J. Mecl. Ent. Vol. 9, DO. I: 111-112 15 March 1972

SEASONAL ABUNDANCE OF DERMANYSSUS HIRUNDINIS AND D. AMERICANUS (: ) IN NESTS OF THE

The nest of the House Sparrow is particularly inter- breeding season of the sparrow, from April to August. esting as a habitat of of potential medical The average number of individuals of Dermanyssus spp. importance, because of the sparrow's wide range, bio- per nest for each of the 8 phases of the yearly cycle of the logical success, and close association with man. sparrows' nesting behavior is shown in TABLE I. The Nests from a sparrow colony were collected for a greatest number of was present during the late period of 1 year from March 1969 to March 1970, at brood ph asp., feeding on late or well developed chicks. intervals of 15 to 20 days timed to correspond roughly Since the parent birds no longer roosted in the nest and Downloaded from https://academic.oup.com/jme/article/9/1/111/2222274 by guest on 29 September 2021 to the beginning and middle of each month. The colony seldom brooded the young during this period, the chicks from which the nests were collected consisted of 100-150 were the main source of blood for the mites. The birds that built their breeding and roosting nests in a population began to increase rapidly during prenesting, thick growth of English ivy on the north wall of Hover early clutch, late clutch and early brood stages. This Laboratory, Eastern Michigan University, Ypsilanti, pattern shows a considerable adaptation of Dermanyssus Michigan. A total of 71 nests was collected, 2 nests on to the annual nesting cycle of the House Sparrow. The the first collection date and 3 nests on each of the fol- peak population of mites is greatest when the nestlings lowing collection dates. The Tullgren modification of are at a maximum size and assumed tolerance to para- the Berlese funnel was employed to extract the arthropods sitism by the . from the nesting materials. The conditions necessary for the mites to multiply are The yearly nesting cycle of the sparrow was broken optimal in the nest during the sparrows' breeding season. down into 8 phases (TABLE I) based on the sparrows' Temperature in the nest remains high due to the almost behavior patterns. constant presence of either the hen sparrow or chicks The only acarine parasites encountered in the nests and the excellent insulation of the nest at this time. belonged to the genus Dermanyssus. Two species of this This combination of high temperature, humidity and genus were found, D. hirundinis (Hermann) and D. amen- availability of the host provides conditions favorable to camlS Ewing (Moss, 1968, J. Med. Ent. 5: 67-84). Pop- a rapid increase in the population of Dermanyssus spp .. ulation figures were compiled without separation of the In the post-fledging nests there was a considerable 2 species due to the large numbers of Dermanyssus en- reduction in the average number of mites per nest from countered. those containing late broods. The drastic decrease in Dermanyssus spp. occurred in 74.5% of the nests col- this phase was probably due to an emigration of Der- lected for examination. The largest populations of manyssus from the nests. When the host bird abandons these mites were found in nests collected during the the nest or the mites are so numerous that there are

TABLE I. Average number of Dermanyssus per nest for each of the 8 phases of the sparrows' nesting cycle. AVERAGE BEHAVIORPATTERN PHASEDURATION No. NESTS % TOTALNO.OF NO.PER PHASE OFTHESPARROW INYPSILANTI COLLECTEDINFESTED Dermanyssus NEST Pre- Nest building by Early March to 12 50 18 1.5 breeding cr, sexual display the middle of and mating April Early Egglaying and From 7 71 16 2.3 clutch incubation; eggs with yolk or 1 the early embryo Late Incubation; eggs middle of 2 100 54 27.0 Clutch with late embryo Early Hatchlings, with- April 5 100 173 34.6 brood out feathers; l adult brood young to the Late Well developed 7 100 21,492 3070.3 brood nestlings; adult middle of sparrow seldom brood August Post- Between broods (Breeding 4 100 335 83.8 fledging or shortly after season) fledging Dis- Post breeding dis- Middle of August 10 80 45 4.5 persal persal of birds to October Winter- Winter-roosting in old October to March 24 66 151 6.3 roosting breeding nests and new roost nests 112 J. Med. Ent. Vol. 9, no. 1 insufficient hosts available, Dermanyssus becomes very Acknowledgments: I am grateful for the advice and active and migrates from the nest in search of another valuable suggestions of Dr Bert M . .Johnson and Dr host (Camin, 1963, Adv. in Acarology, Vol. I, Cornell Donald F. M. Brown, Biology Dept., Eastern Michigan Univ. Press, p. 411-25). A mass migration could ac- University, and Dr W. Wayne ]\·1oss, The Academy of count for this marked drop in the average number of Natural Sciences, Philadelphia.-Wllliam Phlllis, Bio- mites in post-fledging nests. It is during this migration logy Dept., Eastern Michigan University, Ypsilanti, that mites of the genus Dermanyssus may present the Michigan 48197, U.S.A. Present addres.>: Dept. En- greatest danger as a vector of disease because they could tomology and Kematology, University of Florida, attack an alternate, accidental host such as man or other Gainesville, F[orida 32601, U.S.A. that may not be adapted to these parasites. Downloaded from https://academic.oup.com/jme/article/9/1/111/2222274 by guest on 29 September 2021 J. Med. EDt. VoL 9, DO. 1: 112-113 15 Manh 1972

