Generalist red velvet mite predator (Balaustium sp.) performs better on a mixed diet

Abstract

Generalist predators have the potential advantage to control more than one pest and to be more persistent than specialist predators because they can survive on different foods. Moreover, their population growth rate may be elevated when offered a mixture of prey species. We studied a generalist predatory mite Balaustium sp. that shows promise for biological control of thrips and whiteflies in protected rose cultures in Colombia. Although starting its life in the soil, this predator makes excursions onto plants where it feeds on various arthropods. We quantified life history parameters of the predator, offering high densities of three pest species: first-instar larvae of Frankliniella occidentalis, eggs of Trialeurodes vaporariorum and Tetranychus urticae, either alone or in combination. The predators completed their life cycle on each diet. The egg-to-egg period was c. 2 months. All eggs were laid in one batch in 1-2 days, indicating a pronounced semelparous reproduction pattern. In general, females reproduced earlier and laid more eggs on mixed diets, and these early reproducers consequently had higher population growth rates than late reproducers. The best diet in terms of egg-to-egg period and juvenile survival was the combination of eggs from whiteflies and spider mites. Spider mite eggs alone and western flower thrips larvae alone were the worst diets. It remains to be investigated whether mixed diets promote the population growth rate of Balaustium sufficiently for biocontrol of whiteflies and thrips in the presence of alternative prey, such as spider mites, to become effective.

Supplemental food forAmblyseius swirskiiin the control of thrips: feeding friend or foe?

“…However, when Artefeed cysts were combined with F. occidentalis larvae, fecundity of the predator was higher than when providing the two food sources separately. This confirms earlier observations that generalist predators usually have an increased reproductive performance on a mixed diet compared with single‐diet treatments . Our results also suggest that lower‐quality food sources such as Artefeed (yielding the lowest r m value for A. swirskii ) can still be useful when thrips (or other pests present at low numbers) are present in the crop, as the combination of both foods resulted in a higher population growth of the phytoseiid than on the separate food sources.…”

Factors shaping latitudinal patterns in communities of arboreal spiders in northern Europe

“…The stronger decrease with latitude in euryphagous spiders can be explained by higher diversity of many insect groups (in particular those belonging to potential spider prey) at lower latitudes (Willig et al , Hillebrand ), because euryphagous spiders are likely to benefit more from high diversity of prey than more specialised spiders. This explanation is in line with experimentally demonstrated increases in density (Messelink et al ) and performance (Muñoz‐Cárdenas et al ) of generalist predators with an increase in diversity of their prey. The discrepancy between our results and conclusions by Stireman () stresses the need in further exploration of climatic responses in specialist vs generalist species.…”

Supplementary food forNeoseiulus californicusboosts biological control ofTetranychus urticaeon strawberry

“…This could improve retention of the predator in fields at low spider mite densities and thus increase the efficiency of biological control. This result illustrates how the ability of generalist predatory mites to exploit supplementary foods can confer to them advantages over specialist species that are entirely dependent upon prey . In addition, generalists have the potential to control more than one pest species, which could be advantageous to growers in some circumstances.…”

“…Supplementary food resources can be nutritionally limiting for predators or they can support high rates of development and reproduction . Some supplementary foods may enable only predator survival while prey are unavailable . Moreover, different life stages may have different nutritional requirements, rendering certain foods differentially suitable for immatures and adults .…”