Papmahmoodr-Et Al

Historical perspective and achievements in biological management of cotton mealy bug Phenacoccus solenopsis Tinsley in Pakistan

Mahmood, R.,* M. N. Aslam,* G. S. Solangi* & Samad, A.*

*Mahmood, R. Project Manager, CABI South Asia, Rawalpindi-Pakistan *Aslam, M. N. Project Officer, CABI South Asia, Multan-Pakistan *Solangi, G.S. Project Officer, CABI South Asia, Tando Jam-Pakistan *Samad, A. Project Officer, CABI South Asia, Winder-Pakistan

Corresponding author: [email protected]

Abstract

In India subcontinent the mealy bug Phenacoccus solenopsis Tinsley, was first time reported from India in 2004 damaging cotton in Gujarat. In Pakistan it was recorded first time in 2005 on cotton and other plants from Vehari (Punjab) and Sanghar in Sindh. It has now spread almost throughout Pakistan except in the high hills. It has attacked not only cotton but also is damaging a number of vegetables and ornamental plants and is a potential threat to Pakistan cotton. It caused huge economic loss to cotton crop in 2007. In most of the cases pesticides were ineffective in controlling this insect. The pest status of mealy bug on cotton and other crops demanded an appropriate control strategy. Studies were conducted on assessing the role of natural enemies in suppressing pest populations on cotton and other plants in pesticides free environment at Tando Jam (Sindh), Multan (Punjab) and Winder (Balochistan). To maximize biological control of the mealy bug, techniques were developed for utilizing the plant refuses (mealy bug infested drying shoots and leaves) for onsite production of natural enemies of the mealy bug. The predators and parasitoids produced at the site not only naturally dispersed but also could be manually collected and released at farmers’ fields. With these interventions natural enemies populations increased and the mealy bug numbers decreased. At pesticides free farms the biological interventions led to three times decrease of the mealy bug compared with those at the insecticides treated farms. The endemic natural enemy complex recorded on the mealy bug at bio-control farm comprised of nine coccinellids, a chrysopid, a ceccidomyiid, two unidentified predatory bugs. An encyrtid Aenasius bambawalei (Hayat). that might have come with the mealy bug was also recorded in 2008. Cryptolaemus montrouzieri (Muls.) was imported from California, mass bred and released in the country. This was recovered repeatedly from Tando Jam (Sindh) and Winder (Balochistan). It was not recovered from any place in Punjab.

Keywords: Phenacoccus solenopsis, Aenasius bambawalei, natural enemies, Cryptolaemus montrouzieri, cotton

Introduction

Cotton is the world most important fibre crop. It is cultivated on more than 30 million hectares in about 80 countries. The land under cotton cultivation in Pakistan has increased overtime, however, the yield per hectare is much lower compared with other cotton growing countries being fifth in the world (AICCIP, 2007 cited by Dhawan et al, 2009). Insect pests and diseases are considered the foremost reason of the low productivity on farms. Among insects complex on cotton crop the mealy bug Phenacoccus solenopsis Tinsley is a new addition to pests complex of cotton in Pakistan. It was first detected in 2005 damaging cotton and other plants at Agriculture Research Station, Vehari (Punjab) and some places in Sanghar- Sindh. In 2006-2007 the mealy bug spread almost throughout Pakistan and was most devastating to cotton in southern Punjab. It caused huge economic loss of about 3.1 million bales in 2006-07. In 2006 about 12% of the crop and in 2007 about 40% of the crop in Punjab was damaged by the insect (Kakakhel, 2007; CAIR, 2007). The economic impact of this mealy bug has become a major problem for the country. Besides cotton it is very devastating to vegetables, fodders, and ornamental plants.

