No abstract

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.

BACKGROUND: Parasitus bituberosus is common in rose fields and nearby vegetation around Bogotá. In rearing units, it is often aggregated, feeding on Frankliniella occidentalis edaphic phases. Preliminary observations suggested predator immatures can not reach adulthood if isolated. The objectives were to evaluate the suitability of F. occidentalis as prey for P. bituberosus, to evaluate free-living nematodes as complementary food, and to confirm the aggregation effect on predator biology. Aggregation types: (1) isolated mites, (2) mites paired only as deutonymphs and early adulthood, and (3) mites always paired. Diets: thrips (T), nematodes (N) and thrips + nematodes (NT). RESULTS: Parasitus bituberosus juveniles did not feed on live F. occidentalis, but developed and oviposited on nematodes.Approximately 77% of the isolated mites died as immatures. Mortality was low (21-23%) when predators were paired at least in the deutonymph and the early adult phase. Female daily predation rates were comparable to other predators on F. occidentalis (≥2.5). Continuously paired mites had high biotic potential, especially when the diet included nematodes (r m ≥ 0.33; R o ≥ 33.90; daily oviposition rate ≥ 10.9). CONCLUSION:The results of this study warrant further investigation of this predator, to evaluate methods for its mass production, inclusion in conservation biocontrol programs and performance against the pest at a larger scale.