Thyreophagus plocepasseri sp. n., a new parthenogenetic species of acarid mites (Acariformes: Acaridae) from Kenya

To date, some species in the genus Thyreophagus, such as Th. entomophagus and Th. cracentiseta, have been shown to be useful factitious prey for mass-rearing of predacious phytoseiid mites, one of the most common groups of mites used for biological control. Here, we describe a new species, Thyreophagus plocepasseri sp. n. from Kenya that can serve as a factitious prey as well. In addition, the new species is asexual, a trait that can be advantageous for its mass-rearing in industrial settings. In the description, we use high-resolution light microscope imaging and extensive comparison with a similar species, Thyreophagus athiasae, for which the type was studied. We review the literature on asexual acarid mites and point to a lack of data on the presence of sex-manipulating bacteria (Wolbachia, Cardinium) in these asexual mite lineages. Based on the literature, these bacteria are known to induce parthenogenesis in several haplodiploid mites, but they have not been linked so far to parthenogenesis inducement in diplodiploid acarid mites.

Impact of a tarsonemid prey mite and its fungal diet on the reproductive performance of a predatory mite

Phytoseiid predatory mites are the most important group of biocontrol agents currently implemented in protected cultivations worldwide. The possibility to produce these predators at high densities on factitious prey mites is a crucial factor for their success. Commonly used factitious prey mites comprise mainly species belonging to the cohort of Astigmatina. In the present study, we investigated the potential of tarsonemid prey mites as a food source for the spider mite predator Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). The oviposition of N. californicus on mixed stages of Tarsonemus fusarii Cooreman (Acari: Tarsonemidae) was similar to that on its natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). As most tarsonemids are specialized fungus-feeders, we tested the effect of different fungal species on the growth of T. fusarii. Subsequently, we analysed the impact on the fungal growing medium on the oviposition of N. californicus. The fungal growing medium of T. fusarii had a significant effect on the reproductive output of the predatory mite, having a negative effect. When T. fusarii was separated from the rearing medium, these detrimental effects were not observed. The present study shows the potential of using tarsonemid prey mites in the production of predatory mites.

Indirect effects in predator-prey interaction: development and predation rates by immature Neoseiulus cucumeris increased by odour from its prey (Tyrophagus putrescentiae)

Predator-prey interactions have long been of great interest to ecologists. Although the direct consumptive effects have received extensive research, indirect influences of odour derived from their conspecifics and prey on predators have largely been underestimated and overlooked. In this study, the indirect effects of predator-prey interactions were determined with predatory mites Neoseiulus cucumeris and its factitious prey Tyrophagus putrescentiae. The responses of immature N. cucumeris to mixed odour with their conspecifics and prey were determined in a laboratory experiment. Our results showed that the mixed odour with their conspecifics did not demonstrate any obvious influences on the survival rates, developmental periods, predation rates and activities of the predatory mites. Intriguingly, the predators prolonged their protonymphal stage and consumed more prey eggs when exposed to mixed odour with their prey. Our results indicated that the mixed odour with their conspecifics was weak and its influence was insignificant for this species, but the prey odour showed a signifcant influence on the growth and consumption rates of immature predators, which highlighted that the indirect influences of predator-prey interactions on the predator were substantial and cannot be neglected.

Comparison of different pollen grains and a factitious prey as food sources for Amblyseius swirskii (Acari: Phytoseiidae)

Pollen used as an alternative or supplementary food source for a predatory mite not only provides important nutrients but also allows the predator to establish a population before prey becomes available. In this study, we compared the pollen of apricot, pear, hollyhock, opium poppy, and date palm, and a factitious prey, UV-irradiated eggs of Ephestia kuehniella, as food sources for Amblyseius swirskii. Different food items affected all development stages differently, except for hollyhock pollen, where eggs failed to develop to maturity. Food type affected the reproductive ability of females, which did not reproduce when fed on opium poppy during immature stages. Most eggs per female were produced when feeding on the factitious prey, and second most with apricot pollen. Feeding on factitious prey compared with pollen, resulted in greater longevity of both female and male adults. Feeding on pear pollen or factitious prey caused, respectively, the lowest and highest population growth rates (r and λ). Both net (R0) and gross (GRR) reproductive rates were highest when the factitious prey was the food source. Among the pollen diets, apricot was the most beneficial food item. Because of their effects on rates of population increase, either apricot pollen or the factitious prey could be further utilized as cost-effective alternative food diets for both experimental and commercial mass rearing of A. swirskii.

