{"id":{"repo_id":"catania","oai_identifier":"oai:www.iris.unict.it:20.500.11769/594340"},"canonical_url":"https://search.dev.ndltd.org/etd/catania/oai:www.iris.unict.it:20.500.11769/594340","repository":{"repo_id":"catania","name":"Università degli Studi di Catania","base_url":"https://www.iris.unict.it/oai/request"},"display":{"title":"Current status of the scale insect fauna of citrus in Tunisia and biological studies on Parlatoria ziziphi (Lucas)","abstract":"English. The Tunisian scale insect fauna (Hemiptera: Coccoidea), is among the poorly studied fauna in the world. Actually, populations of some species have increased to pest status in many crops and the black scale Parlatoria ziziphi Lucas (Hemiptera: Diaspididae) is one of the most important insect pests attacking citrus crop in Tunisia. In the current study, a revision of the scale insect fauna occurring on citrus in Tunisia was done based on the results of field surveys and literature review. Moreover, effects of two temperatures (T1=20°C; T2=24°C) and plant substrates (green fruits of lemon and seedling plants of sour orange) on the development, fecundity and life table parameters (the intrinsic rate of increase (rm), the mean generation time (T0) and the net reproduction ratio (R0)) of the black scale were assessed. From surveys conducted in the main citrus growing regions located in the northern part of Tunisia, a total of 84 samples were collected and over 200 slide-mounted specimens were identified. Twenty-one species of scale insects are occurring nowadays on citrus trees in Tunisia; three of them were detected for the first time. An inventory of all species injuring citrus crop in Tunisia and their main characteristics (pest status, change in abundance over time, and distribution) is provided. Results on laboratory studies indicated a consistent influence of the temperature more than the plant substrate on the development and reproductive capacity of P. ziziphi. In fact, this species was well adapted at temperatures mainly 24°C. Survival declines clearly at 20°C (37.8% at female stages); while at 24°C very low mortalities were registered. Temperature significantly affected the durations of the majority of immature and adult stages; and total female development approached globally four months at 20oC and two months at 24oC. Sex differentiation showed a strong male-biased sex ratio of about 2:1 at 20°C and 1:2 at 24°C. Low mean fecundities were obtained, 26±3.5 and 47.47±1.5 eggs/female at 20°C and 24°C, respectively. In addition, at each generation, P. ziziphi had the capacity to increase their populations by a mean of 11.0 at 20°C in an average of 161.5 days with an intrinsic rate of increase of 0.015. At 24°C, parameters become better estimated; P. ziziphi populations can multiply meanly 32.35 times in an average of 86 days, with an intrinsic rate of increase of 0.041. As recommendations, the situation of some species is still unclear and it is necessary to continue with prospections in order to have a clearer complete list of species associated with the citrus trees in Tunisia. For life table study, this is a first contribution to assess the biological potential of the black scale under laboratory conditions; studying more temperatures should contribute to a better understanding of the population dynamics of this pest in the field.","abstract_html":"English. The Tunisian scale insect fauna (Hemiptera: Coccoidea), is among the poorly studied fauna in the world. Actually, populations of some species have increased to pest status in many crops and the black scale Parlatoria ziziphi Lucas (Hemiptera: Diaspididae) is one of the most important insect pests attacking citrus crop in Tunisia. In the current study, a revision of the scale insect fauna occurring on citrus in Tunisia was done based on the results of field surveys and literature review. Moreover, effects of two temperatures (T1=20°C; T2=24°C) and plant substrates (green fruits of lemon and seedling plants of sour orange) on the development, fecundity and life table parameters (the intrinsic rate of increase (rm), the mean generation time (T0) and the net reproduction ratio (R0)) of the black scale were assessed. From surveys conducted in the main citrus growing regions located in the northern part of Tunisia, a total of 84 samples were