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STATUS OF TROPHIC GUILD OF INVERTEBRATES UTILIZING WEEDS OF WHEAT AND SUGARCANE FIELDS OF FAISALABAD.

Byline: Muhammad Nadeem Abbas, Shahnaz Akhtar Rana, Hammad Ahmad Khan and Khalil-ur-Rehman

Qualitative synergy level of prey/pest-predator invertebrate populations occurring on weeds of sugarcane and wheat crops was evaluated on the basis of their relative occurrence on the weeds. Seventeen weed species common in and around wheat field harboured 50 species of predators including insects and spiders in addition to 20 known pest species of different crops. These weeds also harboured 14 recycler species. The ratio of pest/prey-predator in the wheat fields was high. Whereas eight weeds common in sugarcane fields harboured 13 species of predator insects and spiders. These weeds were observed to bear 17 known pest species of some major crops in addition to 28 recycler species playing key role (scavenging, fragmenting and decomposing) in some sort of ambient environment of cane fields.

Keywords: Biodiversity, predator, prey, pest, Non crop fauna

INTRODUCTION

Weeds and arthropods interact more frequently in the agroecosystem. It is expected that approximately 26% of the arthropods species are directly associated with approximately 310,000 plants species (Strong et al., 1984). It is estimated that interactions between weeds and arthropods are probably much more frequent than are often recognized. More than 70 families of arthropods recognized as potential crop pests are primarily associated with weeds (Altieri, 1994). Many pest species of arthropods are polyphagous and can feed on plants belonging to various genera and families. Polyphagous pest arthropods species that feed on crops and weeds have potential for direct interaction with weed management. Beneficial arthropods are secondary consumers, utilize pest/prey species which are not only feeding on weeds but also on crop plants. The pest/prey living on weeds may be a crop pest or it may be of no influence on crop production. Secondary or tertiary level consumer feed on primary consumers.

However, some species are omnivorous too. Many secondary consumer arthropods feed directly on plants at some particular stage, usually adult, in their life cycle. Such organisms thus have the potential to interact with weeds both at the primary and the secondary trophic levels. This leads to a complex of multitrophic interactions and this interaction effect soil biodiversity as well (Van Emden and Wratten, 1991; Rana, et al., 2010).

A serious problem may occur when weeds, supporting a pest/prey arthropod within an agroecosystem, are controlled. Following destruction of weeds, the pest/prey arthropods that had been living on the weeds migrate to and attack the crop. One of the earlier reported examples is that of the lesser corn stalk borer in California Zea mays (Reynolds et al., 1959). The insect can utilize many grass weeds as alternative hosts. These authors stated that eliminating out infested weed hosts just before or after planting a susceptible crop can be disastrous, as it forces virtually the entire resident population to feed upon the seedling (crop) plants. This may result in economic loss instead of benefit from weed eradication. This phenomenon has been reported for several different weed- insect-crop associations (John and Capinera, 2005; Shelton and Badenes-perez, 2006; Ruby, et al., 2010), but is often not recognized as part of an integrated crop management program.

Thus the knowledge of cropland weeds as harbourages of invertebrates especially arthropod fauna is imperative to manipulate the pests and potential pest populations in various crop systems. Present study provides a data about the prey/pest-predator population status of various invertebrates utilizing weeds associated with sugarcane and wheat crops in the suburbs of Faisalabad city.

MATERIALS AND METHODS

The present study was conducted in the months of September 2008 through February 2009 and in the months of December 2009 to May 2010 i.e. round the sugarcane and wheat cropping seasons. As many as 24 samples were taken at random from crop fields at different localities like Gatti, Ayub Agricultural Research Institute, Sidhar By-pass, Samundri Road, Sargdha Road and Sheikhupura Road around Faisalabad city. At each locality two acres of crop fields each of sugarcane and wheat were randomly selected from an estimated area of 10 acre block to collect invertebrate fauna associated with the weeds.

