1984, may have been as a result of construction of shelters at the
project site in close proximity to experimental plots. The shelters
housed numerous nests and the wasps were always present within
experimental plots. During the 1981 trials, there were no such
shelters and extremely high levels of fruitworm infestation oc-
curred. This relationship is to be further investigated.
 Spodoptera eridania is basically a defoliator but in high density
situations attacks fruit, making them totally unmarketable. The
black form predominates under such conditions and often ap-
pears lodged within cavities in the fruit. As much as 4.9% fruits
were destroyed by this pest in untreated plots during the dry
season of 1982. Plots treated with B. thuringiensis (16,000 IUP
per mg) in the form of Dipel (0.55kg AI/ha), demonstrated 39%
less fruit damage. The same treatment reduced infestation levels
by 59% during the wet season of that year and when application
rates had been increased to 1.1 kg AI/ha in the dry season trials
of 1983 and 1984, fruit infestation levels were reduced by 68%
and 94% respectively. Like Heliothis, Spodoptera is also preyed
upon by P. canadensis and early instars are trapped in silk spun
by a variety of spiders. Parasites of Spodoptera include a number
of hymenopterans.
 Keiferia lycopersicella has been observed to infest as many as
99% fruits in Southern California (Elmore, 1937). This seems
somewhat astronomic when compared to fruit infestation levels in
Trinidad, which in untreated plots were 0.62, 1.89 and 0.81%
for the dry seasons of 1982, 1983 and 1984 respectively (Table 3).
A wet season trial of 1982 revealed a fruit infestation level as low
as 0.22% The pin worm is a pest of great economic importance
in many tomato growing regions of the world and as a result of
farmers' complaints has been the focus of research in Trinidad for
some time. Experiments conducted at St. Augustine (Katwaru,
1978), Chaguaramas (Katwaru, 1979), Macoya (Barrow et al.,
1979), Piarco, Aranguez and Santa Cruz (Jones, 1981), all revealed
low infestation levels of this pest, damage being confined mainly to
the leaves. Though subsequent investigations revealed higher levels
of infestation, observations were by no means alarming. Pest
populations are definitely much higher under dry conditions, but
even during the very dry spell of 1984 (4.35mm/wk) untreated
plots revealed just 0.81% fruit damage (Table 3). Leaf damage is
considerably higher in Trinidad than is fruit damage (Jones,
1983) but does not appear to affect yields significantly. Thus, pin
worms may be of economic significance only when fruits are be-
ing penetrated. In 1984, fruit infestation was reduced by 79%
when weekly sprays of B. thuringiensis were applied and the same
treatment (1.1kg AI/ha) resulted in a 50% reduction of leaf
damage. Natural enemies of the pin worm in Trinidad include
Euderus sp., Bracon sp., Microchelonus sp. (Barrow et al., 1979),
Chelonus sp., Apanteles sp., Agathis sp., (Des Vignes, 1974), an
unidentified fungus, Polistes canadensis (Jones, 1981) and
Odynerus sp. (Jones, 1984). This rich natural enemy population
tends to suggest that in Trinidad, the pin worm ought not to be a
serious pest in a well managed tomato ecosystem.
 During the dry season of 1982, the army worm Agrotis repleta
 almost totally hindered establishment of vegetable crops, in-
 cluding tomato, in the Moruga/Penal area where it seems to have
 developed resistance to all traditional soil pesticides. As many as
 12 caterpillars/sq ft land surface were counted at peak infesta-
 tion. This pest has not been observed to cause serious damage to
 tomatoes in other areas of Trinidad during the last five years
 despite its wide distribution. Population densities at
 Moruga/Penal have been considerably reduced in 1983 and 1984.
 Manduca quinquemaculata is the most voraciously feeding cater-
 pillar in the system, one larva demonstrating a feeding capacity of
 one large fruit or an entire two week-old plant in less than 24 h.
 Fortunately, population levels are quite low year round, though


slightly higher in the wet season. Manduca is mainly a defoliator,
but unlike other defoliating caterpillars and beetles, it habitually
consumes stems. Should this pest acquire major status, its effects

