neractivity and integration leading to these two kinds vous system, aphids are able to integrate stimuli of response are not different from one another : in both, stimuli from receptors are received, of several different kinds and that this can include not only those which are currently present integrated and acted upon . Studies have been made in aphids on the inbut also some which were present earlier in the life of the animal but no longer prevail . This fluence of various environmental factors both on their skeleto-muscular responses leading to latter phenomenon is in some respects similar to latent learning . larviposition, and on their physiological adjustAfternoon Session MATERNAL BEHAVIOUR AND EARLY POST NATAL DEVELOPMENT IN THE BEAVER (Castor fiber). By L . WILSSON, Institute of Zoology, Stockholm University .

To study the relation between inborn and acquired elements in the behaviour of the bear, young beavers have been reared in isolation . The behaviour of these hand-reared specimens has been compared with the behaviour of wild

animals in captivity and in the wild . The handreared beavers have performed all the activities that are characteristic for the species . The pair formation has been observed in two couples . One of these reached mature age and the female