A. macrorrhizos is a glabrous, terrestrial herb, normally around 1-1.5 m tall but growing up to 5 m (Manner, 2011). Plants are acaulescent with a short, conical corm, produce watery sap and develop an elongated caudex with age. Leaves are arranged in a rosette, ascending;blades flattened, ascending, with basal sinus projecting downward, 25-50 (-100) ? 20-36 (-100) cm, green (although white-variegated in some cultivars), slightly lustrous, lance-ovate, coriaceous, wavy or slightly plicate along secondary veins, the apex acute or obtuse and apiculate, the base hastate, the sinuses non-overlapping, up to 30 cm long, the margins wavy, with a submarginal vein within 2 mm from the margin;mid-vein broad and conspicuous with 4-7 primary lateral veins per side;lower surface with dark spots on secondary vein angles;petioles 60-100 cm long. Two or more inflorescences subtended by brachts. Peduncles 20-45 cm long;spathe a whitish to yellowish green, oblong tube;spadix 11-32 cm, pistil 3-4 cm long and about 1.5 cm thick. Fruit a fleshy berry, red when mature, globose or ovoid (Flach and Rumawas, 1996;Wagner et al., 1999;Acevedo-Rodr’guez and Strong, 2005).
Herbs, perennial, to 45 cm, arising from stout, tuberous rhizomes, stolons present, corms present. Root depth, minimum 0.45 cm (USDA-NRCS, 2009). Leaves erect, those submerged, if present, linear and ribbon-like, emersed ones with blades sagittate, lateral lobes as long as terminal one, linear or ovate-deltate, 2-20 cm long, 0.5-12 cm wide, terminal lobe deltate to ovate-deltate or linear, 3-25 cm long, 0.7-35 cm wide, apex acuminate to subobtuse, petioles 20-70 cm long. Inflorescences racemes, rarely panicles, of 3-9 whorls, emersed, 4.5-28.5, (4-23) cm, peduncles 10-59 cm, bracts connate more than or equal to 1/4 total length, elliptic to lanceolate, 3-8 mm, delicate, not papillose, fruiting pedicels spreading, cylindric, 0.5-3.5 cm. Flowers to 4 cm diameter, unisexual (and the plants monoecious or dioecious), lower flowers pistillate, upper ones staminate, and usually with some perfect flowers in the middle, or rarely all flowers perfect, scapes few, 15-70 (-90) cm long, shorter than or slightly longer than leaves, each with 2-7 verticils of flowers, pedicels 0.5-6 cm long, bracts 2-3 per flower, papery, lanceolate to deltate, 0.5-1 (-1.5) cm long, usually gibbous, sepals ovate, 5-10 mm long, petals white, very broadly elliptic, 1-2 cm long, abruptly narrowed into a claw.
Crocosmia ? crocosmiiflora is an herb 25-50 (-100) cm tall, with corms 2-3 cm in diameter and slender scaly stolons. Leaves narrowly lanceolate, 30-50 cm long, 0.8-2 cm wide. Spikes slightly flexuous, arching horizontally, with several branches, bracts 6-10 mm long;tepals orange, lanceolate, 15-25 mm long, 6-9 mm wide, sub-equal, spreading, the perianth tube slightly curved, 10-15 mm long;filaments 15-22 mm long;anthers 6-8 mm long. Capsules up to 7 mm long, ca. 9 mm wide. Seeds brown, wrinkled, usually not viable (Wagner et al., 1999).
Adult Papuana huebneri are black, shiny and 15-20 mm long. The size and number of head horns in taro beetles varies between species and sexes;P. huebneri has only one small horn, which is larger in the male than the female (Macfarlane, 1987a).
Taro beetles can be detected by: (1) digging up wilting taro plants and examining them for signs of damage;(2) using light traps, particularly on moonless and rainy nights;and (3) sampling wild plant species (e.g. banana, sugarcane and grasses such as Paspalum spp. and Brachiaria mutica) at breeding sites, especially along river banks, on rotting logs and in compost heaps (Carmichael et al., 2008;Tsatsia and Jackson, 2014;TaroPest, 2015).
Adult taro beetles burrow into the soft trunks, plant bases and corms of a range of plants, including taro, making large holes or cavities up to 2 cm in diameter (McGlashan, 2006). The feeding tunnels and associated frass may be visible in infested corms (Biosecurity Australia, 2011). The amount of damage to the crop depends on the age of the plants when attacked and the density of infestation. Feeding activity can cause wilting and even the death of affected plants, particularly in young plants if the beetles bore into the growing points. Older plants infested by beetles grow slowly and a few or all of the leaves wilt (TaroPest, 2015). In severely damaged plants tunnels may run together to form large cavities, making the damaged corms more susceptible to fungal infections (Macfarlane, 1987a;Onwueme, 1999). Similar symptoms of damage are caused to other root crops, e.g. sweet potato, yams and potato (McGlashan, 2006). Taro beetles can ring-bark young tea, cocoa and coffee plants in the field and bore into seedlings of oil palm and cocoa (Aloalii et al., 1993).