collected and over 200 slide-mounted specimens were identified. Twenty-one species of scale insects are occurring nowadays on citrus trees in Tunisia; three of them were detected for the first time. An inventory of all species injuring citrus crop in Tunisia and their main characteristics (pest status, change in abundance over time, and distribution) is provided. Results on laboratory studies indicated a consistent influence of the temperature more than the plant substrate on the development and reproductive capacity of P. ziziphi. In fact, this species was well adapted at temperatures mainly 24°C. Survival declines clearly at 20°C (37.8% at female stages); while at 24°C very low mortalities were registered. Temperature significantly affected the durations of the majority of immature and adult stages; and total female development approached globally four months at 20oC and two months at 24oC. Sex differentiation showed a strong male-biased sex ratio of about 2:1 at 20°C and 1:2 at 24°C. Low mean fecundities were obtained, 26±3.5 and 47.47±1.5 eggs/female at 20°C and 24°C, respectively. In addition, at each generation, P. ziziphi had the capacity to increase their populations by a mean of 11.0 at 20°C in an average of 161.5 days with an intrinsic rate of increase of 0.015. At 24°C, parameters become better estimated; P. ziziphi populations can multiply meanly 32.35 times in an average of 86 days, with an intrinsic rate of increase of 0.041. As recommendations, the situation of some species is still unclear and it is necessary to continue with prospections in order to have a clearer complete list of species associated with the citrus trees in Tunisia. For life table study, this is a first contribution to assess the biological potential of the black scale under laboratory conditions; studying more temperatures should contribute to a better understanding of the population dynamics of this pest in the field.","abstract_has_math":false,"creators":["JENDOUBI, HANENE"],"institution":"Università degli studi di Catania","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["RUSSO, Agatino","RAPISARDA, Carmelo"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-12-08","date_published":"2011-12-08","updated_at":"2026-07-24T01:35:08Z","subjects":["Tunisia,Citrus spp,scale insect fauna,inventory,new records,pest status,P. ziziphi,temperature,plant substrate,life table,fecundity,Tunisie,Citrus spp,faune des cochenilles,inventaire,nouvelle occurrence,révision,nuisibilité,P. ziziphi,température,substrat végétal,table de survie,fécondité"],"languages":["eng"],"rights":["info:eu-repo/semantics/openAccess","license:PUBBLICO - Pubblico con Copyright","license uri:iris.PUB02"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/20.500.11769/594340","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Jendoubi, Hanene","RUSSO, Agatino","RAPISARDA, Carmelo"]},{"key":"dc:creator","label":"Author","values":["JENDOUBI, HANENE"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-12-08"]},{"key":"dc:publisher","label":"Institution","values":["Università degli studi di Catania","place:Catania"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Tunisia,Citrus spp,scale insect fauna,inventory,new records,pest status,P. ziziphi,temperature,plant substrate,life table,fecundity,Tunisie,Citrus spp,faune des cochenilles,inventaire,nouvelle occurrence,révision,nuisibilité,P. ziziphi,température,substrat végétal,table de survie,fécondité"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess","license:PUBBLICO - Pubblico con Copyright","license uri:iris.PUB02"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/20.500.11769/594340"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["English. The Tunisian scale insect fauna (Hemiptera: Coccoidea), is among the poorly studied fauna in the world. Actually, populations of some species have increased to pest status in many crops and the black scale Parlatoria ziziphi Lucas (Hemiptera: Diaspididae) is one of the most important insect pests attacking citrus crop in Tunisia. In the current study, a revision of the scale insect fauna occurring on citrus in Tunisia was done based on the results of field surveys and literature review. Moreover, effects of two temperatures (T1=20°C; T2=24°C) and plant substrates (green fruits of lemon and seedling plants