Use of Beauveria bassiana to control northern fowl mites (Ornithonyssus sylviarum) on roosters in an agricultural research facility.

Treatment of Northern fowl mite (Ornithonyssus sylviarum) infestation on poultry in research facilities can be challenging. The mite has a rapid reproductive cycle (egg to adult in 5 to 7 d), and chemical treatments can be toxic to birds, personnel, and the environment. In addition, antimite treatment may interfere with experimental research designs. The current study evaluated the efficacy of topical application of an entomopathogenic fungus, Beauveria bassiana, in the treatment of a naturally occurring infestation of Northern fowl mites in pen-housed roosters (n = 14; age, 18 mo). Two groups of 7 roosters each were used in 2 experiments: Beauveria (30 mL, 2.9 × 10(10) spores per bird) compared with water (30 mL, control), and Beauveria compared with the common topical organophosphate agent tetrachlorvinphos-dichlorvos (30 mL). We also assessed a higher dose of Beauveria (300 mL, 2.9 × 10(11) spores per bird) in the 7 birds that were not exposed to tetrachlorvinphos-dichlorvos. Beauveria reduced mite levels relative to the control group but did not outperform tetrachlorvinphos-dichlorvos when used at an equal volume and frequency. Increasing the volume and frequency of Beauveria application improved outcomes such that visual inspection failed to detect any mites. The results presented here suggest that, when applied in sufficient doses, Beauveria effectively reduces mites on poultry and can be an important part of an integrated pest management program. Additional research is needed to document the most effective dose, frequency, and location of B. bassiana application to control Northern fowl mites in poultry.

Effects of oral tetrachlorvinphos fly control (Equitrol) administration in horses: physiological and behavioural findings.

Highly reactive horses may pose risks to humans involved in equestrian activities. Among the factors that may affect horses' reactivity to external stimuli are pesticides used for fly control in equine facilities. The organophosphorus (OP) insecticide tetrachlorvinphos (TCVP) is used as a feed-through larvicide to prevent completion of the fly larval life cycle in horse manure. TCVP exerts its effect by inhibiting the enzyme cholinesterase (ChE) leading to the accumulation of the neurotransmitter acetylcholine (AChE) in synapses of the central and peripheral nervous systems. The aim of the present study was to investigate alterations of whole-blood ChE levels associated with feeding a commercially available product (Equitrol, Farnam Companies, Inc.) to horses for fly control. A second aim was to report neurological, physiological and behavioural findings in addition to profiles of selected immune markers (IFN-gamma, IL-12p40 and COX-2) and serum thyroid hormones during and after a 30-day treatment period of TCVP feeding. The results indicated significant decreases in whole-blood ChE activity and concomitant behavioural alterations, manifested as increased reactivity and decreased controllability in treated horses. No changes were detected in physiological or neurological parameters, immune markers or thyroid hormones in treated (n=6) or control (n=4) horses during the course of the study.

Susceptibility of lesser mealworm (Coleoptera: Tenebrionidae) adults and larvae exposed to two commercial insecticides on unpainted plywood panels.

BACKGROUND: The susceptibilities of adult and larval lesser mealworms, Alphitobius diaperinus (Panzer), to two commercially formulated insecticides, cyfluthrin and tetrachlorvinphos, were examined through exposure on treated plywood panels. Lesser mealworms were collected from four caged-layer poultry farms, three in New York and one in Maine. An additional strain was obtained from an infestation occurring in a cricket colony. RESULTS: In all poultry farm derived strains, a portion of the population (1.8-16.2%) survived cyfluthrin exposure. The Maine and cricket colony strains were tolerant of tetrachlorvinphos exposure as both larvae and adults, with 55-74% mortality, whereas nearly 100% mortality was observed with New York strains. The cricket colony adult beetles were highly susceptible to cyfluthrin, with 100% mortality following exposure, but larvae were considerably less susceptible (87.7%). Pesticide use histories for the poultry farms and their impact on the results are discussed. CONCLUSION: The results document that tetrachlorvinphos, an active ingredient with a long use history, may be losing its effectiveness against lesser mealworms in some poultry operations; however, it is still effective in many others.

Resistance to cyfluthrin and tetrachlorvinphos in the lesser mealworm, Alphitobius diaperinus, collected from the eastern United States.

The lesser mealworm, Alphitobius diaperinus (Panzer), is an important pest in poultry facilities. The toxicity of cyfluthrin and tetrachlorvinphos to five strains of the lesser mealworm was compared with the toxicity to a susceptible laboratory strain. Bioassays were carried out with both larvae and adults. For the susceptible strain, cyfluthrin and tetrachlorvinphos had similar toxicity to adults, but cyfluthrin was 5 times more toxic to larvae when compared with tetrachlorvinphos. High levels of resistance to tetrachlorvinphos in two beetle strains were detected in both larvae and adults, although these strains were heterogeneous and still contained susceptible individuals. Resistance to cyfluthrin ranged from 1.7- to 9.5-fold for adults and from 0.5- to 29-fold for larvae at the LC(95). Overall, the patterns of resistance did not mirror the insecticide use patterns reported at these facilities. The implications of these results to management of the lesser mealworms are discussed.

Resistance status of house flies (Diptera: Muscidae) from southeastern Nebraska beef cattle feedlots to selected insecticides.

