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Home > Infestation > Immature figs infestation (eggs) : number of ostiolar scales used in a fig, eggs dissemination.
Author: François DROUET.
Photographs: François DROUET.
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Immature figs infestation (eggs)
Number of ostiolar scales used in a fig, eggs dissemination
Below, my personal observations (no information reported from the literature). Orchard located in the Toulon region, French souhteastern Mediterranean coast, USDA zone 9b.
Chapter plan: number of ostiolar scales used in a fig, eggs dissemination according to the number of used scales. Knowing that another chapter deals with the immature figs infestation by the Silba adipata McAlpine eggs (eggs number per fig, eggs implantation by ostiolar scales types).
NUMBER OF OSTIOLAR SCALES USED IN A FIG
When the fig contains 1 egg, I observe that this one can be implanted under an ostiolar scale or in the ostiolar canal. When it contains 2 to 5 eggs, I observe that these are implanted under a single ostiolar scale, under several ostiolar scales (maximum 3), and/or in the ostiolar canal.
The study of 143 infested figs collected after abscission, which I carried out in July / August 2021 (see chapter), showed that: 64% of the examined figs contain eggs under a single ostiolar scale; 28% contain eggs under 2 ostiolar scales; 6% contain eggs under three ostiolar scales; 2% contain eggs in the ostiolar canal alone.
Note: in the examined batch, none of the figs simultaneously contain eggs in the ostiolar canal and under one or more ostiolar scales, but I have observed these cases before.
Silba adipata McAlpine: reddened immature fig containing 5 chorions distributed under 3 ostiolar scales.
(fig collected from the ground; biferous variety 'Grise de la Saint-Jean', second crop).
When the fig contains a number of eggs greater than 5 (multiple ovipositions in the same fig), I have observed that their dissemination often concerns 1 to 3 ostiolar scales, and sometimes more than 3 ostiolar scales. The maximum number of ostiolar scales containing eggs that I could observe in a fig is 7 (these were first and second level scales, for a total of 29 eggs).
Whatever the number of eggs contained in the fig, the maximum number of eggs grouped in the ostiolar canal that I have observed is 7 (once only).
EGGS DISSEMINATION ACCORDING TO THE NUMBER OF USED SCALES
EGGS DISSEMINATION
The study of 143 infested figs collected after abscission, which I carried out in July / August 2021 (see chapter), provides the number of eggs implanted under each of the ostiolar scales of the examined figs. It follows that we can know the eggs dissemination in the different cases of ostiolar scales use in a fig (one, two or three).
When a single ostiolar scale gathers all the eggs (64 % of the 143 examined figs), I count: 1 egg in 37% of the cases; 2 eggs in 40% of cases; 3 eggs in 14% of cases; 4 eggs in 3% of cases; 5 eggs in 6% of cases.
When all the eggs are distributed under two ostiolar scales (28% of the 143 examined figs), I count: 2 eggs in 38% of the cases - 15 figs (1,1) - i.e. 1 egg under each of the two scales; 3 eggs in 30% of cases - 12 figs (1,2 ) - i.e. 1 egg under a scale, and 2 eggs under the other scale; 4 eggs in 23% of cases - 9 figs, including 7 figs (2,2) and 2 figs (1,3); 5 eggs in 7% of cases - 3 figs, including 2 figs (1,4) and 1 fig (2,3); 7 eggs in 2% of cases - 1 fig (2,5).
When all the eggs are scattered under three ostiolar scales (6% of the 143 examined figs), I count: 3 eggs in 11% of cases - 1 fig (1,1,1); 4 eggs in 33% of cases - 3 figs (1,1,2); 5 eggs in 33% of cases - 3 figs, including 2 figs (1,2,2) and 1 fig (1,1,3); 6 eggs in 22% of cases - 2 figs (1,2,3).
When the eggs are located in the ostiolar canal (2% of the examined 143 figs; 3 figs), I count: 1 egg in the case of one fig, and 2 eggs in the case of 2 figs.
EXAMPLES OF EGGS CONFIGURATION UNDER TWO OSTIOLAR SCALES
Silba adipata McAlpine: dissemination of 2 eggs under 2 ostiolar scales of an immature fig ('Bellone' variety).
Silba adipata McAlpine: dissemination of 3 eggs under 2 ostiolar scales of an immature fig ('Bellone' variety).
(the only possible configuration is 1 egg under one scale, and 2 eggs under the other).
Silba adipata McAlpine: 1 larva, I unhatched egg, and 1 chorion left by the larva stuck to the egg (top scale); 2 chorions (bottom scale).
(a total of 4 eggs laid in this 'Bellone' immature fig; another possible configuration would be 1 egg under one scale, and 3 eggs under the other).
Silba adipata McAlpine: dissemination of 5 eggs under 2 ostiolar scales of an immature fig ('Bellone' variety).
(another possible configuration would be 1 egg under one scale, and 4 eggs under the other).
Silba adipata McAlpine: dissemination of 8 eggs under 2 ostiolar scales of an immature fig - plurality of ovipositions in the fig.
(photographed configuration: 2,6; other possible configurations are: 1,7; 3,5; 4,4).
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