Altica

Reid, C. A. M. & Beatson, M., 2015, Disentangling a taxonomic nightmare: a revision of the Australian, Indomalayan and Pacific species of Altica Geoffroy, 1762 (Coleoptera: Chrysomelidae: Galerucinae), Zootaxa 3918 (4), pp. 503-551 : 507-509

Biology of Altica species

Adult Altica species are relatively weak jumpers ( Schmitt 2004) but with their dark metallic colours and conspicuous diurnal swarming behaviour are likely to be strongly chemically protected ( Phillips 1977), although there are surprisingly few studies of the defence system ( Deroe & Pasteels 1982; Carruthers et al. 2011). Altica species may be monophagous or polyphagous. They may occur in huge numbers, altering plant succession in dynamic habitats ( Bach 1994). Adults also swarm on non-hosts ( Vestjens 1979) and may be associated with damage caused by other organisms, causing confusion in host records. For example, we were informed of damage by swarming Altica to Eleocharis (Cyperaceae) in a swamp on the Murray River, June 2014. The Altica was identified by us as A. aenea , which appears to feed only on Ludwigia (Onagraceae) , so we queried the host record. A closer examination of the damage to the Eleocharis by the correspondent showed that it had been made by grazing kangaroos or horses; Altica -damaged Ludwigia was found nearby. The tussocks of Eleocharis were relatively elevated compared with nearby vegetation and clearly acted as focal points for the swarms of A. aenea .

The general life cycle of Altica is atypical for alticines as the larva is an external feeder: eggs are laid in loose clusters on the hostplant; larvae feed on leaves; pupation is in soil; adults feed on leaves of the larval host but may visit floral nectaries of unrelated plants. All life stages of A. birmanensis have been photographed ( Lee & Cheng 2007) and the larva described ( Takizawa 1978). The immature stages of A. cyanea described and illustrated by the same authors are probably A. aenea , based on the foodplant. Larvae of the two endemic Australian species of Altica are undescribed. Larvae of Altica species worldwide show little variation and the Australian larvae examined by CAMR are similar to their well-described Holarctic counterparts, as reviewed by Hua et al. (2013), with a full complement of dark tubercles and prominent blunt-tipped setae.

The major organisms causing mortality of larvae appear to be Pentatomidae and Tachinidae , but others include Braconidae , Ichneumonidae , Miridae , Sarcophagidae, Nematoda and fungi ( Phillips 1977; de Souza Lopes & Achoy 1986; Cox 1996; Schwenke 1999). Altica larvae are toxic to some predacious Carabidae ( Phillips 1977) . Adult specimens often carry Laboulbenia fungal parasites and the appendages may be heavily encrusted (photographed in Lee & Cheng 2007: 130; pers. obs. CAMR), but the host records provided by Balazuc (1988) may be misidentifications.

The range of host plants of Altica species worldwide is enormous ( Jolivet 1991; Clark et al. 2004), with many northern hemisphere species associated with trees and woody shrubs. A single species occurs on woody shrubs in western Indo-Malaya ( A. cyanea ), but in Australia and the west Pacific, Altica species are recorded feeding only on annual and perennial herbs (with one exceptional record). There is a large literature on the biology of Altica species in the region covered here, but descriptions of individual species’ biology may be based on misidentifications or erroneous synonymy (for example: Hawkeswood 1988; Kimoto 2000; Lee & Cheng 2007). The endemic Australian species have not been studied in detail, but their life histories are unlikely to deviate significantly from south and east Asian species ( Dubey 1981; Singh, Rose & Gautam 1986; Nayek & Banerjee 1987; Lee 1992; Kimoto & Takizawa 1994; Shah & Jyala 1998; Jyala 2002; Lee & Cheng 2007; Zhang, Ge & Yang 2007). Note that in most of these studies the Altica species is wrongly named ( Table 1).

,

Pacific

of

east

Guinea

New

Australia Tasmania of New west Guinea Haloragaceae Onagraceae Melastomaceae Polygonaceae

A. aenea X X X X A. birmanensis X X A. corrusca X X X X A. cyanea X X A. caerulea X X X A. gravida X X X

Wordwide, several Altica species have been suggested for biocontrol of pasture or aquatic weeds, for example A. carduorum Guérin-Méneville, 1858 , on Cirsium arvense ( Wan et al. 1996) and A. lythri Aubé, 1843 , on Lythrum salicaria ( Batra et al.1986) . Some Altica species are pests, including the European A. ampelophaga Guérin- Méneville, 1858, on Vitis ( Picard 1926) , and several pest species in North American horticulture ( Clark et al. 2004). Altica species are of slight significance in the Australian region. Altica corrusca is a pest of strawberry ( Fragaria ) in Victoria ( French 1913; Adam & Prescott 1932) and occasionally a pest of cultivated Onagraceae in gardens. Altica aenea (as A. cyanea ), is a possible biological control agent of onagraceous weeds in irrigated rice ( Oryza ) ( Dubey 1981; Nayek & Banerjee 1987; Xiao-Shui 1990; Naples & Kessler 2005). Altica species have been collected on Oryza (rice), in Australia (label data), Fiji ( Bryant & Gressitt 1957) and Timor Leste (label data), but there is no published confirmation in any study of rice pests that plants are damaged, whereas Ludwigia , a common weed in rice padi, is a definite host of Altica species. We suspect that all records of Altica on Oryza are of nonfeeding individuals. However, A. aenea has been recorded causing damage to leaves of a Citrus species in Kakadu Natonal Park, Northern Territory (label data), so the range of plant hosts may widen in outbreak conditions. Despite these occasional exceptions, hostplants are a useful guide for the identification of Altica species ( Table 2).

Perhaps the most interesting observation on the biology of Altica in Australia is the toxicity of adults and larvae of ‘ A. ignea’ (probably A. aenea ) to mosquito larvae in the Brisbane area ( Hamlyn-Harris 1930). Hamlyn- Harris recorded that naturally released secretions from abundant adults and larvae, dislodged or swimming in the water around their emergent Ludwigia hosts, killed Culex larvae.