Presentation on theme: "Presented by, Mohamed Abd El Wanis Types of mealybugs deployed on different plant hosts in Egypt أنواع البق الدقيقى المنتشرة على العوائل النباتية المختلفة."— Presentation transcript:
Phylogeny and higher classification of the scale insects (Hemiptera: Sternorrhyncha: Coccoidea)* P.J. GULLAN 1 AND L.G. COOK 2 1 Department of Entomology, University of California, One Shields Avenue, Davis, CA 95616, U.S.A. E-mail: email@example.com 2 School of Integrative Biology, The University of Queensland, Brisbane, Queensland 4072, Australia. Email: firstname.lastname@example.org * In: Zhang, Z.-Q. & Shear, W.A. (Eds) (2007) Linnaeus Tercentenary: Progress in Invertebrate Taxonomy. Zootaxa, The Coccoidea is one of the four superfamilies of suborder Sternorrhyncha within the Hemiptera (Schaefer, 1996; Bourgoin & Campbell, 2002; Gullan & Martin, 2003).
(Chun et all.2000) These small insects are 1- 4 millimeters long. The females are covered with a white, cottony or mealy wax secretion and look like tiny cotton balls on plants, taking away a plant’s aesthetic value. They’ve got an oval body outline, and functional legs allow them to be mobile in their immature stage. Some mealybugs are more ornate than others, having filaments around the edge of their bodies or even “tails.” Immature males and females look similar, but they’re very different as adults: The adult male looks like a gnat with one pair of wings. (Only the adult males fly.) Female crawlers go though four developmental stages until they reach maturity. The male goes through five The mealybug is found on stems, leaves, buds, fruit and roots of many plants
Crawlers crawl from an infected to healthy plant. Small crawlers are readily transported by wind, rain, birds, clothing on new plants The waxy coating facilitates passive transport of the insect by their sticking/clinging to equipments, animals or people moving during field operations. Long-distance movement is through transport of infested cotton sticks or seed cotton. Crawlers are also carried through irrigated water, when the mealy bug infested plants are thrown in water channel. Ants, attracted by the honeydew, carry crawlers of mealy bugs from plant to plant.
The economic importance of mealybugs (Williams.2000) Mealybugs rarely attack annuals but are important pests on perennials. They attack roots, stems and leaves. Woody trees, shrubs and, grasses are the most important plants infested. Mealybugs prefer plants with a high nitrogen content.Trees grown in the shade and those that received nitrogenous fertiliser have been observed to have significantly heavier populations of mealybugs. Nutritional differences may explain why some plants are infected with mealybugs while other plants remain free from attack. Even differences in the chemical composition between parts of any one plant could affect the choice of feeding site.
The economic importance of mealybugs (Kosztarab.1990) found that the damage caused by scale insects is not primarily due to plant-sap ingestion itself but more often to the toxic substances in the saliva which are injected into the plant tissue during the feeding process. Enzymatic activity then causes a reaction by the host plant that is manifested in different ways (a) On leaves chlorosis (normally appears as a general or spottily yellowing) (b) On fruits reddish discoloration encircles the insects while underneath the scale the surface remains green (c) Shoot and leaf petiol deformation
(d) Twig and branches deformations usually as depressions on the barks (e) Shallow often inconspicuous open-top pit galls or blister-like galls are produced (f) Rarely pouch-like galls are produced on host twigs and leaves (g) A witches-broom type of deformation caused (h) Necrosis of cambial tissues and stopping of the sap transportation in the phloem is caused in cases of heavy infestation
(i) Abortion of fruits due to feeding on the fruit pedicel is often observed (j)Yellowish-brown discoloration as well as depression and cracking of the fruit skin has been noted on orange fruits (i) Abortion of fruits due to feeding on the fruit pedicel is often observed (j)Yellowish-brown discoloration as well as depression and cracking of the fruit skin has been noted on orange fruits
