• The Korean Journal of Pesticide Science
• /
• v.5 no.4
• /
• pp.11-19
• /
• 2001

This review discusses the effects and roles of insect hormones and insect growth regulators (IGRs) on vitellogenesis in adult insects. Insect vitellogenesis is regulated by hormones such as juvenile hormone (JH), ecdysteroids, and neurosecretory hormones (ovaryecdysteroidogenic hormone : OEH) released by neurosecretory cells, diet, and other elements(male specific protein of sperm fluid). In the fat bodies, the vitellogenins are synthesized by the stimulation of JH released by corpus allatum (CA) and ecdysteroids produced by follicle cells with the ovary in most insects. Furthermore, vitellogenins are released into the hemolymph, transported to the ovarioles by carrier protein, and incorporated into oocytes for the developing ovary. Of IGRs, juvenile hormone and its mimics such as methoprene and pyriproxifen appear to have pharmacological effects such as membrane lysis, destruction of salivary grand and midgut epithlial cells, fat body cells, and ovarian tissue, and also anti-juvenile hormone such as precocenes I and II appear to have specific cytotoxicity such as inhibition of corpus allatum and oocytes development. These results suggest that IGRs may be useful as agents for integrated pest management.

• Journal of Sericultural and Entomological Science
• /
• v.35 no.1
• /
• pp.28-35
• /
• 1993

Treatment of juvenile hormone analogue(JHA) at the 5th instar larvae prolonged the duration of adult development one to one and half days as well as the elongation of feeding time with the increasing of larval body weight. Morphological observation and protein analysis in hemolymphs, integuements, alimentary canals, fat bodies and ovaries also revealed that the development of these tissues and organs for adultation are affected by the JHA treatment.

• The Korean Journal of Pesticide Science
• /
• v.11 no.3
• /
• pp.164-170
• /
• 2007

The concept of innate immunity in insects which refers to the first line of host defense constitutes the humoral and cellular components which are involved in recognition and actively participate in the elimination of the intruding foreign micro- or macro-organisms. Several recent studies suggest that juvenile hormone (JH) modulates the cellular immune reactions in response to pathogen. In this study, pyriproxyfen (a JH agonist as an insect growth regulator) was tested in its any inhibitory effect on the immune reactions of the beet armyworm, Spodoptera exigua. To this end, five different hemocyte morphotypes of final instar S. exigua were identified by phase contrast microscopy. Plasmatocytes and granular cells, which constitute about 90% of the total hemocyte count, were prominently distinguished based on their basophilic/acidophilic nature using Giemsa stain. The role of pyriproxyfen on the functional ability of hemocytes was analyzed using FITC-labeled Providencia vermicola for the phagocytic potential of the hemocytes. Both granular cells and plasmatocytes exhibited phagocytosis behavior. Pyriproxyfen significantly inhibited the phagocytosis of both cell types, proposing its novel action as an immunosuppressant.

• Korean journal of applied entomology
• /
• v.35 no.3
• /
• pp.238-242
• /
• 1996

The second instar milkweed bugs, Oncopeltus fasciatus were exposed to the residue of 6-methoxy-7-ethoxy-2, 2- dimethylchromene(or 7-ethoxy precocene 11, 7-EP-11) with one, two, or four different kinds of synergist(s) deposited as a residue on 9 cm diameter petri dishes. The anti juvenile hormone analog, 7-EP-I1 yielded a 50% effectiveness concentration at 1.18 wg/cmZ. The concentration of 7-EP-I1 and R020-9747 combined gave 0.084 ~*g/cm', as much 14 times more potent than with 7-EP-I1 alone. Most of the other synergists, including geraniol, 4-chalcone oxide, isosafrole, and piperonyl butoxide however, showed comparatively low level synergism with 1.0-4.3 times, depending upon the combinations of the synergist(s). The obtained results were considered that R020-9747, an analog of benzopyran with similar structure to that of 7-EP-I1 inhibited selectively the insect monooxygenase oxidative defense mechanism, in the body except for corpora allata because general antioxidants of piperonyl butoxide, isosafrole, and 4-phenyl chalcone oxide showed relatively mild synergism.

