Greener Journal of Agricultural Sciences Vol. 10(3), pp. 145-151, 2020 ISSN: 2276-7770 Copyright ©2020, the copyright of this article is retained by the author(s) https://gjournals.org/GJAS

Survey of Host Plants of Cotton Mealybug Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae) on Cotton Crops in Middle Awash, Ethiopia

Sharew Abate¹ and Bayeh Mulate²

¹Ethiopian Institute of Agricultural Research, P.O.B 2003 Addis Ababa.

²FAOET, Addis Ababa, Ethiopia.

ARTICLE INFO	ABSTRACT
Article No.: 111219202 Type: Research	The exotic cotton mealybug Phenacoccus solenopsis Tinsley invaded Ethiopia during 2010, and caused widespread infestation across all six cotton growing regions. This New World species has emerged as a serious pest of cotton and other crops and weeds. Forty two host plants of P. solenopsis were identified during the cotton growing season. The host plants of P. solenopsis revealed 42, 31, and 30 species of plants belonging to 21, 16 and 16 families served as hosts for P. solenopsis at Werer, Melka Sedi, and Gewane and across all cotton growing areas of Middle Awash, respectively. The trend of P. solenopsis severity among host plants across growing areas was clearly different although G4 plants were the highest at all growing areas. This information can be helpful in management of this pest.
Accepted: 20/11/2019 Published: 11/09/2020
*Corresponding Author Sharew Abate E-mail: sharewabate92@ gmail.com
Keywords: Cotton mealybug; Phenacoccus solenopsis; host plants; Severity; Ethiopia

INTRODUCTION

Cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is a soft-bodied insect that sucks sap from the host plant phloem tissues, removing biomass and water (Aijun et al., 2004). The attacked cotton plants remain stunted and produce fewer bolls of a smaller size; leaves become distorted, yellow and eventually drop off (Mark & Gullan, 2005). After feeding, the insect ejects honeydew resulting in sooty mold growth that fouls plant surfaces, blocks stomata, so impeding respiration and photosynthesis, and hence reduce yield (Saeed et al., 2007). About 5000 species of mealy bug have been recorded from 246 families of plants throughout the world. Among these, 56 species have been reported from 15 genera of family Malvaceae, including cotton and many other plants of economic importance (Ben-Dov, 1994). In Ethiopia, Cotton mealybug appeared in Melka Sadi locality in July 2010. In this year the infestation was at isolated spots and the damage the pest inflicted was insignificant. In 2011, however, the pest heavily infested wide areas of cotton fields in different localities of Awash Valley.

At present, P. solenopsis is the only major mealy bug species found infesting cotton in all the cotton growing areas of Ethiopia. Through an extensive survey that covered the whole cotton growing places in the country, the cotton mealy bug was found to be very well established from Tibila (Oromia) to Afambo (Afar) in the Awash River Basin. It was also introduced into rain fed cotton growing areas in the Amhara, Gambella, SNNPS, and Tigray regions and irrigated cotton in SNNPS (Bayeh and Meisso, 2013) and escalation of severe damage caused by this pest to one of the most important cash crops in Ethiopia, called for immediate action. As the pest was invading fast in newer areas, furthermore, there was an urgent need to collect information on its distribution, infestation and natural enemies in different cotton growing areas that would help in formulating the management strategy for this species. Therefore, this survey was conducted for identification; to determine plant category and severity level of cotton mealy bug on the different host plants from cotton-growing areas of Werer, Melka Sedi and Gewane in Middle Awash, Ethiopia.

