This document summarizes the tanning process of cockroach ootheca (egg cases). It explains that the female cockroach carries the ootheca until the eggs hatch. The ootheca hardens through a natural tanning process where secretions from the left and right collateral glands of the female interact. The left gland secretes structural protein and an enzyme, while the right gland secretes an acid. When mixed, the acid is released and oxidized to form quinone, which cross-links the protein molecules, hardening the ootheca into a protective sclerotin casing. A schematic representation is provided to illustrate the interaction of secretions from the two glands during tanning.

1. AN INSIGHT ON TANNING OF COCKROACH OOTHECA
Presented by
Sabhavat Srinivasnaik
D. Sai Charan
Course In-charge
Dr.P.Swarna Sree, Professor
Department of Entomology
DEPARTMENT OF ENTOMOLOGY
COLLEGE OF AGRICULTURE, RAJENDRANAGAR
PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY

2. BIOECOLOGY OF COCKROACH
• The female cockroaches carry an egg case or ootheca until
egg hatch occurs. The egg case is 12–15 mm long, light-
coloured, and crescent-shaped. Normally there are about
25–35 eggs per egg case.
• The first ootheca is normally produced about 1 week after
adulthood is attained. Eggs require about 35 days for hatch
to occur when held at 18–24°C.
• Females require 50–80 days between broods. The adult
female typically produce three broods annually, but the
range is one to five. On average, P. indica produces more
eggs than P. surinamensis, although cockroaches from
different geographic locations vary in their reproductive
capacity

4. Introduction
• The name sclerotin was given by Pryor (1940) to
proteins that owe their stability to a process of natural
tanning, which is brought about by the introduction of
aromatic cross-linkages between the protein chains.
The best known of these sclerotizing agents are ortho-
quinones (derived from ortho-dihydroxyphenols).

5. TANNING OF OOTHECA
• The tanning of the protein of insect cuticles is due
to the tanning action of an agent produced by
oxidation of a phenolic agent.
• The walls undergo a process of natural tanning, as a
result of which their constituent substance at first
soft and colorless proteinaceous material, is
changed into a hard and inert sclerotin.
• The material of which an ootheca is composed is
largely derived from the secretions of the two
collateral glands.

6. • The hardening of the cockroach ootheca is an
analogous process and the phenolic substance
responsible in this case is ortho quinone which is
technically 3: 4-dihydroxybenzoic acid
(Protocatechuic acid).
• It has been found that the left collateral gland secretes
the structural protein, a polyphenol oxidase and 4-0-
β-glucoside of Protocatechuic acid, while right
secretes the β-glucosidase.
• Not only this acid but an aqueous solution of
synthetic protocatechuic acid in presence of oxygen
produces the characteristic darkening effect of the
secretion of the right collateral gland of the female
cockroach upon the protein secretion of the left gland.

7. • When mixed in nature or under experimental
conditions, the secretions interact and the β-
glucosidase liberates Protocatechuic acid from its β-
glucoside.
• The resulting acid is then oxidized in the presence of
the oxidase to a quinone which is believed to form
cross linkages between adjacent molecules of the
structural protein giving the tanned product,
Sclerotin.

9. Schematic representation of the interaction of the
secretions of left and right collateral glands of
Periplaneta and Blatta

10. Thank you