Interaction of proteinase inhibitors with Cry1Ac toxicity and the presence of 15 chymotrypsin cDNAs in the midgut of the tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae)

2012 ◽  
Vol 68 (5) ◽  
pp. 692-701 ◽  
Author(s):  
Yu Cheng Zhu ◽  
Sandy West ◽  
Fanny X. Liu ◽  
Yueping He
2019 ◽  
Vol 19 (3) ◽  
Author(s):  
Marisa Nardiello ◽  
Rosanna Salvia ◽  
Andrea Scala ◽  
Carmen Scieuzo ◽  
Sabino Aurelio Bufo ◽  
...  

Abstract Prothoracicotropic hormone (PTTH) is a neuropeptide that triggers a cascade of events within the prothoracic gland (PG) cells, leading to the activation of all the crucial enzymes involved in ecdysone biosynthesis, the main insect steroid hormone. Studies concerning ecdysteroidogenesis predicted PTTH action using brain extract (BE), consisting in a complex mixture in which some components positively or negatively interfere with PTTH-stimulated ecdysteroidogenesis. Consequently, the integration of these opposing factors in steroidogenic tissues leads to a complex secretory pattern. A recombinant form of prothoracicotropic hormone (rPTTH) from the tobacco budworm Heliothis virescens (F.) (Lepidoptera: Noctuidae) was expressed and purified to perform in vitro tests in a standard and repeatable manner. A characterization of rPTTH primary and secondary structures was performed. The ability of rPTTH and H. virescens BE to stimulate ecdysteroidogenesis was investigated on the third day of fifth larval stage. rPTTH activity was compared with the BE mixture by enzyme immunoassay and western blot, revealing that they equally stimulate the production of significant amount of ecdysone, through a transduction cascade that includes the TOR pathway, by the phosphorylation of 4E binding protein (4E-BP) and S6 kinase (S6K), the main targets of TOR protein. The results of these experiments suggest the importance of obtaining a functional pure hormone to perform further studies, not depending on the crude brain extract, composed by different elements and susceptible to different uncontrollable variables.


1988 ◽  
Vol 23 (3) ◽  
pp. 229-233
Author(s):  
J. A. Joyce ◽  
R. J. Ottens ◽  
G. A. Herzog ◽  
M. H. Bass

Laboratory cultures of field-collected larval tobacco budworm, Heliothis virescens (F.), beet army worm, Spodoptera exigua (Hübner), and fall armyworm, S. frugiperda (J. E. Smith) were bioassayed for response to three pyrethroids in combination with piperonyl butoxide (PBO), or MGK-264. The greatest synergistic effects were seen in S. exigua which also displayed the greatest tolerance to pyrethroids without synergists. The highest SR50 (synergist ratio) value for S. exigua was 22.1 with fenvalerate-PBO mixed in a ratio of 1:5, the highest for S. frugiperda was 4.6 with fenvalerate-MGK-264 1:5, and the highest for H. virescens was 1.3 with permethrin-MGK-264 1:5 or with fenvalerate-PBO 1:5.


1989 ◽  
Vol 24 (4) ◽  
pp. 539-544 ◽  
Author(s):  
Abdul K. Mohamed ◽  
Jen-Rong Yang ◽  
Fred R. S. Nelson

Laboratory studies were conducted to determine the response of healthy and cytoplasmic polyhedrosis virus (CPV) infected Heliothis virescens (F.) larvae to LD50 of methomyl and methyl parathion. Methomyl-CPV combination adversely affected pupal weight and fecundity of the female. The effect of this interaction was synergistic. Exposure of CPV infected larvae to LD50 of methomyl resulted in a mean female pupal weight of 243 mg and a fecundity of 382 per female moth. These values were significantly lower than those of all other treatments. In contrast methyl parathion-CPV combinations did not result in a significant reduction in pupal weight as compared to the control. Adult emergence and egg hatch were not affected.


1994 ◽  
Vol 29 (2) ◽  
pp. 192-200 ◽  
Author(s):  
M. R. Bell ◽  
D. D. Hardee

A 9.6-km diam area in the intensive cotton-growing region of the Mississippi Delta was treated with an entomopathogenic virus to determine the effect on populations of adult tobacco budworms, Heliothis virescens (F.), and bollworms, Helicoverpa zea (Boddie), emerging from early season weed hosts. Four aircraft were used to treat ≈ 7,106 ha during 24–28 April at a rate of 100 larval equivalents per ha. Emergence data from cages placed over treated and untreated areas indicated that virus treatments reduced tobacco budworm emergence by 80.6% and bollworm emergence by 46.2%. During the emergence period, tobacco budworm traps in the area surrounding the treated area averaged 11.4 moths per trap per night. Average trap capture per trap per night in the center (6.4 km diam) of the treated area was 6.4 moths, a reduction of 43.9% compared with the untreated area. Correspondingly, reduction in trap counts for bollworm in the center was 21% when compared with the untreated area.


Sign in / Sign up

Export Citation Format

Share Document