Endocrine control of fat body composition and effects of the insect growth regulators methoprene and pyriproxyfen on the development and reproduction of the Argentinian cockroach, Blaptica dubia Serville (Blattaria: Blaberidae)

The present study analysis physiological and endocrine aspects of female adult life of the ovoviviparous Argentinian (Dubia) cockroach, Blaptica dubia. Experiments were done during the first (days 5 to 25 after emergence) and second gonadotropic cycle (days 80 to 100 after emergence), and whilst the period of oothecal transport (gestation) and hatching of the nymphs (around day 70 of adult life for the first gonadotropic cycle). Body weight changes of adult females are closely related with the reproductive processes of ovarian growth, ootheca formation, ootheca deposition, and hatching of the nymphs. The biochemical composition of the fat body was analyzed and revealed the storage lipids as main constituents, followed by glycogen, proteins and free carbohydrates. Changes in fat body chemical constituents as well as in fat body fresh weight correlate well with the reproductive processes. Concentrations of juvenile hormone (JH) III and free ecdysteroids (ecdysone, 20-hydroxyecdysone) were measured in the haemolymph of adult females by the use of HPLC-mass spectrometry. The JH III titer shows significant peaks during vitellogenesis and ovarian growth, and towards the end of the period of gestation. Changes in the concentration of free ecdysteroids in the haemolymph were less clear. Treatment of adult females with the juvenile hormone analogue methoprene during the first 20 days of adult life (topical application of 100 μg methoprene in acetone per day) retarded ovarian development and blocked the formation of the ootheca. The inhibition of the ootheca formation went in line with reduced titers of JH III and free ecdysteroids in the haemolymph of such treated females. Methoprene treatment of females, which had normally developed during the first gonadotropic cycle, from day 30 to 70 of adult life resulted in a complete reabsorption of the ootheca. The JH III titer of such treated females was also reduced, whereas free ecdysteroids were hardly affected. Treatment of adult females with another JH mimic, pyriproxyfen (100 μg per treatment) gave similar results than those for methoprene usage. The results show that both JH analogues have a clear ovicidal activity resulting in “sterilization” of the females and can be used as “third generation pesticides” in adult cockroach biocontrol.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Bayreuth

Year

2013

Author dc:creator

• Alhasan Alamer, Ahmad

Contributors dc:contributor

• Hubert Hoffmann, Klaus

Repository record source_url

https://epub.uni-bayreuth.de/id/eprint/136/

OAI identifier oai:identifier

oai:epub.uni-bayreuth.de:136