(k) Distortion of young fruits like vine is often indicated (L) produce honeydew and infested plants may also exhibit sooty mold fungi
Adult maleAdult female ovisac Eggs hatch in 3 to 9 days into nymphs called (crawlers) Life cycle
1-Scale insects are notorious pests on perennial plants as well as fruit and nut trees. These pests belong to super family Coccoidae that contained twelve families; three of them belong to genus Icerya: I. aegyptiaca (Douglas), I. Purchasi Maskell and I. seychellarum (Westwood). (Ezzat et all,1986) 2- the family Margarodidae is represented by six species of the mealybug (Mohammad,1998 ) 3- the family Diaspididae (the armored scales) represents the largest family of the super family belonging to which includes major pests in Egypt. 72 species were listed of this family in Egypt. The second largest family is Pseudococcidae that have 47 species of the mealybug belong to 28 genera Ghabbour et all,1996) )
4-studied the distribution of the margarodid I.seychellarum on apple trees where 61.9% of the margarodid where concentrated old branches,4.2% on old leaves and 2.2% on new Leaves (Mangoud,2000) 5- Scale insects were present in different parts of the world and they fall within 23 families. Out of them 12 families are found in Egypt and the most important families were: the armored scale insects (Diaspididae), the mealybugs (Morgarodidae and Pseudococcidae) and the soft scales (Coccidae). All important families contain dangerous species that attack different important economic crops in Egypt (Abd-Rabou, 2003
Mealy bug provide ants with their sugary secretion (honeydew) as food and in retur ants help in spreading of mealy bug Ants provide protection to mealy bug from predatory ladybird beetles, parasites and other natural enemies. Ants keep mealy bug colony clean from detritus that accumulate in the secreted honeydew, which may be harmful to the colony
PR REOVCIE. W H: A A WNAITISANA N E DN T P OIMNEOAL. P P S LOEC M. ( E 2 A 0 L 0 Y 3 B ) U 3 G 6 W:9 I – L 2 T 8 9 A Review of the Association of Ants with Mealybug Wilt Disease of Pineapple Gary C. Jahn 1, John W. Beardsley 2, and Hector González-Hernández 3 1, 2, 3 Department of Entomology, University of Hawaii, Honolulu, Hawaii 96822 USA. 1 Current address: International Rice Research Institute (IRRI), DAPO 7777, Metro Manila, Philippines. 2 Passed away on February 5, 2001. 3 Current address: Instituto de Fitosanidad, Colegio de Postgraduados, Montecillo, Texcoco, Edo. De México 56230 Mexico
Ants Associated with Mealybug Wilt Disease of Pineapple In the 1920s, pineapple growers in Hawaii noticed that ants were common in the wilted areas of pineapple fields. They assumed that ants were causing wilt disease and took mea- sures to destroy and prevent ant infestations. Based on observations, rather than experimen- tation, Illingworth (1926a,b) concluded that ants did not cause wilt disease. He recognized the importance of mealybugs as pineapple pests and that ants appeared to benefit mealy- bugs by deterring natural enemies, but thought that, overall, the predatory nature of ants made them beneficial to pineapple growers. Therefore, he did not recommend ant control. A series of experiments led him to change his mind. Illingworth (1931) demonstrated that ants themselves did not cause wilt disease, but that mealybugs did. He noted that without ants, the natural enemies already present in the field might keep mealybugs under control. In light of this, he suggested that poisoning ants might be an effective means of preventing mealybug wilt disease of pineapple. Since then, mealybug wilt disease has been controlled primarily through ant control. Experiments confirm that ant control reduces mealybug popu- lations and prevents mealybug wilt disease (Beardsley et al. 1982; Carter 1933a, 1960; Gonz á lez- Hern á ndez et al. 1999a,b; Jahn 1990). While a number of ant species have been found in Hawaiian pineapple fields, the most