The effects of precocenes in grasshoppers Heteracris littoralis (Orthoptera: Acrididae)

Abstract

Prococenes I or II (20-100/jg/insect) were topically applied to third instar nymphs of the grassh«pper, Heteracris littoralis. Both compounds led to different degrees of precocious metamorphosis, .irreversible with time, at the subsequent moults. Precocene-treated third instar nymphs gave rise to precocious adults at the following moult, though some of the nymphs responded and metamorphosed precociously in the fifth instar. Ovarian development was inhibited by precocene II. Meanwhile, juvenile hormone (20/xg/insect) restored normal ovarian development to some extent.Resume-Le precocene I ou II (20-100/ig/insecte) ont ete localement applique pour nymphes au 3eme stade de Heteracris Littoralis.Les resultats avec l'un ou 1'autre compose conduit pour different metamorphose precoce, irreversible avec le temps, en subsequante mue. Bienque, la 3eme stade treatee par le precocene donne qulques adultes precoce en mue suivante, authre percentage de nymphes a repondre et metamorphose precocete dans la 5eme stade. L'utilisation de precocene II a montre en empechement le developpment d'ovariane. En meme temps, JH III (20/jg/insecte) a paru remettre le developpment d'ovariane jusqu'a sertain niveau.

Physiological Activities of Anti-Juvenile Hormone Agents Against Insects and Their Role For Devising Fourth Generation Insecticides: A Comprehensive Review

“…Different doses of PI or PII (20-100 μg/insect) were topically applied onto the 3 rd instar nymphs of Mediterranean splendid grasshopper Heteracris littoralis. Different degrees of precocious metamorphosis were irreversible with time, at the subsequent moults (Alrubeai, 1986). Pener et al (1986) treated the late embryos or newly hatched 1 st instar nymphs of the locust L. migratoria with precocenes and observed precocious appearance of adult features after the second larval molt, but not earlier.…”

“…Depending on their results, a single application of 10 μg/insect, at the beginning of the post-ecdysial period, onto the noninseminating adult females caused inhibition of oöcyte maturation. The ovarian maturation in the grasshopper H. littoralis was inhibited after topical application of PII (doses of 20-100 μg/insect) onto the 3 rd instar nymphs (Alrubeai, 1986). In blow fly Phormia regina, oocyte development was drastically retarded after treatment with PII and application of a JHA methoprene reversed the the inhibitory effects of precocene on the oocyte development (Yin et al, 1989).…”

Assessment of the toxic and disruptive effects of Precocene II on growth and metamorphosis of the grasshopper Euprepocnemis plorans plorans (Charp.) (Orthoptera: Acrididae).

“…Within Orthoptera, exposure of 4 th instar nymphs of the desert locust Schistocerca gregaria to PII (15 µg/cm 2 ) induced precocious adultoids (Salem et al, 1982 a, b). Different doses of PI or PII (20-100 μg/insect) induced precocious metamorphosis in the Mediterranean splendid grasshopper Heteracris littoralis (Alrubeai, 1986). Among Hemiptera, PII induced precocious metamorphosis in the kissing bugs Rhodnius prolixus and Triatoma dimidiata when applied by either contact exposure or fumigation (Tarrant et al, 1982).…”