Life tables and feeding habits of Proprioseiopsis lenis (Acari: Phytoseiidae) and implications for its biological control potential in Southeast Asia

Development, survival and reproduction of Proprioseiopsis lenis (Corpuz and Rimando) (Acari: Phytoseiidae), a predatory mite distributed in parts of Southeast Asia, were assessed on different foods. These included four pollens (Typha latifolia, Luffa aegyptiaca, Zea mays, Ricinus communis), the natural prey Tetranychus urticae (mixed stages) and Frankliniella occidentalis (first-second instars), and the storage mite Carpoglyphus lactis (mixed stages) as a factitious prey. The total immature developmental time of females fed at 27 °C on T. latifolia pollen (4.1 days) or C. lactis (4.0 days) was significantly shorter than that of those offered Z. mays pollen (5.3 days), R. communis pollen (6.7 days) or T. urticae (4.3 days). Nearly 60% of the predators fed on R. communis pollen died in the immature stages and adult females failed to produce eggs. The daily oviposition rate of P. lenis reared on C. lactis (2.9 eggs/female/day), T. latifolia pollen (2.7 eggs/female/day) and F. occidentalis (2.6 eggs/female/day) was significantly higher than that of females maintained on the other diets. Total fecundity of females offered C. lactis (37.3 eggs/female) was highest, followed by F. occidentalis (26.5 eggs/female), T. urticae, L. aegyptiaca pollen, and T. latifolia pollen and was lowest on Z. mays pollen (7.4 eggs/female). The intrinsic rates of increase (rm) were highest on C. lactis (0.293), T. latifolia pollen (0.285) and T. urticae (0.283), followed by F. occidentalis (0.260) and L. aegyptiaca pollen (0.233) and were lowest on Z. mays pollen (0.115). Our findings suggest that P. lenis may have potential as a natural enemy to be used in augmentative biological control of spider mites and thrips in Southeast Asian greenhouse or field crops. The predator can be reared on the storage mite C. lactis and can also survive on several pollens in case prey is scarce or absent in the crop.

Colombian population of the mite Gaeolaelaps aculeifer as a predator of the thrips Frankliniella occidentalis and the possible use of an astigmatid mite as its factitious prey

Gaeolaelaps aculeifer (Canestrini) is a well-known generalist predator currently commercialized to control several edaphic organisms, including Diptera larvae and thrips pre-pupae and pupae. The recent detection of this species in the Bogotá plateau of Colombia raised the interest to investigate details about the biology of this new population and evaluate its potential as a biological control agent for use in that country against Frankliniella occidentalis Pergande (Thripidae), the western flower thrips. The objective of this study was to evaluate experimentally the biological characteristics of the Colombian population of G. aculeifer and its predation capacity on F. occidentalis, as well as the possibility to use a factitious prey for its mass production or as complementary food in predator field releases. The study was conducted with three diets: F. occidentalis (T), Aleuroglyphus ovatus (A), and A. ovatus + F. occidentalis (TA), in a randomized design experiment using G. aculeifer females. Predation rate was about 2.6 pre-pupae/pupae of F. occidentalis/female/day when only thrips was available as prey, reducing to 2.0 when thrips was combined with A. ovatus. Oviposition was the same when fed each of those prey and their combination (2.5–2.9 eggs/female/day). Some differences between diets were observed for duration of some periods of the life cycle, but no differences were observed for life table parameters. The greatest differences observed between this population and what has been reported for other populations of the same predator (evaluated when feeding other prey) refer to duration of deutonymphal period and Ro (respectively longer and higher in the former). It is concluded that the Colombian population is able to feed, develop, and reproduce on pre-pupae and pupae of F. occidentalis and that A. ovatus can be used for its small scale mass production and as a complementary diet in predator field releases.

The potential of Dicyphus hesperus as a biological control agent of potato psyllid and sweetpotato whitefly in tomato

The potential of the mirid predator Dicyphus hesperus Knight (Heteroptera: Miridae) as a biological control agent of the sweetpotato whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) and the potato psyllid, Bactericera cockerelli Sulcer (Hemiptera: Psyllidae) in tomato was investigated in two experiments. The first experiment focused on the study of the life history traits of D. hesperus when fed on nymphs of the potato psyllid compared with the factitious prey Ephestia kuehniella Zeller (Lepidoptera: Pyrallidae) eggs. Although reproductive and development rates were higher on E. kuehniella eggs, the predator exhibited a good intrinsic rate of natural increase (rm) when feeding on B. cockerelli nymphs (rm: B. cockerelli 0.069 ± 0.0001; E. kuehniella 0.078 ± 0.0001), thus reflecting good potential as a biocontrol agent of this pest. The second experiment focused on the efficacy of D. hesperus as a biocontrol agent of the potato psyllid and the sweetpotato whitefly in a tomato greenhouse. Prey species were offered individually or together in a series of five treatments in greenhouse cages. Results showed that the predator was able to establish and suppress populations of both pests inhabiting tomato plants when pests occurred alone or together. Thus, D. hesperus was demonstrated to be a suitable biocontrol agent of these two important pests that could be used in tomato greenhouses.