Cotton mealy bug remained a hot topic of Standing Committee of Pakistan National Assembly on Agriculture in 2007. This issue was addressed and discussed threadbare in at least five such meetings. It got top priority of the parliamentarians, government institutions and farming community in particular. All corners stressed unanimously for developing a sustainable solution for controlling the menace of the mealy bug. In view of the importance of this exotic pest, Government of Pakistan financed a project in 2007 to find a sustainable solution of the problem as the pesticides used were not only costly but also ineffective in most cases to control the pest (CAIR, 2007). Biological control of the pest was considered the best alternate option, therefore, basic studies on identification, hosts, phenology, population trends of the mealy bug and its natural enemies were made. Techniques were developed for onsite mass production of natural enemies utilizing the mealy bug infested plant refuses. The results are reported here.

Origin, distribution, hosts and spread

Phenacoccus solenopsis was described by Tinsley in 1898 (http://zipcodezoo.com/Animals/P/ accessed on 11/26/2010). Wang et al (2010) reviewed its distribution and suggest that it is native of the US. Its first record was made outside US continent from Hawaii in 1966, (Kumashiro et al. 2001); Mexico in 1978 and South America from 1985 onwards (Williams & Granara de Willink, 1992) and in Asia from 2000s (Hodgson et al., 2008). It is highly polyphagous. Ferris (1950) reported it on Kallstroemia brachystylos from New Mexico; Ambrosia from Texas and Mississippi; Atriplex from Texas; tomato, hollyhock and Helianthus sp from Colorado; cotton from Arizona; Eriophylum sp, inkweed, Encelia ferinosa, alkali bush, Franseria sp from California and an undetermined weed from Washington; Ambrosia tenuifolia from Argentina (Granara de Willink, 2003); Hibiscus rosa-sinensis from Southern Guinea Savanna of Nigeria (Akintola, & Ande, 2008); This mealy bug as a pest of Solanum muricatum is recently noted in Chile (Larraín, 2002), tomato from Brazil (Culik & Gullan, 2005); cotton in Texas (Fuchs, et al., 1991), cotton and other plants in Queensland- Australia (Miles et al., 2010; Neil Foerster, Personal Comm. 2010), cotton and other plants in China (Wu & Zhang, 2009); ornamentals and vegetable crops in Eastern region of Sri Lanka (Prishanthini & Laxmi, 2009).

In India it was first reported damaging cotton in Gujarat in 2004 (Jhala et al. 2008; NCIPM, 2008, Deshpande, 2009). Scientists of National Centre for Integrated Pest Management think that this insect is non-invasive and recorded it in the non-cotton growing areas of Gorakhpur and Lucknow (U.P.), Jabalpur (M.P.) and Bangalore, in high intensity on Parthenium weed. The enquiries revealed that this bug was there around for at least a decade or so. So if at all invasion has happened it was much before the Bt cotton was commercialized in India (Venilla et al., 2010). From India it has been reported from 84 plants (Joshi et al., 2010).

In Pakistan P. solenopsis was detected first time on cotton and other plants at Agriculture Research Station, Vehari (Punjab) in 2005 and Sanghar (Sindh). Previous surveys conducted for scale insects and mealy bugs by CABI South Asia, Rawalpindi, in 1960-66; 1973-77 and 1983-87 (CIBC 1966, CIBC 1977; CIBC 1987; Mahmood et al., 1980) did not include this species from Pakistan. Similarly Shabir (1973), Mohyudddin (1981) in their reviews reported about 150 insects associated with cotton in Pakistan but did not include any mealy bug on cotton. Arif et al. (2009) reported it from 154 plants including cotton one of its most favoured host. It is now widely distributed in Pakistan and was found in different ecological zones with tropical and subtropical type of climate except in high hills with temperate type of climate.

Feeding and damage symptoms

The mealy bug nymphs and adults attack all parts of the cotton plant including young shoots, flowers and fruits. They cause direct damage by sucking plant sap. Their feeding causes growth malformation characterised by curling and crinkling of leaves. Flowers, mature bolls and even leaves fall. Heavy infestations result in plant death. Infested flowers often drop and usually there is little or no fruit production. The insect also produces large quantities of honeydew which encourages growth of black sooty mold on the leaves and twigs resulting in reduced photosynthetic capacity.

