Research Article |
Corresponding author: Kaniyarikkal Divakaran Prathapan ( prathapankd@gmail.com ) Academic editor: Michael Schmitt
© 2016 Koormath Mohammed Shameem, Kaniyarikkal Divakaran Prathapan, Mannankadiyan Nasser, Caroline Simmrita Chaboo.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Shameem KM, Prathapan KD, Nasser M, Chaboo CS (2016) Natural history of Javeta pallida Baly, 1858 on Phoenix palms in India (Chrysomelidae, Cassidinae, Coelaenomenoderini). In: Jolivet P, Santiago-Blay J, Schmitt M (Eds) Research on Chrysomelidae 6. ZooKeys 597: 39–56. https://doi.org/10.3897/zookeys.597.6876
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Members of the Old World hispine tribe, Coelaenomenoderini, are documented on host plants of Arecaceae, Cyperaceae, and Zingiberales. A few species are renowned pests of oil palm, especially in Africa. The host plants and natural history of Javeta pallida Baly, 1858, the only Indian species of the tribe, is reported for the first time. These beetles can densely infest indigenous wild date palms, Phoenix sylvestris (L.) Roxb. (Arecaceae), and also use the introduced date palm, Phoenix dactylifera L., which is an expanding crop in India. Javeta females lay single eggs and cover each with an ootheca. All larval stages mine the leaves and pupation occurs within the larval mine. Adults are exophagous, leaving linear feeding trenches. Natural and induced infestations of J. pallida on these two palms were observed and the potential of J. pallida as a pest of date palm in India is discussed. Javeta pallida completed development on Phoenix palms in 52–88 days (mean 66.38 days) with egg period 11–15 days (mean 12.8 days), larval period 21–54 days (mean 33.02 days) and pupal period 17–23 days (mean 20.52 days). Elasmus longiventris Verma and Hayat and Pediobius imbreus Walker (Hymenoptera: Eulophidae) parasitize the larva and pupa of J. pallida.
Leaf beetles, leaf miner, pest, Arecaceae , Eulophidae , oil palm
The palm genus Phoenix L. (Arecaceae: Phoeniceae) comprises 15 species which are grown as ornamentals and for food and beverage. The sweet fruit of several species are eaten and sap is tapped to make various fermented drinks and vinegar. Nine Phoenix species occur in southern Asia (
The date palm, Phoenix dactylifera L. is one of the first cultivated tree crops, being grown since early Bronze Age (late 4th/early 3rd millenia B.C.) (
The Old World “hispine” tribe Coelaenomenoderini comprises nine genera and 88 species (
Some species are pests of oil palm, Elaeis guineensis Jacq. (
Javeta pallida Baly, 1858, the type species of the genus, is the only species of Coelaenomenoderini known from India (
The goal of this paper is to report the host plants and natural history of J. pallida for the first time, taking advantage of a heavy infestation on Phoenix sylvestris in southern India (Fig.
The study is based on field observations of live populations of J. pallida at Malappuram District, north Kerala, India, led by authors KMS, PKD, and MN. To document the life cycle and biology, beetles were reared on date palm, P. dactylifera and on the wild date palm, P. sylvestris.
(i) The initial infestation of J. pallida was observed on three stray palms of P. sylvestris during December, 2014 (Fig.
(ii) Remnants of natural infestation was observed on a stray date palm of about ten years old at Tirurangadi (N11°02'17.24", E75°55'40.61", 35m above msl) in April, 2015.
(iii) Rearing of J. pallida on P. dactylifera was carried out at Tirurangadi (N11°02'31. 60", E75°55'8.72", 23m above msl) on a three-year old stray date palm.
(iv) Rearing of J. pallida on P. sylvestris was carried out at the Botanical Garden of the Calicut University, Kerala (N11°07'59.01", E75°53'22.83", 77m above msl) on a 10–12 year old, 2.25m tall palm (excluding crown).
