INTRODUCTION
In the seventies and early eighties, Leucaena became widespread and popular worldwide. Although in some cases the local or common varieties are considered weeds, in many situations it is an important plant with its improved varieties purposefully introduced for varied uses. No other tree legumes had been given as much attention as Leucaena. Most feeding trials, reforestation, agroforestry and soil conservation projects made use of or made reference to Leucaena. Too much emphasis was placed on Leucaena and it was looked on as a panacea species. This bias has now proved inadvisable because the psyllid or jumping lice (Heteropsylla cubana Crawford) problem arrived and still persists.
The Leucaena psyllid problem has been reviewed by NFTA (1988) and Napompeth (1989). Various authors have reported the extent of the psyllid damage and solutions being offered in different countries and locations.
Leucaena psyllids, Heteropsylla cubana Crawford, are tiny insects (1–2 mm) in the family Psyllidae (Homoptera). The eggs are yellow, found primarily on young terminal leaves, and hatch in 2–3 days. Nymphs, which resemble aphids, undergo five instars over 8–9 days. Adults are two to three times the size of the largest nymphal instar. Their reported colour has ranged from green to brown to whitish. They use stout legs to jump before taking flight when disturbed. Females begin laying eggs 1–3 days after becoming adults (NFTA, 1988).
The Leucaena psyllid is native to the Caribbean, Mexico and Central and South America. Moving as uninvited passengers on aircraft or in high altitude winds, they arrived in Hawaii in 1984. They were first found in Taiwan in 1985, causing serious damage in 1986 and 1987 (Jiunn-Fuh, 1989) and were reported to be present in Cebu, Philippines in August 1985 (Moog and Sison, 1986). By 1986, they were reported in Australia, the Pacific Islands and Southeast Asia (Thailand, Malaysia, Indonesia, Vietnam). In 1987, they arrived in Sri Lanka, making their way to Burma, China and India in 1988.
DAMAGES CAUSED BY PSYLLIDS
Damage brought about by the psyllid to established Leucaena plantations in different countries is presented in Table 1. Damage ranges from physical effects on the plant by defoliation to indirect, adverse effects on companion crops and reduced biomass for animal feeding, resulting in instability of the production system and financial loss. The socio-economic impact of the infestation is alarming.
IMPACT OF PSYLLID IN THE PHILIPPINES
The psyllid has affected the more intensive smallholder beef producer, where Leucaena is the most valuable component of the animal feeding system. A survey in Malimatoc, a village in the town of Mabini, Batan-gas province, where cattle raising is the primary enterprise in the villages and with Leucaena as the main crop for animal feeding showed the following results (Moog and Sison, 1986).
The foremost problems caused by the infestation were stunted growth and death of plants and feed shortage. The infestation resulted in reduced feed supply so farmers resorted to feeding other plant materials such as banana leaves and trunks, corn stover, coconut fronds, etc. However, with the lower feeding value of these substitute materials, most of the animals became weak and susceptible to diseases. About 74% of farmers reported that their animals became sick and four of them reported death of animals. The majority of the farmers (83.9%) reported loss of profit (Table 2).
