STUDI SUI COLEOTTERI CURCULIONIDI II. BARYTYCHIUS SQUAMOSUS GYLL.
Creators: name: Monaco, Raffaele
Publisher: name: Entomologica
Year: 2016

description: La comparsa più intensa in pieno campo del Barytychius squamosus Gyll. si verifica a fine marzo e gli adulti si nutrono delle foglie ancora accartocciate, dei culmi erbacei e degli ovari di Hordeum murinum L. e Bromus sterilis L. La ovideposizione comincia in aprile; i germi vengono affidati alle cariossidi ancora piccole. 

L'incubazione dell'uovo dura 10-15 giorni, e in 15-20 giorni la larva diventa matura nutrendosi delle cariossidi ancora verdi. Completato l'accrescimento, la larva del Curculionide fora le glume che aderiscono alla cariosside e, du- rante le ore notturne, si lascia cadere sul terreno nel quale si affonda fino ad una profondità di 4-12 cm in media. 

Nel terreno la larva si costruisce una cella ampliando lo spazio intorno a sè mediante movimenti del corpo. La caduta delle larve dalle spighe comincia a metà maggio e termina a fine giugno. Nella celletta la larva compie la ninfosi, trasformandosi poi in adulto 30-35 giorni dopo l'interramento della relativa larva. L'adulto passa l'estate e parte dell'inverno in diapausa; a fine marzo rompe la celletta e attraversando il sovrastante strato di terreno si porta alla luce. 

Il Baritichio allo stato di larva è combattuto da due Imenotteri sincroni: il Calcidide Entedon sp. che è endofago, e dal Braconide Bracon sp. aff. pli- ginskii Tel. che è ectofago. 

Economicamente questo Curculionide è da ritenersi utile perchè contribuisce a limitare lo sviluppo e la diffusione delle piante che lo ospitano, le quali sono infestanti nei riguardi delle normali colture agrarie. 

 

A description of the adult, pupa, matured larva and new-born larva of the Coleopter Curculionidae Barytychius squamosus Gyll. 

From the middle of March the adult begins to leave the small cells in which it had spent the Winter in the ground and comes to surface where it starts searching for hospitable plants, represented by Hordeum murinum L. and by Bromus sterilis L. Its activities on the plants are carried out during the hottest hours of the day, while in the evening and when the sky is cloudy, walking on the plant it gets down to the ground where it seeks occasionai shelter to spend the night, however to protect itself. 

Egg-laying starts at the beginning of Aprii and ends in June; the germs are placed in the caryoxides. The incubation period lasts 10 to 15 days and the larva reaches its complete stage of groth in the following 15-20 days. 

Larvae developes inside the caryoxides still green, at the endosperm's expense; once mature they tear with their mandibles the upper glume and let themselves fall and sink into the ground; this is known to happen in May and June. The caryoxides are abandoned during the night because the larva fears the light. In compact uncultivated soil they sink into the ground vertically reaching a depth of 4 to 14 cm while in softer soil the insect is found at a deeper depth. When the larva terminates its descent into the soil, it builds by means of movements of the body a small lengthened celi in which it grows into a pupa and changes into an adult in about 30 to 35 days after coming out of the relative larva fron the caryoxide; it pauses during the Summer and part of the Winter bringing itself into the light at the end of March. 

Economically this Curculionide is to be considered useful, at least in our zone because it helps to limit the growth of the hospitable plants by damaging the leaves, culms and ovaries as well as the reproduction because it empties up to 30-40% of the caryoxides. 

Parasites of this phytophagous are the Calcidide Entedon sp. and the Bra- conide Bracon sp. aff. pliginskii Tel.
description: Entomologica, Vol 4 (1968)