Synergic effect between Bacillus thuringiensis Kurstaki HD1 δ-endotoxins and Melia azedarach (Meliacea) methanolic extract against the larvae of Thaumetopoea pityocampa Den. & Schiff. (Lepidoptera, Notodontidae)

2017 ◽  
Vol 41 (4) ◽  
pp. 343
Author(s):  
Bachir Kamilia ◽  
Tail Ghania ◽  
Bouragba Nadia ◽  
Zamoum Mohamed ◽  
Trigui Mohamed ◽  
...  
Author(s):  
Fereshteh Khorrami ◽  
Asmar Soleymanzade

Abstract Phthorimaea operculella (Zeller, 1873) is one of the most damaging pests of potatoes in the world. Since the chemical pesticides play a key role in managing of potato tuber moth (PTM), the present study was conducted to assess the efficacy of Proteus®, Takumi®, Avaunt®, Dorsban®, Decis®, Consult® and Vertimec® against neonate larval penetration and one-day-old eggs of P. operculella. But adverse effects of chemical insecticides, actuated researchers to seek secure tools such as medicinal plants and biopesticides like Bacillus thuringiensis Berliner, 1715 for pest managements. Hence, we also examined toxicity of savory, ziziphora and cumin methanolic extracts against the pest under laboratory conditions. We also surveyed the synergistic/antagonistic interactions between the most effective insecticide and methanolic extract with Bt against PTM. Our results showed that both Vertimec® and savory synergized the performance of Bt against neonate larval penetration of P. operculella. Probit analysis of insecticides and methanolic extracts demonstrated that Vertimec® and Takumi® had high toxicities to the neonate larval penetration of PTM which exhibited LC50 values equivalent to 7.09 ppm and 0.008 g L−1, respectively. Savory was the most effective extract against larval penetration and hatching rate of the pest (LC50 = 440.36 and 635.93 ppm, respectively). Oviposition preference demonstrated that Vertimec® and Decis® exhibited inhibitory ovipositional effects against P. operculella.


Author(s):  
Yanyan Sun ◽  
Linlin Yang ◽  
Lianet Rodríguez-Cabrera ◽  
Yushan Ding ◽  
Chaoliang Leng ◽  
...  

After ingestion by a susceptible insect and damaging its midgut epithelium, the bacterium Bacillus thuringiensis (Bt) reaches the insect blood (hemolymph), where it propagates despite the host’s antimicrobial defenses and induces insect death by acute septicemia. Although the hemolymph stage of the Bt toxic pathway is determinant for the infested insects’ fate, the response of Bt to hemolymph and the latter’s role in bacterial pathogenesis has been poorly explored.


2017 ◽  
Vol 88 ◽  
pp. 73-83 ◽  
Author(s):  
Vikas Kumar Roy ◽  
Vanlal Peki ◽  
Maibam Sunita Devi ◽  
Sanasam Sanjeev ◽  
Maurya Khusboo ◽  
...  

2000 ◽  
Vol 66 (4) ◽  
pp. 1553-1558 ◽  
Author(s):  
Carolina Rausell ◽  
Amparo Consuelo Martínez-Ramírez ◽  
Inmaculada García-Robles ◽  
María Dolores Real

ABSTRACT The insecticidal activity and receptor binding properties ofBacillus thuringiensis Cry1A toxins towards the forest pests Thaumetopoea pityocampa (processionary moth) andLymantria monacha (nun moth) were investigated. Cry1Aa, Cry1Ab, and Cry1Ac were highly toxic (corresponding 50% lethal concentration values: 956, 895, and 379 pg/μl, respectively) to first-instar T. pityocampa larvae. During larval development, Cry1Ab and Cry1Ac toxicity decreased with increasing age, although the loss of activity was more pronounced for Cry1Ab. Binding assays with 125I-labelled Cry1Ab and brush border membrane vesicles from T. pityocampa first- and last-instar larvae detected a remarkable decrease in the overall Cry1Ab binding affinity in last-instar larvae, although saturable Cry1Ab binding to both instars was observed. Homologous competition experiments demonstrated the loss of one of the two Cry1Ab high-affinity binding sites detected in first-instar larvae. Growth inhibition assays with sublethal doses of Cry1Aa, Cry1Ab, and Cry1Ac in L. monacha showed that all three toxins were able to delay molting from second instar to third instar. Specific saturable binding of Cry1Ab was detected only in first- and second-instar larvae. Cry1Ab binding was not detected in last-instar larvae, although specific binding of Cry1Aa and Cry1Ac was observed. These results demonstrate a loss of Cry1Ab binding sites during development on the midgut epithelium of T. pityocampa and L. monacha, correlating in T. pityocampa with a decrease in Cry1Ab toxicity with increasing age.


2013 ◽  
Vol 63 (4) ◽  
pp. 1639-1644 ◽  
Author(s):  
Xiao-Jin Liu ◽  
Li-Fang Ruan ◽  
Xiao-Yan Lin ◽  
Chang-Ming Zhao ◽  
Chun-Ying Zhong ◽  
...  

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