Metaseiulus

Abstract: A total of 40 phytoseiid species has been reported from Chile, including the two species (Neoseiulus californicus (McGregor) and Phytoseiulus persimilis (Athias-Henriot) most widely used worldwide for the biological control of the two-spotted spider mite, Tetranychus urticae Koch (Tetranychidae). In this paper we report nine other species found in new collecting conducted since 1989, including three new species: Amblyseius herbicolus (Chant), Amblyseius tamatavensis Blommers, Arrenoseius robertogonzalezi Trincado Martin n. sp., Neoseiulus anonymus (Chant Baker), Neoseiulus bicaudus (Wainstein), Neoseiulus viticolus Trincado Martin n. sp., Metaseiulus (Metaseiulus) camelliae (Chant Yoshida-Shaul), Metaseiulus (Metaseiulus) neoflumenis Moraes Kreiter and Metaseiulus (Metaseiulus) relictus Trincado Martin n. sp.. Chileseius camposi Gonzalez Schuster, 1962 is redescribed, and a list of all species presently known from Chile and a key to help in their separation are given. A new name, Proprioseiopsis kargi Trincado nom. nov., is a replacement name for Proprioseiopsis globosus Karg, 1976, a junior homonym of Proprioseiopsis globosus (Gonzalez Schuster, 1962).

Abstract: Fifty phytoseiid species are reported from French Caribbean islands. Three of them are new to Science: Neoseiulus martinicensis, Typhlodromips neoarcus and Metaseiulus (Metaseiulus) neoflumenis.

Abstract: Predatory mites of the family Phytoseiidae are valued natural enemies that provide effective pest control in greenhouses and on agricultural crops. Mass-reared phytoseiids are occasionally associated with microorganisms and although their effects are not always apparent, some are pathogenic and reduce host fitness. Invertebrate pathogens are encountered more frequently in mass production systems than in nature because rearing environments often cause overcrowding and other stresses that favour pathogen transmission and increase an individual’s susceptibility to disease. Although unidentified microorganisms have been reported in phytoseiids, bacteria and microsporidia have been detected with considerable frequency. The bacterium Acaricomes phytoseiuli is associated with an accumulation of birefringent crystals in the legs of Phytoseiulus persimilis and infection reduces the fitness of this spider mite predator. Wolbachia, detected in Metaseiulus occidentalis and other phytoseiids, may cause cytoplasmic incompatibilities that affect fecundity. However, the effects of Rickettsiella phytoseiuli on P. persimilis are unknown. Microsporidia are spore-forming pathogens that infect Neoseiulus cucumeris, N. barkeri, M. occidentalis and P. persimilis. Microsporidia cause chronic, debilitating disease and these pathogens often remain undetected in mass-rearings until a decrease in productivity is noticed. Routine screening of individuals is important to prevent diseased mites from being introduced into existing mass-rearings and to ensure that mite populations remain free from pathogens. The means by which bacteria and microsporidia are detected and strategies for their management in phytoseiid mass-rearings are discussed.

Abstract: Metaseiulus (=Typhlodromus or Galendromus) occidentalis is an important biological control agent. Functional genomic studies on this predator have been hampered by the lack of reverse genetic tools such as RNA interference (RNAi). In the current study, we evaluated possible RNAi responses in M. occidentalis females by feeding double-stranded RNA (dsRNA) of RpL11, RpS2, RpL8, or Pros26.4 genes in 20 % sucrose solution. Females needed to subsequently feed on two-spotted spider mites (Tetranychus urticae) to elicit a nearly complete loss of egg production. The corresponding gene knockdown was robust, long-term, and was observed in the very few eggs produced (systemic or parental RNAi). Interestingly, dsRNA-mediated gene knockdown could not be induced if these predators were provided only the sucrose diet after ingesting dsRNAs; T. urticae had to be provided to elicit the RNAi response. However, the spider mite diet was not needed for sustaining the dsRNA-mediated gene knockdown once it commenced. Oral delivery of dsRNA will be a valuable tool for efficient genome-wide functional screens in this important predatory mite.