Observations on the biology of Afrotropical Hesperiidae (Lepidoptera). Part 6. Hesperiinae incertae sedis: palm feeders
Author
Cock, Matthew J. W.
m.cock@cabi.org
Author
Congdon, Colin E.
m.cock@cabi.org
Author
Collins, Steve C.
m.cock@cabi.org
text
Zootaxa
2014
2014-07-08
3831
1
1
61
journal article
5307
10.11646/zootaxa.3831.1.1
1301c5d5-c84b-441f-a7d5-ab01a02e119b
1175-5326
4920824
2EF9A3DB-0EAA-4384-8ADA-A7D269E5904D
Zophopetes cerymica
Hewitson, 1867
(in
Hewitson 1867
–1871)
Hewitson (1867
–1871) described
Hesperia cerymica
from Akwa Akpa (=Old Calabar, south-eastern
Nigeria
).
Evans (1937)
treated
cerymica
as two subspecies: the nominate
cerymica
in West Africa, from
Senegal
as far east as
Cameroon
, and what he referred to as
nobilior
Holland
, the eastern subspecies, described from
Gabon
(Lambarene,
French Congo
), but for which Evans only listed specimens from
Uganda
,
Kenya
and
Tanzania
, although it also occurs in
DR Congo
(
Kielland 1990
,
Ackery
et al
. 1995
) and north-west
Zambia
(
Heath
et al
. 2002
).
Lindsey & Miller (1965)
treated
cerymica
and
nobilior
as full species, based on differences in the male genitalia, and this has been followed by subsequent authors, although
Larsen (1991)
suggested they may be subspecies, when documenting the population from the
Kenya
Coast as
Z. nobilior
.
T.B. Larsen (pers. comm. 2013) has now established that the taxon referred to as
nobilior
is not that species, which is currently only known from
two females
from
Gabon
, and near Mbandaka in western
DR Congo
that are much smaller than
Z. cerymica
and with a rather different hind wing underside.
Although
Lindsey & Miller (1965)
considered that the male genitalia of
Z. cerymica
from West Africa and East Africa (their
Z. nobilior
) represent different species, T.B. Larsen (pers. comm. 2013) notes that the material treated as
nobilior
by Evans falls within the range of variation in colouring and male genitalia seen in
Z. cerymica
, so that for the moment at least, it would be more appropriate to treat this as a single variable species without subspecies. We have seen caterpillars from
Togo
,
Côte d’Ivoire
,
Kenya
(coast),
Tanzania
and
Zambia
, which we illustrate separately here. There are no significant differences between the early stages of these populations, supporting the view that
Z. cerymica
is a somewhat variable species found from
Senegal
, east to
Kenya
and south to
Zambia
. However, given the variation that we have reported in caterpillars and male genitalia indicating complex species or species-complexes in the other
Zophopetes
spp.
above, this conclusion perhaps should be considered provisional pending more detailed studies.
In
Kenya
this species is restricted to the coast, where coconut is a regular food plant. Although not as common as those of
Gretna carmen capra
Evans
on coconut, caterpillars can be found without too much difficulty. In
Tanzania
, it is found in forests on the eastern shore of Lake Tanganyika, and in eastern
Tanzania
it is known from
Dar es Salaam
, the Pugu Hills, and the Lukosi River near
Iringa
(
Kielland 1990
). It is not confined to forest, for example, on the Lukosi River as it flows through dry thorn scrub and rocky Acacia woodland for the last
20–30 km
to its junction with the Great Ruaha, it breeds on
Raphia
palms growing on the banks and islands among the channels of the fast flowing river bordered by very degraded remnants of riverine forest. In
Zambia
it is restricted to the north-west (
Heath
et al
. 2002
).
Adult behaviour.
We have no observations, but
Genty (1968)
notes in
Côte d’Ivoire
that
Z. cerymica
adults (
Figure 19
) fly at dusk and are attracted to light,
Sevastopulo (1964)
records this species attracted to light by night in East Africa, and most of the material that T.B. Larsen (pers. comm. 2014) has of this species is from the restaurants of beach hotels in
Ghana
, as well as at the Cape Three Points lighthouse.