Phenology, population trends and natural enemies

As practically no pesticides free cotton fields were available in the main cotton growing areas of the country, therefore, three plots one each of 5 acres (2 ha) pesticides free plots were maintained on the farmers fields at Multan (Punjab), Tando Jam ( Sindh) and Winder (Balochistan). On these plots besides cotton (Gossypium hirsutum) the known regular host plants such as Abutilon indicum, rose of China ( Hibscus rosasinensis), Anthorium (local name of an ornamental plant), sunflower (Helianthus annuus), tomato (Lycopersicon esculentum ) datura (Datura repens), egg plant (Solanum melongena), okra (Abelmoschus esculentus), lantana (Lantana camara), maize (Zea mays) and winter cherry (Withania somnifera), were also grown. The weeds horse purslane (Trianthema portulacastrum) and Euphorbia prostrate that supported mealy bug development were naturally growing on these plots. These centres were named as natural enemy field reservoirs (NEFR) as pesticides sprays were banned here and all those measures which could encourage the natural enemies were taken. Studies on phenology, population trends of the mealy bug and the natural enemies were conducted here. These observations were made in 2007-08.

Phenology

At Tando Jam (Sindh) and Winder (Lasbella-Balochistan) that have tropical type of climate with summer rains and mild winters, the mealy bug continued breeding almost throughout the year on some of the plants Abutilon indicum and rose of China and some of the evergreen ornamental plants such as Anthorium. All stages of the insect including eggs, nymphs and adults were found almost throughout the year. The mealy bug was found breeding profusely in summer on crops such as cotton, sunflower, okra, egg plant, tomato, weeds (datura, lantana, winter cherry, horse purslane and Euphorbia prostrate) and several ornamental plants.

At Multan (Punjab) which has subtropical type of climate with summer rains and colder winters, all stages of the insect were found from February to the middle of November. During this period the females laid eggs in advance development stage in wax fibres pouch attached to their body, however, at the advent of winter from third week of November to middle of December part of the mealy bug population was found laying naked eggs (without forming pouch attached to the body). In the winter months from middle of December to January no female was found laying eggs. During this period its second and third instar nymphs entered the soil and were found on the roots of sunflower, okra and abutilon. Besides plant roots in soil the second and third instar nymphs of the mealy bug were also found in the crumpled dry leaves of sunflower and Anthorium.

Population trends

Population trends of the mealy bug were studied on cotton. Fortnightly sampling of mealy bug was made on cotton at Tando Jam, Multan and Winder on the field measuring 60X110m divided in four quadrants. One twig each measuring 10cm long from the top of a branch of the plant with six leaves on it from top were taken from each quadrant and from the centre of the field. Thus a sample consisted of five twigs and 30 leaves. Counts were made of 2nd and, 3rd instar nymphs and females of the mealy bug.

At Tando Jam on cotton in July 07 when observations were started the mealy bug was recorded breeding and colonies were seen developing on almost all plants. Its numbers continued increasing in August and were maximum in September (Fig.1). Afterwards its numbers started decreasing through November when the crop was harvested. Next year in 2008 the crop was sown in February. The mealy bug started feeding on the cotton from March. The numbers of the mealy bug continued increasing from April and this trend continued through July when it was at its peak (Fig.1). Its numbers started decreasing from August when an encyrtid Aenasius bambawalei Hayat appeared on this plot. With increase in incidence of this parasitoid the mealy bug could not further build up its population throughout the year on cotton as well as on other plants as described below.

