Preferred direction site of the sugar-cane field to infestation by Pulvinaria tenuivalvata (Newstead) and its relation with parasitized Coccophagus scutellaris Hymenoptera Aphelinidae

INTRODUCTION

The wide distribution of Pulvinaria tenuivalvata (Newstead) was observed for the first time by Ali et al (1997). in sugar cane fields at Atfeh locality, Giza Governorate, El-minia, Sohage, Quena, Luxor and Aswan. This reflects the seventy dangerous and bad situations of this pest on sugar-cane in Upper Egypt.

Sugar cane is cultivated in large contiguous areas and remains in the field for the whole year. Therefore, a wide range of insect species cause the most significant losses. Some of the insects are major pests of regular occurrence and cause survivor damage, others are minor species. Among these insect pests are soft scale insects Maareg et al (1992).

In 1995, 1996 season, the first noticed in sugar cane fields in Giza separated widely and quickly to cover of about 18 thousand feddaen in all sugarcane plantation in (2015-2016) season Besheit (2002). The nymph and adult females were found clustering on both leaf surface. They are arranged as a line near the edge of the leaf blade Mau (1992)

P. tenuivalvata causes severe damage due to the sucking leaf juice, leading to a loss of leaves, tender young stems, stored plants growth and even death of the plant (Valand et al. 1989). The chemical control in sugar cane fields is very difficult due to foliage intensity and crowded plants. At the same time, many parasitoids are already found, amongst these parasitoids, Coccophagus scutellaris (Dolman) are the major attackers and represent a big portion of P. tenuivalvata population (Hindawy et al., 2002).

Shalaby (2002) found that, this parasitism ranged between 60.1 in August to 33.1 in December, 1997, but in sugar cane season of 1998, the parasitism activity was higher and ranged between 66.7 – 72.2.

This research aims to evaluate the effects of biotic factors on the population density of the sugar cane soft scale P. tenuivalvata. This can assist to avoid the difficult application of the insecticide and minimize the population of the environment. natural enemies (parasites).  

MATERIAL AND METHODS

Spread pattern of insect all over the sugar cane field

One Fadden was selected for this study at Awadlah, Edfo, belonging to Aswan Governorate. During the period extending from May to January, regular intervals sample of sugar can plant leaves were collected from the field border 1,2,3,4 and 5 m. towards the field center. Sample were taken from the different directions of the sugar–cane field representing east, west, north and south directions, in addition to the center site of the field. For each direction, 20 plants were selected randomly and 3 leaves from each plant (lower, mid, and upper levels) were cut – off, kept in muslin bags and transferred to the laboratory. Regular inspection of P. tenuivalvata scales infesting sugarcane plants in (Edfo-Aswan) Governorate during (2015 and 2016) seasons revealed the incidence of the Aphelinidae parasite Coccophagus scutellaris. Data on the parasite activity was based on 2 weekly counts of parasitized scales. The wide distribution of P. tenuivalvata (Newstead) was observed for the first time by Ali et al.¹ in sugar cane fields at Atfeh locality, Giza Governorate, El-minia, Sohage, Quena, Luxor and Aswan. These results reflect the dangerous and bad effect of this pest on sugar-cane in Upper Egypt.

RESULTS AND DISCUSSION

Data in Table (1 and 2) summarizes the changes in the population density of P. tenuivalvata expressed as monthly numbers of insect

As it appears from Table (1) result for 2015 indicate the presence of this insect during the main period of activity which extended from the first week of May to end of December.

Results also showed that P. tenuivalvata appeared for the first time, in a few numbers during the first week of May (79 insects), in all directions and increased gradually, afterwards. The insect reached the highest peak during the first period of September (445 insects). The population density of P. tenuivalvata decreased until the last period of December (117 insects).

The same trend was detected during the second year (2016) as showed in Table (2). The population of the insect increased gradually starting from June (99 Insects) and reached the maximum number at end of October (331 insects). After that, it decreased to reach (64 insects) on December. Tables (1 and 2) and Figs (1 and 2) summarizes the changes in the population density of P. tenuivalvata and parasites distribution in the different. directions of sugarcane field in Awadlah village (Edfo, Aswan) in 2015 and 2016 seasons.