Boorman (1970)
writes that in
Nigeria
adults fly at dusk and come to papaya flowers, and
Kielland (1990)
notes in
Tanzania
that this species also flies in the early morning when it also comes to flowers.
Forsyth (1966)
records adults sucking citrus fruits on trees in
Ghana
.
FIGURE 19
. Adults of
Zophopetes cerymica
.
1
, male, Port Harcourt, Nigeria [© D. Motshagen];
2
, female, reared on
Raphia farinifera
, Lukosi
River, Tanzania, TCEC.
Food plants.
As noted above, early reports of
Z. dysmephila
as a palm pest in the French West African literature were misidentifications for
Z. cerymica
(rather than
Z. quaternata
, which
Z. dysmephila
resembles). The associated descriptions and figures of the early stages (e.g.
Genty 1968
,
Mariau & Morin 1974
) match
Z. cerymica
rather than
Z. dysmephila
, and
Z. cerymica
replaces
Z. dysmephila
in more recent publications (
Mariau
et al
. 1981
,
Mariau 2000
,
2001
). Thus,
Z. cerymica
(as
Z. dysmephila
) is recorded from oil palm (
E. guineensis
) at Anguédedou,
Côte d’Ivoire
(
Genty 1968
).
Mariau & Morin (1974)
give a general account of
Z. cerymica
(as
Z. dysmephila
) and
Pteroteinon laufella
(see below) as pests of oil palm and coconut in West Africa. The pinned adult butterfly they illustrate as
Z. dysmephila
appears to be a female
Z. cerymica
, and the authors refer to the head of the caterpillar as uniformly golden yellow (
uniformément jaune d'or
), which is diagnostic for
Z. cerymica
(
Figure 20–24
) compared to
Z. dysmephila
(
Figures 7–13
). We note that although the paper title specifies hesperiid defoliator pests of oil palm and coconut, the text only refers to oil palm.
Vuattoux (1999)
only reared this species from
E. guineensis
in
Côte d’Ivoire
. In
Ghana
, T.B. Larsen (pers. comm. 2013) found it most frequently along beaches with many coconut palms (especially between Cape Coast and Takoradi).
Early food plant records from East Africa were under the name
Z. cerymica
, anticipating the present arrangement. Thus
Van Someren (1974)
gives
Raphia
spp.
and
Cocos nucifera
(as
Cocoa nucifer
) as food plants of
Z. cerymica
in his list of food plants of East African butterflies.
Sevastopulo (1975)
repeats these records, and later adds
Phoenix
(
Sevastopulo 1981
)
.
Treating this species as
Z. nobilior
,
Kielland (1990)
lists the food plants as
Phoenix
,
Borassus
and
Raphia
palms, but doesn't mention coconut.
Larsen (1991)
adds coconut, based on MJWC’s rearing, and repeats these food plants for
Z. cerymica
(
Larsen 2005
)
.
Ackery
et al
. (1995)
list the food plants of
Z. cerymica
as
Borassus
,
Phoenix
and
Raphia
.
Heath
et al
. (2002)
give the food plant in north-west
Zambia
as
Raphia
sp.
In
Kenya
, MJWC found this species on
Cocos nucifera
only, whereas TCEC found caterpillars on
E. guineensis
in
Tanzania
, and on
Raphia farinifera
in
Tanzania
and north-west
Zambia
, although some were transferred from
R. farinifera
to
C. nucifera
in order to rear them through. Both authors have tried independently to transfer caterpillars to feed on leaves of
P. reclinata
, and failed. MJWC tried with one caterpillar that only fed a little and then died (89/18B). We doubt that
Phoenix
spp.
are normal food plants of
Z. cerymica
. We also have reservations about the repeated records from
Borassus
spp.
, which TCEC has searched without finding any
Hesperiidae
early stages. MJWC has also reared
Z. cerymica
from
C. nucifera
at Lomé,
Togo
(90/213), and found a caterpillar on an unidentified planted palm in
Côte d’Ivoire
(88/214).
Leaf shelters.
