Amblyseius herbicolus (Chant)

Kreiter, Serge, Payet, Rose-My, Douin, Martial, Fontaine, Olivier, Jacques, Fillâtre & Bellec, Fabrice Le, 2020, Phytoseiidae of La Réunion Island (Acari: Mesostigmata): three new species and two males described, new synonymies, and new records, Acarologia 60 (1), pp. 111-195 : 152-156

Amblyseius herbicolus (Chant)

Typhlodromus (Amblyseius) herbicolus Chant 1959: 84 .

Amblyseius (Amblyseius) herbicolus, Muma 1961: 287 .

Typhlodromus herbicolus, Hirschmann 1962: 23 .

Amblyseius herbicolus, Moraes et al. 1986: 14 ; 1989a: 79; Chant & McMurtry 2004a: 208; Moraes et al. 2004a: 27; Chant & McMurtry 2007: 78.

Amblyseius deleoni, Muma & Denmark 1970: 68 (synonymy according to Daneshvar & Denmark 1982; Denmark & Muma 1989).

Amblyseius giganticus Gupta 1981: 33 (synonymy according to Gupta 1986).

Amblyseius impactus Chaudhri 1968: 553 (synonymy according to Daneshvar & Denmark 1982; Denmark & Muma 1989); Amblyseius (Amblyseialus) thermophilus Karg 1991: 12 (synonymy according to El-Banhawy & Knapp 2011; Demite et al. 2019); Typhlodromus (Amblyseius) amitae Bhattacharyya 1968: 677 (synonymy according to Denmark & Muma 1989).

Amblyseius herbicolus belongs to the largoensis species group as setae J2 and Z1 are present, setae s4 are minute and the ventrianal shield of the female is vase-shaped. It belongs to the largoensis species subgroup as setae Z4 are long, spermatheca has the calyx elongate and the female ventrianal shield is entire (Chant and McMurtry 2004a).

Amblyseius herbicolus is widespread in all tropical and subtropical regions of the world. It is the second most abundant phytoseiid mites on Coffea arabica L. in Brazil, associated with Brevipalpus phoenicis (Geijskes) , vector of the coffee ring spot virus and it was found to be an efficient predator ( Reis et al. 2007). A. herbicolus is also found associated with the broad mite, P. latus in crops such as chili pepper ( C. annuum ) in Brazil and has also a good potential for controlling the pest. Rodriguez-Cruz et al. (2013) have studied biological, reproductive and life table parameters of A. herbicolus on three different diets: broad mites, castor bean pollen ( R. communis ) and sun hemp pollen ( Crotalaria juncea L.). The predator was able to develop and reproduce on all these three diets. However, its intrinsic growth rate was higher on broad mites and castor bean pollen. Feeding on alternative food such as pollen can facilitate the predator’s mass rearing and maintain its population on crops when prey is absent or scarce. Many polyphagous generalist phytoseiid mites are important natural enemies because they can feed on plant provided pollen and various prey species, and thus persist in crops even in the absence of target pests ( McMurtry et al. 2013). Hence, populations of these predators can be established in a crop by providing alternative food, thus increasing biological control. Alternative food affects P. latus control on chilli pepper plants by predatory mites ( Duarte et al. 2015). A. herbicolus had high oviposition and population growth rates when fed with cattail pollen ( Typha latifolia L.), chilli pepper pollen and bee-collected pollen, and a low rate on the alternative prey T. urticae . Supplementing pepper plants with pollen resulted in better control of broad mite populations ( Duarte et al. 2015). Release of A. herbicolus on young plants with weekly addition of honeybee pollen or cattail pollen until plants produce flowers seems a viable strategy to sustain populations of this predator ( Duarte et al. 2015).

Amblyseius herbicolus was collected recently in Comoros archipelago ( Kreiter et al. 2018b). It was already well known from La Réunion since previous studies ( Quilici et al. 1997, 2000). All details of collections were provided in the paper but without any measurements of specimens collected given. Measurements of specimens collected during this study are provided in table 19.

