Populations of the beetle Phaleria acuminata fromfour beaches on the Maltese Islands were sampled for six consecutive seasons to
investigate changes in population size, sex ratio, reproductive state and distribution on the shore. The populations on all the beaches
showed a small decrease in numbers from spring to summer and a pronounced drop from summer to autumn, with a dramatic increase
between winter and spring. Male to female sex ratio varied between 1:1 and 1:1.5. Females of all reproductive stages occurred throughout
the year. There were little seasonal differences in distribution of beetles in the wet and dry zones.peer-reviewe

Borg, Joanna

Deidun, Alan

Schembri, Patrick J.

English

OAR@UM

See	discussions,	stats,	and	author	profiles	for	this	publication	at:	http://www.researchgate.net/publication/234053688Population	ecology	of	Phaleria	acuminata(Coleoptera:	Tenebrionidae)	from	sandy	beachesin	the	Maltese	Islands.CONFERENCE	PAPER	·	JANUARY	2004CITATIONS2DOWNLOADS41VIEWS843	AUTHORS,	INCLUDING:Alan	DeidunUniversity	of	Malta97	PUBLICATIONS			197	CITATIONS			SEE	PROFILEPatrick	Joseph	SchembriUniversity	of	Malta212	PUBLICATIONS			1,329	CITATIONS			SEE	PROFILEAvailable	from:	Patrick	Joseph	SchembriRetrieved	on:	22	September	2015POPULATION ECOLOGY OF PHALERIA ACUMINATA (COLEOPTERA: TENEBRIONIDAE) FROM SANDY BEACHES IN THE MALTESE ISLANDSBorg Joanna 1* , Deidun Alan 2, Schembri Patrick J. 3Department of Biology, University of Malta, Msida, Malta apb@orbit.net.mt, alpra1@mail.global.net.mt, patrick.j.schembri@um.edu.mtAbstractPopulations of the beetle Phaleria acuminata fromfour beaches on the Maltese Islands were sampled for six consecutive seasons toinvestigate changes in population size, sex ratio, reproductive state and distribution on the shore. The populations on all the beachesshowed a small decrease in numbers from spring to summer and a pronounced drop from summer to autumn, with a dramatic increasebetween winter and spring. Male to female sex ratio varied between 1:1 and 1:1.5. Females of all reproductive stages occurred throughoutthe year. There were little seasonal differences in distribution of beetles in the wet and dry zones.Keywords: Phaleria acuminata, population dynamics, sex ratio, sandy shoresRapp. Comm. int. Mer Médit., 37,2004 496Few studies on the population ecology of shore-dwellingtenebrionids have been made. Two species of Phaleria(P. acuminataand P. bimaculata) occur in the Maltese Islands (1), and on somebeaches may account for up to 54% of all individuals of macro-invertebrates collected. We investigated aspects of the populationecology of the commonest species Phaleria acuminata on fourbeaches: White Tower Bay and Golden Bay on Malta, and Ramla l-Hamra and Xatt l-Ahmar on Gozo. Phaleria acuminatawere sampledover six different seasons between October 2001 and March 2003using a constellation of pitfall traps in the wet and dry zones of thebeaches. Sex was determined by dissection and the reproductive stateof females was determined by examining the state of the bursacopulatrix.A total of 8842 individuals were collected from the four beachesover the study period. On all the beaches, more individuals werecollected in spring and summer than in autumn and winter. Thepopulation size on each of the four beaches showed an almostidentical pattern with a small decrease in numbers from spring tosummer and then a sudden drop from summer to autumn. The secondset of autumn and winter samples showed a similar phenology as thefirst set, although a lower number of beetles were collected. Thepopulation increased dramatically during spring especially at Ramla l-Hamra and Xatt l-Ahmar. This contrasts with the results obtained byCarpaneto and Fattorini (2) who found that the Italian Phaleriaacuminatapopulation they studied had the largest drop in abundancefrom spring to summer; Aldryhim et al.