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Immature
Stages of Eurytomidae
Immature stages of Eurytomidae were discussed in detail by
Clausen (1940), as follows: There is a considerable degree of uniformity in the eggs of the
known species of the Eurytomidae. In
the majority of cases, the egg is oblong in form with a somewhat collapsed
stalk at the anterior end and a flagellum of varying length at the opposite
end. The stalk may range in length
from half that of the egg body to five or 6X its length, as in Macrorileya oecanthi. In this species, the stalk is much more
slender than usual, being virtually a filament. In some species, the posterior flagellum is greatly reduced or
lacking. In the externally deposited
eggs of Eurytoma, the
chorion exhibits a distinct sculpturing which, in E. pissodis
Gir., is described as a black pubescence, while in others it is stated to
consist of short but strong "spines" (Fig. 89A). These spines are densely placed and give the
egg a color ranging from brownish to black.
The stalk and flagellum lack this sculpturing. The ovarian egg of E. oophaga
Silv. has reticulate markings on the chorion; after deposition, this
sculpturing is in the form of fine spines.
The egg of E. curta is cylindrical and measures
0.4 by 0.07 mm.; the stalk is 1.1 mm. in length, and the chorion is
unsculptured. Eggs of Macrorileya and Archirileya likewise lack the
surface sculpturing. Please CLICK on picture to view
details: The first‑instar larvae of the family are broadly oval to
elongated in form, with 13 distinct body segments and a relatively large,
hemispherical or conical head. The
head bears a number of sensory setae which, in E. appendigaster,
are very large. The sensory setae, of
which there are four pairs on each thoracic segment and three on the abdomen,
may be minute, as in E. curta, or may exceed the length
of a segment, as in E. robusta and E. parva. The
integumentary setae are abundant in Eurytoma
and may completely clothe the body or occur as a band on each segment. The larva of A. inopinata
is apparently devoid of setae. In E. rosae Nees (Fig.
89B) and E. parva, a pair of small,
sclerotized processes of unknown function is found on the venter near the
median line of the first thoracic segment.
The normal equipment of spiracles in the family is four pairs,
situated on the mesothorax and the first three abdominal segments. E.
parva has five pairs, the
additional one being on the metathorax. E.
curta is provided with 10
pairs, on the second and third thoracic and the first eight abdominal
segments. A. inapinata
has eight pairs, situated on the mesothorax and the first seven abdominal
segments. The second‑instar larva has been described for only a few
species; it differs from the preceding instar mainly in the reduction of the
sensory setae. E. oophaga
still has the four pairs of spiracles situated as in the first instar; in E. parva the number is increased from five to nine and in A. inopinata from eight to nine. They are situated on the last two thoracic and the first seven
abdominal segments. E. dentata Mayr has eight pairs, that on the second thoracic
segment being absent. Five larval instars have been distinguished in a number of
species, and this is presumably the normal number for the family, though only
four are indicated for E. oophaga. In this species the full complement of
nine pairs of spiracles appears first in the third instar. The mature larva of Eurytoma
is more robust than the preceding instars.
The sensory setae are usually small, though they are relatively long
in E. dentata and E.
masii Russo (Fig. 89C). Cuticular spines are minute or
lacking. The larvae of Archirileya (Fig. 89D) and Macrorileya differ markedly
from those of Eurytoma,
being cylindrical, with the caudal segments broad and the last one broader
than those preceding it and forming a disk or sucker. There are 12 apparent body segments rather
than the usual 13, and the anterior ventral region of the abdomen is
appreciably distended. Intersegmental
welts occur dorsally from the first thoracic to the sixth abdominal
segments. The larvae of Axima and Conoaxima have large median dorsal welts on the thoracic
and the anterior abdominal segments.
The nine pairs of spiracles, on the second and third thoracic and the
first seven abdominal segments, occur in all genera, though E. curta is stated to have an additional vestigial pair on
the eighth abdominal segment. References:
Please refer to <biology.ref.htm>,
[Additional
references may be found at: MELVYL Library ] |