At Multan and Winder population trends of the mealy bug on the unsprayed cotton fields were almost the same as described on cotton at Tando Jam 3

Fig 1- Population trends of Phenacoccus solenopsis and its natural enemies on unsprayed cotton fields at Tando Jam

5500 50 Mealybug 5000 45 Predators 4500 Augmentation of parasitoid 40 4000 35 3500 30 3000 25 2500 30 leaves 20 2000 Numbers of predators 15 1500

1000 10

500 5 No. of mealy No. of bugs on five twigs each of 10cm and

0 0 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 1st 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 07 08

Months and fortnights

At Tando Jam on Abutilon indicum sampling of mealy bug was done every fortnight as on cotton. The numbers of the mealy bug were quite high in July 07 on this plant when observations were started numbers further increased in August when they were maximum (Fig. 2). Afterwards the population continued decreasing through September and this trend continued till December. In January next year population of the mealy bug was very low and it started increasing in February (Fig.2). Its numbers continued increasing through July when it was at its peak. In August as described above because of increase in parasitism the mealy bug population decreased drastically and could not further develop its population throughout the year (Fig.2).

Rose of China, an evergreen ornamental plant, grown in parks and houses is another regular host of the mealy bug. The population trends of the mealy bug on this plant were almost the same as on A. indicum but the numbers were comparatively lesser than those observed on A. indicum.

Fig 2- Population trends of Phenacoccus solenopsis and its natural enemies on Abutilon indicum on unsprayed fields at Tando Jam

6500 140

6000 Mealybug Predators 5500 120 Augmentation of parasitoid 5000 100 4500

4000 80 3500

3000 60 30 leaves 2500

2000 40 1500 Numbers of predators

1000 20

No. of mealy No. of bugs on five twigs each of 10cm and 500

Natural enemies

Predators

Surveys in 2005-06

Little information of indigenous natural enemies associated with this mealy bug was available at national level. CCRI Multan and AARI Faisalabad reported only Coccinella septempunctata (L), and Chrysoperla carnea (Stephens) feeding occasionally on the mealy bug. They did not record any parasitoid from the mealy bug.

Surveys in 2007-08

Search for natural enemies of the pest was made mainly on vegetation grown on pesticides free plots, as mentioned above, at Multan (Punjab), Tando Jam ( Sindh) and Winder (Balochistan).

Thirteen species of predators were recorded associated with the mealy bug. These included Coccinellids {Brumus suturalis (Fabricius), Scymnus coccivora (Ayyar), Scymnus sp, Nephus sp, Cheilomenes sexmaculatus (Fabricius), Coccinella septempunctata (L), Hyperaspis sp, Adonia sp and Exochomus sp}; Chrysopid {Chrysoperla carnea (Stephens)}, Ceccidomyid {Diadiplosis sp)} and Hemipterans {unidentified spp (2)} Of these predators B. suturalis was found consistently on all population levels of the mealy bug on all plants examined while others were mostly found on high mealy bug populations.

Phenologies of predators

Of the coccinellids recorded feeding on mealy bug on the pesticides free plots at Multan Brumus suturalis was most dominant and was recorded on all plants throughout the year (Table 1). Scymnus coccivora was another important predator recorded on the mealy between March- November, Cheilomenes sexmaculatus and Coccinella septempunctata were recorded when aphids were common, Hyperaspis sp, Adonia sp and Exochomus sp were common during peak period of activity of the mealy bug between May and October. The chrysopid Chrysoperla carnea was also common however it was rare from June to August. The Ceccidomyiid Diadiplosis sp fed only on eggs and newly hatched nymphs of the mealy bug was recorded in summer months from May to September.

Table 1- Phenology of predators recorded on mealy bug on Pesticides free farm at Multan

# Predator Months J F M A M J J K A S O N D Coccinellidae 1 Brumus suturalis 2 Scymnus coccivora 3 Scymnus sp 4 Nephus sp 5 Cheilomenes sexmaculatus 6 Coccinella septempunctata 7 Hyperaspis sp 8 Adonia sp 9 Exochomus sp Chrysopidae 10 Chrysoperla carnea Ceccidomyidae 11 Diadiplosis sp Hemiptera 12-13 Unidentified (2)

Population trends of predators on different plants

At Tando Jam on Abutilon indicum mostly coccinellids and a chrysopid as described above were common. In 2007 they were most abundant in October two months after the population peak of the mealy bug (Fig. 2). From November their population started decreasing along with the host through December. In January 2008 the predators numbers declined because of slowed down breeding rate of the host in winter thereafter predators were found building up their population until July and drastically decreased with the decrease in host density throughout the year as Aenasius bambawalei incidence increased from August onwards (Fig. 2).

