Aphelenchoides

Sánchez-Monge, Alcides, Flores, Lorena, Salazar, Luis, Hockland, Sue & Bert, Wim, 2015, An updated list of the plants associated with plant-parasitic Aphelenchoides (Nematoda: Aphelenchoididae) and its implications for plant-parasitism within this genus, Zootaxa 4013 (2), pp. 207-224 : 213-215

Main Plant-Parasitic Aphelenchoides spp. (MPPA): A. besseyi , A. fragariae and A. ritzemabosi

A. besseyi , A. fragariae and A. ritzemabosi are the most important species of foliar and bulb nematodes in terms of both, host range and economic yields. In Spermatophyta, these three species are present in 98 out of 99 families within 36 of 37 orders of plants associated with PPA. Only the order Sapindales Dumortier has no associations with the MPPA but only with A. sphaerocephalus on Evodia roxburghiana (Rutaceae) ( Goodey 1953). Flowering plants are the most important group in terms of associations (83% of the reports; see Tables 1 and 2) and within them, dicots hosts are almost five times the number of monocots ( Fig. 1 ). Ferns (Pteridophyta) also represent an important group with 25 families having at least one plant species associated, especially for A. fragariae as 25% of its reports belong to the latter group ( Table 1 , Fig. 1 ).

Remarkably, despite the high number of reported associations and their unspecialized feeding behaviour, it is not common for a plant species to have more than one MPPA. From a total of 925 plant species/varieties only six have reports of the three species, i.e. Dahlia pinnata Cav., Zinnia elegans Jacq. , and Z. violacea Cav. (Asteraceae) , Fragaria x ananasa ( Rosaceae ), Saintpaulia ionantha H. Wendl. ( Gesneriaceae Rich. & Juss. ) and the fern Asplenium nidus L. ( Aspleniaceae Newm. ) on which their inter-specific and host-related interactions have not been documented. In addition to those species, the MPPA have been reported on unidentified species of the genera Begonia , Chrysanthemum and Fragaria L. (see online database). Plant and nematode distribution aside from environmental factors could be affecting potential associations, unfortunately the number of studies on such topic and Aphelenchoides spp. is limited and focused on selected species on specific hosts e.g. A. fragariae in Lantana ( Kohl et al. 2010) , A. ritzemabosi in Alfalfa ( Williams-Woodward & Gray 1999).

According to the compiled data, A. fragariae and A. ritzemabosi are more likely to be found on the same plant species than any other combination of MPPA (65 species, Fig. 2 ). A. fragariae and A. besseyi have only 6 plant species in common; Impatiens balsamina L. ( Balsaminaceae Rich. ), Ficus elastica Roxb. ( Moraceae Gaudich. ), Allium cepa L. ( Amaryllidaceae ), Pinus massoniana (Pinaceae) and the ferns Asplenium jamaicense Jenman (Aspleniaceae) and Lygodium circinatum (Burm.f.) Sw. ( Lygodiaceae C.Presl. ). A. fragariae and A. besseyi have also been found on Lemna sp. ( Asteraceae ). Finally, A. besseyi and A. ritzemabosi record 10 hosts from 6 families in common; Calendula officinalis L., Chrysanthemum morifolium Ramat. , Chrysanthemum maximum L., Lactuca sativa L. and Leucanthemum maximum (Ramond) DC. ( Asteraceae ), Phaseolus vulgaris (Fabaceae) , Solenostemon scutellarioides (L.) R.Br. ( Lamiaceae Martinov ), Fragaria vesca L. ( Rosaceae ), Nicotiana tabacum L. ( Solanaceae Juss. ) and Polianthes tuberosa L. ( Asparagaceae ). The two species were also detected on Tagetes sp. ( Asteraceae ). However, new associations of Aphelenchoides on non-reported plant species as well as new combinations on already reported associations are plausible.

The following plant families have reported associations with the MPPA on different plant species: the dicots Asteraceae , Balsaminaceae , Begoniaceae , Brassicaceae Burnett , Caryophyllaceae Juss. , Convolvulaceae Juss. , Fabaceae , Gesneriaceae , Hydrangeaceae Dumort , Lamiaceae , Oleaceae Hoffmanns. & Link , Plantaginaceae Juss. , Rosaceae and Solanaceae and the monocots Amaryllidaceae , Asparagaceae and Poaceae (see online database).

Figures

FIGURE 1. Number of species / varieties of plants associated with foliar nematodes in ferns (Pteridophyta), monocots (Liliopsida), dicots (Magnoliopsida) and other botanical groups

FIGURE 2. Number of single and shared associated plant species (left) and families (right) of foliar nematodes (Aphelenchoides). Between brackets is the corresponding number of ferns for each case