On
R. farinifera
at Lukosi River,
Tanzania
, TCEC noted that the young caterpillars roll the tip of a leaf into a tube and eat their way back down the leaf as they grow. When the midrib becomes too tough, the shelter is abandoned, after the caterpillars have eaten down to it from one or both sides.
The medium grown caterpillars (penultimate or previous instar) feed from the apex of a leaflet, where they make a shelter by rolling one or both edges of the leaflet over upwards. Rolling the flap upwards is the line of least resistance, as the young leaflets are naturally V-shaped, and if they rolled downwards caterpillars would have to deal with the sharp thorns on the underside of the midrib of the leaflet. Fully grown caterpillars make a tubular shelter, usually at the apex of the partly consumed leaflet, by rolling both edges of the leaflet under. Feeding usually leaves the distal end of the leaflet truncate, but pointed at the midrib.
Pupation was either in a tube as used by mature caterpillars, or in a shelter made between two leaflets, one on top of the other (
7 Nov 1990
, Lomé,
Togo
, 90/213). A pupal shelter found at Diani Beach,
Kenya
(
26 Mar 1989
; 89/18A) was made about
25cm
from the apex of a
C. nucifera
leaflet on which there had been no feeding. The edges of the leaflet were held with thick strands of silk to make a tube, and the posterior (basal) portion had been largely blocked off with silk webbing. About
50mm
of the shelter was lined with white waxy powder which was also present on the pupa.
Ovum.
The ova are laid on the leaflets of
C. nucifera
; they are similar to those of
Z. dysmephila
but larger.
Mariau & Morin (1974)
and
Mariau
et al
. (1981)
refer to the ova of
Z. cerymica
and
Pteroteinon laufella
as
1.5mm
in diameter and laid in variable numbers (
en nombre variable
) on the leaflet under surface. Ova from the
Kenya
coast measured 1.8 x
1.2mm
wide x high (n=2). Ova hatch in 5–6 days (
Genty 1968
). We have found ova of
Z. cerymica
only singly, so suggest that the references to ‘variable numbers’ should be considered to apply to
P. laufella
only, until new observations suggest otherwise.
Caterpillar.
Brief descriptions of material from the
Kenya
coast were prepared based on collection 87/22 (Diani Beach,
29 Sep 1987
), which was not successfully reared, but considered to match later collections that were. When collected in the penultimate instar, the caterpillar measured
24mm
; head light brown with diffuse central marking on face; narrow dark pronotum; body creamy green with a yellow dorsolateral stripe; anal plate speckled yellow. This brief description is compatible with
Figure 20.1
, where the detail of the marking on the central face can be seen, the pronotum is white on the anterior margin, and the spiracles are inconspicuous. Four head capsules measured 3.0 x
3.5mm
wide x high (range 2.9–3.1, 3.3–3.7).
FIGURE 20.
Caterpillars of
Zophopetes cerymica
collected on
Cocos nucifera
, Diani Beach
, Kenya.
1
, penultimate instar, detail of head, anterodorsolateral view; collected and photographed 13 Dec; moulted to final instar 19 or 20 Dec; 90/114B or C.
2
, final instar, detail of head, anterodorsolateral view; collected as penultimate instar caterpillar 29 Sep 1987; moulted to final instar 2 Oct; photographed 7 Oct; died 13 Oct; 89/18B.
3
, final instar, detail of head, dorsolateral view; collected 13 Dec 1990; moulted to final instar and photographed 20 Dec; pupated 2–7 Jan 1991; 90/114C.
4
, final instar, detail of head, anterodorsolateral view; collected as penultimate instar caterpillar, Diani Beach, 29 Sep 1987; moulted to final instar 2 Oct; photographed 7 Oct; died; 87/22.
5
, final instar, collected as #3, moulted to final instar 20 Dec 1990; photographed 24 Dec; adult male 27 Jan 1991; 43mm; 90/114C.
6
, final instar prepupa, dorsolateral view; Diani Beach, collected and photographed 29 Mar; pupated 3 Apr; 48mm long x 8mm at widest.