Dry season. Nine adults were released and confined with pieces of nylon net (mesh size 0.701mm–0.827 x 0.628–0.686mm; Nylon Maharani Net http://www.indiamart.com/goldfinchcreators/fabrics.html) on a frond on 23.IV 2015 for two days. On a second frond of the same palm, five adults were confined on 27.IV 2015 and a sixth adult was added on 30.IV.2015. The beetles were maintained on the frond until 3.V.2015.
Rainy season. During the rainy season, seven adults were confined on a third frond of the same palm of P. dactylifera on 10.VI.2015 and five more were added on the next day. All of them were retained on the frond till the eighth day. On a fourth frond, seven adults were confined on 17.VI.2015, and were retained till 20.VI.2015.
Rearing was carried out only during rainy season on P. sylvestris. Three young fronds were selected and 12 adults were used in the study. On the first frond, 12 adults were confined with nylon net for five days from 10.VI.2015. The same adults were shifted to the second frond on 15.VI.2015 and confined for two days. They were again shifted to a third frond on 17.VI.2015 and confined on it for a single day.
All adults used in rearing experiments were collected from the wild population of J. pallida on P. sylvestris at the first field site in Tirurangadi.
Individual eggs were counted and marked on the leaflets every day and the development was followed through larva and pupa till the emergence of adult. Developmental periods such as egg, larval and pupal duration of all individuals, which could be tracked, were recorded. The date of hatching of the eggs was determined by observing the beginning of the leaf mine (Fig.
Life stages of Javeta pallida. 3 Egg covered with ootheca 4 Egg, ootheca removed 5 Beginning of leaf-mine 6 Leaf mine and adult of J. pallida 7 Larva in leaf-mine, exposed 8 Pupa in leaf-mine, exposed 9 Adult exit hole 10 Adults and feeding trenches 11 Larva, ventral view 12 Larva, dorsal view 13 Pupa, ventral view 14 Pupa, dorsal view. (Figs
Mean values of developmental periods of individuals reared during dry season (eggs laid in April, 2015) and rainy season (eggs laid in June, 2015) on P. dactylifera were compared using t-test of significance (Panse and Sukhateme 1985). Similarly, the developmental periods of individuals reared during rainy season on P. dactylifera and P. sylvestris were compared using the same tool to find out possible statistical difference in developmental periods on the two host species of Phoenix.
Visits to commercial plantations. Two visits, during January and April, 2015, were made to the commercial plantations of date palms in Dharmapuri, Tamil Nadu, southern India.
Collection of natural enemies. Naturally infested leaves of P. sylvestris from the first field site were brought to the laboratory and kept in plastic containers of about 5 L capacity for emergence of adult parasitoids.
Specimen collection. A total of 173 adults, 81 pupae, 41 larvae, and nine eggs were collected at Tirurangadi on 12, 14, and 28.XII.2014 (KMS and KDP); one adult was collected at Jakkur Lake, Bangalore on 12.VIII.2012 (KDP), and eight adults were collected on 9–11.XI.2014 at Bangalore (H. M. Yeshwanth) on P. sylvestris. Voucher specimens of J. pallida are deposited in the Kansas Natural History Museum, KS, USA, National Bureau of Agriculturally Important Insects, Bangalore, and the Travancore Insect Collection, Kerala Agricultural University, Vellayani, India. Vouchers of the parasitoids are deposited in the Zoological Survey of India, Western Ghats Regional Station, Kozhikode. A plant voucher of P. sylvestris (accession no. 6863) is deposited in the Calicut University Herbarium, India.
Life cycle of J. pallida. At Tirurangadi (field site 1), three palms of Phoenix sylvestris were observed heavily infested (Fig.
We observed the presence of larval mines and adult exit holes on 21 leaflets of the single P. dactylifera at Tirurangadi (field site 2) in April, 2015, proving the occurrence of natural infestation of J. pallida on the date palm in Kerala, where it is of little commercial importance. A dead larva and pupal cases were recovered from the leaf mines, though no live insect was observed.