| Country | Role/Use of Leucaena | Psyllid Damage/ Impact | Research Concern/ Control/Action Taken |
|---|---|---|---|
| AUSTRALIA Bray et al. (1989) | Pasture | Production reduced by 50 % | Resistant varieties Alternative species Predator Parasites |
| INDIA Veeresh (1989) | Fodder | Plantation Devastated | Natural enemies: Coccinalids, praying manthids, mirids and chrysopids, staphylivid beetle, white muscardine fungus, anthacorid bug |
| Krishnamurthy et al. (1989) | Fodder/ Alley crop | Fodder yield reduced | Resistant species/cultivars |
| INDONESIA Malessy (1987) | Fodder | Fodder production decreased Farmers stopped fattening cattle. Reduced cattle sales resulting in reduced local government income | |
| Mangoendihardjo et al. (1989) | Shade | 35 to 50 percent loss in harvest of coffee. Loss in income from sale of Leucaena seed | Spraying with insecticide Use of predator Curinus coerulus |
| Oka (1989) | Shade tree Fodder Reforestation Charcoal/firewood green mixture, timber leaf meal, veg. | Economic loss | National Task Force for Psyllid Control was created Released of predator Curinus coeruleus |
| Oka et al. (1987) | Millions of trees died Hampers reforestation and soil reclamation programmes | Systemic insecticide (monocrotophos); Curinusadults was introduced and being multiplied | |
| Hollenbeck (1987) | Shade Re-greening Feed Fuelwood | Reduced crop (cacao, coffee, black pepper and cardamon) yield and income Less feed resulting to use of low-quality feed materials. Greater soil loss and instabi- lity of water tables to regenerate quickly | Wide spectrum insecticide (expensive) Lady bugs (Curinus coeruleus) Olla abdominalis Resistant varieties/alternative species |
| Piggin and Parera (1987) | Soil stabilization Fodder | 50 % of trees affected Losses in exports of live- stock, coffee, cocoa and vanilla | Cutting and burning both infested and uninfested trees and spraying diagmon and injection of azodrin |
| MALAYSIA Lim et al. (1989) | Fodder | Trees defoliated | Resistant varieties |
| PHILIPPINES Sanchez (1989) | Fuelwood Fodder Alley crop | 50 % loss in production Leaf meal production reduced Price of fuelwood rose Farmers became reluctant to plant | Biological studies on psyllid Resistant varieties |
| De Guzman (1987) | Feed/fodder reforestation Soil conservation Green manure Nurse trees | Mortality of plants reduced animal holding Reduced farmers' income Weakened link between rural people and government | Resistant alternative species |
| SRI LANKA Gunasena et al. (1989) | Fodder Leaf meal Fuelwood Alley crop Shade Compost | Most farmers shifted to Gliricidia | Annual cropping between alleys of Leucaena Pruning and burning of leaves Resistant species |
| TAIWAN Jiunn-Fuh (1989) | Serious damage | Replaced by other tree species Spraying insecticides by airplane Resistant species Natural enemies: -Parasitic wasp -Coccinelids -Bugs -Entomopogous fungi | |
| THAILAND Napompeth (1989) | Vegetable Fodder Alley crop Agroforestry | Young shoots disappeared in the market Plantation abandoned, ploughed up and replaced by other crops Farmers could not supply leaves to feed mills | Ecology, evaluation and introduction of natural enemies and entomopathol- ogens, IPM Covering young top shoots |
| VIETNAM Ich and Tru (1989) | Defoliation of trees | Coccinelids as predators | |
| WESTERN SAMOA | Weed Cocoa shade | 75 % of infested plants died | Spraying Demettonte (Perfecthion) Grow cocoa under coconuts using Sesbania grandiflora as shade |
| Problems | Respondents (31) | |
|---|---|---|
| Frequency | Percent | |
| Stunted/Poor growth of Ipil-Ipil | 31 | 100 |
| Death of Ipil-Ipil | 31 | 100 |
| Feed shortage | 31 | 100 |
| Animals became susceptible to | 9 | 29 |
| diseases/animals got sick | ||
| Thinning of animals | 23 | 74.2 |
| Death of animals | 4 | 12.9 |
| Profit loss | 26 | 83.9 |
| Before Infestation | During Infestation | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Animal Holding | No. of Farmers | No. of Animals* | Animal Holding/No. of farmers | No. of Animals* | |||||
| 0 | 1 | 2 | 3 | 4 | |||||
| 8 | 2 | 16 | 1 | - | 1 | - | - | 2 | |
| 7 | 3 | 21 | - | - | 1 | - | 2 | 10 | |
| 6 | 2 | 12 | - | 1 | - | - | 1 | 5 | |
| 5 | 3 | 15 | - | 1 | 1 | 1 | - | 6 | |
| 4 | 4 | 24 | 1 | 1 | 1 | - | 1 | 10 | |
| 3 | 3 | 9 | - | 1 | 2 | - | - | 5 | |
| 2 | 9 | 18 | 2 | 2 | 5 | - | - | 12 | |
| 1 | 1 | 1 | - | 1 | - | - | - | 1 | |
| 0 | 2 | 0 | 1 | 1 | 1 | - | - | 2 | |
| TOTAL | 31 | 116 | 53 | ||||||
* Animal holding multiplied by number of farmers
The 31 farmer respondents were raising a total of 115 animals before infestation occurred. However, due to the severe damage suffered by Leucaena, the number of animals was reduced to 50 percent (Table 3). Three quarters of the respondents reduced the number of animals they raised. One of the two farmers raising 8 head totally stopped raising cattle, while the other reduced it to 4.