MATERIALS AND METHODS

These studies were carried out from year 2013 to 2014 through fortnightly surveys in three representative cotton growing areas of Middle Awash viz., Werer, Melka Sedi and Gewane. The cotton cultivation at Middle Awash was completely under irrigation. All production areas had largely 100 percent cultivated Delta Pine 90 variety. Weed hosts in the cotton ecosystem harboring P. solenopsis were located. At each specific locality, three cotton fields located at the entrance to the farm, in the middle ground and at the end were selected in a diagonal way and one hectares of each field were sampled. For each hectare, about 10 sample plants were randomly selected for cotton mealybug assessment by diagonal cotton fields. Then, severity of infestation by cotton mealybug was scored. Severity of infestation was measured using zero to four scale viz. (Anon., 2008), Grade 0(G0) – no mealybug; Grade 1(G1) – scattered appearance of few mealy bugs on the plant; Grade 2(G2) – severe incidence of mealybug on any one branch of the plant; Grade 3(G3) – severe incidence of mealybug on more than one branch or half portion of the plant and Grade 4(G4)– severe incidence of mealy bug on the whole plant. The weed plants were also collected and preserved as herbarium to confirm their botanical identity from Addis Ababa University, College of Biology. The host-plant species studied were identified, listed; the infested parts of each host plants. The number of plants found hosting P. solenopsis among cotton growing areas, their distribution across plant families and severity of weeds and locations were recorded.

RESULTS AND DISCUSSION

Host Plants

The results of this study have been summarized in one table (Table 1 below). Table 1 shows the list of host plants species in alphabetical order of families, plant species in order of plant category and grading of severity level on host plants throughout the season conducted during the observation of the CMB in the field from 2013 to 2014.

In the present study, a total of 42 host-plants in 21 families are reported. P. solenopsis has been recorded on members of 31 major plant genera in 13 families (Ben-Dov et al., 2008), these results are in accordance with the present study. The diversity of host plants observed during the surveys reflected the preferences of the CMB in natural conditions. Amaranthus dubius Mart. ex Thell., Amaranthus viridis L., Parthenium hysterophorus L., Xanthium strumarium L., Spathodea campanulata P. Beauv., Acalypha indica L., Abelmoschus esculentus L., Abutilon indicum L. Sweet, Gossipium barbadense L., Gossipium hirsutum L., Sida alba L., Sesamum indicum L., Datura stramonium L., Solanum incanum L. and Corchorus trilocularis L. were preferred host plants.

Table 1. List of host plant species in alphabetical order of families, Plant Category and Severity.

S. No	English Name	Scientific Name	Plant category	Severity Werer
					Werer	M. sedi	Gewane
1	Acanthaceae	Velvet bushwilow	Justicia nyassana Lindau	Weed	***
2	Acanthaceae	Ruellia	Ruellia patula Jacq.	Weed	**	**	**
3	Aizoaceae	Desert horsepurslane	Trianthema portulacastrum L.	Weed	***	***	***
4	Aizoaceae	Red Spinach	Trianthema triquetra Willd.	Weed	**	**	**
5	Aizoaceae		Zaleya Pentandra (L.) Jeffery	Weed	***	***	***
6	Amaranthaceae	Devils horse whip	Achyranthes aspera L.	Weed	***	**	**
7	Amaranthaceae	Pig weed	Amaranthus dubius Mart. ex Thell.	Weed	****	****	****
8	Amaranthaceae	Pig weed	Amaranthus viridis L.	Weed	****	****	****
9	Apocynaceae	Rubber vine	Cryptostegia grandiflora R. Br.	Weed	**	**	**
10	Asclepiadaceae	Gun powder bush	Calotropis procera (Ait.) Ait. F.	Weed	*	*	*