pestiferous species in pineapple are Pheidole megacephala (Fabricius), Solenopsis geminata (Fabricius), and Linepithema humile (Mayr). P. megacephala, the big-headed ant, is the dominant ant species below 600 m elevation, where most Hawaiian pineapple fields are located (Fluker & Beardsley 1970, Reimer et al. 1990a). P. megacephala was already com- mon on the Hawaiian island of Oahu in 1879 (Blackburn and Kirby 1880). The ants most commonly associated with pineapple mealybugs throughout the world are species of Pheidole and Solenopsis (Table 1). The Role of Ants in Mealybug Wilt Disease of Pineapple Phillips (1934) hypothesized that mealybugs were associated with ants in pineapple fields because: 1) ants protected mealybugs from natural enemies; 2) ants protected mealybugs from adverse weather by building earthen shelters around them and moving them to pro- tected places; 3) ants transported mealybugs from plant to plant between and within fields, thus facilitating mealybug dispersal; 4) ants stimulated increased feeding by mealybugs; and 5) ants removed honeydew from mealybugs, thereby preventing fungi from attacking mealybugs. Rohrbach et al. (1988) hypothesized that honeydew feeding by ants could ben- efit mealybugs by preventing the accumulation of honeydew on the mealybugs themselves. Presumably, immature mealybugs get stuck in honeydew and die if ants do not remove it. Protection from natural enemies. Saying that ants “ protect ” mealybugs from natural enemies does not necessarily mean that ants are attacking the natural enemies to save hon- eydew as a food resource. Possibly, ants are consuming the natural enemies as food and mealybugs benefit by happenstance (Jahn and Beardsley 1994). There are numerous ex- amples of ants deterring the predators and parasites of scales, mealybugs, and aphids (e.g., Van der Goot 1916; Way 1954, 1963; Wimp and Whitham 2001). For instance, in the ab- sence of Argentine ants, L. humile, parasites suppress populations of lecaniine scale insects (Bartlett 1961). Ants also reduce parasitism of the cassava mealybug, Phenacoccus manihoti Matile- Ferrero (Cudjoe et al. 1993). Larval coccinellids eliminate green scales (Coccus viridis (Green)) from coffee trees in Hawaii unless P. megacephala is present (Reimer et al. 1993). Green scales in Sri Lanka also cannot survive without ants (Oecophylla smaragdina Fabricius), but the ants apparently do not reduce parasite and predator attacks on the scales (Bess 1958). A wide variety of natural enemies prey on pineapple mealybugs (Table 2). Ants protect mealybugs from their natural enemies (Gonz á lez- Hern á ndez et al. 1999a,b). In laboratory experiments with coccinellids, D. neobrevipes did not thrive on pineapples, unless ants were present (Illingworth 1931). In the absence of natural enemies, laboratory populations of D. neobrevipes were not significantly different on pineapples with and without ants (Jahn and Beardsley 1996). In the field, P. megacephala had a positive association with D. neobrevipes and a negative association with the predators of mealybugs (Jahn and Beardsley 1998, 2000). Collectively, these experiments suggest that P. megacephala deters predators from attacking D. neobrevipes.
Conclusions The available evidence suggests that mealybug wilt disease of pineapple is a viral disease, though it is possible that wilt is a toxemia induced by a virus that affects the mealybug itself. The disease is managed primarily by controlling ants. In the absence of ants, natural enemies suppress mealybug populations on pineapple. Chemical control of ants allows bio- logical control of mealybugs to occur.
Table 1. Ants associated with pineapple mealybugs in various parts of the world.
Table 1. Ants associated with mealybugs in various parts of the world
Families of mealybugs (Moursi et all.2009) mealybugs belong to more than family most prominent in Egypt, three families Fam / Pseudococcidae عائلة البق الدقيقى Pseudococcus citri Pseudococcus sacchari Phenococcus hirsutus Planococcus longispinus Ferrisia vergata SPECIES
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