Biology: In Southwest, Nigeria, adult Zonocerus variegatus becomes sexually mature with the onset of the rains. Their eggs `are laid from the middle of march to April, with the majority of the laying occurring during the first week in April, but do not hatch until late October or November with embryonic development, which includes diapauses taking 6-7 months Entwistle [1]; Page [1]; Omole [7]. In Eastern Nigeria, there is one annual generation but two definite broods, most eggs being laid in March/April and August/ September. Each female lays 1-4 egg pods, which is 40- 45 mm long, each containing 20-90 eggs. The pods are buried 5-8 cm deep in the soil. As many as 3,500 pods have been found on a site of 16 m2 Toye [8]. This shows that egg pods are normally concentrated in selected egg-laying sites. The egg development is dependent on high level of soil moisture and takes place at the end of the wet season. Zonocerus variegatus generally has six nymphal instars in the field although a small percentage of the insect will have only five instars Chapman [9]. The nymphal development proceeds during the dry season and adults are dead before the next rain or at the onset Entwistle [6]; Toye [8]. Lee and Wood [10] stated that as plant tissue is either directly or indirectly the source of food for termites, vegetation must be an important factor in determining their distribution and abundance.

Damage characteristics: In Nigeria, various species have been reported to cause serious damage on virtually all the economic crops across the Mangrove and Fresh water swamp forest, Rain forest, Guinea savannah and Sudan savannah HarriS [7]; Malaka [12-14]. The polyphagous pests: Zonocerus variegatus L.; Brachytrypes membranaceus Dury and Gryllotalpa africana Beauv, were not left behind as they were seen feeding on kola foliage and young stems causing excessive defoliation and death of seedling plants Daramola [15]. The females deposit egg capsules in the soil during the rainy season. The eggs hatch and nymphs appear in November, while adults emerge in late January to March Daramola [15]; Toye [16]. The nymphs of the variegated grasshopper, Z. variegatus are gregarious, and often very numerous and it is at this stage that most damages are done. They are sluggish and migrate only slowly by walking and hence attack tends to be patchy. The adult grasshoppers are less gregarious than the nymphs, which eat up the leaves, leaving the veins intact, especially of seedlings. Both the nymphs and adults feed on new flushes, moving from one plant to the other after stripping the former bare. Their feeding activities always result in severe damages to young kola stands. Grasshoppers are known to feed on wide range of plants, showing preference to various annual herbs. Field observations on the damage caused to economic crops in Nigeria by Z. variegatus have been recorded by several authors Toye [16,17], Anya [5]; Youdeowei [2]; COPR [18,19]; Page [1]; Omole [7]. They all have illustrated accounts of the nature of damages to important economic crops such as banana, plantain, cassava, citrus, cocoa, kola, cotton, cashew, cowpea, tea etc.

Control measures

a) Cultural control: Toye [9] however reported that control operations on grasshopper should be carried out in November and early December when young nymphal aggregations are dense. A drastic reduction of the Zonocerus population could be achieved by digging up the egg laying sites and exposing them to high surface temperatures so that the eggs are killed. If all or nearly all the sites in a large area are cleared in this way the population of the grasshoppers can be reduced well below the damage threshold at no financial cost and with very little labour Page [1]; Toye [8]. According to the COPR [20], it is possible to reduce a Zonocerus population by 90% through this method. Also, studies carried out in two egg-laying areas showed that potential hatches were reduced by 83-91% through exposure of dug egg pods to desiccation Page [1].

b) Chemical method: All instars of Z. variegatus can be killed easily by the common insecticides (Fenitrothion) using solutions of 0.1% wt/vol. a.i., though 0.5% a.i. could equally achieve effective control on the target. The best time for spraying is in the early mornings or late afternoons when the insects are less active and preferably on the highly aggregated early instars of the insect. However, due to the well dispersal and high mobility of later instars of the insects, spraying them would be uneconomical unless the crop is of high economic value, in which case spraying at regular intervals according to the rate of re-invasion, would be worthwhile Page [1]; Toye [8]. Ndubuaku [21] effectively controlled nymphal aggregations on weeds with kerosene applied using a motorised mist blower.

c) Grasshoppers (Orthoptera: Acrididae): They are gregarious and feed on young immature leaves thereby reducing their photosynthetic area and damaging the leaf quality of tea leaves. They are usually brown in colour and mature adults are about 4-6 cm long. Mature females lay their egg pods (which usually contains 80-100 eggs) in shade on abandoned farmlands. In the drier regions of Nigeria, eggs are laid at the end of one raining season and hatch at the beginning of the following year rains. The eggs are encased in a capsule made from the soil to prevent desiccation

Crematogaster buchneri Gorel

Importance: Ants are general nuisance pests, building nests in trees, biting aggressively and making harvesting difficult.