The mature caterpillar (
Figure 20
) is one of the largest of Kenyan skipper caterpillars, measuring up to
46mm
and taking about 14 days to complete development. The head capsule measures 4.0 x
5.2mm
wide x high (range 3.8–4.3, 4.6–5.6, n=6). Caterpillar 87/22 moulted to the final instar three days after collection, and on the following day (4 Oct) it measured
28mm
(
Figure 20.4
). Head 3.9 x
4.8mm
wide x high; shiny, rugose; plain yellow brown except for a black posterolateral band from just before vertex, where it is narrow with a brown posterior margin, widening to the bottom where it runs from the posterior margin to the stemmata. Shiny black pronotum to just above spiracles. Body pale green; T2–A9 a dorsolateral yellow-white line, about
1mm
wide; spiracles light brown; anal plate almost chordate; flanged posteriorly; a network of yellow markings anteriorly. Subsequent collections have shown that the black lateral marking of the head may be reduced to a basal bar from near the posterior margin to the stemmata (
Figure 21.3
) or just a small black spot covering the stemmata (
Figure 20.2
). When it has finished feeding, the caterpillar turns dirty yellow, losing the dorsolateral lines (
Figure 20.6
)
The final instar caterpillar recorded in
Tanzania
is similar (
Figure 21
). The head marking of the caterpillar shown (
Figure 21.3
) is an extensive black marking from the vertex laterally, and anteriorly to the stemmata, as heavy as the heaviest documented from
Kenya
(
Figure 20.4
). Instar 2 (
Figure 21.1–2
) has the dorsal two-thirds of the head dark, almost black, and the ventral one-third brown; body pale green with pale subdorsal lines.
FIGURE 21
. Caterpillars of
Zophopetes cerymica
, collected on
Elaeis
sp.
, Tanzania, [TCEC].
1–2
, instar 2, dorsolateral view, 4 Feb 2002, Lukosi River;
1
, head in anterior view;
2
, head in anterolateral view.
3–5
, final instar, Kimboza Forest, foot of Uluguru Mts, eastern Tanzania;
3
, detail of head, lateral view, 6 Feb 2002;
4
, detail of head, anterior view, 6 Feb 2002; 5, dorsal view, 4 Feb 2002.
The caterpillars from
Zambia
are also similar. The early instars were not reported from
Kenya
(above), but instar 1 from
Zambia
(
Figure 22.1
) can be seen to have a brown head, with a dark brown line adjacent to and close to the epicranial suture; darker on the frons; narrow black pronotum and a plain yellow-green body. In the penultimate instar (
Figure 22.2–3
) the yellow-brown head has a W-shaped mark on the face, the outer arms parallel to the epicranial suture, and a diffuse dark patch over the dorsal part of adfrontals and adjacent epicranium. The final instar shown in
Figure 22.4–6
appears to be mature and starting to turn yellow. It is similar to that from
Kenya
; in the example photographed there is a minimal black marking around stemmata (
Figure 22.4
), comparable to one example from
Kenya
(
Figure 20.2
).
FIGURE 22
. Caterpillars of
Zophopetes cerymica
, collected 24 Apr 2000 on
Raphia farinifera
, Jimbe
, north-west Zambia [TCEC].
1
, instar 1, dorsal view;
2
, penultimate instar, dorsolateral view;
3
, penultimate instar, detail of head, frontal view;
4
, final instar, dorsolateral view;
5
, final instar, detail of anal plate;
6
, final instar, dorsal view.
No detailed description of the caterpillar was prepared for the caterpillars from West Africa, but they were documented with photographs (
Figures 23–25
). The n-2 instar head (
Togo
90/213) measures 2.1 x
2.6mm
wide x high (n=3); pale brown; bottom of epicranial suture and clypeal sutures dark; short diffuse, dark line parallel to epicranial suture from just above top of adfrontals to level with top of frons; posterior margin dark. The penultimate instar measures 3.1 x
3.7mm
wide x high (n=4); face of the penultimate instar from
Togo
(
Figure 23
) has a variable diffuse W-shaped mark across the top of the adfrontals and adjacent epicranium; stemmata black, sometimes with a black patch around them; posterior margin dark in some individuals. This instar is intermediate to that shown from
Kenya
(
Figure 20.1
) and that shown from
Zambia
(
Figure 22.3
).