A total of twenty five frequently occurring weeds were sampled out of which seventeen Viz., Convolvulus arvensis, Polygonum plebejum, Cenchrus setigerus, Phalaris minor, Coronopus didymus, Euphorbia prostrata, Cynodon dactylon, Rumex dentatus, Euphorbia spp., Cyperus rotundus, Dactyloctenium aegyptium, Launaea nudicaulis, Ageratum conyzoides, Avena fatua, Cnicus arvensis, Chenopodium murale, and Malva neglecta were sampled from wheat fields, whereas eight species of weeds namely Solanum nigrum, Cyperus rotundus, Euphorbia hirta, Malvestrum coromandelianum, Conyza ambigua, Convolvulus arvensis, Poa annua and Oxalis corniculata were sampled for invertebrate fauna from sugarcane fields. All the invertebrates visible with naked eyes were collected from the above weeds. These were mostly arthropods and pulmonates, including all the immature and adults whether sitting, moving or residing (sticking on the foliage or stem) on weeds.

All the sampled specimens were put in properly labeled vials with 10 % formalin then preserved in 70% alcohol containing few drops of glycerine after washing with tap water.

The collected specimens were identified using the literature given by Brunetti (1923), Christophers (1933), Henery (1935), Borror (1954) and Talbot (1986) and online taxanomic keys available on internet. For the identification of weeds, weeds taxonomists were consulted in the Department of Botany, University of Agriculture, Faisalabad.

RESULTS

Ashiq et al. (2003) reported 38 weed species occurring in the wheat and 24 in sugarcane crop fields. Accordingly Chenopodium album, Chenopodium murale, Convolvulus arvensis, Melilotus indica, Anagallis arvensis, Cirsium arvensis, Coronopus didymus, Lathyrus aphaca, Medicago polymorpha, Polygonum plebejum, Rumex dentatus, Gallium aparine, Cnicus arvensis, Ephedra spp., Cynodon dactylon, Cenchrus setigerus, Trianthema partulacastrum, Anagalis arvensis, Trianthema pentandra, Fumaria indica, Centaurea iberica, Carthamus oxyacantha, Asphodelus tenuifolius, Datura fastuosa, Vicia sativa, Spergula arvensis, Cirsium arvensis, Medicago polymorpha, Trigonella monantha, Tribulus terrestris, Phalaris minor, Avena fatua. Malva neglecta, Cyperus rotundus, Dactyloctenium ageyptium, Launaea nudicaulis, Ageratum conyzoides, and polypogon monspelliensis were reported from wheat fields of punjab.

The weeds generally found in sugarcane fields were Phyla nudiflora, Trianthema pentandra, Rumex dentatus, Solanum nigrum, Amaranthus spinosus, Mukia maderaspatana, Conyza striata, Melilotus alba, Medicago polymorpha, Euphorbia granulata, Panicum antidotale, Setaria viridis,

Brachiaria reptans, Cyperus rotundus, Chenopodium murale, Euphorbia hirta, Convolvulus arvensis, Oxalis corniculata, Polygonum plebejum, Tribulus terrestris, Trianthema spp., Sonchus spp., Conyza ambigua, and Poa annua, accordingly.

Presently, seventeen and eight commonly occurring weeds of wheat and sugarcane respectively were as follows. The selected wheat weeds were Malva neglecta, Chenopodium murale, Cyperus rotundus, Dactyloctenium ageytium, Launaea nudicaulis, Avena fatua, Ageratum conyzoides, Cnicus arvensis, Ephedra spp., Rumex dentatus, Cynodon dactylon, Convolvulus arvensis, Polygonum plebejum, Cenchrus setigerus, Phalaris minor, Euphorbia prostrata and Coronopus didymus. Similarly the weeds selected from sugarcane were Solanum nigrum, Cyperus rotundus, Euphorbia hirta, Malvestrum coromandelianum, Conyza ambigua, Convolvulus arvensis, Poa annua and Oxalis corniculata.

The weed species found common in both wheat and sugarcane crop fields and along their edges were Cyperus rotundus and Convolvulus arvensis during the study period. Invertebrates on weeds: Various species of invertebrates belonging to different trophic levels were found associated to weeds occurring in and around wheat and sugarcane crops in Faisalabad district. Tables 1 and 2 provide the list of invertebrates collected from weeds of wheat and sugarcane crops respectively. The trophic diversity on weeds of respective crops has been shown in Fig. 1 and 2. Accordingly, two relatively different pictures with respect to the status of prey-predator number were depicted in the two types of crop fields.