Biology: Ant colonies have some fertile males called drones and one or more fertile females called queens.

Damage characteristics: Eguagie [22] reported that the ant, Crematogaster buchneri Gorel scrapes off the epidermis of the leaves and follicles of cocoa. The damage usually results in the shedding of leaves and the premature dropping of shrivelled follicles. The associated beneficial insects like scale insect, Stictococcus sjostedti CKII has large colonies whose piercing and sucking feeding injuries cause stunted growth and pod drop. Also, the feeding injury of the mealybugs, Planococcus citri Risso; Planococcus njalensis Laing; Ferrisiana virgata CKII on the cocoa flowers, flower stalk and pods, impair fruit development Ndubuaku [21].

Control measures a) Cultural method

Farm sanitation like pruning and shade management is effective in insect management.

b) Chemical method

Aldrex 40 is proven effective for the control of insect.

Ancistrotermes spp, Amitermes spp, Captotermes spp and Macrotermes spp

Importance: Ancistrtermes spp, Amitermes spp, Captotermes spp and Macrotermes spp (Termite) colonies are started by the sexual forms, which fly from the nests at the start of the rainy season and lose their wings before re-entering the soil or other hiding places NRI [23]. Termite, Macrotermes bellicosus, is however an emerging pest of Cocoa tree plantation.

Biology: Termites undergo incomplete metamorphosis; the younger instars of their nymphs greatly resemble the adults and take on important functions in the nest at an early stage Kranz [24]; Malaka [14]; Pearce [25]. Copulation is eventually accomplished and eggs laid into excavated initial cell which terminated courtship in termites. In an established colony, the queen lays egg and the eggs may be carried by the workers to other chambers or to a separate part of the royal chamber during incubation for hatching. The larvae are translucent with large setae. They can be assisted in hatching by workers who pull off, eat the eggshell and clean the larvae thoroughly to remove any remains. The larvae on hatching, remain in the brood chamber with the reproductives who looks after and clean them, until the first workers develop to take on the role of foraging for food and looking after the young ones.

Damage characteristics: Termites cause damages on the field by attacking the trunks and pods of cocoa/kola tree causing the plant and the pods to dry up after severe infestations. They feed on dead vegetation and tunnel into the roots and stems of trees of any age resulting in destruction by weakening of the tree structure causing them to collapse or giving access to the entry of pathogenic organism (fungus and other diseases). The fungal pathogen is responsible for rot infection. Other insect damage activities included bark nibbling and scraping, which can cause the death of seedling and even mature plants. Damage is most severe in stands which are under severe water stress, old stands and those subjected to bad pruning which leaves dead and dying tissue on the plant NRI [23].

Control measures a) Cultural method

Crop rotation or rotational cropping system is effective in the control of the subterranean insect pest. Avoid continuous cultivation on the same area of land to prevent the termite population build up.

b) Chemical method

Termites could effectively be controlled by the application of insecticides (Methidathion, Carbofuran, Endosulfan, Pyrinex, Dursban, Termicid, Endocarp and Fenitrothion) to the soil around the base of the kola seedlings and mature plants or coppiced stems just before the outset of the dry season NRI [23]; Adejumo and Asogwa [26]. Oyedokun [27] reported that the aqueous extracts of Phyllanthus amarus, Acassia albida and Tithonia diversifolia caused 40-56%, 24-60% and 42-88% mortality of termite, after 140 minutes of exposure (MOE) to the extracts. Similarly, ethanolic extracts of the P. amarus, A. albida and T. diversifolia resulted in a significantly (P<0.05) higher percentage mean mortality of 64- 91%, 36.4-76% and 36-68% respectively (Table 1a, b).

Source: Asogwa et al. [6].

Source: Asogwa et al. [6].

