J. MecLEnt. Vol. 8. no. 6: 735-737 30 Dece:rnber 1971

TAPINOMA MELANOCEPHALUM AS AN INHIBITOR OF RHODNIUS PROLIXUS POPULATIONSl

By J. C. G6m.ez-Nuiiez2

Abstract: In a study of factors inhibiting Rhodnius prolixus with a 300-mesh cloth. Openings in the latter in the Venezuelan littoral, predation by the were sufficiently small to restrain first instal' nymphs mtlallOteplwlul/l appeared to account for a 62% reduction in the expected population growth. This predator and others, but not to exclude the . All field flasks were rather than abiotic factors, may be the main cause of R. prolixus placed in a shaded shelter about 10 m distant from being absent from the Venezuelan coast. a house intermittently occupied by humans. A census was made every month of eggs, nymphs, In investigating potential biological controls and adults. To check the possibility of nymphs for vectors of Ohagas' disease, captive populations escaping, batches of eggs were periodically examined of Rhodnius prolixus were established in an area to note any discrepancy between hatching and frec of this vector but apparently similar to infested number of nymphs. The significance of the dif- an'as, on the premise that factors responsible for ference was determined by both F- and t-distribution local absence of this would be evident during tests, for population variances and means respec- the course of its population growth. tively, and significance was based on a 5 % level. An appropriate area was available in the Vene- zuelan littoral where surveys for many years had RESULTS failed to reveal the presence of in a R. prolixus Population growth and their characteristics are habitat with temperature and humidity similar to given in FIG. I and TABLE 1. those of the highly infested llanos biotope. Popula- Growth was similar in all populations during tions were started under 3 different conditions: the first 4 months but after the sixth month dif- at an insectary for control purposes, at the littoral ferences between the 3 groups increased even but exposed only to climate and micro-organisms, though all populations followed an ascendant and at the littoral but also exposed to any predator trend. Differences between the yearly density smaller than a first instal' nymph of R. prolixus. This paper reports on the relationship found between R. prolixus and the pan tropical tramp ant, POPULATIONS;

Tapinoma melanocePhalum (Fabricius, 1793); this 1.300 A. INSECTARY A ant has been widely distributed by commerce and B. LITTORAL: ANT-FREE navigation, and it is quite prevalent in Venezuelan 1.200 coastal areas but not in the interior of the country. 1.100 C. LITTORAL: ANT- EXPOSED >- •... 1000 MATERIALS AND METHODS III Z 900 In each of the 3 situations, 2 populations were ILl o started during the same day with a pair of R. BOO Z prolixus from the same age flask maintained in a o 700 laboratory colony under standard conditions .... ~ 600 (G6mez-Nufiez 1964). During a year of experi- ..J ::;) mental observation the were kept in 3900-cc Q. 500 o Q. flasks and given the opportunity to feed on hen 400 blood for 2 hI' every 14 days. Temperature and 300 RH were as follows: insectary, 28°C and 60-70%; at the littoral, 23-32°C and 70-88%. The ant- lOO

free "climate" flasks were covered with a 8S0-mesh 100 (U.S. Standard) cloth and the ant-exposed flasks o 'This investigation was supported in part by U.S. Public o l 3 4 5 6 7 B 9 10 11 Il Health Research Grant IA05799 from the National Institute MONTHS of Allergy and Infectious Diseases. FIG. 1. Growth of R. prolixus populations under 3 differ- 'Malariologia (E.R.), Av. Bermudez, Maracay, Venezuela. ent conditions. 736 J. Med. Ent. Vol. 8, no. 6

