Potential Of Mites Research Articles

Molecular typing of Rickettsia akari

Rickettsia akari, an obligately intracellular bacterium, is the causative agent of the cosmopolitan urban disease rickettsialpox. R. akari is an atypical representative of spotted fever group rickettsiae (SFG) as it is associated with rodent mites rather than ticks or fleas; however, only limited information is available about the degree of genetic variability found among isolates of R. akari. We examined 13 isolates of R. akari from humans, rodents and mites in the USA, the former Soviet Union, and the former Yugoslavia made between 1946 and 2003 for diversity in their tandem repeat regions (TR) and intergenic regions (IGR). The 1.23 Mb genome of R. akari strain Hartford CWPP was analyzed using Tandem Repeat Finder software (http://tandem.bu.edu) and 374 different TRs were identified, with size variation from 1 to 483 bp and with TR copy numbers ranging between 21 and 1.9, respectively. No size polymorphisms were detected among the 11 TR regions examined from 5 open reading frames and 6 IGR. Eighteen non-TR IGR’s were amplified and sequenced for the same isolates comprising a total of 5.995 bp (0.49%) of the Hartford CWPP strain chromosome. Three single nucleotide polymorphism (SNP) sites were detected in two IGR’s which permitted separation of the five R. akari isolates from Ukraine SSR from the other eight isolates. In conclusion, this is the first study reporting genetic heterogeneity among R. akari isolates of different geographic origins. Further exploration of this genetic diversity is needed to understand better the geographic distribution of R. akari and the epidemiology of rickettsialpox. The potential of mites as hosts for other rickettsial agents also needs further investigation.

A Laboratory Evaluation of the Astigmatid Mite Hemisarcoptes cooremani Thomas (Acari: Hemisarcoptidae) as a Potential Biological Control Agent for an Armored Scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae)

Abstract The host stage and species utilized by a parasitic mite, Hemisarcoptes cooremani Thomas (Acari: Hemisarcoptidae), was studied to evaluate the mite's potential as an augmentative biological control agent against California red scale, Aonidiella aurantii (Maskell) (Diaspididae: Homoptera). We compared how readily the mite established on five oleander scale, Aspidiotus nerii (Bouche), stages and eight red scale stages using no-choice experiments in which mites were offered a single scale stage and species. We also offered the mite a choice between two stages of the same species, a choice between oleander and red scale in the same stage, and a choice between oleander and red scale in the same two stages. We found that few mites established on scales younger than second molt, but they readily established on the older oleander scale stages. They accepted gravid and parturient female red scale less readily than they did the same oleander scale stages. We suspect that the heavily scleratized body of California red scale attached to the cover in these stages prevented the mite from gaining access to the scale body on which to feed. Our results suggest that red scale is a poor-quality host for the mite. Consequently, this predator/parasitoid is unlikely to be an effective augmentative biological control agent against A. aurantii in California's San Joaquin Valley. The younger stages provide insufficient resources for the mite to develop and reproduce and the older stages are too difficult to feed on.

Colonization of Languedoc vineyards by phytoseiid mites (Acari: Phytoseiidae): influence of wind and crop environment

A natural increase of phytoseiid mite populations (Kampimodromus aberrans, Typhlodromus pyri and Phytoseius plumifer) was observed in vineyards in Languedoc, Burgundy and Corsica under integrated pest management strategies. The aim of the present study was to characterize the mechanisms of this colonization in space and time in Languedoc. The abundance of phytoseiid mites in the vegetation close to three grape fields was determined twice a year (May and July). Aerial (funnels with water) and soil (felt strip) traps were placed in and around grape fields, in order to assess the colonization potential provided by aerial dispersal and ambulatory locomotion. The populations of phytoseiid mites in the crops were studied twice a month in order to gain information on the make up of the dispersal populations. The species K. aberrans was found in largest quantities in the traps, in the natural vegetation and in the crops. Predatory mite dispersal occurred essentially by aerial dispersal and was dependent on the wind intensity and wind direction. Identical sex ratios were observed in migrant populations and in populations present in the grape fields, woody areas and hedges. A large proportion of immatures was found to move by aerial dispersal. The colonization potential (rapidity, intensity and regularity) was directly associated with the abundance of the phytoseiids and the proximity of natural vegetation. A deep, dense and tall woody area containing suitable host plants for predatory mites constituted the most stable source of phytoseiid mites. Natural colonization of vineyards provides considerable phytoseiid mite potential that could be managed in an agricultural landscape.

Control of Histiostoma laboratorium in Drosophila Cultures1

An almost universally used animal in genetic research and teaching is the vinegar fly, Drosophila melanogaster (L.). Media and culture conditions used for Drosophila are ideal for reproduction of several kinds of mites. Some mites are able to feed on pupal cases. One mite is so common in genetics laboratories that it was given the name Histiostoma genetica (Stolpe 1938). It is now known as H. laboratorium Hughes (1950). Strickberger (1962) recommends that, once infestation of Drosophila stocks has been discovered, all such stocks should be autoclaved. He suggests that valuable stocks may be saved by starting new cultures with flies that have been carefully examined and found free of mites. However, even with extreme caution it is extremely difficult to eliminate mites from Drosophila cultures. The reproductive potential of mites is much greater than Drosophila and the reproductive cycle is much shorter. Thus Drosophila cultures rapidly become overrun with mites.