Biology

Some phytoseiid species are common natural enemies in the ecosystem (e.g.

Phytoseiulus persimilis). They usually lived in plant or soil, feed on small arthorpods (e.g. spider mites, aphids, and thrips), provided important contribution in ecological balances, and also famous biological control enemies in agroecosystem (Moraes et al.

2004b; Chant & McMurtry 2007; Demite et al. 2019). However, they have very different food habits and lifestyles. They could be carnivorous, and some species also feed on pollens, fungi spores, or plant debris (Huffaker et al. 1970; Chant 1985;

McMurtry 2010; McMurtry et al. 1970; 2013). Since 1960s, they have received much attention, more than 4,000 articles discussing the application value of phytoseiids (Kostianinen & Hoy 1996).

Although phytoseiid mites are famous due to their biological control potential, but many of them are very different lifestyles. McMurtry & Croft (1997) provided the first time to review the diversity of lifestyles of Phytoseiidae. They categorized four types of lifestyles: Type I, specialized predator of Tetranychus spider mites (e.g. Phytoseiulus species); Type II, selective predators of tetranychid mites (e.g. Galendromus, Neoseiulus, Typhlodromus species); Type III, generalist predator (e.g. Neoseiulus, Typhlodromus, Amblyseius species); Type IV, specialized pollen feeder/generalist predators (e.g. Euseius species). Among them, Phytoseiulus species were most popular for biological control, and also were imported to many countries. McMurtry (2010) proposed the evolution of lifestyles based on currently classification system by Chant &

McMurtry (2007). The prototype phytoseiid should live on soil surface or tree bark with

original morphology, widely food habits. For examples, Austroseiulus australicus、

Chileseius camposi、Macrocaudus multisetatus. After that, polyphagous phytoseiids who lived on plants were evolved. And then, phytoseiids were evolved different morphology to adapted different habitat plants. Finally, phytoseiids were evolved two different ways, pollen feeder or specialized predators, respectively.

McMurtry et al. (2013) revised the lifestyles of phytoseiids according to their food preferences, microhabitat and morphology. The four main types were divided into ten different types:

Type I: Specialized mite predators, the types were divided into three different styles by different food sources: I-a. Specialized predators of Tetranychus. I-b.

Specialized predators of web-nest producing mites. I-c. Specialized predators of tydeoids. The I-a species have the ability to adapt the CW-u (complicated web) spider mites (e.g. Tetranychus spp. or some Eotetranychus sp.). They are probably as effective predators for these spider mites, such as Phytoseiulus persimilis has been used commercially for control Tetranychus urticae. However, althought this species are famous for controlling spider mites, but several studies (e.g. Sato et al. 2011) reported the performance is limited on tomato, due to trichomes on leaves. Species in I-b subtype have adapted for WN-u (Web nest) type spider mites (e.g. Schizotetranychus spp., Stigmaeposis spp, and some Oligonychus spp.). For example, Typhlodromus (Anthoseius) bambusae has been found co-evolution with Schizotetranychus celarius, and also an effective natural enemy (Saito 2010). Subtype I-c is a group for preying tydeoid mites, which comprised Paraseiulus and Typhlodromina, and some Proprioseiopsis species. For example, Paraseiulus talbii show the effective control the density of tydeoid population in vineyard (Camporese & Duso 1995).

Type II: Selective predators of tetranychid mites. Type II species are selective

predators of tetranychid mites, associated with dense web producing species (e.g.

Oligonychus and Tetranychus species) (McMurtry & Croft 1997; McMurtry et al. 2013).

It comprised Neoseiulus, Galendromus and apparently, the rickeri group of Typhlodromus (Anthoseius). These species are associated with different life-type spider mites, including CW-u, WN-u, WN-c. In addition, they also provided a wider range of food preference than type I, including Eriphyidae, Tarsonemidae, Tydeoidea, pollens of plants. Neoseiulus californicus is the most famous species in this group, and many commercial products in the world.