As it appears from Tables (3 and4) and Figs (1 and 2) a significant positive relationship holds between the numbers of insects and parasites in both years such relationship seemed to be stronger in 2015 than 2016.

Numbers of scale insect, Coccophagus scutellaris and the parasite Coccophagus Scutellaris were estimated from May to December in sugar cane field during 2015 and 2016 seasons.

Data in Table (1) showed, the numbers of P. tenuivalvata and Coccophagus scutellaris distribution in different direction of sugar cane field in Awadlah, Edfo Aswan Governorate during 2015 season.

Results on parasitism in 2015 season in sugar cane field indicated that, the its activity increased of July by increasing the numbers of Pulvinaria tenuivalvata especially at the West direction then decreased at the end of December the data in Table (1) also showed that’s the parasite activity increased in September at the West and North directions compared with other directions during 2015 season.

The highest total number of parasites appeared in west direction (359) during the whole season of 2015. The lowest total number of parasites appeared in South direction (87) during the whole season of 2015.

Parasitoid activity fluvtuted during the activity period of P. tenuivalvata (June- December).

The data recorded high abundance in September in West direction (64 parasite with 168 insect pest).

Data in Table (2) clarified, the relationship between P. tenuivalvata and Coccophagus Scutellaris as a parasite in Awadlah, Edfo, Aswan Governorate during season 2016.

The highest population of Pulvinaria tenuivalvata and their parasite was recorded at the West direction then North direction.

The lowest population of P. tenuivalvata and their parasite was recorded at the East and south directions during season 2016.

The data indicated that the numbers of parasite were gradually increased in all directions by increasing their host P. tenuivalvata fromat the first of June till the first of December. Hot months (July, August, September and October) had considerable high populationof P. tenuivalvata scales, consequently, the number of parasites increased a close relationship between the parasite activity and the population density of insect pests especially at the west and north directions 2015 and 2016 seasons. 

The highest total number of insect pests was recorded at the North and West directions (371and 676 insect), while the highest number of parasites was recorded at the West and North directions (369 and 219 insect) during 2016 season. (Table 2).

The highest number of insect pest recorded at the West and North direction (766 and 437 insect), while the highest number of parasites recorded at the west and north direction (359 and 197 insect during 2015 season (Table 1).

In 2015 sugar cane season, the parasitoid activity was higher than 2016 season, the parasitoid activated one week earlier than 2015. Number of parasitized increased steadily in the following months particular during July, August and September. The numbers scales were estimated from May to December of cane season 2015 and 2016. It was estimated in different sites of cane– fields, i.e. East, North, south west, and Center.

Results presented in Table (1) and (2) showed that this pest increased from May to December in all field sites, while scales numbers were intensively through August, September and October (322,445, and 359n respectively). The same trend was exhibited in 2016, reached to 231,309, and 331 respectively in the same months.

Hot months with high relative humidity (July, August and September) had considerable high population of P. tenuivalvata scales, consequently, the number of parasitized scales increased the relationship between the parasite activity and the population density of insect pests.

The Aphelinidae parasites particularly these of Coccophagus spp. play a great role in management of soft scale insect population. Coccophagus lymenia is an internal parasite of the immature stage of Parthenalecanium quercifex, Fex attacking willow Oak in Virginia (USA) and parasitism rate averaged 10-60 %. Concerning P. tenuivalvatascale insects, Blumberg et al. (1984). In Egypt two species Coccophagus bivittatus and Coccophagus lycinnie were recorded by Abd- Rabou et al. (1998) on Coccus hesperidus and known as internalparasites of different insect scale species. No other species rather than C. scutellaris could be detected as parasiteof P. tenuivalvata in sugar cane plantation.

Mahmoud (1981)showed that Nymphal stage tended to be concentrated in northern- west of sugar- cane field. The plants locating in this site may heavily suffer from being infested by this pest.

In the meantime, P. tenuivalvata is distributed in different sites of cane field. It was found that plants located in west site were intensively infested and recorded the highest population of scales (95.8 mean scales/leaf) followed by north site (54.4 mean scales/leaf). Other fields sites showed lower infestation plants locating in field center received the lowest scales population (21.1 mean scales/leaf). East and south received approximately similar population number (Table 1). In 2016 season, insect heavily existed sugar cane plants locating in west and north sites (676 and 371 scales/leaf. Moderately infestation was found in east and center (154 and 131 scale /leaf). The lowest population was recorded in south (105 scale/leaf) (Table 1) and 2). Sugar–cane plants infested with P. tenuivalvata showedconsiderable variation in the insect distribution, not only on plant leaves, but also in different field sites.