General Control of Insect Pest Damages

The following cultural, chemical, botanical, integrated Pest Management (IPM) strategy and legislative control measures have been proposed and perfected for the control of insect pests of Coffee. These measures are also applicable to all economic crops like Cacao, Kola etc.,

Cultural control measures

These involve the use of simple cultural practices such as farm sanitation, physical removal and killing of insects, controlled burning, shifting cultivation, crop rotation, intercropping and interplanting, tillage practices, use of shade crops, use of alternative hosts, pruning and excision, timely and prompt harvesting, processing outside the farms etc. These cultural operations are very cheap and stabilize the populations of most insect pests below their economic threshold. The practices are also human and environmentally friendly and do not have any side effects. Some of the cultural practices are as follows:
i. Use of shade crops – Adequate provision of shade and timely removal of infested seedlings also reduce infestation and activities of root feeding termites in newly established and young coffee, plantations. Experience has shown that farmers prefer to use recommended nurse shade plants which have economic value as they give the farmer some income before the coffee begins to yield fruit. Farmers in Nigeria, Ghana, Cameroon and Ivory Coast who produce 70 per cent of the world’s coffee, are peasant farmers with very small holdings. They need money during the period of establishment to supplement their meager incomes, to assist in helping to discharge their civic duties, such as payment of taxes and above all, pay the school fees of their children.
ii. Crop processing outside the farms - Preliminary processing of these crops are usually carried out in the area around the farms before taking them to the store or market. Such preliminary processing should best be done outside the farm environment to reduce the chances of reinfestation of the farms from already infested produce.
iii. Prompt harvesting – Timely harvesting of coffee cherries minimizes the quantitiy of cherries that drops into the litter, as these serve as pest reservoir for future attack. Also prompt harvesting of late maturing cherries left after the main harvest on regular basis is very effective but labour-intensive. The practice ensures that no coffee borer remains in the plantation after the season.
iv. Physical removal – Hand picking and subsequent destruction of the later instar larvae of the foliar pests of coffee, Epicampoptera spp and Cephanodes hylas and pupae of the former have been found to effect control of these pests to some extent.
v. Tillage practices – A drastic reduction of the Zonocerous variegatus population could be achieved by digging up the egg pods in the egg laying sites around young coffee plots thereby exposing them to high surface temperatures that desiccate the eggs. If all or nearby all the sites in a large area are cleared in this way the population of the grasshoppers can be reduced well below the damage threshold at no financial cost and with very little labour. It is possible to reduce the population by 90% through this method.
vi. Farm sanitation – The use of farm sanitation method for the control of this pest has remained the best option. Farm sanitation involves the removal of burry fruits containing the eggs and progenies of the pest from the plantation and destruction of developmental stages inside them by burning such fruits outside the plantation. This farm sanitation method is encouraged for all the insect pests of coffee and other tree crops e.g. cashew, cocoa, kola and tea.

vii. Pruning and excision – Pruning is usually embarked upon to maintain a good canopy and to achieve tree structure convenient for harvesting and spraying. It usually entails removal of dead, diseased and insect damaged woods, which are destroyed to prevent further pathogen and insect development. This helps to decrease number of primary wood-boring insects and also reduces the number of sites at which termites can gain a foothold. There are two main aspects to termites control in coffee and other tree crops eg cashew, kola and tea
a) Prevention of root, collar and basal stem attack in the nursery and in young plants in the field
b) Prevention of termite establishment in wounds and dead wood on mature trees so as to avoid spread of infestation to healthy wood. Treatment should be an organized part of routine farm or plantation maintenance and consists of careful pruning of dead wood, preferably with saw cuts close to the branch origin, and the treatment of cut and damaged surfaces with paint, coal tar or copper fungicide until they are callused over. The improvement of pruning technique, routine removal of all dead plant parts and manipulation of the shade and soil moisture through intermittent irrigation during the dry season may minimize attack by termites

viii. Use of alternative hosts – With polyphagous insects the wild host plants may be so numerous that special eradication would be impracticable, but where insect pests have a restricted host range, their removal may be especially beneficial. All the alternate host plants within the vicinity of the main crop plantation should be cut down so as to prevent the pests from hibernating on them during the off season in biological reports, plants which tolerate specific phases of the development stages of the insects or serves as temporary source of food and survival are often referred to as alternative host plants, whereas they are better regarded as incidental host plants, fortuitous host plants or trap plants. Typical examples of these cases are:
a) Incidental host plant – The activities of some alternative host plants of coffee pests have been reported. Apart from Gardenia spp, first reported in 1985 at CRIN, eggs and larvae (1^st-4^th instars) of Cephanodes hylas were seen on young flushes of the single lxora; Ixora coccinea Linn (Rubiaceae) in November 1987. These were, however observed to be very few compared with those on Coffee and Gardenia. This may be due to the limited Ixora foliage available as food for the pest. In addition, Crematogaster spp. (Hymenoptera; Myrmecinae), which abound on the Ixora plant preyed readily on the larvae of the pest and this may largely be responsible for the low incidence of the pest on this plant. The single Ixora therefore may be regarded as an incidental host plant of C. hylas and as such, its presence may not likely pose any threat to coffee cultivation.
b) Fortuitous host plant – The results from comparative laboratory study of the life cycle of Cephonodes hylas on Coffea canephora; Gardenia ellis; Ixora coccine and Ixora spp (unidentified) showed that G. ellis, C. hylas because the moth completed its life cycle on the plant. The various larval instar and pre-pupae of the pest were of similar size with those bred on coffee. But two Ixora spp. did not allow the moth to complete its life cycle on them, hence could be regarded as fortuitous host plants of the moth/ pest. Furthermore, all the larval instars reared on the Ixora spp. were highly stunted when compared with those reared on Coffee and Gardenia spp (Okelana et al., 2018)