of sour orange) on the development, fecundity and life table parameters (the intrinsic rate of increase (rm), the mean generation time (T0) and the net reproduction ratio (R0)) of the black scale were assessed. From surveys conducted in the main citrus growing regions located in the northern part of Tunisia, a total of 84 samples were collected and over 200 slide-mounted specimens were identified. Twenty-one species of scale insects are occurring nowadays on citrus trees in Tunisia; three of them were detected for the first time. An inventory of all species injuring citrus crop in Tunisia and their main characteristics (pest status, change in abundance over time, and distribution) is provided. Results on laboratory studies indicated a consistent influence of the temperature more than the plant substrate on the development and reproductive capacity of P. ziziphi. In fact, this species was well adapted at temperatures mainly 24°C. Survival declines clearly at 20°C (37.8% at female stages); while at 24°C very low mortalities were registered. Temperature significantly affected the durations of the majority of immature and adult stages; and total female development approached globally four months at 20oC and two months at 24oC. Sex differentiation showed a strong male-biased sex ratio of about 2:1 at 20°C and 1:2 at 24°C. Low mean fecundities were obtained, 26±3.5 and 47.47±1.5 eggs/female at 20°C and 24°C, respectively. In addition, at each generation, P. ziziphi had the capacity to increase their populations by a mean of 11.0 at 20°C in an average of 161.5 days with an intrinsic rate of increase of 0.015. At 24°C, parameters become better estimated; P. ziziphi populations can multiply meanly 32.35 times in an average of 86 days, with an intrinsic rate of increase of 0.041. As recommendations, the situation of some species is still unclear and it is necessary to continue with prospections in order to have a clearer complete list of species associated with the citrus trees in Tunisia. For life table study, this is a first contribution to assess the biological potential of the black scale under laboratory conditions; studying more temperatures should contribute to a better understanding of the population dynamics of this pest in the field.","La faune des cochenilles (Hemiptera: Coccoidea) en Tunisie est l une des faunes les moins étudiées dans le monde. De nos jours, quelques espèces de cochenilles causent des dégâts énormes à plusieurs cultures, on cite le pou noir, Parlatoria ziziphi Lucas (Hemiptera: Diaspididae) qui est considéré l'un des ravageurs clés de la culture des agrumes en Tunisie. Dans le présent travail, la liste de la faune des cochenilles inféodées aux agrumes en Tunisie a été revue en se basant sur les résultats d une prospection conduite en plein champ et une étude faite sur les précédentes publications. En outre, les effets de la température (T1 = 20°C; T2 = 24°C) et du substrat végétal (fruits du citronnier et plants de semis de bigaradier) sur le développement, la fécondité et les paramètres biologiques (le taux de croissance intrinsèque (rm), le temps moyen de génération (T0) et le ratio net de reproduction (R0)) du pou noir ont été évalués. Suite aux enquêtes menées dans les principales régions agrumicoles au nord de la Tunisie, 84 échantillons ont été prélevés et plus que 200 spécimens montés entre lame et lamelle ont été identifiés. A présent, vingt et une espèce de cochenilles sont présents dans les différentes parcelles d'agrumes en Tunisie ; Trois d'entre elles sont mentionnées pour la première fois. Un inventaire de toutes les espèces de cochenilles et leurs principales caractéristiques (nuisibilité, changement temporel de la densité et distribution) a été défini. Les résultats obtenus sur les études biologiques menées au laboratoire sur P. ziziphi ont montré que la température a une influence plus effective que celle du substrat végétal sur le développement et la capacité de reproduction de cette espèce. En effet, elle a montré une bonne adaptation aux températures, en particulier 24°C. Les taux de survie montrent une baisse distincte à 20°C (37,8% au stade femelle), tandis que de très faibles taux de mortalité ont été enregistrés à 24°C. La température affecte de façon significative les durées de développement des différents stades