Adults confined on the first frond of P. dactylifera during dry season at Tirurangadi (field site 3), laid 14 eggs. Twelve out of the 14 eggs hatched. Of the 12 larvae, nine pupated and finally emerged into adults. On the second frond 12 eggs were laid, however, only four of them hatched. Only one of the four larvae pupated and reached adulthood.
During the rainy season on the third frond of P. dactylifera, 22 eggs were laid and 18 of them hatched. Five of them reached pupal stage and all five emerged as adults. On the fourth frond, nine eggs were laid and all of them hatched. Of these nine larvae, five pupated and all emerged as adults.
On a wild date palm, P. sylvestris, in the Botanical Garden of the University of Calicut (field site 4), we observed 21 eggs on a first frond during rainy season (second week of June, 2014 onwards). Nineteen of the 21 eggs hatched; 12 larvae pupated, and 12 adults emerged. On a second frond, we observed 29 eggs of which 24 hatched, 15 larvae pupated and 14 adults emerged; one pupa was observed dead inside the leaf mine. On a third frond, we observed 21 eggs; 19 hatched, and eventually 12 larvae reached pupal stage and adulthood.
Mature larvae and pupae often exited when the leaf mines were ruptured and such larvae pupated normally inside the glass beaker or nylon mesh in which they were confined and adults emerged.
A total of 58 adults were reared on P. dactylifera and P. sylvestris. However, the duration of all life stages from egg to adult could be tracked only in the case of 42 individuals, as at times the mines merged. Data on the developmental periods of J. pallida (based on the above 42 individuals), on P. dactylifera during dry and rainy season as well as on both P. dactylifera and P. sylvestris during rainy season are presented in Table
Developmental periods of Javeta pallida on Phoenix dactylifera and P. sylvestris during dry and rainy seasons.
Host | Season | No. of individuals tracked up to adulthood | Egg period (days) | Larval period (days) | Pupal period (days) | Total developmental period (days) | ||||
---|---|---|---|---|---|---|---|---|---|---|
Mean | Standard deviation | Mean | Standard deviation | Mean | Standard deviation | Mean | Standard deviation | |||
Phoenix dactylifera | Dry | 10 | 12.2* | 0.63 | 26.3* | 3.59 | 20.2 | 1.32 | 58.7* | 4.08 |
Rainy | 8 | 13* | 0.93 | 37.5* | 4.47 | 21.13 | 0.99 | 71.63* | 5.15 | |
Phoenix sylvestris | Rainy | 24 | 13.04 | 1.0 | 34.33 | 5.85 | 20.45 | 1.32 | 67.83 | 6.53 |
t test | Dry vs Rainy seasons on P. dactylifera | t value | 2.18 | 5.90 | 1.645 | 5.946 | ||||
P. dactylifera vs P. sylvestris in rainy season | t value | 0.103 | 1.31 | 1.306 | 1.490 |
During rainy season, egg, larval, pupal and total developmental periods of J. pallida on both P. sylvestris and P. dactylifera were statistically on par with each other.
In short, Javeta pallida completed development on Phoenix palms in 52–88 days (mean 66.38 days) with egg period 11–15 days (mean 12.8 days), larval period 21–54 days (mean 33.02 days) and pupal period 17–23 days (mean 20.52 days).
No beetles or signs of infestation were observed in commercial plantations of date palm in Dharmapuri, Tamil Nadu, during January or April, 2015.