FIGURE 23
. Penultimate instar caterpillar of
Zophopetes cerymica
collected on
Cocos nucifera
, Lomé
, Togo, 7 Nov 1990; photographed 17 Nov; moulted to final instar 7 Dec; 20mm; 90/213H.
1
, dorsolateral view;
2
, detail of head anterodorsolateral view.
In the final instar from
Togo
(
Figure 24
), the head is 4.2 x
5.1mm
wide x high (n= 3, 6); plain orange brown, apart from a black patch around the stemmata (
Figure 24.2
), matching
Figure 20.2
from
Kenya
; T1 broadly white, with a narrow black pronotum; body white, more or less opaque, with broad yellow dorsolateral stripes with diffuse edges; T1–3 and A9 and anal plate with a strong yellow tint; spiracles pale brown, contrasting with white body; legs concolorous. The caterpillar takes about a month to develop (
Genty 1968
).
FIGURE 24
. Final instar caterpillar of
Zophopetes cerymica
collected on
Cocos nucifera
, Lomé
, Togo, 7 Nov 1990; photographed 17 Nov.
1, 3
, pupated 11 Dec; 33mm; 90/213H;
1
, dorsolateral view;
2
, lateral view.
2, 4,
pupated 2 Dec; 50mm; 90/213C;
2
, head, frontal view;
4
, anal plate, dorsal view.
The body of the caterpillar from
Côte d’Ivoire
(
Figure 25
) is a brighter white than those from
Togo
(
Figure 24
), but otherwise there is no great difference. It too has a small black spot over the stemmata like
Figure 20.2
from
Kenya
.
Pupa.
Pupae were not described, but are similar in all populations; the interior of the pupal shelter and the pupa are both covered with white waxy powder (
Figure 26
). They are superficially similar to those of
Z. dysmephila
, but larger (
25–34mm
), and the proboscis sheath extends
7mm
beyond the wing cases (
Figure 26.4
). The pupa is held by a girdle consisting of 10–14 strands of thick silk; erect setae dorsally on the thorax and forward directed setae dorsally on the posterior part of A1 (which grip the silk girdle); erect setae dorsally on A2–A4; a protuberance frontally, a pair of protuberances just above this and one at the base of the antenna. One character noted on West African and Zambian material is a tuft of backwardly angled stiff brown setae dorsolaterally on a thickened area at the base of the cremaster. Kenyan material is similarly thickened but lack the tuft of setae (
Figure 27
). We do not know the function or significance of this character. However, there are rare observations of more robust structures in this situation in other species of
Hesperiinae
, which suggest a possible function.
Cock (2010b)
noted a robust dorsal plate on the dorsal posterior end of the pupa of the Neotropical
Anthoptini
species
Corticea corticea
(Plötz)
, with two robust posterolateral spikes on each side and suggested that since pupation is in a tightly rolled grass leaf shelter, this posterior plate may be used to prevent access by parasitoids or small predators which may enter the pupal shelter at the posterior end; the heavily chitinized plate would be difficult for small predators to attack, and the posterolateral spikes at the side could be used to crush an intruder against the side of the shelter. The pupa of the Asian palm-feeder
Gangara thyrsis
(Fabricius)
(
Hesperiinae
,
incertae sedis
) has a very strong posteriorly directed spike at this point (
Figure 28.2
) which may also have a defensive function. The pupal stage lasts 21–23 days under Nairobi conditions, although in
Côte d’Ivoire
,
Genty (1968)
recorded the duration as about a month.
FIGURE 25
. Final instar caterpillar of
Zophopetes cerymica
collected on unidentified palm, Adiopodoumé, Côte d’Ivoire, 6 Dec 1988; photographed 4 Dec; died at pupation 19 Dec; 48mm; 88/214;
1
, dorsal view;
2
, detail of head and anterior segments with macrotype tachinid ova, anterodorsolateral view;
3
, detail of head and T1, lateral view.
Natural enemies.