larvaires et adultes; et le développement total de la femelle était environ quatre mois à 20 oC, et près de deux mois à 24oC. La différentiation sexuelle a présenté un puissant male sex ratio, environ 2:1 à 20°C et 1:2 à 24°C. La fécondité moyenne était faible, soient 26±3,5 et 47,47±1,5 ufs/femelle, respectivement à 20°C et 24°C. En outre, à chaque génération, P. ziziphi avait la capacité d'accroître sa population par une moyenne de 11,0 à 20°C pendant un temps moyen de 161,5 jours et avec un taux de croissance intrinsèque de 0,015. A 24°C, les paramètres deviennent mieux estimés; les populations du pou noir pouvaient se multiplier en moyenne 32,35 fois dans 86 jours, avec un taux de croissance intrinsèque de 0,041. Comme recommandations, l état de certaines espèces de cochenilles demeure incertain et il est nécessaire de poursuivre les prospections afin d'obtenir une liste plus claire et complète sur l ensemble des espèces associées à la culture d'agrumes en Tunisie. Pour l'étude des tables de survie de P. ziziphi, il s agissait d une première contribution à évaluer les potentialités biologiques de ce ravageur au laboratoire, et l essai d autres valeurs de température apportera une meilleure compréhension de la dynamique des populations de ce ravageur en plein champ."]},{"key":"dc:title","label":"Title","values":["Current status of the scale insect fauna of citrus in Tunisia and biological studies on Parlatoria ziziphi (Lucas)"]}]}],"canonical_facts":{"dc:contributor":["Jendoubi, Hanene","RUSSO, Agatino","RAPISARDA, Carmelo"],"dc:creator":["JENDOUBI, HANENE"],"dc:date":["2011-12-08"],"dc:description":["English. The Tunisian scale insect fauna (Hemiptera: Coccoidea), is among the poorly studied fauna in the world. Actually, populations of some species have increased to pest status in many crops and the black scale Parlatoria ziziphi Lucas (Hemiptera: Diaspididae) is one of the most important insect pests attacking citrus crop in Tunisia. In the current study, a revision of the scale insect fauna occurring on citrus in Tunisia was done based on the results of field surveys and literature review. Moreover, effects of two temperatures (T1=20°C; T2=24°C) and plant substrates (green fruits of lemon and seedling plants of sour orange) on the development, fecundity and life table parameters (the intrinsic rate of increase (rm), the mean generation time (T0) and the net reproduction ratio (R0)) of the black scale were assessed. From surveys conducted in the main citrus growing regions located in the northern part of Tunisia, a total of 84 samples were collected and over 200 slide-mounted specimens were identified. Twenty-one species of scale insects are occurring nowadays on citrus trees in Tunisia; three of them were detected for the first time. An inventory of all species injuring citrus crop in Tunisia and their main characteristics (pest status, change in abundance over time, and distribution) is provided. Results on laboratory studies indicated a consistent influence of the temperature more than the plant substrate on the development and reproductive capacity of P. ziziphi. In fact, this species was well adapted at temperatures mainly 24°C. Survival declines clearly at 20°C (37.8% at female stages); while at 24°C very low mortalities were registered. Temperature significantly affected the durations of the majority of immature and adult stages; and total female development approached globally four months at 20oC and two months at 24oC. Sex differentiation showed a strong male-biased sex ratio of about 2:1 at 20°C and 1:2 at 24°C. Low mean fecundities were obtained, 26±3.5 and 47.47±1.5 eggs/female at 20°C and 24°C, respectively. In addition, at each generation, P. ziziphi had the capacity to increase their populations by a mean of 11.0 at 20°C in an average of 161.5 days with an intrinsic rate of increase of 0.015. At 24°C, parameters become better estimated; P. ziziphi populations can multiply meanly 32.35 times in an average of 86 days, with an intrinsic rate of increase of 0.041. As recommendations, the situation of some species is still unclear and it is necessary to continue with prospections in order to have a clearer complete list of species associated with the citrus trees in Tunisia. For life table study, this is a first contribution to assess the biological