CHEMICAL FOG DISPERSAL WITH GROUND EQUIPMENT FOR MOSQUITO CONTROLl

Fogging for mosquito control has long been centered The fogging commenced at 1900 hI' and was accom- around the thermal fog and non-thermal fog. Recently plished by walking at the rate of 4 km/hr for 120 m a new concept in mosquito control called a chemical across the end of a 1080-m grass airplane landing strip. fog was reported by Stokes (1967, Proc. Calif. Mosquito The discharge rate of Dursban was calculated to be 226 g ContI'. Assoc. 35: 122). Stroud & Stevens (1968, Mos- per min. The wind was approximately 3 kIn/hr directly quito News 28: 569-71) reported the effectiveness of down the landing strip. this method as a ground application with propoxur and Adult Aedes aegypti were placed in cages made from fenthion. An aerial application technique and the 1/2-liter ice cream cartons that had 90% of the side description of the chemical reaction was described by replaced with a 20-mesh cotton cloth. Ten adults were Knapp (1968, Mosquito News 28: 516-24). Basically, placed in each of 4 cages at 30.5 cm and 2 at 61.0 em this consists of hydrated silicon dioxide (SiOz) particles above the ground at each test station. The stations impregnated with the insecticides in association with were located every 30 m downwind for 360 m. Ten cages were placed upwind of the treated area, 5 at 15 m a fog of ammonium chloride (NH4Cl) particles. These 2 products are formed by a chemical reaction resulting and 5 at 30 m, and served as untreated checks to deter- mine (1) natural mortality and (2) if any of the fog from combining silicon tetrachloride (SiCI4) and 5% dispersed upwind of the treatment area. One hour ammonia water mixed in the atmosphere [SiCI4 + 4NH8 + 2HzO-SiOz(s) + 4NH4Cl(s)]. after treatment the cages were removed to the laboratory, Further evaluation of a ground application technique and the adult mosquitoes were transferred to new cages is reported here. As a prelude to this investigation, and held for subsequent mortality counts. Dursban® [0, O-diethyl 0-(3, 5, 6-trichloro-2-pyridyl) One-kg waxed cheese cartons containing 500 ml of phosphorothioate] and naled, 2 insecticides known to be water and 10 A. aegypti larvae (2nd and 3rd instars) each effective in controlling mosquitoes (Ludwig & McNeil, were placed at 15-m intervals for the first 75 m and at 1966, Mosquito News 26: 344-51; Knapp & Gayle, 30-m intervals thereafter to a distance of 285 m. Four 1967, Mosquito News 27: 479-82) were tested to cartons were placed at each test station. One covered

determine their miscibility with SiCI4• Dursban was carton was placed at each of these stations, as a check on found to be miscible whereas naled was not. natural mortality during the test period. One hour A modified Buffalo Turbine Mity Mite sprayer2, as after the treatment, the covers on the check cartons were described by Stroud & Stevens (loc. cit.), was used in removed. Larval mortality counts were made at 15 and this test. Dursban (40.8% EC) was mixed (l: 1) with 24 hI' at the test site. All data were adjusted to account

SiCl4 and placed in one tank, and another tank contained for natural mortality. 5% ammonia solution. The 2 materials were gravity Stroud & Stevens (loc. cit.) found that more effective fed through .951-cm aD tygon tubing into the air blast mosquito control was achieved if the chemical fog was chamber. Screw clamps on the tubing controlled the applied when the wind velocity was low, and Knapp (loc. cit.) reported that low temperature in combination flow rate to obtain a ratio of 1 part SiCl4 insecticide mixture to 3 parts of the ammonia solution. The reac- with high humidity produced denser fogs. The con- tion which took place within the air blast formed the ditions for this test were considered nearly ideal-i.e., insecticidal fog. slight air movement (approximately 3 km/hr), an ambient temperature of 21°C, and a high humidity. lThe investigation reported in this paper (7[-7-27) is in con- nection with a project of the Kentucky Agricultura[ Experi- Fifteen hI' after treatment adult and larval mosquito ment Station and is published with approval of the Director. mortality was 100% at all test stations with the exception 'Sprayer modified by Martin pinto, LYA Sociedad anonima of an average of 88% larval mortality at the 225 and Quimica E Industria[, Buenos Aires, Argentina. 255-m stations. At 24 hI', no larvae survived at the