Immunotoxic and cytotoxic effects of atrazine, permethrin and piperonyl butoxide to rainbow trout following in vitro exposure

For many current use pesticides, limited information exists on their cytotoxicity and immunotoxicity in non-target organisms such as fish. We examined the effects of atrazine, permethrin and piperonyl butoxide (PBO) exposure, in vitro, on rainbow trout (Oncorhynchus mykiss) lymphocyte viability and proliferation. Purified rainbow trout peripheral blood leukocytes (PBLs) were exposed in vitro to the test chemicals (0, 0.01, 0.1, 1 and 10 μM) for 96 h, with and without the mitogen lipopolysaccharide. All three chemicals caused a decrease in both lymphocyte viability and proliferation at 10 μM, while atrazine also suppressed proliferation of PBLs at 1 μM. The in vitro toxicity of these chemicals to this salmonid underscores the need for further investigation using in vivo studies and host resistance models.     

The effects of selection for size in cattle on horn fly population density

Abstract. Statistically significant differences were observed in the population density of the horn fly, Haematobia irritans irritans L., on Angus cows having significantly different frame sizes. Angus cows, averaging <112.5 cm in height at the hip, had significantly lower numbers of horn flies than Angus cows that measured 112.5–117.5 cm, 117.5–120 cm, 120–126 cm and >126 cm in height at the hip. The Angus I cows(126 cm). The estimated heritability (h²) of horn fly resistance was 0.43 ± 0.07 and 0.95 ± 0.31 for 1989 and 1990, respectively. Horn fly counts on the Angus I herd (<112.5 cm in height) was 118.1 (probable breeding value, PBV = -20.69) to 165 horn flies per cow (PBV = 26.9 flies per cow in 1989) and from 75.9 (PBV = -29.1) to 134.5 (PBV = 29.5) flies per cow in 1990. Angus I bulls had PBV = -23.7 to 13.4 and from-26.5 to 14.75 in 1989 and 1990, respectively. The Angus II cows had horn fly counts that ranged from 159.6 (PBV of-23.5) to 208.1 (PBV of 25) per cow in 1989 and from 232.3 (PBV of-56.2) to 378.7 (PBV of 90) per cow in 1990. Angus II bulls had PBVs that ranged from-17.1 to 18.9 in 1989 and from -28.1 to 48.8 in 1990. The Angus I cows had significantly (P < 0.0001) lower numbers of hom flies (mean of 63.8 horn flies per m²) than the small, medium or large Angus II cows (mean of 129.4, 149.6 and 145.5 hom flies per m², respectively). The data indicated that some specific factor(s) associated with cow size contribute(s) to innate resistance of cattle to the horn fly.     

The effects of hair density of beef cattle on Haematobia irritans horn fly populations

Abstract We show the relationships that exist between the amount of hair and quantity of sebum on cattle skin and the population density of the horn fly, Haematobia irritans. Brahman and Chianina steers had means of 2390 and 1587 hairs per cm², respectively, significantly more than the mean number of hairs on Angus, Brahman x Angus Crossbred, Charolais, and Red Poll steers. The Chianina steers had > 30% more sebum present on their skin and hair (0.58g/929cm²) than the Angus, Charolais, and Red Poll steers at the Beef Cattle Research Station Savoy, Arkansas. The Brahman steers had a significantly greater amount of sebum present on the skin (1.51 g/ 929 cm²) than the Crossbred and purebred Angus steers (0.55 and 0.25g/929cm², respectively) at the South Central Family Farms Research Centre Booneville, Arkansas. The Brahman and Chianina steers had means of 61.9 and 17.0 horn flies per steer, respectively, during the fly season, whereas the Angus, Crossbred, Charolais and Red Poll steers had fly season means that ranged from 76.9 to 265.8 flies per steer. Regression analysis showed that an increase of 100 hairs per cm², was associated with a reduction of 11 horn flies in the Angus II, 5 in Angus I, 20 in Charolais, 37 in Red Poll, and 0.4 in Chianina steers at the Savoy Station and a reduction of 6.6 horn flies for the Angus, Brahman, and Crossbred steers at the Booneville Centre. Regardless of cattle breed, an increase of 1.0 g of sebum per 929 cm² output by the steer was associated with 478.5 additional hairs per cm² on the animal. Each increase of 0.25 g of sebum per 929 cm² resulted in a decrease of 9.2 horn flies per steer. We conclude that some of the factors responsible for fly-resistance in cattle are hair density and the corresponding amount of sebum present on cattle skin and hair.     