On cotton at Tando Jam the population trends of the predators in 2007 were almost the same as described for Abutilon indicum. Their population was at peak in October (Fig.1) and afterward they decreased along with the decrease of host density through November when the crop was harvested (Fig. 1). In 2008 the predators were found at peak in July when the numbers of the mealy bug were high but afterwards they decreased for the similar reasons as described above.

At Multan and Winder the population trends of the predators on cotton were almost the same as described for cotton at Tando Jam.

Parasitoids

In three year survey in 2005-07 in the country no parasitoid was detected on this mealy bug, the parasitized mealy bugs (mummies) were first time detected in the beginning of August 08. This was sent to Natural History Museum UK for identification and they described it as Aenasius sp nov. nr longiscapus Compere. It is closest to a neotropical species and therefore it is possible that it has been accidentally introduced into India from the Caribbean or somewhere in South or central America. (Mr Lee Rogers, NHM, UK, Pers. Comm. 23 September, 2008). This new species was described as Aenasius bambawalei (Hymenoptera: Encyrtidae) by an Indian Zoologist Mohammad Hayat of Aligarh Muslim University (Hayat, 2009). It is a very aggressive parasitoid and did not let the mealy bug develop its population where it established.

Redistribution of Aenasius bambawalei

In August 2008 this parasitoid was not found from any place surveyed throughout in Punjab, Balochistan, Khybepakhtoonkha and upper Sindh therefore it was mass produced in the CABI SA laboratories at Multan and Tando Jam and released there. It was recovered from all places it was released.

Conservation biological control

In three year surveys in 2005-07 no parasitoid was recorded from this mealy bug, however, generalists were found feeding on the mealy bug . At this stage decisions could not be made for classical biological control of this exotic pest as no information was available on its exact identification and also the status of endemic natural enemies was no clear therefore, firstly the basic information on its seasonal abundance, hosts and population trends the natural enemies was collected and studies were designed to test the efficacy of the generalists in the manipulated environment that could help them in their breeding and population build up.

On about two hectare cotton area as mentioned above, besides keeping it pesticides free and growing of alternate host plants on the borders of the cotton area as shown in the table 2, some additional steps were also taken that could help the natural enemies in their survival. In centre of the cotton plot a roof shade of 7x14m on 3m high pillars (see picture 1) was constructed.

Table 2. Lay out of the plants grown on 2 ha area at Multan

Tomato Maize Winter cherry Lantana camara Egg plant Maize Maize Cotton Cotton Cotton 60x110 m 60x110m 60x110m

Sun Shed 7x14x3 m flower Okra

Anthorium Rose of China Rose of China Abutilon indicum Datura

The floor of this area was made of concrete (30 cm above the ground level) and around the border of this floor a channel was provided in which water was kept standing and replaced at intervals. The mealy bug infested drying plant shoots were removed from fields, kept in the rearing tin trays (measuring 60x60x120cm). They were half filled with this refuse. The naturally occurring parasitoids and predators had easy access to these and also disperse from here to the adjoining areas.

It was presumed out of experience that the mealy bug crawlers would start coming out from the tray, therefore, to trap them two grease bands each of 6 cm width were put around the tray. One was put on at 15 cm below the top margin of the tray and the other at 15 cm below the top grease band. The 15 cm high foot rest at the corners of tray was kept dipped in water in bowl as shown in the pictures 1 &2.