Wheat Fields: Seventeen weed species common in and around wheat field harbored 42 species of predators including insects and spiders. The known pest species of different crops were 31 whereas five species were the saprophagus/omnivores species playing a key role in the recycling (conversion of plant as well as animal residue present in the crop fields) into organic matter making the soil nutrients again useable to the plants. The ratio of pest/prey-predator in the wheat fields of Faisalabad was high in favor of predators. The presence of greater number of predator species on the weeds as compared to those of herbivorous (prey/pest) species depicted an inverted pyramidical picture which should have been otherwise on an agro-ecosystem when there were large number of producers (crop as well as weed plants). It was noted that these weed plants in the wheat crop fields were the survivors of the weedicidal treatment of the fields.

That indicated severe competition among them for their food (pest/prey species) which may lead to starvation and ultimately to extinction of some of the predator species. Consequently, an outbreak of any pest or potential pest could be expected. It was also noteworthy that the predator species occupying the higher trophic levels were relatively safer from agrochemicals

Table 2. Trophic guild of invertebrates occurring on some weeds in sugarcane crop.

Species###Weeds###Feeding Habit

###Poa annua Oxalis###Convulvulus###Cyperus###Malvestrium###Conyza###Solanum###Euphorbia###Total

###corniculata###arvensis###rotundus###coromandelianu###ambigua###nigrum###hirta

Ischnura aurora###-###-###-###-###-###01###-###-###01###Feeding on small insects and nymphs

Coenagrion spp###-###-###02###-###-###-###-###-###02###feeding on small insects and nymph

Acrida spp.###-###-###-###01###-###-###08###01###10###Plant feeder, Grasses, Roots

Acrida nymph###01###-###03###18###-###06###-###01###29###Feeds on plants

Aeolopus thalassinus###01###-###03###04###-###01###03###01###13###Plant feeder, grasses,

Trilophidia turpis###-###-###02###-###-###-###-###-###02###Feeds on plants

Acrididae immature###-###-###03###-###-###-###-###-###03###Feeds on plants

Melanoplus sanguinipes###-###-###-###-###01###-###-###-###04###Several plant species

Leptysma marginicollis###-###-###-###-###-###01###-###05###06###Graminivorous

Neoconocephalus triopes###-###-###-###06###-###-###-###-###06###Grass seeds, especially panic grass

Neoconocephalus ensiger###01###02###-###-###-###-###-###-###03###Seed eater

Lepidogryllus spp###06###09###01###-###-###-###-###-###16###Omnivorous

Gryllus lineaticeps###05###-###02###-###-###-###-###-###07###Omnivorous, scavengers

Keyacris scurra###01###-###04###-###-###-###-###-###05###Feeds on plants

Juvenile###-###-###-###01###-###-###-###-###01

Euschistus servus###-###-###-###-###-###-###01###-###01###Seed and plant feeder

Dysdercus koenigi###-###-###01###-###01###-###-###-###02###Seed and plant feeder

Coccinella trifasciata###-###-###-###01###-###-###-###01###Feed on Aphids

Coccinella septumpunctata###03###-###01###-###-###01###03###-###06

###Aphids and Mites

Gonocephalum elderi###-###-###-###01###-###-###-###-###01###Litter, wood, leaves

Chrysolenia cerealis###-###-###-###-###-###01###02###01###04###Feeds on plants

Longitarus spp###-###-###-###01###-###-###-###-###01###Feeds on plants

Chrysolina conglomerate###-###01###01###-###-###-###-###-###02###Feeds on plants

Raphidopala foveicollis###08###06###04###02###04###-###-###-###24###Leaf litter, foliage eater

Amphicyrta spp###-###-###-###01###-###-###-###-###01###Succulent leaves, Damage vegetables

Hylobius pinastri###-###-###-###-###-###01###-###-###01###Feeds on pine seedlings and plants

Synanthedon exitiosa###01###-###-###-###-###-###-###-###01###Plants including trees such as peach

Eilema soroucla###03###-###-###-###-###-###-###-###03###Nectar feeder, Leave and stem

