Dysdercus Koenigii Research Articles

Studies on the neurosecretory system and the functional significance of NSM in the aortal wall of the bug, Dysdercus koenigii

The neurosecretory system of the bug, Dysdercus koenigii is described with the help of PF, PAVB, PATh in situ preparations, and sections. There are two groups of 9 to 10 A-cells in the pars intercerebralis medialis, and the NSM elaborated by them is found to be positive to cystine and/or cysteine. Their neurosecretory pathways immediately after formation cross each other and emerge as NCC I from the tritocerebrum. The NCC I run dorsal to the corpora cardiaca and innervate the aorta wall after completely bypassing these glands. NSM, elaborated by the A-cells and transported by their axons, is found in ample quantity in the aorta wall and the latter is therefore considered to be the neurohaemal organ for the A-material. Four to six B-cells are present in each pars intercerebralis lateralis, and their axons form NCC II after running directly and emerging also from the tritocerebrum. Distally the NCC II join the corpora cardiaca, and, on the basis of B-cell type material in the glands, they are considered as the storage-and-release organs for the B-material. The corpora cardiaca are not associated with the aorta wall and are found to be devoid of A-cell NSM. It is suggested that in D. koenigii two independent organ complexes: (1) the A cells, their pathways, and the aorta wall and (2) the B-cells, their pathways, and the corpora cardiaca constitute the neurosecretory system. The probable physiological significance of this anomaly is discussed.

‘Paper Factor’ as an Inhibitor of the Metamorphosis of the Red Cotton Bug, Dysdercus koenigii F.

MATERIALS composed of American paper-pulp have been shown to contain an extractable, heat-stable lipid which exhibits high juvenile hormone activity when topically applied or otherwise brought into contact with the European bug, Pyrrhocoris apterus L. (Heteroptera; Pyrrhocoridae1,2). The active principle is synthesized by certain species of pulp trees—more particularly, the American balsam fir (Abies balsamea). The ‘paper factor’ (PF) proves to be an extremely potent analogue of the juvenile hormone of Pyrrhocoris apterus3. Yet, so far, it has proved completely inactive when tested on other laboratory insects including two other species of Heteroptera—Oncopeltus fasciatus (Lygaeidae) and Rhodnius prolixus (Reduviidae)1,2.

Identity of veins in dysdercus koenigii (Fabr.) (Heterotera: Pyrrhocoridae) on the basis of development of wings

Identity of veins in dysdercus koenigii (Fabr.) (Heterotera: Pyrrhocoridae) on the basis of development of wings

Food Intake in Relation to the Growth of Dysdercus koenigii (Heteroptera)

The feeding activity of fifth-instar nymphs of Dysdercus koenigii (Fabricius) at different time intervals after the fourth molt can be expressed in terms of duration of feeding per individual in 4-hour periods, and on the basis of percentage of individuals showing a feeding response during a 30-minute or a 4-hour period. Fifth-instar nymphs began to feed about 16 hours after the molt. Their feeding activity reached the maximum level between 24 and 32 hours after ecdysis, then declined until about the 80th hour, after which there was no more feeding on cotton seeds until the nymphs had become adults. Feeding on cotton leaf or on water alone remained uniformly low throughout the instar, and was significantly less than feeding activity on cotton seeds during the active phase from the 17th to the 80th hour after the preceding molt. In nature the insects probably use the cotton leaf largely or wholly as a source of water. Individuals allowed continuous access to cotton seeds throughout the first four instars, but deprived of his food during the fifth instar, failed to mature as adults but survived as fifth-instar nymphs for twice the normal duration of the fifth instar. Individuals allowed to feed on cotton seeds for only a restricted period during each nymphal instar suffered higher mortality, but the survivors completed their development from egg to adult in a period only very slightly longer than that required by nymphs given continuous access to the diet.