Metamorphosis of the red flour beetle,Tribolium freemani Hinton (Coleoptera: Tenebrionidae): Alteration of octopamine content modulates activity of juvenile-hormone esterase, ecdysteroid level, and pupation

Abstract

Under crowded conditions, Tribolium freemani larvae exhibited a delay in the increase of octopamine (OA) content, activity of juvenile‐hormone esterase (JHE), and ecdysteroid content, leading to a delay in pupation compared to the larvae under isolated conditions. Under crowded conditions, a peak OA content appeared at days 2–4, followed by a peak of JHE activity at day 7, the second OA peak at day 9, and an ecdysteroid peak at day 11 of the instar. Optical stress, on the other hand, caused an increase in OA and ecdysteroid contents, leading to an acceleration of pupation compared to controls. Whole‐body OA content reached its maximum 3 days before pupation and the ecdysteroid level 2 days later in larvae isolated, crowded, or optically stressed. The OA content, JHE activity, and ecdysteroid level showed a similar pattern after pupation till adult emergence both in crowded and uncrowded animals: peaks of OA content and JHE activity were observed at pupation, followed by the highest peak of ecdysone 4 days later (2 days before emergence). The ecdysteroid levels were higher in the crowded larvae reared under 24 h light conditions or treated with OA agonists than those in control larvae kept in the dark. Hence, isolation and optical stress increase OA content followed by JHE activity and ecdysteroid titer, leading to changes in metamorphosis program. Some OA agonists actually had the same effect as isolation and optical stress did, suggesting that OA is a causative agent in pupation programming of T. Freemani by inducing an increase in JHE activity, thus decreasing JH titer followed by an increase in ecdysteroid level and delayed pupation. Arch. Insect Biochem. Physiol. 37:34–46, 1998. © 1998 Wiley‐Liss, Inc.

Comparative Studies on the Larvicidal Action of Novaluron (Mosquiron® 100EC) and Moringa Oliefera (LAM) Seed Oil against Aedes Aegypti (Diptera: Culicidae) Larvae

“…Novaluron action is by chitin inhibition according to Soltani et al (1995), Mulla et al (1974Mulla et al ( , 2003 and Kostyukovsky and Trostanetsky (2004) for novaluron and MOSO action as growth regulator and by blocking the respiratory surfaces. According to Hirashima et al 1998, Enan, 2001) some plant essential oil block the octopamine neuroreceptors that regulate the movement, heart rate, behaviour, metabolism, and pupation of insects. This regulatory activity of these two insecticides was evidenced by the death recorded in both 1 st and 4th instar larvae and inhibition of their emergence to pupae.…”

Juvenile Hormone Paces Behavioral Development in the Adult Worker Honey Bee

“…Such a stress effect could be mediated by JH, as this hormone is known to be sensitive to stress in a variety of insect species (Jankovic-Hladni, 1991). Other neuroendocrine factors could be involved, such as the biogenic amine octopamine (Hirashima, Takeya, Taniguchi, and Eto, 1995;Hirashima, Hirokado, Tojikubo, Takeya, Taniguchi, and Eto, 1998). Grabbing a bee with forceps and holding its legs in an alligator clamp for several minutes triggers a transient increase in octopamine levels in the bee brain (Harris and Woodring, 1992), and high brain octopamine levels are associated with foraging (Harris and Woodring, 1992;Wagener-Hulme, Kuehn, Schulz, and Robinson, 1999;Schulz and Robinson, 1999).…”

How Tyramine β-Hydroxylase Controls the Production of Octopamine, Modulating the Mobility of Beetles

“…In locusts, OA plays an important role in flight activity [ 7 ] and olfactory attraction [ 8 ]. In Tribolium freemani, OA was reported to modulate the activity of the juvenile hormone esterase [ 9 ]. It has been previously suggested that OA could modulate various behaviors in the model insect Drosophila melanogaster [ 1 ].…”