Papuana huebneri is one of at least 19 species of known taro beetles native to the Indo-Pacific region;it is native to Papua New Guinea, the Molucca Islands in Indonesia, the Solomon Islands and Vanuatu, and has been introduced to Kiribati. Taro (Colocasia esculenta) is an important crop in these countries;high infestations of P. huebneri can completely destroy taro corms, and low infestations can reduce their marketability. The beetle also attacks swamp taro or babai (Cyrtosperma chamissonis [ Cyrtosperma merkusii ]), which is grown for consumption on ceremonial occasions. Infestations of taro beetles, including P. huebneri, have led to the abandonment of taro and swamp taro pits in the Solomon Islands and Kiribati, resulting in the loss of genetic diversity of these crops and undermining cultural traditions. P. huebneri also attacks a variety of other plants, although usually less seriously. Management today relies on an integrated pest management strategy, combining cultural control measures with the use of insecticides and the fungal pathogen Metarhizium anisopliae.
Papuana huebneri is a pest of taro (Colocasia esculenta;known as ‘dalo’ in Fijian;McGlashan, 2006) (Masamdu, 2001;International Business Publications, 2010), which is grown primarily as a subsistence crop in many Pacific Island countries, including Kiribati, Papua New Guinea, the Solomon Islands and Vanuatu, where P. huebneri is found (Aloalii et al., 1993). Taro also has value in gift-giving and ceremonial activities (Braidotti, 2006;Lal, 2008). The beetle also attacks swamp taro or babai (Cyrtosperma merkusii or Cyrtosperma chamissonis), which is grown for consumption on ceremonial occasions (Food and Agriculture Organization, 1974;Dharmaraju, 1982;International Business Publications, 2010).
Other plants attacked by Papuana huebneri include tannia (Xanthosoma sagittifolium), bananas (Musa spp.), Canna lily (Canna indica), pandanus (Pandanus odoratissimus [ Pandanus utilis or P. odorifer ]), the bark of tea (Camellia sinensis), coffee (Coffea spp.) and cocoa (Theobroma cacao), the fern Angiopteris evecta (Masamdu, 2001), and occasionally the Chinese cabbage Brassica chinensis [ Brassica rapa ] (International Business Publications, 2010).
Species of Papuana behave similarly to each other and feed on the same host plants (TaroPest, 2015). For taro beetles in general, primary host plants other than taro include giant taro (Alocasia macrorrhizzos), Amorphophallus spp., the fern Angiopteris evecta, banana (Musa spp.) and tannia (Xanthosoma sagittifolium). Secondary hosts include pineapple (Ananas comosus), groundnut (Arachis hypogaea), betel nut (Areca catechu), cabbage (Brassica oleracea), canna lily (Canna indica), coconut (Cocos nucifera), Commelina spp., Crinum spp., yam (Dioscorea spp.), oil palm (Elaeis guineensis), sweet potato (Ipomoea batatas), Marattia spp., pandanus (Pandanus odoratissimus [ Pandanus utilis or P. odorifer ]), Saccharum spp. including sugarcane (Saccharum officinarum) and Saccharum edule [ Saccharum spontaneum var. edulis ], and potato (Solanum tuberosum);they occasionally ring bark young tea (Camellia sinensis), coffee (Coffea spp.) and cocoa (Theobroma cacao) plants (Macfarlane, 1987b;Aloalii et al., 1993;Masamdu and Simbiken, 2001;Masamdu, 2001;Tsatsia and Jackson, 2014;TaroPest, 2015).
The most thorough description available is by Hayes et al. (2012), in which P. canaliculata and P. maculata are compared. The following brief description is modified from that publication.
The most recognizable sign of the presence of P. canaliculata (and other related apple snail species) is their bright-pink egg masses, which are laid on emergent vegetation (including wetland crops) and other hard surfaces above the water line, such as rocks, logs and bridge supports (Hayes et al., 2009b). These egg masses are very noticeable and can even be seen from a moving vehicle.
In wetland rice the first symptom of damage by P. canaliculata is a reduced plant stand where the snails have severed the plant stalks below the water level. The tillers are cut first and then the leaves and stems are consumed under water. The crop is highly vulnerable at the early seedling stage. In taro, damage to the corms is readily visible, and active snails are easily seen feeding on both corms and leaves that have drooped so that their tips break the water surface.
P. canaliculata is a freshwater snail native to parts of Argentina and Uruguay. The distribution of P. canaliculata has been steadily increasing since its introduction to Asia, primarily as a human food resource but perhaps also by the aquarium trade, beginning around 1979 or 1980 (Mochida, 1991;Halwart, 1994a;Cowie, 2002;Joshi and Sebastian, 2006). Once introduced to an area, it spreads rapidly through bodies of water such as canals and rivers and during floods. It feeds on aquatic plants and can devastate rice (in South-east Asia), taro (in Hawaii) and other aquatic or semi-aquatic crops. It may out-compete native apple snails (Halwart, 1994a;Warren, 1997), prey on native fauna (Wood et al., 2005, 2006) and alter natural ecosystem function (Carlsson et al. 2004a). It is also an important vector of various parasites including the nematode Angiostrongyulus cantonensis, which causes human eosinophillic meningitis (Lv et al., 2011;Yang et al., 2013).