Specimens examined — 114 ♀♀ + 8 im. in total, 15 ♀♀ measured. Saint-Paul – Savannah (aasl 61 m, Long 55°29’43” E, Lat 21°20’41” S), 2 ♀♀ in P. vulgaris flowers, 28/7/2015; Les Avirons – Tévelave (aasl 1328 m, Long 55°21’23” E, Lat 21°12’9” S), 1 ♀ on P. persica , 11 ♀♀ on Citrus reticulata Blanco , 12 ♀♀ on A. conyzoides , 2 ♀ on Psidium guajava L., 8/12/2015; Le Tampon – Grand Tampon, Janick Bénard farm (aasl 861 m, Long 55°32’90” E, Lat 21°12’80” S), 3 ♀ on R. raphanistrum , 24/5/2016, and 1 ♀ on R. raphanistrum , 20/9/2016; Petite Île – Piton Bloc, Yébo Luguy farm (aasl 973 m, Long 55°34’6” E, Lat 21°18’64” S), 6 ♀♀ on Citrus limon (L.), and 1 ♀ on P. lanceolata , 9/12/2015, 1 ♀ on B. catharticus , 10 ♀♀ + 1 im. on P. lanceolata , 9 ♀♀ + 1 im. on R. raphanistrum , 18/10/2016; 14 ♀♀ + 2 im. on Citrus sp., and 6 ♀♀ + 2 im. on S. mauritianum , 29/11/2016, 4 ♀♀ + 3 im. on L. camara , 5 ♀♀ on Acacia dealbata Link , and 5 ♀♀ on P. aquilinum , 9/1/2017; Montvert-les-Hauts – EARL Le Mont Vert farm (aasl 582 m, Long 55°32’19” E, Lat 21°19’42” S), 1 ♀ on C. annuum , 14/12/2015; Ravine Langevin – Grand-Galet Waterfall (aasl 850 m, Long 55°21’33” E, Lat 21°17’47” S), 8 ♀♀ on Syzigium jambos L., and 1 ♀ on D. incanum , 11/12/2016; Forêt de Bélouve – Gîte (aasl 1500 m, Long 55°33’36” E, Lat 21°6’0” S), 1 ♀ on Fuchsia boliviana Carrière , 20/12/2016 ; Cap Blanc – Waterfall (aasl 1400 m, Long 55°38’24” E, Lat 21°16’48” S), 7 ♀♀ + 1 im. on Bohemeria macrophylla Jacq. , 3 ♀♀ + 1 im. on S. jambos , and 1 ♀ on Polyscias bernieri (Baill.) , 25/12/2016; Salazie – Voile de la Mariée Road (aasl 798 m, Long 55°32’24” E, Lat 21°2’24” S), 2 ♀♀ on Morus alba L., 7/1/2017; Sainte-Rose – Anse des Cascades (aasl 2 m, Long 55°49’34” E, Lat 21°11’6” S), 1 ♀ on Brillantaisia owariensis P. Beauv. , 21/1/2017 .

Remarks — Measurements of 15 females collected in La Réunion ( Table 19 ) agree well with those of females from Grande Comore ( Kreiter et al. 2018b) and females of Kenya ( El-Banhawy and Knapp 2011).

The species was described as Amblyseius deleoni Muma and Denmark and synonymized after by Daneshvar and Denmark (1982) and Denmark and Muma (1989) with A. herbicolus . Although Muma and Denmark (1970) reported males of A. herbicolus from Florida, there are no other records of males from other regions of the world in the whole literature. Whereas the male of A. deleoni has been described from Florida, it has not been found on leaf samples taken on a regular basis over five years from citrus leaves in New South Wales, Australia ( Schicha 1981c). Blommers (1976) failed also to observe even a single male in the mass rearing of the species in Madagascar. Van der Merwe (1968) and McMurtry (unpublished obs. but mentioned in McMurtry and Moraes 1984) confirmed thelytoky in populations of A. herbicolus from South Africa and California, respectively, by rearing isolated immatures to adult females and observing reproduction of these females.

Males collected in this study appear to be compatible with the description of adult males of A. herbicolus . Unfortunately, they were collected alone, without females or any association link with a nearby (female) population of A. herbicolus . So they cannot be reliably identified as males of A. herbicolus . We have collected 114 females from different localities, habitats and plants of the Island, with and no sign of males despite females sometimes collected in high densities. The thelytoky of this species is thus strongly suspected.