11	Asteraceae	Wild lattuce	Launaea cornuta (Oliv. & Hiern. ) C. Jeffrey	Weed	**	**	**
12	Asteraceae	Parthenium	Parthenium hysterophorus L.	Weed	****	****	****
13	Asteraceae	Vernonia	Vernonia galamensis (cass.) Less.	Medicinal	**
14	Asteraceae	Cocklebur	Xanthium strumarium L.	Weed	****	****	****
15	Bignoniaceae	Fountain Tree	Spathodea campanulata P. Beauv.	Tree	****
16	Capparidaceae	Spider flower	Gynandropsis gynandra	Weed	**	**	**
17	Convolvulaceae	Sweet Potato	Ipomoea batatas (L.) Lam.	Vegetable	***
18	Cucurbitaceae	Wild Pumpkin	Cucumis dipsaceus Ehrnb. ex spach.	Weed	**	**	**
19	Cucurbitaceae	Pumpkin	Cucurbita pepo L.	Vegetable	**
20	Euphorbiaceae	Indian acalypha	Acalypha indica L.	Weed	****	****	****
21	Euphorbiaceae	Asthma Plant	Euphorbia hirta L.	Weed	***	***	***
22	Fabaceae	Alysicarpus	Alysicarpus quartinianus A. Rich.	Weed	**	**	**
23	Fabaceae	Indigo	Indigofera coerulea Roxb.	Weed	**	**	***
24	Fabaceae	Lead tree	Leucaena leucocephala L.	Tree	**
25	Fabaceae	Madras thorn	Pithecellobium dulce (Roxb.) Benth.	Tree	*	*
26	Fabaceae	Mequite	Prosopis juliflora (sw.) DC.	Tree	**	**	**
27	Fabaceae	Least snout-bean	Rhynchosia minima (L.) DC.	Weed	**	**	**
28	Malvaceae	Okra	Abelmoschus esculentus L.	Vegetable	****
29	Malvaceae	Indian mallow	Abutilon indicumL. Sweet.	Weed	****	****	****
30	Malvaceae	Egyptian cotton	Gossipium barbadense L.	Crop	****
31	Malvaceae	American Cotton	Gossipium hirsutum L.	Crop	****	****	****
32	Malvaceae	Paddy’s lucerne	Sida alba L.	Weed	****
33	Nyctaginaceae	Tar-vine	Boerhaavia ercta L.	Weed	***

Table 1. Contd….

S. No	Family	English Name	Scientific Name	Plant category	Severity
					Werer	M. sedi	Gewane
34	Palmeae	Date palm	Phoenix dactylifera L.	Fruit Crop	*
35	Pedaliaceae	Sesame	Sesamum indicum L.	Crop	****
36	Portulacaceae	Purslane	Portulaca oleracea L.	Weed	***
37	Rutaceae	Lemon	Citrus limon L.	Fruit Tree	**
38	Solanaceae	Thorn apple	Datura stramonium L.	Weed	****	****	****
39	Solanaceae	Tomato	Lycopersicum esculentum (L.) Mill.	Vegetable	***
40	Solanaceae	Sodom apple	Solanum incanum L.	Weed	****	****	****
41	Tiliaceae	Humera Weed	Corchorus trilocularis L.	Weed	****	****	****
42	Zygophyllaceae	Puncture Vine	Tribulus terrestris L.	Weed	**	**	**

Severity: *=G1 **=G2 ***=G3 ****=G4

Host plant categories

Largest number of hosts of P. solenopsis was from weeds (28) followed by trees (4), vegetables (4), field crops (3), Fruit plants (2) and medicinal plant (1) also served as hosts of P. solenopsis in Middle Awash which results similar with in coastal region of West Benga by (Patel et al.,2011). The order of hosts of P. solenopsis across plant categories at Werer, Melka Sedi and Gewane cotton growing areas were similar, with weeds occupying the top position. Fruit plants and medicinal plant in their decreasing order represented the lower end of host spectrum (Table 1 above). The spread of host range largely across weeds, trees and vegetables over field crops indicate the priority of monitoring and management of P. solenopsis on these categories of plants in the cotton production system across growing areas.

