SOME ECOLOGICAL ASPECTS on the STRIPED MEALYBUG Ferrisia
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Arab Univ. J. Agric. Sci., Ain Shams Univ., Cairo, Egypt 82(1), 337-348, 2082 Website: http://ajs.journals.ekb.eg 333 SOME ECOLOGICAL ASPECTS ON THE STRIPED MEALYBUG Ferrisia virgata (COCKERELL) INFESTING ACALYPHA SHRUBS IN QALYUBIYA GOVERNORATE, EGYPT [25] Dalia Nabil1*, Amin2 A.H., Omnia M.N. Elashn1 and Youssef2 E.E.Y. 1- Plant Protection Research Institute Agriculture Research Center, Dokki, Giza, Egypt 2- Plant Protection Dept., Fac. of Agric., Ain Shams Univ., P.O. Box 68, Hadayek Shoubra 11241, Cairo, Egypt *Corresponding author: [email protected] Received 9 February, 2020 Accepted 1 April, 2020 ABSTRACT was ranged between 80-85 days which occurred during summer months. While the second genera- Acalypha shrubs Acalypha wilkesiana Mull.(Eu- tion was lasted 75 days and occurred during au- phorbiaceae) found to be favorable host for the tumn. Statistical analysis revealed that separate ef- striped mealybug Ferrisia virgate (Cockerell) (Pseu- fect of each mean, two weeks earlier of the four se- dococcidae). This mealybug species is attacked all lected weather factors on changes in population plant parts and caused considerable damages to density of F. virgata most factors had insignificant this host. Some ecological aspects were carried out effects except mean minimum temperature which on F. virgata infesting acalypha shrubs throughout had positive significant effects throughout the both two successive years (2014-2015) and (2015-2016) years (r coefficient values were 0.589 and 0.677). in Qalyubiya Governorate. While the combined effects of the four selected fac- Results obtained showed that population den- tors (mean minimum, maximum temperature, aver- sity was more abundant during the second year age temperature and mean percentage of relative than the first one, the annual means of total popula- humidity), two weeks earlier, had significant effects, tion were 62.02 and 52.01 individuals/leaf), respec- as a group on the change in population density es- tively. Also, results revealed that, seasonal abun- pecially during (2014-2015) , the explained variance dance of F. virgata found to be active from June to was 79.2% and F value 14.4. January of next year. The population density was Keywords: Ferrisia virgata; Acalypha shrubs; Sea- reached its maximum activity on October during sonal fluctuations; Ecological studies; Number of both years being 123.0 and 145.2 individuals /leaf generations for the first and second year, respectively. The pre- vailing main average temperature and relative hu- INTRODUCTION midity were ranging between 22.8°C, 24.2°C and 67%, 64% for the 1st and 2nd years, respectively. During last decade the striped mealybug Fer- These conditions seemed to be favorable conditions risia virgate (Cockerell) became the most common for insect activity. After this activity period all stages pseudococcid species which widely distributed in of this species were disappeared from all plant different localities of Egypt. This mealybug species parts. This phenomenon indicate that this mealy- was recorded for the first time in Egypt infesting aca- bug species was overwinter during winter and lypha shrubs and ornamental plants in Port Said spring seasons till the next summer. From these Governorate (Hosny 1943).This insect is polypha- findings it could be stated that any control measure- gus and found to attack 203 plant genera of 77 fam- ments must be early applied during June, at the be- ilies (Garcia et al 2016). In Egypt F. virgata found ginning of activity period of this mealybug species. to attack a wide range of host plants especially or- Also, results clarified that F. virgate was passed namental plants and fruit trees. All stages of this through two annual overlapping field generations on mealybug species found to attack all plant parts, acalypha shrubs. Duration of the first generation leaves, root, branches, fruits and trunk sucking a 338 Dalia Nabil; Amin; Omnia Elsahn and Youssef large amounts of plant sap then producing honey counted. These different developmental stages dew which considered as suitable media for growth were 1st, 2nd, 3rd nymphal instars and adult females. of the black sooty mold fungi forming a black layer on leaves which delay photosynthesis and block 1- Seasonal fluctuations of insect population respiration. Also, this species has the ability to transfer viruses which cause many diseases to Data of half monthly counts were used to calcu- some host plants (Franco et al 2009). Acalypha late some ecological parameters. Mean of total shrub Acalypha wilkesiana Mull. (Euphorbiaceae) is numbers of alive individuals/leaf in each sample an important ornamental plant in Egypt and found to were considered as population index for population be a favorable host plant for this mealybug species density. Mean of total numbers of immature all over the country. This mealybug species at- stage/leaf were calculated and considered as sea- tracted the attentions of many authors in Egypt. sonal activity period of nymphal stage throughout They were published several