Psyllid in Cebu province
The infestation also affected the feed milling industry which utilized it as a source of xanthophyll and carotene in mixed feeds. Likewise, it also affected the smallholder farmers who grow, harvest and sell the leaves to merchants and feedmills. A survey in Cebu showed the effects of the infestation on the smallholder farms and on the export of pelleted ipil-ipil leaf meal.
Table 4 shows the effects of psyllid infestation among the three ipil-ipil farmers' associations involving 770 members in Cebu. Each association used to harvest 6–8 tonnes of dried ipil-ipil leaves per month. Their Ipil-ipil plantations were totally infested and, when the infestation occurred, they reported no harvest. Some farmers who raised cattle stopped raising animals or reduced the number of animals they raised. It was observed that the infestation had also brought down livestock sales and transaction in the nearby livestock market. Dumanjug Cattle Raisers' Association reported that animal holdings of its members were reduced from 495 to 250 head, a reduction of about 50% (similar to the observations in Batangas). In the absence of ipil-ipil, they used banana leaves and trunks, leaves of rain tree (Samanea saman) and whatever grasses were available as animal feed.
Annual export of ipil-ipil from 1983 to 1985 ranged from 6,400 to 8,900 tons (Table 5). Although the quantity of exports in 1985 was higher than that of 1984, the amount of ipil-ipil exported went down during the months of October, November and December 1985 when the infestation occurred (Moog and Sison, 1986). Exports from October to November 1985 was only 24% of that for the same months in 1984. No exports were recorded from 1986 to date.
| ITEM | CATMON Ipil-Ipil Planters Ass'n. | DUMANJUG Cattle Raiser's Association | ALOQUINSAN Ipil-Ipil Planters' Ass'n. |
|---|---|---|---|
| No. of Members | 113 | 557 | 65 |
| Area (ha) planted to ipil-ipil | 113 | 557 | 100 |
| Main Use of Ipil-ipil | Firewood | Feeds & Firewood | Feeds & Firewood |
| % Infestation | 100 | 100 | No data available |
| Data when pest first observed | August 1985 | 2nd week of October 1985 | 2nd week of October 1985 |
| Leaf production per month | |||
| Before infestation | 6–7 tons | 8 tons | 6 tons |
| During infestation | 0 | 0 | 0 |
| No. of animals fattened Before infestation | no available data | 495 | no available data |
| During infestation | -do- | 250 | -do- |
| Substitute feeds | -do- | Mostly grasses, banana leaves & trunks & other legumes such as Samanea and Gliricidia | -do- |
Source: Department of Agriculture, Cebu City
| Year | 1983 | 1984 | 1985 |
|---|---|---|---|
| January | 594 | 727 | 549 |
| February | 687 | 449 | 103 |
| March | 725 | 549 | 885 |
| April | 965 | 549 | 1123 |
| May | 892 | 545 | 989 |
| June | 879 | 720 | 1004 |
| July | 914 | 630 | 669 |
| August | 107 | 627 | 342 |
| September | 798 | 586 | 148 |
| October | 40 | 391 | 142 |
| November | 501 | 347 | 48 |
| December | 723 | 274 | 50 |
| TOTAL | 8894 | 6393 | 8252 |
Source : Animal Feed Control Division, BAI
CONCLUSIONS
Too much emphasis has been placed on Leucaena and its infestation with H. cubana is a catastrophe. The principles of ecology are that the more diverse the community is, the more stable will be. Organized evaluation trials on psyllid-resistant Leucaena species and cultivars are in progress but results may not be forthcoming in the short-term. Meanwhile, there is a pressing need to change the reliance on Leucaena. The tropics are imbued with numerous tropical fodder legumes like Sesbania, Erythrina and Gliricidia and their potentials should be tapped and enhanced.
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