First report of Phylloxera quercus (Hemiptera: Sternorrhyncha ...

Bulletin OEPP/EPPO Bulletin (2016) 0 (0), 1–4

ISSN 0250-8052. DOI: 10.1111/epp.12323

First report of Phylloxera quercus (Hemiptera: Sternorrhyncha: Aphididae) in Algeria M. Laamari LATPPAM Laboratory, Department of Agronomy, Institute of Agronomic and Veterinary Sciences, University of Batna, 05000, Batna, Algeria; e-mail: [email protected]

Surveys were conducted on 6 June 2015 in a suburban stand of Quercus ilex near Inoughissen (Province of Batna, Aures Mountains). The results of the surveys are presented in this paper, which provides the first report of the presence of Phylloxera quercus in Algeria. Heavy infestations in 2015 are thought to be related to the high amount of rainfall recorded during the spring of that year. Symptoms included severely discoloured leaves and wounds on young shoots.

Introduction Quercus ilex L. (holm oak) is among the most important forest species of the Mediterranean region, covering an area of about 2 000 000 ha (Dahmani-Megrerouche, 2002). It is abundant in North Africa, especially in Morocco and Algeria. In 1955, Q. ilex covered an estimated 700 000 ha in Algeria (Boudy, 1955). However, by 2010, only 149 419 ha remained (El Achi Dieb, 2010). This alarming reduction is due to climate change and anthropogenic effects (Quezel, 2000). Quercus ilex is widely distributed from the coast to the high elevations of the main mountain ranges. The entomofauna of holm oak has not been widely studied. Some of the most important research was conducted by Arahou (2008) in the Moroccan Middle Atlas mountain range during the period 1983–87. This author identified 310 species of insects and Coleoptera, comprising more than two-thirds of the collected species. In Algeria, the study conducted by Benia et al. (2015) in the forest of Tafat (Setif, North-East Algeria) revealed the presence of 231 insect species on oak, with Coleoptera being the most dominant order. According to Eastop & Blackman (1994), 25 species of aphids (Homoptera, Sternorrhyncha) were registered on holm oak, of which 3 belong to the family Aphididae. These species are Phylloxera coccinea (von Heyden), Phylloxera ilicis Grassi and Phylloxera quercus Boyer de Fonscolombe. There is considerable taxonomic uncertainty about the oak-feeding Phylloxeridae (Eastop & Blackman, 1994). Several described species may not represent unique taxa but rather are different morphological forms of the same species found on different host plants. The P. quercus group consists of the following species: P. coccinea, Phylloxera foae Borner, P. ilicis, Phylloxera italicum Grassi and P. quercus (Blackman & Eastop, 1994). According to Blackman & Eastop (1994), the P. quercus group is reported to feed on the undersides of leaves of deciduous and evergreen Quercus species (Fagaceae).

Quercus ilex, Quercus robur, Quercus petraea, Quercus coccifera, Quercus pubescens and Quercus pyrenaica are reported as hosts of P. quercus (Blackman & Eastop, 1994). According to Croci et al. (2012), P. quercus is the most frequently reported species causing damage to oak trees in Italy, especially in urban and suburban areas. Mimeur (1937) considers P. quercus as a Palaearctic species. This aphid was found in Southern Europe, North Africa and the Middle East (Blackman & Eastop, 1994). In North Africa, Mimeur (1937) reported this aphid on Q. ilex for the first time in the Middle and High Moroccan Atlas. Mimeur also found this aphid on Q. suber L. in the north of Morocco. In the north of Tunisia, traps placed in seed potato plots allowed the collection of alatae of P. ilicis (BoukhrisBouhachem et al., 2007). Prior to the finding presented in the present paper no species of Phylloxera had been reported on oak in Algeria.

Present study: description and results In the context of a study conducted on aphids associated with the forest in the region of the Aures, it was observed that some oak trees surveyed in the locality of Inoughissen (Province of Batna, Eastern Algeria) had severely discoloured foliage. The samples collected on 6 June 2015 and analysed in the Laboratory of Plant Protection (University of Batna) revealed the presence of P. quercus for the first time in Algeria. The studied and identified specimens were deposited in the insect collection of the Department of Agronomy, University of Batna (DZA). The infested oak trees were located close to this location at an elevation of 1410 m (35.27°N, 5.54°E). These trees range in age from approximately 10 to over 100 years and their heights are between 1.5 and 6 m (Table 1). They are located beside a river on a steep slope. In this region of the Aures Mountains (Saharian Atlas) Q. ilex is the only species in the genus Quercus. This region is characterized by a semi-arid climate