Natural enemies of J. pallida. Two species of chalcidoid parasitoids emerged from the larvae and/or pupae of J. pallida collected at Tirurangadi. Six females and six males of Elasmus longiventris Verma and Hayat (Figs
The trophic selection of J. pallida, within Arecaceae, corresponds to that in other known members of the genus as well as most Coelaenomenoderini, as host plants of three Javeta species are previously known (
The fundamental features of the life cycle of J. pallida follow the pattern in Coelaenomenoderini: single egg deposition, mining larvae with up to four instars, endogenous solitary pupation, and heavy infestation on the appropriate hosts. The female’s repertoire of making linear slits in the leaf, laying eggs singly within the slits, and then covering the egg firmly with brown colored material appears to be unique to Javeta within the tribe. In the most intensively studied Coelaenomenodera (Coelaenomenodera) elaeidis, females lay eggs in clusters at the ends of adult feeding scars and cover them with regurgitated leaf fibre (
Drying of leaves due to adult feeding starts from the apex of leaflets towards the petiole. This appears to conserve the leaf as feeding near the base of the leaf lamina would result in drying up of the entire leaflet that could otherwise have been consumed.
At 74–97 days from egg to adult, the development of Coelaenomenodera spp. is relatively long among Cassidinae (
Hymenoptera parasitoids belonging to the families Eulophidae and Trichogrammatidae act as the most important natural enemies of Coelaenomenoderini (
Although some papers have been titled “morphology” they give only minimal information about morphological structures. Therefore detailed comparative study of all life stages, including scanning electron microscopy, is needed both to uncover many more taxonomic and phylogenetic characters to strengthen understanding of systematics and evolution and to better manage a notorious economically-important pest.
One of the most remarkable aspects of Coelaenomenoderini life cycles is the alternation of mixed populations of different stages with synchronized populations in outbreak periods. This has been described for C. (C.) elaeidis (
Several factors contribute to their success. The females have very high fecundity (for Cassidinae) and there can be up to four generations per year (
The severity of infestation observed on P. sylvestris suggests that J. pallida poses a potential pest of any species of Phoenix, including P. dactylifera. Our study foresees a native leaf beetle becoming a serious pest on an exotic crop of immense economic potential in India.
Chemical control with sprays and injection of trees have been used to control Coelaenomenodera pests (
World-wide interest in more sustainable and healthier harvesting and processing of food is stimulating shifts to organic farming, including in date-palm and wild date palms (
Conclusion. Comparative study of morphology and biology across Coelaenomenoderini will certainly yield many novel phylogenetic characters. Our study here suggests that the oviposition (number and coverage of eggs), number of instars and morphology, pupation site, and eruptive population behaviors might be considered as character complexes. Palms are one of the most important crops in the world and their insect fauna needs further study. Within Cassidinae, we also need to understand the evolutionary relationship of certain tribes with palms. Furthermore, study of the insect milieu—the predator and parasitoid complex—can help us understand their impacts on the beetles’ evolution and provide models for sustainable biocontrols of palm resources. We plan to continue documenting the biology, pest status, and insect enemy complex of J. pallida in the field. Our next step is also a detailed morphological study of the juvenile and adult stages.
We are indebted to H. M. Yeshwanth for bringing the occurrence of Javeta pallida in Bangalore to our notice, to A. P. Balan, Indian Cardamom Research Institute, Myladumpara, A. K. Pradeep, University of Calicut for the plant identifications, S. Santhosh, Malabar Christian College, Calicut for the parasitoid identifications, to Charles Staines and Jennie Unnikrishnan for sending some literature, to K. M. Yashik, Hilite Construction Pvt Ltd for support and hospitality during our visits to infested palms in their premises in Tirurangadi, to N. K. Ramachandran for permitting us to carryout rearing of Javeta pallida on a date palm in his garden at Tirurangadi, to J. E. Thoppil, Department of Botany, University of Calicut for permitting us to carryout biology experiments on a Phoenix sylvestris in the Botanical Garden, and to K. B. Shyamna and V. M. Jaseef for help with field work. Vijayaraghava Kumar, Kerala Agricultural University helped with the statistical analysis. PKD’s work is supported by the Indian Council of Agricultural Research, New Delhi through the Network Project on Insect Biosystematics. CSC’s research is supported by the University of Kansas. KMS is a recipient of the Junior Research Fellowship of the University Grants Commission, New Delhi.