Initial observations on the mealy bug and predators’ behaviour in the trays

In July 2007 when observations were started, the mealy bug crawlers were seen coming out of the trays consistently up to 10 days. These got trapped in the grease bands or were being eaten by predators’ adults and larvae inside the walls of the trays and on the top margin of the trays. The predators’ adults and larvae were seen common inside the trays feeding on all stages of the mealy bug. The twigs and leaves dried over a week interval and mealy bugs could not survive. Maximum of them died or were eaten up by the predators. The Coccinellid predators adults were seen coming out of the trays and dispersing to the outside area on the crops grown.

Numbers of predators reared per tray from plant refuse in different intervals

AT Multan six trays of the same size as described above were half filled with almost same quantity of mealy bug on infested plants twigs and leaves as shown in picture 1 at the same time in the beginning of October 07 under the shade. Of these six trays one was examined at 10th day, second on 15th, third on 20th, fourth on 25th, fifth on 30th day and sixth on 35th day for the predators reared and to know the state of the mealy bug. The predators found in trays were so many that they could only be collected with the help of motor operated aspirators (see pictures 2 &3).

From a tray examined on 10th day highest numbers (5577) of the predators (mostly of B. suturalis and S. coccivora, Cheilomenes sexmaculatus and Chrysoperla carnea) were collected (Fig. 3). On 15th day from the second tray the numbers of predators collected were comparatively lesser than those from the tray examined on 10th day. This decrease in numbers in the tray examined on 15th day was primarily due to dispersal of adults to the surroundings because they did not find much of host left in the tray. For similar reasons the decreasing trend of the predators collected from the trays examined on 20th, 25th and 30th day was seen. Only one B. suturalis adult was found in the tray examined on 35th day indicating that all predators had left the tray. Thus over a fortnight interval by applying this technique predators could be reared in thousands from mealy bug infested plants refuses. Improvements are being made to enhance the production of predators and parasitoids.

Impact of conservation of predators and rouging on mealy bug population

These studies were made in 2007 on about 2ha plot at Multan where cotton and other plants were grown as described above. From the marked area of 60x110m plot rouging of the mealy bug infested twigs and leaves was done. In rest of the plot no rouging of infested plants was done and the mealy bug was allowed to develop naturally. The infested plants which were removed from the plot were kept in the trays under shed as described above. Thus besides keeping the plot unsprayed onsite breeding of the predators was also being helped. Fortnightly sampling of the mealy bug and the predators was done from these plots and compared with the pesticides treated plots at about 5 km away.

The mealy bug population was comparatively higher in the plot where no rouging was done while it remained very low on the plot where rouging was done throughout from August to November (Fig. 4). On this unsprayed cotton field the predators became abundant (see figure 5) and kept the mealy bug population about two times lesser on the plot where no rouging was done compared with those at the pesticides sprayed farmer field (Fig. 4). The population of the mealy bug on the plot where rouging was 8 being done was about eight times lesser than at the pesticides treated farmer’s field (Fig. 4). These observations indicated that with the conservation of predators mealy bug can be largely kept under control in tolerable limits and rouging of infested plants was further useful.

Fig. 3- Numbers of predators collected from 6 trays examined at different intervals

Fig. 4- Population trends of mealy bug on cotton in sprayed and unsprayed fields at Multan in 2007

Fig. 5. Population trends of predators on cotton in sprayed unsprayed fields at Multan in 2007

Yield per hectare and profit gained for cotton grown on sprayed and unsprayed farm

In the year 2010 at Tando Jam the seed cotton yield per ha, (obtained from three pickings on the project managed unsprayed farm from the variety NIAB -78 sown in February and harvested in November) was 740 kg compared with 820 kg of pesticides sprayed farmer farm of the same cotton variety. The marginal benefit of increase of 80 kg fetched about Rs 6250 additional compared with unsprayed farm. This benefit was at par with the additional amount spent on labour and costs of insecticides. Thus the gains obtained from cotton production in monetary terms on unsprayed farm were as good as on sprayed farm whereas benefits of renewable natural resources were additional.

