Irving Fox

Multi-Resistant Aedes aegypti in Puerto Rico and Virgin Islands.

The Isla Verde, Puerto Rico, laboratory colony, highly resistant to DDT and dieldrin in 1959, became even more so by 1960; resistance to organic phosphates was also greater than before. In laboratory tests Bayer 29493 was best for killing resistant larvae and adults. It is improved with piperonyl butoxide at the ratio of 10:1.

Effect of pH on molluscicidal activity of Bayer 73 vS. Australorbis glabratus of Puerto Rico under laboratory conditions.

Abstract : A Laboratory strain of Australorbis glabratus of Puerto Rico when exposed for 24 hours in Bayer 73, 5-chlorosalicylic acid (2-chloro, 4-nitro) anilide, at 0.2 parts per million in aerated tap water (pH 7.0-8.2) invariably succumbs, 100% of the snails being killed. However, in test waters of high acidity (pH 4 and pH 5) and high alkalinity (pH 9.3-9.9) 4 to 8 times as much molluscicide or 0.8 to 1.6 ppm may be necessary to effect 100% mortality. Different kinds of water such as distilled, chlorinated tap, aerated tap, and the like, give markedly different mortality results in toxicological experiments in various laboratories throughout the world. This may be partly explained by the different qualities of the water, of which an important one is the pH. (Author)

Circulating precipitating antibodies in the rabbit from mite infection as shown by agar-gel tests.

In agar-gel tests, extracts of Psoroptes cuniculi (Delafond), against the sera of rabbits with ear canker, a disease caused by this mite, resulted in precipitation bands indicating at least two antigenantibody systems. Agar-gel double diffusion techniques can be used to show antigen-antibody systems resulting from natural infection of man and animals with helminth parasites (Kagan and Norman, 1963). But antibodies naturally produced against different species of arthropods when they invade the tissues, suck blood, inject venom, or act as allergens have not heretofore been demonstrated by such methods (Langlois et al., 1963). Blacklock et al. (1930) first demonstrated precipitins in guinea pigs to insect parasites. Little progress seems to have been made since that time. This paper reports results with agar-gel tests which confirm those of Culbertson (1935) obtained by the ring test. MATERIALS AND METHODS The serum samples came from rabbits involved in an outbreak of ear canker, scab, or psoroptic mange in the animal houses of two separate institutions. It was acquired and spread naturally, without deliberate human intervention. In all, sera from 25 rabbits exposed to the epidemic, including clean rabbits as well as scabby ones were studied. Of these, two rabbits were severely affected as follows. The first case, G-7, was a small extremely thin animal weighing 3 to 4 lb. Thick, dry grayishbrown crusts completely filled both ear canals and extended over both surfaces of the ears without interruption (Fig. 1). The remainder of the body was covered with the same type of exudate. The thickness of the crust varied from approximately 0.75 to 1.0 cm over the head, back, and feet to about 2 mm over the abdomen. Many mites were seen on the bare surface of the skin after removal of the scabs and hair. The other severe case, rabbit No. 4 had extensive crusts in both ears with large quantities of grayish yellowish odorous pus. Received for publication 8 August 1966. * This investigation was supported in part by Research Grant AI-03821 and Graduate Research Training Grant 5-T1 AI 15 from the NIAID, U. S. Public Health Service. Two large abscesses below the right ear were opened and drained. Swabs were made and scabs collected for bacterial and fungal cultures. Mites were recovered from the scabs and identified. Scabs from rabbit G-7 were put in 250-ml beakers each containing about 100 ml of merthiolated physiological saline. Three such beakers were filled and stored in the freezer. Later pieces of the material were thawed and searched for mites using a stereoscopic microscope. Literally thousands of specimens of the scab mite Psoroptes cuniculi (Delafond) were found. There were also some specimens of Notoedres cati (Hering) (-Sarcoptes cuniculi Gerlach, according to Lavoipierre, 1964) and Listrophorus gibbus Pagenstecher, but they were not sufficiently abundant to be used in this study. Extracts of Psoroptes cuniculi were prepared directly without lyophilization. Large mature specimens were removed with forceps, weighed, and homogenized in saline solution with merthiolate at 1:5,000 in a tissue grinder to give dilutions at 1:5 and 1:10. About 1,200 specimens weighed 30 mg which when diluted in 0.3 ml (300 , liters) of saline provided sufficient extract at 1:10 to make six agar-gel slides. More than 40,000 specimens were obtained from rabbit G-7, enough material to provide extracts for most of the tests. The bacteria Pseudomonas aeruginosa, Proteus species, Diphtheroid species, and Staphylococcus aureus were cultured on blood agar, and Aspergillus species was cultured on Sabouraud dextrose agar from the material obtained from rabbit No. 4. Extracts were made of each of these by scraping the agar, weighing, homogenizing in a hand tissue grinder, and diluting 1:10 in merthiolate saline without the intention of disrupting or disintegrating the bacteria and mold. Extracts of adult females of the yellow fever mosquito, Aedes aegypti and the southern house mosquito Culex quinquefasciatus were made from material obtained from laboratory colonies (Fox et al., 1963). A laboratory colony also provided the material for extracts of the domestic rat mite, Laelaps nuttalli Hirst. For agar-gel tests, the microslide technique of Yakulis and Heller (1959) was used with SeaKem( Agarose.

Antigenic relationships among mosquitoes and sand flies demonstrated by agar-gel tests☆

Abstract : The data suggest that species of the same genus, as Aedes aegypti and Aedes taeniorhynchus, may be very similar antigenically, those of different genera, as Aedes and Culex, may cross-react to a great degree but have demonstrably unique antigens, and those of different families as Culicidae (mosquitoes) and Ceratopogonidae (sand flies) demonstrate little antigenic relationship. If these serological tests are to be used as an indication, one may conclude that an attempt to desensitize a subject sensitive to sand fly bites by using extracts of mosquitoes or any other immunologically unrelated family of insects would fail. Nevertheless, results from pooled extracts indicated that a mixture of insect species might succeed in the desensitization of a particular case of allergy even without knowledge of the exact offending species, provided that the selection of insect species for the extract be based on epidemiological data and serological tests.