Type III: Generalist predators. This is a diverse group, with wider food range, and also different habitats. Most of phytoseiid species belong to this category. III-a.

Generalist predators living on pubescent leaves. III-b. Generalist predators living on glabrous leaves. III-c. Generalist predators living in confined space on dicotyledonous plants. III-d. Generalist predators living in confined spaces on monocotyledonous plants.

III-e. Generalist predators living in soil/litter habitats. Subtype III-a comprised Paraphytoseius, Phytoseius, Kampimodromus, Typhlodromalus, Typhlodromus spp..

These species are usually found on pubescent leaves. Previous studies (e.g. Duso 1992) found these phyotoseiid mites show smaller and flatter body shapes, and some species have strong and serrated setae. Acarologists considered these characters can provide them ability to move and live among leaf trichomes. Rather than III-a, species of subtype III-b are not particularly small (McMurtry et al. 2013). It comprised Amblyseius and Neoseiulus and Amblydromalus species. In this subgroup, Amblyseius swirskii, A.

andersoni, Amblyd. limonicus have been used commercially for control pests. Subtype III-c species are living in confined spaces of dicotyledonous plants, such as galled leaves, domatia, growing tips. Gall-forming eriophyids are often being food sources for these phytoseiids. Their microhabitats are different with other lifestyles. In some cases,

Ferreira et al. (2008) reported that some phytoseiids may get benefit from domatia but domatia is unnecessary. These species are not included in subtime III-c. Subtype III-d species are found in restricted space of monocotyledonous plants (e.g. corn, miscanthus, rice). In Taiwan, Neoseiulus baraki, and N. taiwanicus are famous species belonging to this subtype, and always found in leaf sheath. They are smaller and flatter body shapes.

Species of subtype III-e are found on low-growing plant and also soil, litter. In this subtype, N. barkeri and N. cucumeris are used commercially for controlling thrips. In addition, species of Proprioseiopsis are also belonging to this group; Ho & Chen (2001) reported the life history of Prop. asetus.

Type IV: Pollen feeding generalist predators. This type means these phytoseiids use pollen as an important diet, including genera Euseius, Iphiseius, and Iphiseiodes spp.. They usually observed on glabrous leaves. Euseius ovalis is famous member of this type in Taiwan. In addition, some species are oberserved the piercing ability for plant leaf (Adar et al. 2012).

Although McMurtry et al. (2013) provided a complicated revision of phytoseiid lifestyles; two special circumstances are not included in the frame, aquatic and plant cell piercing phytoseiids. Until now, no swimming phytoseiids were found, but some species were reported from coastal area on rocky shore (e.g. Typhlodromus (Anthoseius) crossostephium) (Liao et al. 2017c) and wetland habitats (e.g. Neoseiulella paralias) (Stathakis et al. 2016), and also in pitcher of pitcher plant (e.g. Macroseius biscutatus) (Muma & Denmark 1967). In addition, Evansoseius macfarlanei and Macrocaudus multisetatus (tribe Neoseiuilini) were found on floating plants, and also have uncommon setae on dorsal shield (Sheals 1962; Moraes et al. 2003). The first report about plant feeding ability of phytoseiid can trace back to Chant (1959b). Typhlodromus (Anthoseius) rhenanus, T. (A.) pyri and Euseius finlandicus were tested for plant feeding

ability. Recently, E. scutalis was reported about plant piercing ability (Nomikou et al.

2003). Adar et al. (2012) reported the plant feeder phytoseiid movable digit is shorter than the fixed digit; and non-plant feeder phytoseiid have shorter fixed digit. As we know, phytoseiid have received much attention due to their biological control potentials, more than 4,000 articles were reported for the application value (Kostianinen & Hoy 1996). Despite the extensive practical applications of phytoseiids for the biological control for pests, we still understand the limited knowledges about microhabitats and food preferences of phytoseiids.