• Korean journal of applied entomology
• /
• v.61 no.1
• /
• pp.109-115
• /
• 2022

Vitellogenesis is the process by which yolk accumulates in developing oocytes. The initiation of vitellogenesis represents an important control point in oogenesis. When females of the model insect Drosophila melanogaster molt to become adults, their ovaries lack mature vitellogenic oocytes, only producing them after reproductive maturation. After maturation, vitellogenesis stops until a mating signal re-activates it. Juvenile hormone (JH) from the endocrine organ known as the corpora allata (CA) is the major insect gonadotropin that stimulates vitellogenesis, and the seminal protein sex peptide (SP) has long been implicated as a mating signal that stimulates JH biosynthesis. In this review, we discuss our new findings that explain how the nervous system gates JH biosynthesis and vitellogenesis associated with reproductive maturation and the SP-induced post-mating response. Mated females exhibit diurnal rhythmicity in oogenesis. A subset of brain circadian pacemaker neurons produce Allatostatin C (AstC) to generate a circadian oogenesis rhythm by indirectly regulating JH and vitellogenesis through the brain insulin-producing cells. We also discuss genetic evidence that supports this model and future research directions.

• Korean journal of applied entomology
• /
• v.28 no.2
• /
• pp.82-87
• /
• 1989

Mass production of Spodoptera litura nuclear polyhedrosis virus (SINPV) was carried out on massively reared host insects. The yield of SINPV was maximal with $6.7{\;}\times{\;}10^9$ PIBs per larva on the 8th day post inoculation, when 5th instar larvae were inoculated with $1.1{\;}{\times}{\;}10^7$ PIBs per ml, and 2 g of artificial diet was sufficient for food consumption of a larva. The moribund larvae were more suitable for handling and mass production of virus than the completely dead larvae. The larvae, when treated with methoprene ($Manta^{\circledR}$), prolonged their larval period and consequently became bigger to result in higher yield(about 15%) of virus.

• Journal of Sericultural and Entomological Science
• /
• v.36 no.1
• /
• pp.26-29
• /
• 1994

The topical application of methoprene a kind of juvenile hormone(JH) on 4th instar larvae at 48th hour after ecdysis-3 , followed by insulin on 5th instar larvae and silkgland weights, cocoon weight and cocoon shell weight, and fecundity ; and significantly decreases percent of cocooning and moth emergence. After treatment with methoprene followed by insulin, cocoon weight increase by 17~20% and cocoon shell weights by 18~32% respectively.

• The Korean Journal of Zoology
• /
• v.37 no.4
• /
• pp.495-503
• /
• 1994

Hemolymph SHBP (hJHBP) was partially purified from last instar larvae of Bombyx zori by gel filtration and their optimal reaction conditions of dextrin coated charcoal binding assay were determined. Dissociation constant (KD) of hJHBP for JH III was calculated to be 1.45 $\times$ 10-7 M at $4^{\circ}C.$ The molecular weight of hJHBP was estimated to be 30 kDa by gel filtration on a calibrated Sephadex G-100 column and 33 kDa by SDS-PAGE. These results indicate that hSHBP consists of a single polvpeptide chain. Isoelectric point of hJHBP was found to be pH 5.1 and 19 of the first 20 amino acid residues were determined from N-terminus of purified hJHBP.

• The Korean Journal of Zoology
• /
• v.37 no.1
• /
• pp.66-75
• /
• 1994

Juvenile hormone binding protein was identified in the hemolymph of fifth instar larvae and purified using column chromatography. Hemolymph was mixed with [3H] JH-III and electrophoresed on 691 NON-SDS gel, indicating that radioactivity peak appears at Rf value of 0.55. Gel filtration showed two radioactivity peaks equivalent to bound and free [3H]JH-III, respectively. JHBP was purified from hemolymph through gel filtration (Sephadex G-100), anion exchange chromatosraphv (DEAE Sepharose CL-6B), chromatofocusing chromatographv (PBE 94) and preparative electrophoresis.

• Journal of Sericultural and Entomological Science
• /
• v.34 no.1
• /
• pp.15-20
• /
• 1992

Effects of starvation, ligation, refeeding and methoprene treatment in the feeding phase of the fifth instar larvae of Bombyx mori on the regulation of juvenile hormone esterase(JHE) activity were investigated. Starvation and ligation contributed to the reduction of JHE activity, however, JHE levels in starved larvae were slightly higher than in legated larvae. Haemolymph JEH activity of starved larvae was increased by refeeding, and duration of increasing time of JHE activity after starvation was related to duration of starvation. When starved larvae were applied methoprene topically, JHE activity were not changed at day 0 and 1, but were increased by 1.3-1.4 times between day 2 and 5. When ligated larvae were applied methoprene topically, JHE activity was not changed at day 0, but were increased by 1.9-2.3 times between day 1 and 5. These results suggest that head factor, juvenile hormone(JH) and nutrient are major factors in the regulation of JHE in the feeding phase of the fifth instar larvae of Bombyx mori. Especially JHE might be regulated by the co-operative action of head factor and JH. However, head factor plays important role in the early stage, while JH plays important role thereafter.