Classical Biological Control

Cryptolaemus montrouzieri (Muls.) was introduced by CABI SA from California in December 07. Since that time it is being mass produced and released at farmers’ fields by Agriculture Research Institute, Tando Jam; Ayub Agriculture Research Institute, Nuclear Institute of Agriculture and Biology, Faisalabad; Central Cotton Research Institute, Multan and Agriculture Research Institute Dera Ismail Khan and CABI SA, Multan and Tando Jam. The recovery surveys are being carried out at the release sites. There seem positive trends towards its establishment in Pakistan. Though in small numbers, this was recovered repeatedly at NEFRs at Tando Jam and at winder. It has not been recovered from any place in Punjab.

Present status of the mealy bug

In pesticides free environment the parasitoid Aenasius bambawalei kept the mealy bug under control, whereas on the pesticides treated farms mealy bug built up high population because of disruption in natural control. Surveys were conducted for the mealy bug in 2009 and 2010 on the farmers’ fields in September in cotton in Punjab, Sindh and Balochistan and compared with the NEFRs. No hot spots of the mealy bug developed on unsprayed fields at the NEFRs at Multan, Tando Jam and Winder, whereas at the pesticides treated farms hot spots were seen in the range of 16.6 – 40% (Table 3). Directorate Pest Warning and Pesticides Quality Control Government of Punjab reported sharp decline in percentage of hot spots of mealy bug at peak period of its population that was 43.6% in 2007 came down to 16.47 % in 10

2009 and 10.88% in 2010 (Table 4) . In some cases, however, as at Shujabad highest 67.5% hot spots were recorded in 2010.

Besides impact of profuse use of pesticides in crops on the parasitoid Aenasius bambawalei a hyper Promuscidea unfasciativentris Girault has started attacking it. Thus overtime the parasitoid population may decline and the natural control get weaken.

Table 3- Percentage hot spots*of mealy bug in cotton in September based on 30 spots examined at every 5 km on about 5 acres at Multan, Tando Jam and Winder

Place Project managed Pesticides treated farmers farm pesticides free farms (NEFRs) Year 2009 Year 2010 Year 2009 Year 2010 Multan (Punjab) 0 0 16.6 26.6

Tando Jam (Sindh) 0 0 20 16.6 Winder (Balochistan) 0 0 30 40 * visible spots of drying cotton plants

Table 4- Hot spots of mealy bug in cotton in 1st week of October in Punjab

Year Hot spots of the mealy bug (%) 2007 40.15 2008 43.6 2009 16.47 2010 10.88 (source Directorate Pest Warning & Quality Control of Pesticides, Punjab, Lahore)

Services given to farmers

In 2007- 2008 at the three centres {natural enemies field reservoirs (NEFRs)} one each in Punjab, Sindh and Balochistan the main activity had been the mass production of mealy bug predators whereas in 2009 and 2010 with the discovery of the parasitoid its production took over the predators. Besides the predators and the parasitoid that naturally dispersed from these sites they were manually collected and handed over to farmers for release at their farms (see tables 5 & 6). Over 7 million of predators were produced in 2007-2010 at these centres (Table 5) and over 10 million of the parasitoid were produced in 2008-2010 (Table 6).

For distribution of the parasitoid the parasitized mealy bugs (mummies) pasted on cards (see pictures 4 & 5) or adults held in tubes/small jars were handed over to the farmers for release at their farms. Thus with the above mentioned practice not only that the mealy bug was removed mechanically from the field but also this refuse was used for production of useful insects and their conservation. It was supplied to the national institutes throughout Pakistan for mass production and release in their respective areas.

Improvements are being made on mass production of parasitoids and the predators in laboratory as well. Different hosts for mealy bug rearing were tried. These included lokki (local name of a cucurbit), pumpkin (Cucurbita maxima), lady finger, potato tubers and their shoots (Solanum tuberosum). Pumpkin had good life and survived for about 7 months, potato tubers lasted 3-4 months, lokki for 15-20 days and okra for 5- 7 days in the laboratory. Highest rate of increase of numbers of mealy bug was observed on lokki, followed by potato tubers and pumpkin. Lady finger was a good host for mealy bug development, however, the fruit did not last longer as compared with other laboratory hosts tested.