ª 2016 The Authors. Journal compilation ª 2016 OEPP/EPPO, EPPO Bulletin 0, 1–4

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but, unusually, high rainfall was recorded during the spring of 2015. The observations noted in 2015 and 2016 confirmed that these aphid colonies were formed only on young shoots (Table 1). No presence was detected on senescent leaves formed in previous years. Young trees were more highly infested than mature trees, and the foliage of some young shoots was completely desiccated. On the underside of each infested leaf several apterous females could be seen. Around each female, up to 50 eggs and larvae could be observed. Each apterous female (Figs 1 and 2) was yellow, measured up to 0.9 mm and had 6 rows of digitiform tubercles on its body (Fig. 3). Some winged females (alatae) could also be observed. For these alatae, the digitiform tubercles were only present in the frontal sinus (Fig. 4). As Q. ilex is the only Quercus species in this region it is clear that this insect completes its life cycle on this host plant. Some galls with emergence holes were observed on older leaves (Fig. 5), but it is not known whether these galls were caused by P. quercus. The lower side of infested leaves has a normal appearance, unlike the upper side which is completely or partially discoloured (Fig. 6). On 29 June 2015, these aphid colonies completely disappeared. This is thought to be due to high temperatures, the senescence of leaves and the presence of predators (Syrphidae, Chrysopidae and Coccinellidae).

Fig. 1 Apterous Phylloxera quercus female surrounded by eggs on the lower face of a Quercus ilex leaf.

Discussion These observations, noted in 2015 and 2016, show that P. quercus attacks occur quite late in the year. Attacks were observed only after sufficient growth of young shoots and at the time of flowering. On younger trees, infestations were more severe and the foliage was partially or totally discoloured. Generally, infested trees showed no signs of weakness or defoliation. Furthermore, monitoring carried out for 2 years showed that infestations have not progressed to other trees. Trees that are located more than 100 m from the river show no signs of attack. It was also noticed that the infestation period did not exceed 1 month and complete disappearance of colonies was observed after fruit set and hardening of the leaves. In 2016, some Telaxes suberi individuals were recorded among the colonies of P. quercus,

Fig. 2 Microscopic view of an apterous Phylloxera quercus female.

Table 1. Some parameters measured on oak trees attacked by Phylloxera quercus in the locality of Inoughissen (Batna, Algeria) in 2015 and 2016 Measured parameters

2015

2016

First appearance of colonies Age of trees Height of trees Length of young shoots Leaves on young shoots attacked (%) Average number of apterous females per leaf Average number of winged females per leaf Average number of larvae per leaf Date of disappearance of colonies First appearance of Telaxes suberi

6 June 10 to more than 100 years 1.5–6 m 5–15 cm 60 3 2 98 29 June 29 June, or after the disappearance of P. quercus

28 May The same trees The same trees 3–12 cm 55 3 1 76 24 June 28 May (mixed colonies)


Phylloxera quercus in Algeria

Fig. 3 Form of tubercles present on the body of an apterous Phylloxera quercus female.

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Fig. 5 Gall found on leaves of Quercus ilex.

Fig. 6 Discolouration observed on the superior face of Quercus ilex leaves infested by Phylloxera quercus.

Premier signalement de Phylloxera quercus (Hemiptera: Sternorrhyncha: Aphididae) en rie Alge Fig. 4 Tubercles present only on the frontal sinus of Phylloxera quercus alatae.

confirming that there is no competition between the two aphid species.

Conclusion The aphid P. quercus, that was observed for the first time in Algeria on some holm oak trees in the locality of Inoughissen (Batna, Aures Mountains), is not currently a threat to this forest species. Monitoring carried out in 2015 and 2016 showed that infestations have not progressed to other trees. It will be interesting to continue observations for a long period to determine the evolution of its attacks over time and space. Moreover, it will also be interesting to determine its hosts, its life cycle and its distribution through Algeria.

Une prospection a ete realisee le 6 juin 2015 dans un peuplement forestier de Quercus ilex, en zone peri-urbaine, proche d’Inoughissen (Province de Batna, massif de l’Aures). Le rapport de cette prospection est presente dans cet article, et comprend le premier signalement de Phylloxera quercus en Algerie. Les fortes infestations observees en 2015 sont probablement liees aux fortes precipitations enregistrees au printemps de cette même annee. Les sympt^ omes consistaient notamment en des decolorations importantes de feuilles ainsi que des blessures sur jeunes pousses.

Пepвoe cooбщeниe o Phylloxera quercus (Hemiptera, Sternorrhyncha, Aphididae) в Aлжиpe 6 июня 2015 в пpигopoдe Инyгиcceнa (в paйoнe Бaтнa, гopы Opec) были пpoвeдeны oбcлeдoвaния нacaждeний


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Quercus ilex. B cтaтьe пpeдcтaвлeны peзyльтaты этoгo oбcлeдoвaния, кoтopыe впepвыe гoвopят o пpиcyтcтвии Phylloxxera quercus в Aлжиpe. Пpeдпoлaгaeтcя, чтo cepьeзныe зapaжeния в 2015 гoдy были cвязaны c oбильными дoждями, зapeгиcтpиpoвaнными вecнoй пpoшлoгo гoдa. Cимптoмы включaли в ceбя cильнoe oбecцвeчивaниe лиcтьeв и изъязвлeния мoлoдыx пoбeгoв.

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