Spilostethus pandurus pdf

The collection area was mainly covered with shrubs of C. Green leaves of the three plants above were offered t o the insects every 24 hours. The food preference of S. The plants tested were C. T w o types of food choice-chambers were used. The first was made of a circular metal ring 5 cm high and 14 cm in diameter. The inside space of the ring was divided into four equal compartments using hard paper. The partitions were incomplete allowing free move- ment of the insects from one compartment t o the other.

The second food-choice-chamber was a wooden cage measuring 48 X 48 X 20 cm with sides made of mosquito netting. H a l f the space of the cage was divided into four equal chambers by incomplete vertical partitions. The position of the defense gland's orifices of S. The insect was then stained in acid fuchsin and cleared in xylene.

The orificies could also be spotted by squeezing the thoracic region and marking the area where the secretion excluded. Abushama, A. Ahmed The structure of the defense gland was studied by cutting transverse series sections through the head and thorax of adult insects.

The material was double embedded. The tissue was then embedded in paraffin wax. Sections 8 p zyxwvuts thick were cut and stained in eosin-haematoxylin. The procedure used for the extraction of cardenolides from various tissues was based on that of the lipid exraction method by FOLCHet al.

Glycosides normally appear as purple spots. Orange spots were accentuated by spraying the plate with concentrated sulpharic acid till the background became white. Extracts from S. Chloroform-methanol lO was used as solvent. Silica-gel plates spotted with the different extracts were sprayed with the chloromine- trichloro-acetic acid reagent and heated for 7 min at looo C in dry air.

Results 3. Food preference I n a preliminary experiment one leaf each of C. The fourth compartment of the chamber was left empty. The successive photographs taken at five minute intervals indicated the preference of S.

In the second experiment, 15 adults aRer being starved for 24 hours were introduced in the ring food choice-chamber prepared as above. The distribu- tion of the insects was recorded every 10 minutes.

AAer each reading, the zyxwvu insects were taken out of the apparatus and placed in an innert air chamber for five minutes before being used again in the experiment. This was repeated ten times and the mean result is shown in fig. The distribution indicated a significantly higher percentage of S. Fresh leaves of C. These areas were first examined under the microscope be- fore the leaves were offered t o the insects in the separate compartments of the cage.

Distribution of S. Feeding activity of S. ARer 24 hours the number of sucking marks on the exposed sur- faces of the leaves were counted.

The experiment was repeated ten times and the mean result shown in fig. It is to be seen that S. Defense gland The position and structure of the defense glands of S. Each gland opened to the outside through two orifices, one on the base of the prothorax and the other a short distance in front fig. The insect discharged its defense gland's contents when handled. The turbid secretion exuded, solidified on standing. The defense gland, dissected under the microscope, composed of two membranous sac-like structures each in a groove on the dorsolateral side of the prothoracic tergite fig.

Ahmed layers of cells. The cells of the inner layer were laden with dark stained globules indicating a probable secretive function. This is lined from inside with a thin cuticular layer. The outer layer is of large epithelial cells fig. Position and structure of S. Function of the gland Experiments were carried out in order to clarify the role played by the glands in the defense of S.

To the starved cat, fresh beef covered with defense gland secretion was offered. The experiment was repeated five times and the mean result is shown in table 1. This indicates that the predators tested, all rejected S. The predators however actively selected and ate the grasshoppers offered while they rejected those grass- hoppers whose bodies had been covered with the defense gland secretion.

Cats also rejected meat smeared with the latter secretion. Mean percentage of meals eaten by three different insect predators Mean oercentaze of meals. House sparrow Passer domesticus 0 S. Analysis of defense gland and food-plants extracts zyxw Occurrence of cardenolides in extracts from: defense glands of S.

Table 3. Rfs range of extracts from S. Number of detecred 2 zyxwv card e n o I I d e s Rfs range 0. Ahrned above. The result is shown in table 2. Birch L. Bongers J. Butani D. Indian J. Chopra N. Dingle H. El-Sherif H. Thesis, Cairo Univ. El-Sheriff H. Egypt 71, 61— Garcera M. Hokyo N. I—Incidence and intensity. Entomol Zool. Kapoor K. India J. Plant Prot.

Kugelberg O. Ent, Exp. Mailloux G. May R. Blackwell Scientific Publications, Oxford. McDonald G. Parihar D. Forestry 4, — Price W. Priesner H. Fouad 1er Ent.

Prabhakar B. Ram P. Solbreck C. Oikos 60, — I—Habitat batch structure and spatial dynamics. Oikos 58, — Thangavelu K. Indian Acad. Insects 15, 93— Vishakantaiah M. Madras Agric. Download references. You can also search for this author in PubMed Google Scholar. Reprints and Permissions. El-Shazly, M. Int J Trop Insect Sci 16, 17—25 Download citation. Accepted : 14 May Published : 14 May Issue Date : March Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article.