Effect of piperonyl butoxide and diphenylamine on lipid peroxidation in ozonated chloroplasts

Lipid peroxide (LPO) formation was remarkable when isolatedtobacco chloroplasts were bubbled with high concentrations ofozone, though the fatty acid composition and the fractionationpattern of glycolipids and phospholipids in the chloroplastlipids changed little after ozone fumigation of the leaves.Piperonyl butoxide (PB), a potent protectant against ozone injury,strongly inhibited LPO formation in ozonated chloroplasts. PBalso prevented ozone-induced decreases in the amounts of linolenicand linoleic acids in the chloroplast lipids. These resultssuggest that PB inhibition of LPO formation may be involvedin the protective mechanism against ozone phytotoxicity. However,the mode of PB action differed on some points from that of diphenylamine,which is an antioxidant and also effective against ozone injury.The mode of PB action is discussed. ¹ Present address: The Central Research Institute, Japan Tobacco& Salt Public Corporation, Umegaoka, Midori-ku, Yokohama227, Japan. (Received July 5, 1976; )     

Effect of piperonyl butoxide on organic anion and cation transport in rabbit kidneys

Piperonyl butoxide has been shown to reduce accumulation of cephaloridine in rabbit renal cortex; however, the mechanism responsible for this effect remains unclear. Cephaloridine is a zwitterion and its accumulation in renal cortex has been suggested to be regulated by both organic anion and cation transport systems. Thus, it was of interest to determine the effect of piperonyl butoxide on renal transport of p-aminohippurate (PAH, an organic anion) and tetraethylammonium (TEA, an organic cation). Although pretreatment with piperonyl butoxide markedly inhibited renal cortical uptake of cephaloridine, the same treatment had less inhibitory effect on either PAH or TEA uptake. Efflux of PAH from preloaded renal cortical slices was enhanced by pretreatment with piperonyl butoxide; however, TEA efflux was unaffected. Thus, piperonyl butoxide appears to have effects on renal membrane functions which result in differential effects on PAH, TEA, and cephaloridine transport.     

Dynamics and mechanisms of permethrin resistance in a field population of the horn fly, Haematobia irritans irritans

A study was conducted at the Pressler ranch, near Kerrville, Texas, USA between 2002 and 2006 to determine the dynamics and mechanisms of resistance to permethrin in a field population of the horn fly, Haematobia irritans irritans (L.). Changes of resistance to pyrethroid insecticide associated with use of a pour-on formulation of cyfluthrin in 2002 and use of diazinon ear tags in subsequent years were studied using a filter paper bioassay technique and a polymerase chain reaction assay that detects two sodium channel mutations, kdr and super-kdr resistance alleles. A maximum of 294-fold resistance to permethrin was observed in the summer of 2002. A significant decrease in the resistance level was observed in spring 2003, and resistance continued to decline after animals were treated with diazinon ear tags. In response to pyrethroid treatments, the allelic kdr and super-kdr frequency increased from 56.3% to 93.8% and from 7.5% to 43.8%, respectively in 2002, and decreased significantly in 2003 when the pyrethroid insecticide was no longer used to treat animals. Females were found to have a higher allelic super-kdr frequency than males in 2002, while no difference was detected between males and females in the allelic kdr frequency. There was a significant positive correlation between frequencies of the sodium channel mutations and levels of permethrin resistance, suggesting that the sodium channel mutations, kdr and super-kdr , are the major mechanisms of resistance to pyrethroids in this horn fly population. Results of synergist bioassays also indicated possible contributions of two metabolic detoxification mechanisms, the mixed function oxidases (MFO) and glutathione S-transferases (GST). Compared to a horn fly infestation of an untreated herd, treatments with the pyrethroid pour-on formulation failed to control horn flies at the Pressler ranch in 2002. Sustained control of horn flies was achieved with the use of diazinon ear tags in 2003 and subsequent years.     