VOL. XX-PROCEEDINGS of the CARIBBEAN FOOD CROPS SOCIETY


on yield would be far more drastic than those ot any other pest.
Prophylactic measures should include preservation of the wasp
Microptilis sp. which parasitizes the larva. White egrets and brown
doves are suspect predators of larval stages.
 Fruit-piercing bugs Nezara viridula and Phthia picta cause fruits
to ripen prematurely with corky blotches. Fruits are again of poor
quality for the fresh market. In 1983 and 1984, 1.17% and 0.05%
fruits in combined treated and untreated plots were damaged by
such bugs against which Dipel application is ineffective. The eggs
of Nezara are parasitized by a wasp Trisolcus bassalis.
 A number of Chrysomelid beetles including Epitrix spp.,
Ceratoma spp. and Diabrotica spp. feed on tomato leaves from
the seedling stage. They scrape away layers of leaf tissue creating
tiny shot holes, but loss of chlorophyllic tissue is negligible and
these insects present no serious threat to tomatoes in Trinidad.
 Leaf miners, Liriomyza sativae, infest tomato leaves by burrow-
ing through mesophyllic tissue. Population density fluctuates,
considerably, but is usually higher under dry conditions. Presence
of the pest did not necessarily affect tomato yields in California
(Johnson et al., 1980) and does not appear to do so in Trinidad
either. In commercial areas, particularly in Aranguez, leaf miner
populations have been rising since 1982. It has not been
established whether this is due to pesticide induction as in the
case of methomyl in California, but that probability cannot be
ruled out (Johnson et al, 1980). Leaf miners have been observed
to be parasitized in Trinidad by yet unidentified wasps.
 The mole cricket S. vicinus is a seedling pest and has been
observed to do serious damage in experimental plots at Piarco
under conditions of poor weed control within the surrounding
area (1982). Less than 1% seedling damage occurred when good
weed control had been practised in 1983 and 1984. In commercial
areas, crickets appear to be a serious seedling pest because of poor
field sanitation and developing resistance to such insecticides as
Malathion, Methamidophos, Aldrin, Chlordane, Cartap
Dimethoate, Carbaryl, Decamethrin, and Carbofuran.
 Spider and russet mites have become serious problems in some
 commercial and home gardens since 1983. They now persist
 throughout dry and wet seasons. Feeding on the under sides of
 leaves, young stems, flowers and fruits, they give rise to chlorosis,
 crimping, flower and fruit shed, wilting, russeting and other
 pathological symptoms with resultant low yields. In addition,
 fruits may be deformed and bronzed, and thus unattractive for
 the fresh market. Prior to 1983, mites were not reported to be a
 serious pest of tomatoes and occurrence seemed to be quite
 sporadic and limited to the dry season, the first showers of rain
 being sufficient to significantly reduce population levels.
 Documentation on russet mites as pests of tomatoes in Trinidad is
 unavailable. Outbreaks have occurred in controlled environment
 -systems and in open fields since the advent of pyrethroid insec-
 ticides and the Speedling method of producing seedlings, but
 mites have not yet been observed in experimental plots.
 Pest composition of the tomato ecosystem in Trinidad appears
 to be rather complex and observations suggest that pest outbreaks
 are induced through improper pest management practices. Dif-
 ficulty in reducing mole cricket populations may be related to
 poor field sanitation and pesticide abuse, while pin worm out-
 breaks in commercial plots seem related to improper application
 of pesticides. In view of the number of potentially dangerous
 pests associated with the crop, it is imperative that the system be
 managed in a manner such that secondary pests are not induced
 to cause major damage. This necessitates that the natural enemy
 population be protected and facilitated in functioning optimally.

 Management Strategies
 Cultural Practices In controlled environment systems, mites
 seem to be the only pest of significance. They do damage that is
 as serious as that done by the entire pest complex in open fields.


The hot, dry conditions which prevail in most controlled environ-


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