TABLE 1. Effect of the ant T. melanocephalum on some para- rates were the only significant differences between meters of R. prolixus populations. the insectary and the ant-free littoral populations, POPULATION GROUPS it appears unlikely that temperature and humidity Littoral Littoral variables were wholly responsible for those dif- PARAMETERS Insectary ant-free ant-exposed ferences; such variables probably would also have Average number of insects at 12 months 1240 509 193 affected the percentage of eggs hatching and the Average monthly rates: time required to complete the life cycle (Gomez- eggs per adult 5.1 2.5 0.8 Nunez & Fernandez M. 1963, Gomez-Nunez specific nymphal 1964). On the other hand, previous observations mortality (X 100) 0.2 2.3 5.3 specific adult have shown that mortality and oviposition are mortality (X 100) 15.9 21.1 36.1 mainly affected by starvation (Gomez-Nunez 1964) % adults 13.7 15.9 18.4 and that high temperature at the moment of feeding decreases the percentage of R. prolixus that means of the 3 groups of populations were signifi- feed (Gomez-Nunez & Fernandez M. 1963). cant. Because littoral populations were always fed near The time required to complete the life cycle was midday, when temperatures were usually above the same in all groups; first instal' nymphs appeared 30°C, it is conceivable that the differences between after 1 month, fifth instal' after 5 months and those populations and the insectary ones were par- adults during the sixth month. The only visible tially induced by the procedures used and not signs of predation were noted during the fourth totally by such environmental factors as salinity, month, and thereafter, when egg destruction and mean temperature and humidity, light and micro- removal of fragments by T. melanocephalum ocurred organisms. However, since all littoral populations in the flasks covered by the coarse mesh. In all were handled in the same way, differences between populations 80-90% of the eggs hatched, and the the ant-free and ant-exposed populations can be number of first instal' nymphs was in accord with assumed to have been caused by the predatory the number of eggs that hatched. action of T. melanocePhalum which began about 4 Comparing the populations of the 3 groups, months after the experiment's beginning. Since climatic differences apparently reduced the yearly in this locality T. melanocePhalum colonies are found increase in the littoral to less than 1/2 of that in only within houses, the time lapse before the in- the insectary and the ants further reduced the itiation of predation is probably dependent on population increase to about 1/6 of that in the both ant density and distance between vector and insectary. A similar proportional effect was also ant population foci. observed in the average number of eggs per adult. Although eggs per adult rates were low in the In flasks exposed to ants the reduction in egg littoral populations the proportion of adults was quantity became apparent only after the fourth kept near insectary level probably by the higher month. nymphal and adult mortality rates in those popula- tions. Since the proportion of adult females was Although both specific nymphal and adult mortality rates were increased by climatic factors not determined, eggs per adult only indicates and by exposure to ants, the nymphal relative general reproduction and not actual fecundity values. mortality increase was the most severe. Proportion Regarding the observation that an increase in of adults remained fairly stable in all populations. mortality, especially that of nymphs, was one of Although Telenomus has been found to parasitize the principal causes of population inhibition in Triatoma maculata eggs in some areas of Venezuela, the flasks exposed to ants, the question is raised and probably also R. prolixus eggs in the llanos of how the ants, apparently specific predators of biotope, no evidence of its presence in the littoral eggs, might have caused this effect. Some of the was noted during the experiment. possibilities being investigated are direct attack, harassing of nymphs and adults, the removal of DISCUSSION the symbiont Nocardia from the outer surface of The differences in the yearly growth shown by eggs, and the introduction of a pathogen by the the 3 population groups suggest that in addition ants. to ants there were other environmental factors, From this study no attempt can be made to not present in the insectary, affecting the littoral explain exhaustively why R. prolixus does not occur populations. Because mortality and oviposition in the littoral; but the data, combined with those 1971 G6mez-Nuiiez: Tapinoma melanocePhalum and R. prolixuJ 737