Zizina labradus###-###-###01###-###-###-###-###01###01###Feeds on stem leaves

Pyrilla perpusilla###-###-###-###07###-###-###-###-###07###Nectar and plant feeder

Culex pipens###-###01###-###-###03###-###02###01###07###Nectar Feeders

Ozodiceromya spp.###-###-###-###01###-###-###-###-###01###Honey Dew, Flower nectar and Pollen

Dolichoderus taschenbergi###-###-###07###02###01###03###06###08###27###Nectar and seed eater, fungus feeder

Dolichoderus fuscus###02###-###-###-###-###-###-###-###02

Dicamma ceylonense###-###01###-###-###-###-###-###-###01###Nectar and seed eater, fungus feeder

Dolichoderus quadripuntatus###-###01###-###-###-###-###-###-###01###Nectar and seed eater, fungus feeder

Athalia proxima###01###-###01###-###-###-###-###-###02###Nectar feeder, seed eater,

Vespa spp###01###-###01###-###-###-###-###-###02###Insects and spiders

Cotesia marginiventris###-###-###-###-###-###02###-###01###03###Feeds on other insects

Oxyopes javanus###04###07###07###08###04###10###05###05###50###Insect eater

Peucetia spp###-###-###-###-###-###01###-###-###01###Lepidopteran and heteropteran pests

Biomphalaria peregrine###-###01###-###-###-###-###-###-###01###Detritivorous

Planorbis planorbis###-###01###-###01###01###-###-###-###03###Plant feeder like algae and diatoms

Anisus leucostoma###-###01###-###01###10###-###-###-###12###Feeds on surface, tissue and algae

Galba truncatula###-###-###-###01###-###-###-###-###01###Feeds on the algae on the surface

Discus rotumdatus###-###-###-###03###-###-###02###-###05###Feeds on leaf litter, fungus and plants

Punctum pygmaeum###01###-###-###-###-###-###-###-###01###Feeds on leaf litter

Aegopinella nitidula###-###-###-###02###-###-###01###-###03###Predates on other snails

Physopelta gutta###01###-###-###03###-###04###-###02###10###Seed and plant eater

Mantis religiasa###-###01###01###-###-###-###01###01###04###Feeds on other insects

Tomocerus minor###-###-###-###01###-###-###-###-###01###Feeds on algal diet (mycophagous) also on fungi

Panorpa lugubris###-###-###-###-###02###-###-###-###02###Scavengers, nector

Total number of specimens###40###32###45###66###27###32###34###28###304

Total number of species###16###12###18###21###09###12###11###12###53

Feeding Habit for family

(especially weedicides which were frequently used in wheat fields) than prey/pest species, because they directly depend on producers (wheat or weed plants) at the first or lowest trophic level of the wheat agro-ecosystem.

Habitat Breadth: The invertebrates occurring exclusively on eight weed species common in sugarcane fields harbored 10 species of predators including insects and spiders, 28 known pest species of some major crops, and four were the saprophagus/omnivorus species scavenging, fragmenting and decomposing in the ambient environment (Fig. 2). This crop seemed to show a relatively balanced prey-predator species structure probably due to no use of weedicides in the crop.

Habitat Breadth: Fig. 4 shows the number of weed species preferred by invertebrate species. Accordingly, 55% invertebrates preferred to live on or utilized single species of weed. 19% used two weed species whereas 9% species were found on three weed species. These invertebrates were Acrida spp., Lepidogryllus spp., Chrysolina cerealis, Planorbis planorbis and Anisus leucostoma. About 6% species, including Coccinella septempunctata, Culex pipiens, Mantis religiosa and Physopelta gutta preferred to live on or utilized fours species of weeds. Similarly, 2% arthropods namely, Raphidopala foveicollis and Acrida nymph used five and Dolichoderus fuscus and Aeolopus thalassinus used six weed species as their living resource respectively. Only 2% (Oxyopes javanus) arthropods utilized eight weed species.

