Input text with Pivot Table

Hy ...I'm new to Laracast. I have a problem and I try to explain.

I have three tables
• pellets
• specie
• specie_pellet (The specie are the trees)

The tree_pellet is a pivot table with fields
• pellet_id
• specie_id
• percentage

I have setting my models for the relations so:

Pellet

public function specie()
    {
        return $this->belongsToMany(Specie::class)->withPivot('percentuale');
    }

Specie

public function pellets()
    {
        return $this->belongsToMany(Pellet::class)->withPivot('percentuale');
    }

I have also create a Form for Update the tree_pellet so:

{!! Form::model($pellet, ['method' => 'PUT', 'route' => ['composizione.update', $pellet->id]]) !!}


Specie
Percentuale
Azione


@foreach($pellet->specie as $specie)

{!! Form::select('specie[]', $listaSpecie, $specie->id, ['class' => 'form-control']) !!}

Elimina 

@endforeach


{!! Form::submit('Aggiorna Composizione', ['class' => 'btn btn-success']) !!}
{!! Form::close() !!}

A pellet can have multiple configurations:
• 5 - 1 - 50 (5 is the pellet_id - 1 is the specie_id - 50 is the percentage)
• 5 - 7 - 50 (5 is the pellet_id - 7 is the specie_id - 50 is the percentage)
• (example: a bio pellet is make with 50% of silver fir and 50% red fir)

But when I try to update i receive this error:

SQLSTATE[42S22]: Column not found: 1054 Unknown column '0' in 'field list' (SQL: insert into `pellet_specie` (`0`, `pellet_id`, `specie_id`, `1`) values (1, 5, 0, 7))

Someone can try to help me please?