Does Phenoloxidase Contributed to the Resistance? Selection with Butane-Fipronil Enhanced its Activities from Diamondback Moths

Abstract

Using microtitration method, the relationship between Phenoloxidase activity and the resistance of the diamondback moth Plutella xylostella (Linnaeus) to the novel insecticide butane-fipronil was determined in vitro. After selection of the tenth-generation by butane-fipronil, the resistance of the fourth instar larvae was increased 83.80-fold as compared to the susceptible strain. Phenoloxidase activity of the resistant strain (POr) was 1.29-fold higher than the susceptible one (POs). However, the Km and optimum pH values were similar in resistant and susceptible strains, which were 1.11 mM and 6.5, respectively. Both POr and POs have maximum stability at pH values less than 7.0, although POs was less stable at lower pH values than POr. In addition, the thermal stabilities of the two phenoloxidase were very similar. It is suggested that PO may play an important role in the increasing resistance of pests to pesticides.

Comparative Evaluation of Phenoloxidase Activity in Different Larval Stages of Four Lepidopteran Pests After Exposure toBacillus thuringiensis

“…It was previously reported that PO levels increased in succeeding larval instars of S. littoralis and P. interpunctella (Ishaaya et al 1974; Hartzer et al 2005; Valadez-Lira et al 2010). With P. interpunctella and S. exigua , an increase in immune response was related to decreased susceptibility to entomopathogens (Gassmann et al 2009) and chemical insecticides (Liu et al 2009). However, increased tolerance to Bt svar.…”

Critical electrolyte concentration of silk gland chromatin of the sugarcane borer Diatraea saccharalis, induced using agrochemicals

“…In studies using butane-fipronil on the 4th instar of Plutella xylostella larvae, Liu et al (2009) observed that the larvae resistance increased 83.80 times after 10 generations compared to the control larvae.…”

Effect of Plant Based Essential Oil on Immune Response of Silkworm, Antheraea assama Westwood (Lepidoptera: Saturniidae)

“…Increase in phenoloxidase activity has long been correlated with increased resistance to pathogen (Brookman et al, 1989;Soderhall and Cerenius, 1998;Sugumaran, 2002;Shelby and Popham, 2006) and decrease of phenoloxidase activity is attributed to weakening of immune system (Hiromori and Nishigaki, 2001). In addition to pathogens, the system is also activated in response to presence of other nonself materials like chemical insecticide, glass beads etc (Pathak, 1993;Liu et al, 2009). Activation of PO activity confers resistance against invading nonself material, but it may not always adequately reflect overall resistance against all insults (Schwarzenbach and Ward, 2007).…”

“…It has been well documented that insect haemocytes mediate immune response in invertebrates on presence of foreign material, toxin and microorganisms (Gupta, 1991;Pathak, 1993) and the response is exhibited in terms of phagocytosis in case of small sized particle and encapsulation and nodulation in case of large sized material and pathogens (Gillespie and Kanost, 1997). In addition defensin and phenoloxidase are two important protein molecules involved in insect immunity (Pathak, 1993;Hillyer and Christensen, 2005;Liu et al, 2009). Phenoloxidase located in cuticle, haemolymph and oenocyte is involved in sequential conversion of dopa into melanin and thus helps in the fight against nonself.…”