The list of crops and other plants affected is not an exclusive list of all wild plant species potentially affected. P. canaliculata is primarily a generalist macrophyte herbivore and determining what plants it does not eat may be more important than generating a long list of plants it will eat (Cowie, 2002).
Regarding the most important crop affected, rice, it is the young seedling stage that is most vulnerable (Halwart, 1994a;Okuma et al., 1994b;Schnorbach, 1995;Naylor, 1996;Cowie, 2002;Wada, 2004). All parts of wetland taro plants are eaten because the snails can access the leaves when they droop down to the water surface.
Because of its generalist feeding habits, P. canaliculata has been suggested as a biological control agent for aquatic and wetland weeds in rivers (Cazzaniga and Estebenet, 1985;Fernández et al., 1987) and rice fields (Okuma et al., 1994b;Wada, 1997;Joshi et al., 2006). It can be used to control weeds without eating the rice plants only if rice seedlings are transplanted and at the 3-leaf stage (21 days), so that they are too tough for the snails to eat, and the ground is allowed to dry until water is introduced to a 2 cm depth after 6-8 days after transplanting (Joshi et al., 2006).
C. indica is a rhizomatous, perennial, erect, robust herb, up to 3.5 m tall. Rhizome branching horizontally, up to 60 cm long and 10 cm in diameter, with fleshy segments resembling corms, covered with scale leaves, and thick fibrous roots. Stem fleshy, arising from the rhizome, usually 1-1.5 m tall, often tinged with purple. Leaves arranged spirally with large open sheaths, sometimes shortly petiolate;blade narrowly ovate to narrowly elliptical, up to 60 cm x 15-27 cm, entire, base rounded to cuneate, gradually attenuate to the sheath, apex acuminate, midrib prominent, underside often slightly purplish. Inflorescence terminal, racemose, usually simple but sometimes branched, bearing single or paired, irregular, bisexual flowers;bracts broadly obovate. 1-2 x 1 cm;sepals 3, ovate, acute, 1-1.5 x 0.4-0.9 cm;corolla 4-5 cm long, the lowermost 1 cm fused into a tube, lobes free;lobes 3, linear, 3-4 x 0.3-0.6 cm, pale red to yellow;androecium petaloid and forming the showy part of the flower, composed of an outer whorl of 3 staminodes and an inner whorl of 2 connate staminodes (one of which forms a large lip or labellum) and 1 fertile stamen;outer staminodes spathulate, 4-6 x 1-1.5 cm, often very unequal in length or only 2 clearly visible, fused at the base, reddish, labellum narrowly oblong-ovate, 4-5 x 0.5-0.8 cm, yellow spotted with red;stamen 4-5 cm long, petaloid portion involute, anther 0.7-1 cm long and adnate to the petaloid portion at base;ovary inferior, trilocular, style fleshy, 4-5 cm long, reddish, adnate at base to androecium. Fruit a loculicidally dehiscent ovoid capsule, 3 x 2.5 cm, outside with soft spines. Seeds numerous, globose, 0.5 cm in diameter, smooth and hard, blackish to very dark brown.
X. sagittifolium is a glabrous, erect, herb up to 2 m tall, acaulescent when young, mature plants with a thick, erect, fleshy stem up to 1 m long, these with numerous leaf scars and sometimes with aerial roots, the base enlarged, ovoid, producing lateral, elongated subterranean, edible tubers or corms. Leaves several, nearly in a rosette in acaulescent plants, or in a distal crown in mature plants;blades horizontal to slightly nodding, with the posterior lobes ascending, 40-100 ? 40-70 cm, simple, upper surface dark green with light green primary and secondary veins, lower surface light green, with dark green venation, the apex obtuse, ending in an acute point, the base cordate with non-overlapping lobes, the lowest pair of secondary veins surrounded by marginal tissue at their insertion with the petiole, the margins undulate;petioles erect, 1-1.5 m long, green, invaginate on lower 2/3, with straight, wavy or sometimes involute margins. Inflorescences 1-3, axillary, ascending;peduncles up to 20 cm long;spathe chartaceous, 13-15 cm long, the tube 6-7 cm long, grayish green, oblong-ovoid, the blade elliptic, erect, concave, adaxially cream to white, shortly acuminate at apex;spadix slightly shorter than the spathe, the pistillate zone cylindrical, the sterile staminate zone conical, pinkish, the fertile staminate zone elongated, ellipsoid, cream. Fruit a small, yellow berry (Acevedo-Rodr’guez and Strong, 2005;Langeland et al., 2008).
A solid, short, swollen underground stem which serves as an asexual propagule for the plant, lasts only one year, and bears the next year's growth at the top of the old corm.