from other studies (D'Ascoli & G6mez-Nunez REFERENCES 1966, G6mez-Nunez 1969), suggest that predation D'Ascoli, A. & J. C. G6m.ez-N66ez. 1966. Notas sobre by and small vertebrates, and not los medios de dispersi6n del Rhodnius prolixus (StM). climate, is probably the most important factor Acta Cient. Venezolalza 17: 22-25. in maintaining the coasts of Venezuela free from G6mez-NWiez, J. C. 1964. Mass rearing of Rhodnius R. prolixus. prolixus. Bull. WId. Hlth. Organ. 31: 565-67. 1969. Resting places, dispersal and survival of CO••- tagged adult Rhodnius prolixus. J. Med. Ent. 6: 83-86. Acknowledgment: I wish to thank Drs Walter W. W. Kempt, OFM, Brazil, and]. E. Rabinovich, IVIC, Venezuela, for in G6m.ez-NWiez, J. C. & J. Fernandez M. 1963. La colonia formation about TaPinoma melanocePhalum and Telenomus respe- de Rhodnius prolixus en eI IVIC. Bol. [nf. Dir. Malariol. ctively. Salz. Ambient. (Venezuela) 3: 132-37.

J. Med. Ent. Vol. 8, DO. 6: 737-746 30 December 1971

THREE NEW OF RADFORD/ELLA (ACARINA: MACRONYSSIDAE) PARASITIC IN THE MOUTH OF PHYLLOSTOMATID BATS1

By Frank J. Radovsky2, J. Knox Jones, Jr.3.4 and Carleton J. Phillips3.5

Abstract: Three species of Radfordiella are described from known to have adapted in any stage to the mouth the protonymphs: R. oricola from uptonycteris nivalis and Anoura as an apparently specific parasitope. Three new geojfroyi; R. anourae from Anoura geoifroyi; and R. monophylli from MOllophyllus redmani. Protonymphs of the new species were species of Radfordiella, including the one noted found embedded in protected sites in tissue of the soft palate by Phillips et al. (1969), have been found in similar ncar the first premolar. Other stages are unknown. Hosts are oral loci in 3 genera of Glossophaginae (Phyllosto- all in the subfamily Glossophaginae of the chiropteran family matidae). The new species are known only from Phyllostomatidae. Radfordiella is rediagnosed based on the protonymphs and a key is given to protonymphs of the 6 de- the protonymphs. scribed species. The relationships of species in the genus and The protonymph is of particular taxonomic the morphology of the protonymphs are discussed. Comments importance in the Macronyssidae because of the are made on some aspects of the host-parasite relationships. unusal life cycle. It is the only pre-imaginal stage that feeds (deutonymph "larviform" and The discovery of protonymphs of Radfordiella quiescent) and has a host-parasite relationship in the mouth of glossophagine bats was reported contrasting with that of the adult. The nymph by Phillips et ai. (1969). Cavity-dwelling is is a slow feeder in the manner of an ixodid tick exceptional in the Macronyssidae and was pre- (cf. neosomy-see Audy et ai. 1963, Audy et aI., viously known only for Draconyssus belgicae Yunker in press), whereas the adult engorges rapidly. & Radovsky, 1966, females of which were washed As a consequence, protonymphs are sometimes from the nasal passages of teiid lizards. The mouth found on a host without adults. The protonymphal is an unusual site for mites generally, and the stage has not been given sufficient attention tax- species described here are the first Mesostigmata onomically, in part because the relatively simple lResearch supported by Grant No. GB-20087 from the Na- and constant morphology infrequently includes tional Science Foundation and Grant No. AI-07337 from prominent features of obvious taxonomic signifi- the National Institutes of Health (FJR) j other support from contract DA-49-193-MD-2215 from U. S. Army Medical cance. However, the structural simplicity permits Research and Development Command. rapid survey and brief description of the whole 'Bernice P. Bishop Museum, P. O. Box 6037, Honolulu, external surface, so that characters of diagonostic 96818, U.S.A.; part of this work was carried out at the value can be easily recognized. There are, of G. W. Hooper Foundation, University of Medical Center, San Francisco. course, structures not yet sufficiently analyzed or 'Museum of Natural History, University of , Law- described to permit full utilization in systematic rence, Kansas 66044, U.S.A. work, most notably the mouthparts other than 'Present address: Graduate School, Tech University, the chelicerae and pedipalps. Lubbock, Texas 79409, U.S.A. DPresent address: Department of Biology, Hofstra Uni- The importance of studying macronyssid proto- versity, Hempstead, Long Island, 11550, U.S.A. nymphs is demonstrated with the 3 new species.