Reyes Marlene, Angulo Victor Manuel, Sandoval Claudia Magaly
Escuela de Biología, Facultad de Ciencias, Universidad Industrial de Santander, Piedecuesta, Santander, Colombia.
Biomedica. 2007 Jan;27 Suppl 1:75-82.
The susceptibility to insecticides of triatomine species must be evaluated because of their involvement in the transmission of the Chagas disease. In each region with Chagas endemicity, evaluation of insecticide response is necessary to predict the success of the control campaigns.
The baseline susceptibility was determined for the active principles deltamethrin, beta-cypermethrin and fenitrothion in nymphs of first and fifth instar of Triatoma dimidiata and nymphs of first instar of Triatoma maculata.
The insecticide activity in triatomines was evaluated by the technique of topical application.
The values of the LD50 in nymphs of first instar for T. maculata, expressed in nanograms per insect (ng/i), were 0.07, 0.05 and 4.12 for deltamethrin, beta-cypermethrin and fenitrothion respectively. The corresponding LD99 values were 1.08, 0.37 and 17.89 ng/i. In T. dimidiata, the LD50 values were 0.44, 0.46 and 16.45 ng/i; the LD99 values were 2.22, 1.97 and 36.07 ng/i. In nymphs of fifth instar T. dimidiata, the LD50 values were 510.7, 1623.6 and 838.9 ng/i; the LD99 values were 9607.5, 11,717.9 and 1525.0 ng/i, respectively.
In first instar nymphs of T. dimidiata and T. maculata, the pyrethroid insecticides were more effective; in fifth instar nymphs of T. dimidiata, the effectiveness of the pyrethroids and the organophosphate differed in the LD50 comparison--the nymphs required much higher doses compared with the other triatomines and suggested a low susceptibility. The LD99 for the organophosphate (fenitrothion) was significantly lower and may indicate its greater effectiveness in field. Studies of synergistic effects amonst insecticides are important to clarify the role of biochemical mechanisms that determine tolerance to the pyrethroids. Insecticide tolerance represents a new challenge for control campaigns in the Andean and Central American countries where Chagas disease is endemic.
由于锥蝽物种参与恰加斯病的传播，因此必须评估其对杀虫剂的敏感性。在每个恰加斯病流行地区，评估杀虫剂反应对于预测防治运动的成效很有必要。
确定了溴氰菊酯、高效氯氰菊酯和杀螟硫磷这几种活性成分对二色锥蝽一龄和五龄若虫以及黄斑锥蝽一龄若虫的基线敏感性。
通过局部施药技术评估锥蝽体内的杀虫剂活性。
黄斑锥蝽一龄若虫的半数致死剂量（LD50）值，以每只昆虫的纳克数（ng/i）表示，溴氰菊酯、高效氯氰菊酯和杀螟硫磷分别为0.07、0.05和4.12。相应的LD99值分别为1.08、0.37和17.89 ng/i。在二色锥蝽中，LD50值分别为0.44、0.46和16.45 ng/i；LD99值分别为2.22、1.97和36.07 ng/i。在二色锥蝽五龄若虫中，LD50值分别为510.7、1623.6和838.9 ng/i；LD99值分别为9607.5、11717.9和1525.0 ng/i。
在二色锥蝽和黄斑锥蝽的一龄若虫中，拟除虫菊酯类杀虫剂更有效；在二色锥蝽的五龄若虫中，在LD50比较中拟除虫菊酯类和有机磷类的有效性有所不同——与其他锥蝽相比，这些若虫需要更高的剂量，表明敏感性较低。有机磷类（杀螟硫磷）的LD99显著更低，可能表明其在野外更有效。研究杀虫剂之间的协同效应对于阐明决定对拟除虫菊酯耐受性的生化机制的作用很重要。在恰加斯病流行的安第斯和中美洲国家，杀虫剂耐受性对防治运动构成了新的挑战。