Table 5- Numbers of predators reared from trays at different NEFRs

NEFR Years 2007-2008 2008-09 2009-10 (millions) (millions) (millions) Multan 1.213 1.656 0.311 Tando Jam 0. 514 1.712 0.332 Winder 0.236 1.513 0.245 Total 1.963 4.881 0.888

Table 6- Numbers of Aenasius bambawalei reared at different NEFRs

NEFR Years 2008-2009 2009-10 (millions) (millions) Multan 0.769 3.854 Tando Jam 1.888 1.944 Winder 0.505 1.5 Total 3.162 7.298

Discussion and conclusions

Keeping pesticides free environment, though in present studies restricted to a small area of 2ha, largely helped in understanding the population behaviour of natural enemies and their role in controlling mealy bug population. On pesticides free plots, with intervention of techniques for conservation and mass production of natural enemies from the plant refuses enabled in high built up of their populations and impacting on pests population. With conservation of generalists not only that better control of the mealy bug was obtained they were also useful in controlling other sucking pests on cotton. Net gains of cotton production were even better than those at pesticides treated farms. This exercise laid down the greatest foundation for the future to promote conservation biological control and reduce burden on pesticides use in crops specially in cotton which at present is the main recipient of pesticides used in the country.

The recommendations made by the department of agriculture of burning or burying the mealy bug infested plants shoots and twigs need to be revised. As a matter of fact when the twigs were burnt the crawlers and other mealy bug instars were seen moving away from the site and if the cut plants were buried the mealy bug crawlers (1st instar nymphs) were seen emerging from soil. Practicing this recommendation given by the agriculture department was actually detrimental to predators’ larvae and the parasitoid developing inside host body that died out of burning of the twigs. If the infested plants were buried in soil the parasitized mealy bugs also got crushed.

Acknowledgements

Financial assistance from Ministry of Food and Agriculture Federal Government of Pakistan for conducting studies on biology and ecology of the mealy bug and its natural enemies is gratefully acknowledged. We thank Mr. Hidayatullah Chhajro, Director General, Agriculture Research Sindh, for providing land area at Agriculture Research Institute Tando Jam to grow cotton and other plants in pesticides free environment for studies on population behaviour of the mealy bug and its natural enemies. We specially thank Dr. M. Ashraf Poswal, Regional Director, CABI South Asia, Rawalpindi; Mr. Anayatullah Khan, Agriculture Development Commissioner, Ministry of Food and Agriculture, Government of Pakistan; Dr Qadir Bux Baloch Agriculture Development Commissioner, (R) Ministry of Food and 12

Agriculture, and Dr. Masood Amjad Rana, Commissioner Cotton (R), Ministry of Food and Agriculture Government of Pakistan and Dr Ibad Badar Siddiqi, National Project Director, “Biological control of major cotton pests including mealy bug in Pakistan” for their consistent encouragement and support during the studies. Lastly thanks to Dr. Abdul Sattar Buriro, Director, Agriculture Research Institute Tando Jam and Mr. Muhammad Usman Shar, Entomologist ARI Tando Jam for providing facilities for conducting research at their laboratory.

References

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Natural enemies in-field mass production in pictures

Picture 1. View of roof cover and predators and Picture 2. Predators being collected from the tray parasitoids rearing trays with the help of motor operated aspirator

Picture 4- Piles of mummies and Brumus Picture 3 Predators being released in cotton suturalis adults lying at bottom of rearing tray at NEFR Multan

Picture 6- Cotton leaf carrying parasitized mealy bug at NEFR Tando Jam Picture 5- - Mummified mealy bugs pasted on cards for delivery to farmers