Pest control of Storage for Maize.docx

1、Pest control of Storage for MaizePest control of Storage for Maize:InsectsRodents4.1. Characteristics of Storage Insect PestsBeetles and moths are the most predominant pests in the tropic causing great loss and deterioration to food grain. These pests typically have a four stage life cycle: egg, lar

2、va, pupa and finally adult as shown in the following figure 40:Fig. 40. Cycle of life of a typical storage insect pest.Adapted from (AGROTEC/UNDP/OPS, 1991)The eggs are laid either on the surface of grain kernel (normally on physically damaged part of the grain or inside a tiny hole partly bored on

3、the kernel by the parent. The eggs hatch into larvae which voraciously eat their way within the grain, and are responsible for most of the damage on crop. The larvae gradually transform into pupae, a dormant non-feeding stage. These later hatch into adults which eat their way out of the grain kernel

4、 and (if beetles) immediately start aggressive feeding on and further destruction of the grain. The Prostephanus truncatus or larger grain borer (LGB) losses in the range of 10-35 percent in 5-6 months in household storage and up 60 percent losses over a 9 month storage period. Adult moths are short

5、-lived and do not feed, but their larvae voraciously feed and cause heavy contamination to the stored product through webbing and frass.Insect pest damage to grain may fold into one of the following categories: Bored holes in the grain and disappearance of a large portion of the endosperm. Injury to

6、 the germ reducing the nutritive value and loss of liability of the grain. Heating and condensation and moulding of the grain causing reduction in nutritive value and risk to formation of toxic substances as aflatoxin. Contamination of stored grain with excrement and frass. Infested grain, specially

7、 by Sitotrogacerealella figure 41A-3,may have a sickening smell and taste that makes the grain un-palatable. Main insect causing significantly damage to cereal, including maize, as shown in the following figure 41A and 41B.Fig. 41A. Common insect pests of maize.1). Tribolium casteanum, 2). Sitophilu

8、s granaries, 3). Sitophilus oryzae or zeamais, 4). Cryptolestes ferrugineus.(Source:casa Bernardo Ltda) Fig. 41B. Common insect pests of maize.1. Orizaephilus surinamensis, 2). Prostephanus truncatus (LGB), 3). Sitotroga cerealella, 4).Ephestia cautela. (Source: casa Bernardo Ltda)This list include

9、the larger grain borer LGB introduced in Africa in 1981 (figure 41B-2). It causes severe losses on maize grain and even dry cassava in Tanzania, Kenya and Togo and threatening all neighbouring countries. Moreover, the table 24 present some properties of important grain infesting insects with emphasi

10、s for maize. Table 22: Some properties of most important grain infesting insectsScientific Name Common Name Products infested/ DamagedType of DamageTemp. for population control (C) Optimum temp. for reproduction. (C) Sitophilus granarius Sitophilus zeamais Sitophilus oryzae Granary weevil Maize weev

11、il Rice weevilMaize, sorghum, wheat, rice, paddy. Larvae develop inside kernel and feed on starchy interior. Adults hatch and eat their way out of the grain and continue to feed voraciously on the grain1718 1828 - 3()29 -3129 -31 Rhizopertha Dominica Prostephanus truncatusLesser grain borer Larger g

12、rain borerPaddy, rice, wheat, maizedried cassava / potatocs Maize, and dry cassava tubers or chips.Larvae enter grain and feed on starchy interior. Adults bore grain freely and voraciously eat and may destroy entire grain kernels 21183()-35 32Oryzaephilus surinamensis Trogoderma granarium Ev. Saw-gr

13、ain beetle Khapra beetleMaize, wheat, sorghum, rice, pulses, oil seeds Larvae and adults feed on broken and damaged grain.The larva is a very serious stored product pest, the beetle itself does no damage.19223433 - 37Tribolium Confusum Tribolium ConstaneumCryptolestes speciesConfused flour beetleRus

14、t-red flour beetleFlat grain beetleMaize, wheat, sorghum,flour, groundnuts, milled cereal products, dried fruit, legumes, tapioca. Larvae and adults feed on broken and damaged grain.Larvae free-living on broken and damaged grain. Adults will attack the germ of sound 21222030 - 333633- 35Sitotroga ce

15、realella (Oilv)Ephestiacautella WalkCorcyracepalonica StaintAngoumois grain moth Tropical warehouse moth Rice moth Maize, wheat, rice, paddy, sorghum Groundnuts, rice, maize, wheat, sorghum Maize, wheat, rice, millet, sorghum, groundnuts, cocoaPrimary pest, attacks grain in field. Most damage occurs