CONCLUSION

The herein investigation indicated that, there are many biotic factors that can affect the population density of the sugar cane soft scale P. tenuivalvata. This can assist to avoid the difficult application of the insecticide and minimize the population of the environment. natural enemies (parasites).

REFERENCES

Abdo Rabou, S.S., 1998. The species of Metaphycus Marcet (Hymenoptera Encyrtidae) recorded from Egypt. Bull. Ent. Soc. Egypt, 7, 67-76.

Ali, M.A., El-Khouly, A.S., El_Metwally, F.E., Shalaby, M.S., 1997. First recorded of the sugar-cane scale, saccharolecanium krugeri (Zehntner) in Giza, Egypt. Bull. Ent. Soc. Egypt, 75, 156-159.

Besheit, S.Y., Abaziad. A.A., Gomaa, A.M.E.S., El-Hamd, A.S., 2002. The influence of the infestation by the soft scale insect. Pulvanaria tenuivalvata (Newested) Coccidae: Homoptera on sugarcane stalk weight., juice quality and sugar yield in Upper Egypt, Assut J. Agric. Sci., 33 (4),17-28.

Blumberg, D.S., Swirski, E.A., 1984. Response of three soft scales (Homoptera: Coccidea) to parasitization by Metaphycus Smrskii. Phytoparasitica. 12 (1), 29-35.

Hindawy, A.S., Abd El-Samea, S.E., 2002. Scientific not Coccophagus scutellaris (Dalman) (Hymenoptera: Aphelinidae), a new record parasitoid attacking sugarcane soft scale Pulvanaria tenuivalvata (Newested) in Egypt. Egypt. J. Agric.Res., 80 (1), 219-222.

Maareg, M.F., Hassanein, M.A., Abu Dooh, A.M., 1992. Preliminary survey of the scale Insects attacking sugar cane in Egypt. Commun. Sci. Dev. Res., 495, 223-230.

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Citrus, and the effect of some recent insecticides on them and their parasites. M.Sc. Thesis, Fac. Agric., Cairo Univ., Egypt.

Mau, R.F, Martine Kessing, J.L., 1992. Green shield scale Pulvanaria pasidii (Maskell). crop knowledge Mast. WWW.extento.Hawaii.Edu/Kbse/Crop/Type/Croop-est.htm.

Shalaby, M.S., 2002 Ecological and biological studies on the sugar cane scale Pulvanaria tenuivalvata (Newstead) infesting sugar cane in Giza Governorate. PhD. Thesis, Fac. Agric., Al-Azhar Univ., Cairo, Egypt.

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Table 1. Monthly counts P. tenuivalvata distributed in different direction of a sugar–cane fields, in (Edfo- Aswan Governorate (2015) season.

Grouping of number insect of P. tenuivalvata in different sites of sugar cane field (West 95.6 A - North 54.6 B- East 34.6 C- East 34.6 C -South 31.9 C -Center 21.1 D)-

Table 2. Monthly counts P. tenuivalvata distributed in different direction of a sugar – cane fields, in (Edfo- Aswan Governorate (2016) season.

Grouping of number of insect P. tenuivalvata in different sites of sugar cane field (-West 84.5 A -North 46.37 B-East 19.25 C-Center 16.37 C -South 13.12 D )-

Table 3. No. of P.tenuivalvate and parasites distribution in different directions of Sugar cane fields in Awadlah village at Edfu district ,Aswan Governorate during (2015) season.

Paras. = parasite

Table 4. No. of P.tenuivalvate and parasites distribution in differcnt directions of Sugar cane fields in Awadlah village at Edfu district ,Aswan 

Governorate during (2016) season.

Parasite.= paeasites

Figure1. Relationship between the parasitoid Coccophagus scutellaris and population of P. tenuivalvata on sugar cane fields during 2015 season Awadlah, Edfo Aswan Governorate at different directions.

Figure 2. Relationship between the parasitoid Coccophagus scutellaris and population of P. tenuivalvata on sugar cane fields during 2016 season Awadlah, Edfo Aswan Governorate at different directions.