Mariau & Morin (1974)
did not distinguish between
Pteroteinon laufella
and
Z. cerymica
, when they treated the natural enemies of these two skippers in West Africa. However, more recently,
Mariau (2001)
treats all the same natural enemies under
P. laufella
and mentions none for
Z. cerymica
, so we follow this arrangement here. The only exception to this is the record of an unnamed entomopathogenic fungus, which is illustrated on a pupa of
Z. cerymica
(
Mariau & Morin 1974
,
Figure 9
). The single caterpillar which MJWC found at Adiopodoumé,
Côte d’Ivoire
, had several macrotype tachinid ova on its body (
Figure 25
), but it died at pupation.
MJWC reared several parasitoids from material collected on
C. nucifera
at the
Kenya
coast. Ova are parasitized;
two adults
of an unidentified orange species emerged from an ovum collected at Diani Beach (
29.iii.1989
; 89/23). The corpse of a fourth instar caterpillar was found in its shelter surrounded by empty euplectrine pupae (Diani Beach,
22.viii.1995
; 98/110), but living material of this parasitoid has not been obtained. A field-collected pupa from Diani Beach (
26.iii.1989
; 89/18A;
Figure 26.4
) was parasitized by a gregarious
Brachymeria
sp. (Chalcididae)
, which appears to be the same species reared from
Gretna carmen capra
(below);
37 adult
wasps emerged from the
one pupa
, 20 days after collection. A three-quarter circle of diameter
2.2mm
was cut in the sub-dorsal abdomen, through which the adult wasps emerged. Although there was some white waxy powder on the inside of the pupal shelter, there was very little on the parasitized pupa itself (
Figure 26.4
). An empty field-collected pupa collected on the same occasion (89/18C) had a 3.0mm diameter emergence hole probably made by a
Brachymeria
sp.
FIGURE 26
. Pupae of
Zophopetes cerymica
.
1
, dorsal view, collected on
Raphia farinifera
, Hillwood
, north-west Zambia, 24 Apr 2000 [TCEC];
2
, lateral view, collected on
R. farinifera
, Lukosi
River, Tanzania, undated [TCEC];
3
, dorsolateral view; collected on
Cocos nucifera
, Diani Beach
, Kenya, as final instar caterpillar 13 Dec 1990; pupated and photographed 20 Dec; female emerged 10 Jan 1991; 34mm; 90/114A.
4
, ventrolateral view, parasitized pupa; collected on
C. nucifera
as pupa, Diani Beach, Kenya, 26 Mar 1989; photographed 3 Apr;
Brachymeria
sp.
adults emerged 15 Apr; 89/18A.
Economic damage.
Mariau & Morin (1974)
state that
Z. cerymica
(as
Z. dysmephila
) is commoner on oil palm than
Pteroteinon laufella
, but do not separate the two species in their assessment of the damage.
Genty (1968)
describes an outbreak in
Côte d’Ivoire
where up to three-quarters of the foliage was eaten. Outbreaks can occur on oil palms of all ages, including newly planted estates. Defoliation at this stage can be severe (
Genty 1968
) and set back crop development. Attacks on older palms are less common, the damage usually less serious and normally localised on the edge of plantations. An economic threshold of 20 hesperiid caterpillars per frond has been proposed for mature palms, based on a sample of two fronds per ha at the point of heaviest attack (
Mariau
et al
. 1981
).
There have been no reports of
Z. cerymica
occurring in high enough numbers to cause damage to palms in East Africa, or elsewhere in its range, perhaps because of the action of natural enemies keeping populations in check. Nevertheless,
Z. cerymica
should be considered a quarantine pest for areas outside Africa where palms, especially coconut and oil palm are grown.
Discussion.
The caterpillars and pupae of
Z. cerymica
appear almost identical throughout its range. The variation in the extent of the black ventrolateral marking seen on the head of the final instar caterpillar from different collections in
Kenya
encompasses all forms seen elsewhere. The presence of the tuft of setae dorsolaterally at the base of the cremaster of West African pupae but not on those from East Africa is the only consistent difference we have noticed between the two areas. Nevertheless, at this stage, treating
Z. cerymica
as a single slightly variable species throughout its range seems reasonable.