16、 in storage only through larvae. Adults do not feed.Characicrised by heavy webbing and frass on produce. Damage only by larvae. Adult moths are short-lived and do not feed.16 161828 - 3028 - 3230 - 32SOURCE: AGROTEC/UNDP/OPS, 1991 4.2. Nature of Insect Pest InfestationsSome of the maize pests have f

17、light ability and often start the infestation in the field several weeks before the crop is harvested or when the maize is being filled dry in stalks or in shocks. The ability of the insects to fly long distances between fields and to and from maize stores as shown below can quickly spread the infes

18、tation.The problem is aggravated by bad practice such as: Poorly managed storage structure to maize field Careless disposal of all crop or of crop residue swept from infested store Leaving fits and pieces of infested cob maize in unplugged fields, or lying all around the farm yard.The infestation in

19、itially in the field often continue an intensifies in storage, reaching high proportion within 2 to 3 months of storage unless efforts are made to control the pest.4.3. Loss Magnitude by Insects Pests in Traditionally storageGrain must be guarded against insect infestation in the field by timely har

20、vesting. Protection must also be availed during drying, so as to minimize drying and storage losses.Weight loss on maize grain varies from region to region, depending on crop variety, storage condition and duration, and on pest combination in storage. Studies conducted on Zambia gave weight losses f

21、rom insects pests at a small holder storage for different maize varieties to be in the following ranges: Local varieties weight loss ranged: 1-3 percent Improved varieties weight loos ranges: 5-6 percent Hybrid varieties weight loss: 8-9 percentThese cases were obtained in traditionally storage for

22、6 to 9 months, with similar work done in Kenya, Tanzania and Uganda. The low level of loss in local varieties is attributed to their resistance to insect attack because of hard kernel and to the complete and better coverage by the sheaths which protect considerably the grain in the field, during dry

23、ing and in storage if in sheaths. In spite of their susceptibility short-coming , improved and hybrid varieties are normally high yielding in fast maturing compared to local varieties. These justifying their production.4.4. Insect pests control strategy.The control of insects for maize must start be

24、fore the harvest and not only when they are detected in storage. For a better control the following point should be taken in considerations: The best strategy involve timely harvesting and then proper drying and cleaning of the maize prior to storage. Is important also to prepare in advance all stor

25、age structure and containers to be used, making them ready and safe to recieve the new crop. Some recommendations depend upon the type of containers of structures, such as:- metal, earthware, plastic containers must be washed, desinfected with hot water and well dried before using.- Sacks of jute, s

26、isal and nylon should be washed and boiled in hot water to kill off insects pests or theirs eggs and larvae and dried prior to use- Reed-woven indoor granary and out-door basket, mud-wall bins or brick-wall silos must be re-plastered using local materials (cow dung, mud, sand, wood, ash, etc) to sea

27、l off cracks, holes and crevices which could hide insects pests and their eggs- Granaries, cribs, silos and warehouses must be cleanly swept, repaired where possible, desinfected using pests control chemicals, see table 23.Table 23: Residual spray recommended for store fabrics and their dossage rate

28、s (wettable and dispersible powdered) ProductConcentrationMalathion 1-2 gm/sq meter Pyrethrin/piperonylbutoxide 0.1-1.0 gm/sq meter Phoxim 0.25 gm/sq meter Pytethrins 0.25-0.5 gm/sq meter Etrimfos 0.25-0.5 gm/sq meter Mechacrifos 0.25-0.5 gm/sq meter Pirimiphos methyl 0.25-0.5 gm/sq meter Bromophos

29、0.5 gm/sq meter Fentirothion 0.5 gm/sq meter Dichloryos 50-70 gm/sq meter 4.5. Traditional insect pest control methods.Traditional methods used for farmers to reduce infestation of the crop may fall into three groups: 1). Special practices 2). Use of material such as ashes (for its abrasive and leta

30、l effect on the insects cuticle), mineral and oil in which physical barrier effects are responsible for the control of insects and 3).The use of whole or parts of the plants where there may be some natural insecticidal, fungicidal or repellent effect (mainly alcohols, alkaloids and terpenes). These

31、methods include as follows: Storing very well dried crop or re-drying when infestation is detected Storage of maize in sheaths for protection by the husk Use of repulsive local herbs and plants to scare off the pests (Nim ground seed, leaves of acanthaceae, acardiaceas, annonaceae, myrtaceae, other plants extract, etc, Use of dried inert material such as, sand, crushed limestone, wood ash at 1-5 percent w/w filling up in granular space and hindering insect activity, diatomaceous earth, etc Use of abrasive ash from paddy h