DISCUSSION

The general concept of a weed is that of a plant whose presence is unwanted in the crop fields because of their competition for soil nutrients and space. Such a concept becomes erratic when the ecological importance with respect to supporting biodiversity and sustainability of the cropping system is addressed. This suggests the identification of most important weed species (Marshall and Moonen, 2002; Kostov and Pacanoski, 2007; Hussain, et al., 2009). If undesirability with the agro-ecosystem is linked to loss of yield resulting from inevitable crop-weed competition (Benvenuti, 2004), then some weeds are needed to be maintained within crops for insects, birds and small mammals. Insects constitute 41.7% of food items taken by little spotted owl (Athene brama) and 33.3% of small Indian mangoose (Herpetes auropuctatus) in addition to rodent pests of cropland (Mushtaq-ul-Hassan et al., 2003; Rana et al., 2005; Ruby, et al., 2011). Weeds and arthropods interact in agricultural systems.

Weeds can directly serve as food sources or provide other ecosystem resources for herbivorous arthropods, and indirectly serve carnivorous (beneficial) arthropods by providing food and shelter to their prey. Weeds can serve as alternative hosts for pest and beneficial arthropods when their preferred crop host is absent. The similar observations were put forward by many researchers (Norris and Kogan 2000; Norris and Kogan, 2005; Strong et al., 1984; Aguyoh, et al., 2004). An important point in favour of keeping weed diversity in the crop system was that most of the weeds were observed growing on the field margins showing no competition with crop plants. In other words they help sustaining the phytomorphic diversity in the system and thus favours faunal diversity.

Liu and Chen (2001) found that the common green lacewing, Chrysoperla carnea ate 14 to 16 Aphis gossypii per day, 11-12 Myzus persicae, and 5-6 Lipaphis erysimi per day in laboratory conditions. Siddiqui (2006) also calculated a predator-prey ratio of C. carnea and two species of aphids Microsiphum miscanthi and Aphis maidis ranging from 1/10 to 1/16 in various low chemical input wheat fields of Punjab. Taking this ratio as natural (necessary for survival) in the wheat agro-ecosystem, the figure of prey-predator ratio (210/348) or 1/ 1.65 revealed in the present study was highly deviated from prey-predator ratio in situ.

The alarmingly high ratio in favour of predators in wheat system indicates severe competition among predators for their food (prey) species which may lead to starvation and ultimately to the extinction of some of the important predator species. Consequently, an outbreak of any pest or herbivorous potential pest could be expected. It seemed that prey and predator species occupying the different trophic levels received differential effects of weedicides or other chemicals used in the system. Further, most of the weed plants grew along the sides of the crop fields and the sprays were done across the crop. It seemed that the predator species, being more active, took refuge on these weed plants. Contrary to the wheat fields the weed fauna of sugarcane fields depicted a relatively balanced (82/131) or 1/1.59 predator-prey ratio. This was probably due to the lesser or no use of weedicides in sugarcane crop.

By and large, the fauna in the sugarcane field was low in abundance probably due to the use of insecticides on this crop.

The question that all or most or some of the naturally occurring weed plants in the crop system should stay in or be eliminated from the system, still needs precise probe for each plant species in the crop and this demands the knowledge of the economic, medicinal and ecological importance of each species and production requirements of the system.

REFERENCES

Aguyoh, J.N., J.B. Masiunas and C. Eastman. 2004. Interaction of insects and weeds in a snap bean agroecosystem. Amer. Soc. Hort. Sci. 39: 287-290.

Altieri, M.A. 1994. Biodiversity and Pest Management. Food Products Press, New York.

Ashiq, M., M.S. Iqbal and N. Muhammad. 2003. Weeds of Major Crops in Punjab and their control. Agriculture Society, Govt. of Punjab, Lahore, Pakistan.

Benvenuti, S. 2004. Weeds dynamics in the Mediterranean urban ecosystem: Ecology, Biodiversity and Management. Weed Res. 44:341-354.

Borror, D.J. 1954. An introduction to study of insects. p. 415- 423. Ohio Uni. Press. Ohio.

Brunetti, E. 1923. The Fauna of British India, including Ceylon and Burma, Diptera (Pipunculidae, Syrphidae, Conopidae and Cesteridae). Today and Tomorrow's Printers and Publishers, Karol Bagh, New Dehli, India. Christophers, S.R. 1933. The Fauna of British India, including Ceylon and Burma, Diptera (Culicidae). Today and Tomorrow's Printers and Publishers, Karol Bagh, New Dehli, India.