Influence of permethrin, diazinon and ivermectin treatments on insecticide resistance in the horn fly (Diptera: Muscidae)

The history of insecticide resistance in the horn fly, Haematobia irritans, and the relationship between the characteristics of horn fly biology and insecticide use on resistance development is discussed. Colonies of susceptible horn flies were selected for resistance with six insecticide treatment regimens: continuous single use of permethrin, diazinon and ivermectin: permethrin-diazinon (1:2) mixture; and permethrin-diazinon and permethrin-ivermectin rotation (4-month cycle). Under laboratory conditions, resistance developed during generations 21, 31 and 30 to permethrin, diazinon and ivermectin, respectively. The magnitude of resistance ranged from < 3-fold with ivermectin to 1470-fold with permethrin. Field studies demonstrated that use of a single class of insecticidal ear tag during the horn-fly season resulted in product failure within 3-4 years for pyrethroids and organophosphates, respectively. In laboratory studies, use of alternating insecticides or a mixture of insecticides delayed the onset of resistance for up to 12 generations and reduced the magnitude of pyrethroid resistance. In field studies, yearly alternated use of pyrethroids and organophosphates did not slow or reverse pyrethroid resistance (Barros et al., unpublished data), while a 2-year alternated use with organophosphates resulted in partial reversion of pyrethroid resistance. When pyrethroid and organophosphate ear tags were used in a mosaic strategy at two different locations, efficacy of products did not change during a 3-year period.     

Effect of ozone on photosystem II of tobacco chloroplasts in the presence of piperonyl butoxide

Inhibitors of photosynthetic electron flow and electron donorsfor photosystem II effectively protected tobacco leaves againstozone injury, suggesting that this photosystem is closely linkedwith the development of ozone injury. Hill reaction activityof the chloroplasts isolated from tobacco leaves immediatelyafter ozone fumigation was significantly lower than that ofthe chloroplasts isolated from non-fumigated leaves. This ozone-induceddecrease in Hill reaction activity was partially prevented whenthe leaves were pretreated with piperonyl butoxide (PB), whichis highly effective against ozone injury. Ozone bubbling into the isolated chloroplast suspension markedlydecreased the rate of DPIP photoreduction. PB reduced this decreaseabout 50%. PB also prevented the ozone-induced decrease of chlorophylland carotenoids. ¹Present address: The Central Research Institute, Japan Tobacco& Salt Public Corporation, Umegaoka, Midori-ku, Yokohama227, Japan (Received June 14, 1976; )     

Influence of piperonyl butoxide on the toxicity of organophosphate insecticides to three species of freshwater benthic invertebrates

Toxicity tests were conducted with amphipods (Hyalella azteca), chironomids (Chironomus tentans) and oligochaetes (Lumbriculus variegatus) exposed to a series of organophosphate insecticides in the absence or presence of piperonyl butoxide (PBO), an inhibitor of cytochrome(s) P450. Piperonyl butoxide effectively reduced the toxicity to H. azteca and C. tentans of three organophosphates (diazinon, chlorpyrifos, azinphos-methyl) which undergo metabolic activation by cytochrome(s) P450. Coadministration of PBO with another organophosphate (dichlorvos) which is not activated by cytochrome(s) P450, did not reduce the toxicity to the two species. Lumbriculus variegatus was relatively insensitive to the organophosphates, and PBO did not reduce their toxicity to the oligochaete. These data indicate that both H. azteca and C. tentans possess cytochrome P450-mediated MOs capable of metabolizing organic xenobiotics. However, the degree to which L. variegatus might be capable of the oxidative metabolism of organic xenobiotics is uncertain.     

Inhibitory and inductive effects of piperonyl butoxide on dihydroisodrin hydroxylation in vivo and in vitro in black cutworm (Agrotis ypsilon) larvae

Biphasic inhibition and stimulation of microsomal oxidase activity in tissue homogenates in vitro and of dihydroisodrin (DHI) hydroxylation in vivo in black cutworm Agrotis ypsilon larvae have been produced by pretreating larvae with piperonyl butoxide (PB). Gut homogenate had greatest DHI hydroxylase activity of tissues tested and PB molar I₅₀ was 6.4 × 10^?5M. Two hours after topical application of PB (1.4 mg/larva) DHI hydroxylase was reduced 39, 30, 19 and 48% in fat body, gut, head and Malpighian tubule homogenates, and after 15 hours activity was increased 145, 69, 28 and 97% in the respective homogenates. The effects are time- and dose-dependent. In vivo three hours after PB administration, the rate of DHI hydroxylation was reduced 26%, but 15 hours after pretreatment the rate was increased 25%.