©Trap plants – The two Ixora spp highlighted above could be employed as trap plants in the control of the pest because these plant species did not support the completion of the pest’s life cycle. In general, the alternative host plants of major and minor pests of cocoa, coffee, cashew, kola and tea should be avoided while intercropping their young seedlings with food crops. This deters rapid invasion and multiplication of such pest in such farms. Therefore. an alternative host plant can be broadly defined as that which tolerates all facets of the insect developmental activities (from egg to adult) in addition to serving as source of food to the various instar stages. It is common in biological studies to often refer plants, which only tolerate some phases of the developmental stages of an insect as an alternative host plant.

ix. Use of cover crops - Any rehabilitation method other than growing young cocoa under old trees increases the weed problem. The area becomes exposed and weeds and pests invade it. To avoid the ingress of grasses, cover crops, some of which may have economic value, e.g. beans, melons, could be tried. The use of cover crops will reduce soil erosion which could aggravate the soil fertility problem. Row weeding must, however, be done to keep the immediate surrounding of the coffee plants free of weeds, thus reducing competition for nutrients. Results of experiments at Kade, Ghana revealed that no particular cover was superior to natural regeneration, although the use of Tephrosia and Indigofera Sumatrana (both legumes) encouraged early and are replaced by natural regeneration. Mulching and use of legume covers gave higher coffee yield than natural regeneration. This was attributed to better early growth rather than the residual effects of the cover on the soil.

Biological control measure

It entails the use of an organism to control another organism. The population and activity of insect species can be altered through introduction of another organism including bacteria, viruses, insects and other natural enemies may be by introduction or man’s intervention with the stable ecological factors (abiotic and biotic factors). The concept of prey-predator relationship gives an overall view of biological control. However, rearing of biological control agents is an expensive venture. In most cases, the nature enemies of the insects within their existing ecological conditions are consciously preserved by man through judicious and selective chemical applications. If need be, thus the concept of integrated pest management gives an adequate protection to the maintenance of natural enemies in their natural environments. Unprecedented high levels of parasitism of the various developmental stages of the foliar pests of coffee, most especially Cephonodes hylas have been reported. The parasite Telenomus spp. (a Scelionid wasp), which parasitizes the foliar insect pests of robusta coffee, ranged from 75-90%, while larval parasitism by Euplectrus spp, was about 25% with most (about 70%) of the early instar larvae dying of desiccation. Also a parasite Exorista sp. (Tachinidae) was found attacking the caterpillars of Parasa euchlora in coffee fields. In August 1985 adult Tachinid flies were found common in the field hovering over the colonies of the stinging caterpillars in search of the points to lay their parasitic eggs. The eggs remain on the caterpillars till they hatch.

The coffee berry borer, H. hampei (Ferrari) is indigenous to Central Africa and it is there that three important natural enemies are found. These are two Bethylids: Prorops nasuta; Cephalonomia spp and predator. The adult parasite feeds on eggs and young larvae while the larvae attack the fully-grown larvae and pupae of the borer. The larvae of Cephalonomia spp lives as ectoparasite on the last stage larvae of the berry borer. The adult of this parasite also lives, in the berries feeding on the predator feed on bugs and aphids on tea. Biological control is now a complete eradication method. The parasite does not completely exterminate the host as it will affect them if they do so. Therefore, biological control is a density dependent affair, but it keeps the pest population to a tolerable level. This method is known to be permanent once it is introduced and established, it is very economical, self-sustaining and highly specific (i.e. predator-prey relationship).