Henery, S.P. 1935. A manual of common invertebrate animals. p. 557-692. Mc Graw Hill Books Com. NY, USA.

Hussain, A., A. Nadeem, I. Ashraf and M. Awan. 2009. Effect of weed competition periods on the growth and yield of black seed (Nigella sativa L.). Pak. J. Weed Sci. Res. 15:71-81.

John, L. and Capinera. 2005. Relationships between insects, pests and weeds: an evolutionary perspective. Weed Sci. 53:892-901.

Kostov, T. and Z. Pacanoski. 2007. Weeds with major economic impact on agriculture in Republic of Macedonia. Pak. J. Weed Sci. Res. 13:227-239.

Liu, T.X. and T.Y. Chen. 2001. Effect of three species of aphids on development, survival, and predation of Chrysoperla carnea. Appl. Entomol. Zool. 36:361-366.

Marshall, E.J.P. and A.C. Moonen. 2002. Field margins in northern Europe: their functions and interactions with agriculture. Agric. Ecosys. Environ. 89:5-21.

Mushtaq-ul-Hassan, M., A. Gill, B. Dar, and M.I. Khan. 2003. Diet of little spotted owl from Faisalabad and Skeikhupura, Pakistan. Acta Zoologica Bul. 55:53-58.

Norris, R. E and M. Kogan. 2000. Interactions between weeds, arthropod pests, and their natural enemies in managed ecosystems. Weed Sci. 48:94-158.

Norris, R.F. and M. Kogan. 2005. Ecology of interactions between weeds and arthropods. Ann. Rev. Entomol. 50:479-503.

Rana, S.A., S.M. Smith and M.J.I. Siddiqui. 2005. Scat analysis of Indian Mongoose feeding on fauna of some high and relatively low input crop fields of Faisalabad, Pakistan. Int. J. Biol. 7:777-780.

Rana, N., S.A. Rana, H.A. Khan. and A. Sohail. 2010. Assessment of possible threats to soil macro- invertebrate diversity in wheat fields from high input farming. Int. J. Agri. Biol. 12:801-808.

Reynolds, H.T., L.D. Anderson and L.A. Andres. 1959. Cultural and chemical control of the lesser cornstalk borer in Southern California. J. Econ. Entomol. 52: 63-66.

Ruby, T., S.A. Rana, M. Afzal and M. Hameed. 2010. Biodiversity of foliage arthropods in the cropland of Punjab, Pakistan. Int. J. Agri. Biol. 12:861-866.

Ruby, T., S.A. Rana, N. Rana, T.P. Inayat, M.J.I. Siddiqui and N.A. Khan. 2011. Weeds as viable habitat for arthropod species in croplands of central Punjab. Pak. J. Agri. Sci. 48:141-148.

Shellton, A.M., F.R. Badenes-perez. 2006. Concept and applications of trap cropping in pest management. Ann. Rev. Entomol. 51:285-308.

Siddiqui, M.J.I. 2006. Studies on the biodiversity of invertebrates in the wheat farm agroecosystems of Punjab, Pakistan. Ph.D. Thesis, Dept. Zoology and Fisheries, UAF. Strong, D.R., J.H. Lawton and T.R.E. Southwood. 1984. Insects on plants: Community patterns mechanism. Blackwell Sci. Oxford, UK.

Talbot, G. 1986. The Fauna of British India, including Ceylon and Burma, Butterflies. 3rd reprint. Today and Tomorrow's Printers and Publishers, Karol Bagh, New Dehli, India.

Van Emden, H.E and S.D. Wratten. 1991. Tri-trophic interactions involving plants in the biological control of aphids. p. 29-43, In: Peters, D.C., J.A. Webster and C.S. Chlouber (ed.) Aphid- Plant Interactions: Populations to Molecules. Stillwater, Oklahoma State University, Oklahoma, USA.

Zhang, C.Q. and M.L. Ye. 1990. A good forage in Guanzhou: its cultivation and utilization of Kuduzu. Guizhou Agri. Sci. 3:63-65.

1Department of Zoology and Fisheries, University of Agriculture, Faisalabad

2Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad

Corresponding author's e-mail: nademkhan531uaf@gmail.com
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