papers on biology, the year. The rate of increase in the population den- ecology and natural enemies of this insect species sity was calculated by dividing the total number of i.e. Ammar et al (1979); Attia (1997); Balboul alive populations in any count over the total num- (2003); El-Shazly (2006); El-Batran et al (2015) bers of the previous one. and Adly et al (2016). The present studies were conducted to investi- 2- Number and duration of annual field genera- gate some ecological aspects on F. virgata infesting tions acalypha shrubs in Qalyubiya Governorate through- out two successive years. These aspects were sea- Number and duration of annual field generations sonal fluctuation in population density, number and were estimated on acalypha shrubs in Qalyubiya lo- duration of annual field generations and the effect of cality throughout the two years. Data of the half four weather factors on the changes in insect popu- monthly counts of mean alive total population/ leaf lation. These aspects could be detected the proper were used to estimate the number and duration of time for application of control measurements the annual field generations. These data were against this insect pest. worked out according to the methods suggested by Audemard and Millaire (1975) and emended by MATERIAL AND METHODS Iacob (1977). The graphical representations of these data were carried out by using computer soft- These studies were carried out to investigate the ware program (Sigmaphot, ver.11). seasonal fluctuation in population density and num- ber of annual field generations of the mealybug 3- Effects of certain weather factors on the Ferisia virgata (Cockerrel) infesting acalypha changes of population density shrubs Acalypha wilkesiana Mull. in Qalyubiya Gov- ernorate throughout two successive years (2014- Four main weather factors were selected i.e.; 2015) and (2015-2016). mean minimum, maximum temperature, average temperature and mean percentage of relative hu- Sampling and counting procedures midity. These data were obtained from the nearest Meteorological Station in Qalyubiya belonging to the Five acalypha shrubs of the same age, size, Central Laboratory for Agricultural Climate vegetation and height were chosen for sampling (C.L.A.C.), Ministry of Agriculture, Giza, Egypt. procedures at the Faculty of Agriculture, Ain Shams The half monthly means of these main weather University, Shoubra El-Kheima, Qalyubiya Gover- factors were calculated. These means were used to norate. No chemical control measures were applied investigate the effects of these selected weather two years before sampling periods as well as during factors, two weeks earlier, on the change of popula- sampling procedures. tion density of F. virgata. Half monthly mean num- Regular samples were taken at half monthly in- bers of F. virgata total population were used as de- tervals from acalypha shrubs throughout the two pendent factor (Y), while means of half monthly rec- successive years. Each sample was consisted of ords of main weather factors, two weeks earlier, 50 leaves taken randomly (10 leaves/ shrub). These were used as independent factors, mean minimum samples were kept in polyethylene bags and trans- temperature (X1); mean maximum temperature (X2); ferred to the laboratory for inspection using a stere- average temperature (X3) and mean percentage of omicroscope. The numbers of alive individual of dif- relative humidity (X4). ferent developmental stages were sorted and AUJASCI, Arab Univ. J. Agric. Sci., 22(1), 2082 Some Ecological Aspects on the Striped Mealybug Ferrisia virgata (Cockerell) 339 Infesting Acalypha Shrubs in Qalyubiya Governorate, Egypt Statistical analysis procedures were conducted During the second year the insect population in two steps, the first one to investigate the effect of nearly followed the same trend but began to be ac- each factor separately by applying simple correla- tive on 1st June (15 days later than the first year). tion formula and regression coefficient was used as Total insect population began with few numbers a measure of significance. The second step by ap- and increased gradually throughout successive plying C-multiplier formula (Fisher, 1950) to investi- counts and recorded the highest peak of seasonal gate the combined effects of the four tested factors abundance on 1st October, 2015 (145.20 individu- as a group on the changes of the population density als/leaf). Then insect population was decreased expressed a percentage of explained variance gradually throughout successive counts till 1st Jan- (E.V.%) and the variance ratio (F value) was used uary 2016. Afterwards, the insect population was to- as measure of significance. All calculations were tally disappeared till next June. The rate of increase carried out using the computer program (SPSS was recorded two maximum rates on mid-July and ver.20). mid-August 2015, being 4.57 and 3.29, respectively. From these results it could be stated that seasonal RESULTS AND DISCUSSION abundance of F. virgata found to be active from June to January and reached its maximum activity 1- Seasonal fluctuations in population of differ- on October on both years.