The status of resistance to three insecticides (permethrin, stirofos, and methoxychlor), relative to a laboratory-susceptible colony, was evaluated in field populations of house flies, Musca domestica L., collected from two beef cattle feedlots in southeastern Nebraska. Topical application and residual exposure to treated glass surfaces were suitable methods for determining the resistance status of house flies to permethrin, stirofos, or methoxychlor. However, in most cases, residual exposure was more sensitive in resistance detection (i.e., higher resistance ratios). The field populations tested were moderately resistant to permethrin (RR = 4.9-fold and RR = 7.3-fold, for topical application and residual exposure, respectively) and extremely resistant to stirofos and methoxychlor (not accurately quantifiable because of low mortality at the highest possible concentrations or doses). Probable explanations for the resistance status of these house fly populations and implications for global feedlot fly management are discussed.

Alkylation of urinary guanine in mice by the organophosphorus insecticide tetrachlorvinphos.

The methylating capability of tetrachlorvinphos on urinary guanine in mice has been investigated using an insecticide labeled at both O-CH3 groups. Following intraperitoneal administration of the 14C-labeled insecticide to mice, about 0.57% of the radioactivity in the O- to 24-hr samples was associated with the purine fraction. The amount of [7-14C]methylguanine in 0- to 48-hr urine samples, estimated as fraction of applied dose, was 26-31 X 10(-5). The results obtained indicate possible chemical alkylation of urinary guanine. On the other hand, a considerable portion of radioactivity is probably incorporated via the C-1 pool.

Cytological effects of the insecticide tetrachlorvinphos.

The effect of the organophosphorus insecticide tetrachlorvinphos (Gardona) has been studied on the mitosis and meiosis of Vicia faba, using the pure insecticide. An aqueous saturated solution of tetrachlorvinphos affected neither mitosis (after seed-soak and root treatment) nor meiosis (after spraying the plants at the flowering stage). The obtained results may be attributed to the low solubility of tetrachlorvinphos. A saturated solution of tetrachlorvinphos in Tween-60: water mixture (1:99) induced a statistically significant percentage of abnormal cells in root-tip meristems after root treatment for 4 h. Chromosome stickiness, disturbed meta- and anaphases and anaphase bridges were observed.

Microbial mutation studies with tetrachlorvinphos (Gardona)).

The mutagenic activity of tetrachlorvinphos was investigated in agar-layer cultures of Escherichia coli WP2 and WP2 uvrA, Salmonella typhimurium TA1535, TA1538, TA98 and TA100. Assays were carried out both in the presence and in the absence of S9 fractions of liver homogenates from rats and mice, both from untreated animals, and from animals pre-treated with Aroclor 1254. The induction of mitotic gene conversion by tetrachlorvinphos was studied in stationary phase cultures of the yeast Saccharomyces cerevisiae D4. No mutagenic effects, as determined by reverse gene mutation, were detected in vitro in the bacterial/mammalian microsome assay when a range of bacterial tester strains were exposed to tetrachlorvinphos at amounts up to 2000 micrograms per plate, either in the absence or in the presence of S9 fractions from non-induced or Aroclor-induced mouse or rat livers. Tetrachlorvinphos did not increase the mitotic gene conversion frequency in stationary phase cultures of the yeast, Saccharomyces cerevisiae D4.

Dual effects of tetrachlorvinphos on procaine toxicity and procainesterase activity in rats.

The effect of tetrachlorvinphos (TCVP) on liver procainesterase (PROCase) and procaine toxicity was studied in rats. TCVP is an organophosphate with an inducible effect on drug metabolizing enzymes. A single oral dose of 500 mg/kg of TCVP caused a remarkable decrease in PROCase (40% of control) 24 hr later and increased the motality after injection of procaine (250 mg/kg, i.p.) from 54% to 87%. Conversely, it was observed that PROCase elevated to 140% of the control and mortality decreased from 54% to 25% on day 3. With repeated administration of TCVP (500 mg/kg/day) for 5 days, the PROCase activity that was inhibited on day 1 was gradually restored to normal levels by 5 days and the mortality altered to 25%. The inducible effect on PROCase was examined using desmethyl-TCVP, a metabolite of TCVP without inhibitory effect on the enzyme; PROCase activity was enhanced to 1.6-fold of the control and procaine concentration in the brain was reduced to 30% of the control, accompanied with no death of rats after procaine injection. Electrophoresis of the solubilized liver microsomal fraction confirmed the inducible effect of TCVP on PROCase; microsomal protein from the TCVP-treated rat was more deeply stained than that from the control, and the PROCase activity of two anodic bands increased in the TCVP-treated microsomes. These results indicate that TCVP has a dual action on PROCase, inducible and inhibitory, and that the direct inhibitory effect of TCVP might mask the increased amount of the enzyme induced by repeated administration of TCVP. The dual effect of TCVP on PROCase would cause the change in procaine toxicity.

Application phenomena and efficacy of concentrated acaricide dusts for northern fowl mite control on caged laying hens.

Fluorescent pigments were used to measure plumage coverage when caged laying hens were dusted for northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), control. Carriage type electrostatic or high velocity backpack equipment produced superior coverage 2 hr posttreatment when the rates of 454 g (1 lb) dust per 100 or 500 hens was employed. A redistribution of dust was noted 48 hr posttreatment, and a subsequent experiment demonstrated that this phenomenon resulted from intracage cross contamination dependent upon bird caging density. Carbaryl 80% wettable powder (WP) at 454 g/1600 hens and tetrachlorvinphos 50% WP at 454 g/1000 hens provided northern fowl mite control for 11 and 5 weeks posttreatment, respectively.