potential of the black scale under laboratory conditions; studying more temperatures should contribute to a better understanding of the population dynamics of this pest in the field.","La faune des cochenilles (Hemiptera: Coccoidea) en Tunisie est l une des faunes les moins étudiées dans le monde. De nos jours, quelques espèces de cochenilles causent des dégâts énormes à plusieurs cultures, on cite le pou noir, Parlatoria ziziphi Lucas (Hemiptera: Diaspididae) qui est considéré l'un des ravageurs clés de la culture des agrumes en Tunisie. Dans le présent travail, la liste de la faune des cochenilles inféodées aux agrumes en Tunisie a été revue en se basant sur les résultats d une prospection conduite en plein champ et une étude faite sur les précédentes publications. En outre, les effets de la température (T1 = 20°C; T2 = 24°C) et du substrat végétal (fruits du citronnier et plants de semis de bigaradier) sur le développement, la fécondité et les paramètres biologiques (le taux de croissance intrinsèque (rm), le temps moyen de génération (T0) et le ratio net de reproduction (R0)) du pou noir ont été évalués. Suite aux enquêtes menées dans les principales régions agrumicoles au nord de la Tunisie, 84 échantillons ont été prélevés et plus que 200 spécimens montés entre lame et lamelle ont été identifiés. A présent, vingt et une espèce de cochenilles sont présents dans les différentes parcelles d'agrumes en Tunisie ; Trois d'entre elles sont mentionnées pour la première fois. Un inventaire de toutes les espèces de cochenilles et leurs principales caractéristiques (nuisibilité, changement temporel de la densité et distribution) a été défini. Les résultats obtenus sur les études biologiques menées au laboratoire sur P. ziziphi ont montré que la température a une influence plus effective que celle du substrat végétal sur le développement et la capacité de reproduction de cette espèce. En effet, elle a montré une bonne adaptation aux températures, en particulier 24°C. Les taux de survie montrent une baisse distincte à 20°C (37,8% au stade femelle), tandis que de très faibles taux de mortalité ont été enregistrés à 24°C. La température affecte de façon significative les durées de développement des différents stades larvaires et adultes; et le développement total de la femelle était environ quatre mois à 20 oC, et près de deux mois à 24oC. La différentiation sexuelle a présenté un puissant male sex ratio, environ 2:1 à 20°C et 1:2 à 24°C. La fécondité moyenne était faible, soient 26±3,5 et 47,47±1,5 ufs/femelle, respectivement à 20°C et 24°C. En outre, à chaque génération, P. ziziphi avait la capacité d'accroître sa population par une moyenne de 11,0 à 20°C pendant un temps moyen de 161,5 jours et avec un taux de croissance intrinsèque de 0,015. A 24°C, les paramètres deviennent mieux estimés; les populations du pou noir pouvaient se multiplier en moyenne 32,35 fois dans 86 jours, avec un taux de croissance intrinsèque de 0,041. Comme recommandations, l état de certaines espèces de cochenilles demeure incertain et il est nécessaire de poursuivre les prospections afin d'obtenir une liste plus claire et complète sur l ensemble des espèces associées à la culture d'agrumes en Tunisie. Pour l'étude des tables de survie de P. ziziphi, il s agissait d une première contribution à évaluer les potentialités biologiques de ce ravageur au laboratoire, et l essai d autres valeurs de température apportera une meilleure compréhension de la dynamique des populations de ce ravageur en plein champ."],"dc:identifier":["https://hdl.handle.net/20.500.11769/594340"],"dc:language":["eng"],"dc:publisher":["Università degli studi di Catania","place:Catania"],"dc:rights":["info:eu-repo/semantics/openAccess","license:PUBBLICO - Pubblico con Copyright","license uri:iris.PUB02"],"dc:subject":["Tunisia,Citrus spp,scale insect fauna,inventory,new records,pest status,P. ziziphi,temperature,plant substrate,life table,fecundity,Tunisie,Citrus spp,faune des cochenilles,inventaire,nouvelle occurrence,révision,nuisibilité,P. ziziphi,température,substrat végétal,table de survie,fécondité"],"dc:title":["Current status of the scale insect fauna of citrus in Tunisia and biological studies on Parlatoria ziziphi (Lucas)"],"dc:type":["info:eu-repo/semantics/doctoralThesis"]},"updated_at":"2026-07-24T01:35:08Z"}