Host records

Forty two, 31, and 30 species of plants belonging to 21, 16 and 16 families served as hosts for P. solenopsis at Werer, Melka Sedi, and Gewane and across all cotton growing areas of Middle Awash, respectively (Table 1 above). Vennila et al. (2011) reported that 71, 141, 124 and 194 species of plants belonging to 27, 45, 43 and 50 families served as hosts for P. solenopsis at North, Central, and South and across all cotton growing zones of India, respectively. Weed hosts constituted 66.67, 64.26 and 64.26 per cent in respect of Werer, Melka Sedi, and Gewane. Out of the total 42 hosts of P. solenopsis documented across the Middle Awash, 66.67 % were weeds (Fig. 1).

Fig.1. Families of host plants of P. solenopsis

Diversity of weed hosts

A total of 42 plant species from 21 different plant families served as hosts of P. solenopsis in Middle Awash which results were 13 plant species lower than those recorded in Pakistan by (Abbas et al., 2010). The diversity of hosts for P. solenopsis was greater at Werer (100%) followed by Melka Sedi (73.81%) and Gewane (71.43%) cotton growing areas. While common hosts were minimal between Werer + Melka Sedi (31) and Werer + Gewane (30) cotton growing areas, the highest commonality was observed between Werer + Melka Sedi (31) cotton growing areas. One monocot host plant Phoenix dactylifera L. was the only common hosts between Werer + Gewane and one medicinal plant in Werer research field (Table 2 above).

Highest number of weed hosts of P. solenopsis belonged to Fabaceae (6) > Malvaceae (5) > Asteraceae (4) > Aizoaceae= Amaranthaceae= Solanaceae (3) > Acanthaceae= Cucurbitaceae= Euphorbiaceae (2). Twelve families had single weed species as host plants for P. solenopsis (Fig.2).

Fig. 2. Distribution of host plants of P. solenopsis

Severity of P. solenopsis on host plants

The trend of P. solenopsis severity among host plants across growing areas was clearly different although G4 plants were the highest at all growing areas. More number of Grade 4 hosts at all three growing areas indicated their possible role in carryover than perpetuation of P. solenopsis. The host plants with extreme severity (G4) in order of importance were: Werer >Melka Sedi >Gewane and a total of 15 (35.71%) hosts had G4 severity among the total host plants documented for the country (Table 2). Twenty eight, 19, 14 and 23 host plants represented 34, 27, 12 and 27% of P. solenopsis severity with Grade 1, Grade 2, Grade 3 and Grade 4, respectively. These results are similar with the study of Vennila et al.( 2010).

Table 2. Severity of P. solenopsis among hosts plants

S. No.	severity	Cotton growing area			Middle Awash
		Werer	Melka Sedi	Gewane
1	Grade 1 (G1)	3	2	2	3
2	Grade 2 (G2)	15	11	12	15
3	Grade 3 (G3)	9	4	5	9
4	Grade 4 (G4)	15	14	11	15
Total		42	31	30	42

CONCLUSIONS

It may be concluded that effective weed control, biological control, chemical control, field sanitation, following proper crop rotation and quarantine measures will be of high significance while adopting management strategy of this cotton mealybug.

It should be emphasized that this work was done at three locations (Werer, Melka Sedi and Gewane) at Middle Awash in a single year and a limited number of host plants of cotton mealybug Phenacoccus solenops in some of these results may differ under more intensive study from year-to –year and location-to- location of all cotton growing areas, to advance the recommendation and useful information for developing effective and efficient pest management technologies for cotton mealybug Phenacoccus solenopsis (Tinsley).

ACKNOWLEDGMENTS

I wish to thank and express my heartfelt gratitude to Ethiopian Institute of Agricultural Research (EIAR) and Werer Agricultural Research Center (WARC) for the financial support and facilitation of vehicle for this research work and Adiss Ababa University, College of Biology for identified herbarium.

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Cite this Article: Sharew, A; Bayeh, M (2020). Survey of Host Plants of Cotton Mealybug Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae) on Cotton Crops in Middle Awash, Ethiopia. Greener Journal of Agricultural Sciences 10(3): 145-151.