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Unfed adult Ixodes scapularis Say were treated with spores of the entomopathogenic fungus Metarhizium anisopliae Metschnikoff in the laboratory and in the field. An M. anisopliae suspension containing 4 x 10(9) spores per milliliter caused 96% mortality in the laboratory, versus 53% mortality among field-treated ticks. The LC50 value for unfed adult I. scapularis in the laboratory was 4 x 10(7) spores per milliliter. Our results indicate that M. anisopliae was highly pathogenic to unfed adult ticks and showed potential for controlling questing adult I scapularis.

Effectiveness of the entomopathogenic fungus Metarhizium anisopliae, for controlling nymphal Ixodes scapularis, was tested in laboratory and field trials. In the laboratory, M. anisopliae (Metschnikoff) Sorokin strain ESC1 was moderately pathogenic, with an LC50 of 10(7) spores/ml and induced 70% mortality at 10(9) spores/ml. In a field study, however, 10(9) spores/ml M. anisopliae did not effectively control questing I. scapularis nymphs, and significant differences were not detected in pre- and post-treatment densities. For nymphs collected and returned to the laboratory for observation, mortality was low in treatment groups, ranging from 20 to 36%. To assess whether a chemical acaricide would synergistically enhance pathogenicity of the fungus, we challenged unfed nymphal I. scapularis with combinations of M. anisopliae and permethrin, a relatively safe pyrethroid acaricide, in two separate bioassays. Significant interactions between M. anisopliae and permethrin were not observed, supporting neither synergism nor antagonism.

A computational analysis of flow in simplex fuel atomizers using the arbitrary-Lagrangian-Eulerian method is presented. It is well established that the geometry of an atomizer plays an important role in governing its performance. We have investigated the effect on atomizer performance of four geometric parameters, namely, inlet slot angle, spin chamber convergence angle, trumpet angle, and trumpet length. For a constant mass flow rate through the atomizer, the atomizer performance is monitored in terms of dimensionless film thickness, spray cone half-angle, and discharge coefficient. Results indicate that increase in inlet slot angle results in lower film thickness and discharge coefficient and higher spray cone angle. The spin chamber converge angle has an opposite effect on performance parameters, with film thickness and discharge coefficient increasing and the spray cone angle decreasing with increasing convergence angle. For a fixed trumpet length, the trumpet angle has very little influence on discharge coefficient. However, the film thickness decreases, and spray cone angle increases with increasing trumpet angle. For a fixed trumpet angle, the discharge coefficient is insensitive to trumpet length. Both the spray cone angle and the film thickness are found to decrease with trumpet length. Analytical solutions are developed to determine the atomizer performance considering inviscid flow through the atomizer. The qualitative trends in the variation of film thickness at the atomizer exit, spray cone angle, and discharge coefficient predicted by inviscid flow analysis are seen to agree well with computational results. NomenclatureA a = air core area at orifice exit A o = orifice area A p = total swirl slot area A t = the trumpet end area A ta = air core area at the trumpet end C d = discharge coefficient,ṁ/A o (2 p/ρ) 0.5 D s = spin chamber diameter d o = orifice diameter d t = trumpet diameter at atomizer exit f = body force K = atomizer constant, A p /(D s d o ) K t = A p /(πr t r s ) K 1 = A p /(πr o r s ) L s = spin chamber length l o = orifice length l t = trumpet length p = static pressure Q = volume flow rate = radial distance from axis to inlet slot r o = orifice radius, d o /2 r s = spin chamber radius, D s /2 r t = d t /2 S(t) = surface enclosing control volume V (t) t = film thickness at exit t * = dimensionless film thickness, t/(d o /2) U = average total velocity at the end of orifice U = arbitrary velocity vector for the control volume V (t) u = axial-velocity component u = velocity vector u o= average axial velocity at the end of orifice u oa = axial velocity at the liquid-air interface at the end of orificē u t = average axial velocity at the end of trumpet u ta = axial velocity at the liquid-air interface at the end of trumpet V (t) = control volume w = tangential velocity component w i = average tangential velocity at the inlet w o = average tangential velocity at the end of orifice w oa = tangential velocity at the liquid-air interface at the end of orificē w t = average tangential velocity ...

Ixodes scapularis Say adults, nymphs, and larvae were treated with the entomopathogenic fungus Metarhizium anisopliae in a combination of field and laboratory experiments to assess sublethal effects of the fungus on I. scapularis fecundity and body mass. Postengorgement and egg mass weights were 33 and 50% lower, respectively, in adult females treated with M. ansiopliae in the field before engorging on laboratory rabbits. M. anisopliae did not significantly reduce egg mass weight, conversion efficiency, or oviposition period in I. scapularis females treated with the fungus after engorging on white-tailed deer, although only 33% of treated females oviposited. Engorged nymphs and larvae treated with M. anisopliae converted significantly lower percentages of their engorged weight to their molted adult and nymphal weights. This study indicates that M. anisopliae reduces fitness (fecundity and body mass) in all active I. scapularis stages and indicates that its impact as a biocontrol agent might be higher than that suggested by direct mortality alone.

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