Among specialized olygophagous insects of amaranth the only species has been
revealed – it was amaranth weevil Lixus subtilis. This pest damages the plants from
Amaranthaceae and Chenopodioideae [31]. In all regions of amaranth growing, intra-
stalk pests are the most injurious. The larvae of Lixus subtilis develop inside stalks and
petioles of amaranth. We studied its food specialization [29]. It was found, that
amaranth weevil is constantly present in agrocenoses of the northeastern part of the
Forest-Steppe of Ukraine on weeds: Amaranthus retroflexus L. and Chenopodium
album L. It periodically significantly damages the crops of sugar beet, but prefers the
crops of cultivated amaranth. It is explained by larger diameter of stalk (4–5 mm) and
petioles (not less than 3 mm) of amaranth, which is suitable for weevil oviposition and
larvae development [26]. In addition, the tissues of cultivated amaranth are more tender
and juicy tissues. One or two weevil larvae can develop in one amaranth petiole, and
over 10 larvae can develop in one stalk. Larvae browse galleries of length 1–3 cm (in
petioles) and 10–30 cm (in stalks of amaranth) [30]. Adults overwinter; the weevil has
one generation per year. Natural enemies include ants Lasius sp. (who steal the eggs of
weevil),
ichneumonid parasitoid
Exeristes roborator (Fabricius, 1793) (whose larvae
parasitize on the larvae of older instars and pupae of Lixus subtilis); robber flies
(Asilidae) (which hunt adult weevils).
Phytophages of the third group were few and used amaranth (its pollen) for
maturation feeding.
Predators were attracted by victim – black bean aphid (Aphis fabae
Scop.
).
Among predators, coccinelids were the most abundant – Scymnus frontalіs (Fabricius,
1787), Coccinella septempunctata Linnaeus, 1758, Coccinula quatuordecimpustulata
(Linnaeus, 1758), Hippodamia variegata Goeze, 1777, Psyllobora vigintiduopunctata
(Linnaeus, 1758), Harmonia axyridis (Pallas, 1773). Predatory thrips (Aeolothrips
fasciatus (Linnaeus, 1758)) and solitary wasps (Sphecidae) were common.
Common parasitoids were represented by aphidophags: Aphidencyrtus
aphidivorus (Mayr, 1876) and Lysiphlebus sp. (Hymenoptera: Braconidae:
Aphidiidae) [25], in some years parasitoids – pipunculid flies (Tomosvaryella
coquilletti (Kertesz, 1907)) were able to control leafhoppers population [12].
Numerous parasitoids consumed amaranth pollen during maturation feeding: the
species of Chalcіdoіdea, Sarcophaga sp., parasitoids of noctuid (Peletіerіa
nіgrіcornіs Meigen, 1838) and scarabaeids larvae (Microphthalma disjuncta
Wiedemann, 1824).
Saprophags (Drosophіlіdae, Phorіdae, Lonchopterіdae) were solitary.
The pests of amaranth generative organs are of high economic importance,
because they are able to significantly reduce the grain crop and quality. We have
shown, that entomofauna of amaranth generative organs includes 90 species from 40
families of 8 orders (Table 2).
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