Chemical control measures

Chemical control method is encouraged as the last resort to complement other methods or to address major pest outbreak problem. Presently, conscious efforts are directed towards judicious and selective chemical usage. This will combat the problem of resistance to pest, toxicity to man and tainting of plant products. The pyrethroids, though costly, are considered safer than other class of chemicals including organochlorine, organophosphate, carbamates etc. The chemical control should be at the initial stage of infestation of all the foliar pests since the later stages inflict greater injuries on the plant than the early stages. Spraying of insecticides should be carried out early in the morning or by late evening. All instars of Zonocerus variegatus can be killed easily by the common insecticides (Fenitrothion) using solutions of 0.1% wt/vol. a.i. The best time for spraying is in the early mornings or late afternoons when the insects are less active and preferably on the highly aggregated early instars of the insect. However, due to the well dispersal and highly mobility of later instars of the insects spraying them would be uneconomical unless the crop is of high economic value, in which case spraying at regular intervals according to the rate of re-invasion, would be worthwhile Termites could effectively be controlled by the application of insecticides (Methidathion, Carbofuran, Endosulfan, Pyrinex, Dursban, Termicid, Endocap and Fenitrothion) to the soil around the base of the cocoa seedlings and mature plants just before the outset of the dry season

Pesticides considered safe for protection of tree crops

The following synthetic insecticides such as Actara 25 WG, Esiom 150 SL, Proteus 170 0-TEC, Avesthrin, Termicid, Capsida, Phostoxin, Zap, Confidor etc. were screened against attacks of Coffee and other tree crops like kola/Cocoa weevils/mirids. This is to determine biodegradability of the insecticides with little or no residue effect that may pollute the environment Asogwa [27]. Among the chemical insecticides screened, Actara 25 WG, Esiom 150 SL and Proteus 170 0-TEC passed through all the stages and considered effective and thus recommended for use on Coffee tree or their products.

Use of natural plant products (Botanicals)

Due to the hazard effects of synthetic chemicals there is an urgent need to develop an alternative form of pest control that is non-toxic, biodegradable and affordable for the management of pests of agriculture and public health. This will help to protect the environment and reduce the economic and social costs of agricultural production. Crude extracts from selected plant species and other materials of biological origin appear to offer an effective method of pest control especially when used within an integrated pest management schedule. Plant extracts can provide a simple means of control that can be used by farmers. Botanical protectants have a great deal of advantage over all other types of protectants. This is because they do not lead to the buildup of resistance by insect pests. Most of these botanicals are acquired freely in the environment. They do not pose health hazard to the local farmers, as most of them are either medicinal plants or vegetables that are consumed as food. It also can help in rural development and employment for the rural populace through the establishment of cottage industries for the processing of selected plant materials for pest control.

The natural pesticides from these plants may be utilized in the form of powdery, oil or aqueous formulations and could be applied in various ways ranging from the broom sprinkling method to the use of knapsack sprayer.

Legislative control (Quarantine)

This involves the regulation of plant materials from one region to another in order to restrict the introduction of exotic pests, which may be accidentally transported by those plant materials. The government of each country or region enforces this law (Quarantine laws), which are prohibitive at all ports of entry into a given country. The law requires all imported plant materials to be brought in with an import permit accompanied by a phytosanitory certificate, which guarantees the state of health of imported materials. Regulatory control also prevents the spread of pests from one location to a wider area in a given zone.

Integrated pest management (IPM)

Integrated pest management (IPM) is process consisting of the balanced use of cultural, biological and chemical procedures that are environmentally feasible and socially acceptable to reduce pest populations to tolerable levels. It could also be defined as a sustainable approach to managing pests by combining biological, cultural, physical and chemical tools in a way that minimizes economic, health and environmental risks. Integrated pest management (IPM) involves the judicious utilization of two or more of the control methods to achieve a more effective control. For instance strict cultural practices can be used effectively with minimal pesticide sprays to get rid of most devastating stages of insect pests. IPM approach discourages the use of persistent pesticides (Organochlorine and organophosphates), rather Carbamates, Pyrethroids, Natural plant products (Botanicals) and Bio-insecticides (formulation based on pest pathogenic microbes) are now being favoured for use on agricultural products. In view of the above scenario, concerted research efforts were made to identify and evaluate various control techniques (Cultural, biological and chemical), which could be harnessed for integrated management of these most important pests and diseases in Nigeria.

Conclusion

The knowledge of ecology combined with life cycles of insect pest would enhance better understanding of the best option of pest management strategies to employ. Therefore, the sparingly use of chemical (0.025 ml) with other control options in a compatible manner would achieve effective and sustainable pest management. Some chemicals have been banned but the information is yet to reach those who buy in ignorance and apply without knowledge. In the foregoing, the approved and prohibited pesticides are provided to make producers to take right decision. Accredited sources in Nigeria have been provided so that fake chemicals are avoided and recognized Asogwa [27]. Some of these chemicals must be used at specific times and locations in the value chain of the crop. Consequently, it is important to use the right chemicals so that the quality of the farm products would not be affected when used for food items Asogwa and Dongo [29]; [30- 74].

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