(3) describe a similar patternin Saudi Arabia.The sex ratio did not vary much at Golden Bay and Ramla l-Hamra;however, at White Tower Bay and Xatt l-Ahmar there were largeseasonal variations. In general, more females than males werecollected, with a few exceptions: the spring sample from White TowerBay, the first autumn sample from Golden Bay, and the spring andsummer samples from Xatt l-Ahmar, when males outnumberedfemales. However, there was no significant seasonal variation in sexratio on any of the beaches (Kruskall-Wallis test). At Xatt l-Ahmar,the overall sex ratio was very close to 1:1 whereas on the otherbeaches it was approximately 1.5 females for every male. Sex ratiomay give an indication of how stressed a population is; the greater thestress, the greater the deviation from a 1:1 ratio, as the populationtends to produce more individuals of the energetically economicalsex. In this regard it is worth noting that Xatt l-Ahmar is an isolatedbeach with a low number of visitors whereas the other beaches arevery popular recreational resorts especially during summer.In general, females of all reproductive stages occurred throughoutthe year, showing that a percentage of the population is reproductiveat all times. However, in spring and summer there was an increase inthe percentage of females of low reproductive potential, probablyrepresenting newly emerged, unmated adults. This correlates wellwith the increase in numbers of individuals trapped during theseseasons, suggesting a peak in emergence during the warmer part of theyear.Krosnov and Shenbrot (4) found that shore-dwelling tenebrionidson Israeli beaches occupied the wet zone in the warmer months andmoved upshore towards the dunes during the colder months. In thepresent study, there was no clear seasonal pattern for either sex in theoccurrence of the beetles in the wet and dry zones of the beachesstudied. Although more beetles occurred in the wet zone during thewarmer months of the year, the difference was not statisticallysignificant.References1-Mifsud D., Scupola A. (1998). The Tenebrionidae (Coleoptera) of theMaltese Islands (Central Mediterranean). Annali del Museo Civico diStoria Naturale “G. Doria”,92: 191-229.2-Carpaneto, G. M., Fattorini S. (2001). Spatial and seasonalorganization of a darkling beetle (Coleoptera, Tenebrionidae) communityinhabiting a Mediterranean coastal dune system. Italian Journal ofZoology, 68; 207-214.3-Aldryhim, Y. N., Mills C.W., Aldawood A.S. (1992). Ecologicaldistribution and seasonality of darkling beetles (Coleoptera:Tenebrionidae) in the central region of Saudi Arabia. Journal of AridEnvironments, 23: 415-422.4-Krosnov B., Shenbrot G. (1997). Seasonal variation in spatialorganization of a darkling beetle (Coleoptera: Tenebrionidae) community.Environmental Entomology, 26(2): 178-190.pg_0496 http://www.ciesm.org/online/archives/abstracts/pdf/37/comites/pg_0496.htm1 of 1 11/06/2013 19:28

Ecological distribution and seasonality of darkling beetles (Coleoptera: Tenebrionidae) in the central region of Saudi Arabia.

Seasonal variation in spatial organization of a darkling beetle (Coleoptera:

Spatial and seasonal organization of a darkling beetle (Coleoptera, Tenebrionidae) community inhabiting a Mediterranean coastal dune system.

The Tenebrionidae (Coleoptera) of the Maltese Islands (Central Mediterranean).

Population ecology of Phaleria acuminata (Coleoptera : Tenebrionidae) from sandy beaches in the Maltese Islands

https://www.um.edu.mt/library/oar/bitstream/handle/123456789/5227/Population%20ecology%20of%20Phaleria%20acuminata%20%28coleoptera%20tenebrionidae%29%20from%20sandy%20beaches%20in%20the%20Maltese%20Islands.pdf?sequence=1&isAllowed=y

Population ecology of Phaleria acuminata (Coleoptera : Tenebrionidae) from sandy beaches in the Maltese Islands

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