Agricultural entomology: Altica of chard

Classification and host plants

Class: Insects
Order: Beetles
Suborder: Polyphages
Family: Chrysomelids
Genus: Chaetocnema
Species: C. tibialis Illiger

Bibliographic reference:
“Phytopathology, agricultural entomology and applied biology” – M.Ferrari, E.Marcon, A.Menta; School edagricole - RCS Libri spa

Host plants: Chard.

Identification and damage

The Chard of the Chard is a small beetle (about 12 mm long) of a bluish-green color with metallic reflections, in particular on the elytra. The larvae live in the soil, in the rhizosphere, where, however, they are not considered harmful. The damage is determined by the adult stages; it occurs on the aerial apparatus, especially on young plants with cotyledonary leaves or with the first true leaflets.
The adults, with their robust chewing apparatus, perform rounded erosions on the leaf flap, affecting the mesophyll and the lower lepidermis, leaving the upper lepidermis intact; this necrotizes and subsequently detaches, creating a peeling of the leaf which is perforated in several places. If the attack is early and affects the young seedlings, serious failures can occur, due to the death of the seedlings themselves.

Biological cycle

The chard of the beet winters in the adult stage in the soil or on the wild plants at the edge of the crops, sheltered at their base.
At the beginning of spring, end of March-April, the wintering adults go to the Chard fields and begin their trophic activity, causing the damage described. After about 15-20 days they mate and lay in the ground, close to the host plants. The newborn larvae descend into the ground without causing serious damage.
From these larvae new adults originate which can either winter directly or, in certain favorable climatic conditions, originate a 2nd generation, summer, of little importance. Therefore, ltica performs 1-2 generations a year.

Chard Altica - Chaetocnema tibialis Illiger (photo www.biol.uni.wroc.pl)

Fight

The fight against the chard insects (in particular the Altica, the Casside, the Elateridi, the Cleono and the Lisso) is obligatory in respect of the D.M. 03/11/1951. The control of the Altica however is not carried out directly; the normal geodisinfestant treatments, with systemic action, distributed to the sowing for the other phytophages in fact control the populations of Altica without other interventions.
In case of intense attacks on the aerial apparatus, for the lack of geodisinfestation, treatments with insecticide products can be carried out. The treatments must be timely and carried out on the vegetation. It is possible, in any case, to activate visual sampling of the damage to establish an intervention threshold, which is set as follows:
- presence of holes on the cotyledons;
- presence of 2-4 holes respectively on plants with 2-4 real leaves.

Video: ENTOMOLGY Part 1 for AFO 2018, JRF, NABARD, Any other agricultural compititive exams (June 2022).