large, pocket infestations should be the first to be attacked since
these are the foci for mite dispersal in the dry season. In this man-
ner, the major source of the mite would be reduced rapidly. It is
not necessary to inject trees with Kilval as a protective measure.
The persistent nature of the chemical tends to prevent other
generations of the mite developing from existing eggs under the
calyx.

Pesticide Residues
 The main biologically active metabolite of vamidothion is the
sulfoxide which has a higher systemic acaricidal activity than the
parent compound. Oxidizing agents convert this further to the
sulfone. Simultaneously with oxidation in plants, hydrolysis of
the compound also occurs with the formation of harmless
dimethylphosphoric acid and phosphoric acid.
 In many countries, a tolerance level of 0.6 p.p.m has been
allowed for vamidothion. In numerous countries, a minimum in-
terval of between three and six weeks must be observed between
last application and harvesting of the crop. Such countries in-
clude Great Britain, Brazil, France, Italy, Japan and numerous
others. The dosage level of vamidothion which is without effect
in man is just over 50ug/kg bw/day. Such data are supplied by
the technical bulletin on vamidothion.
 In the recommended use ofvamidothion for coconut mite con-
trol, all edible fruit should be removed from the tree before treat-
ment. Fruits less than seven months old would require at least
another five months before they are edible as copra. The
youngest fruits which absorb most of the chemical would need six
months to one year before being ripe. Such a prolonged time-
interval will allow for the chemical to break down in any part of
the plant.
 The method employed for the routine analysis of residues in
the 7-month old fruits required the extraction of the entire fruit
(1000 gms or more) with acetone under vacuum, a clean-up pro-
cedure with hexane and oxidation with acid potassium per-
mangate. Dichloro-methane was used to extract the oxidized
metabolites of vamidothion. These were dried up by filtration


through anhydrous magnesium sulphate and evaporated to
dryness under reduced pressure. The final compounds were
hydrolysed with 0.1 N sodium hydroxide and titrated with 0.01
N iodine and sodium thiosulphate with starch as indicator.
Results were compared with standards prepared from
vamidothion.
 The method, though accurate to 1 p.p.m equivalent of
vamidothion, showed that 7-month old fruits remaining on
palms after treatment had less than 1 p.p.m equivalent of the
pesticide six weeks after the second treatment. Its real impor-
tance, however, lies in the fact that five months after treatment
the fruits would be free from all pesticide residues.

CONCLUSIONS
 The Eriophyid mite, Eriophyes guerreronis Keifer, which is at
present causing serious injury in coconut groves in Trinidad, as
well as in many countries around the world, can be controlled
almost permanently by integrating chemical control with weather
conditions unfavorable to the mite. Control methods utilizing
the phosphorus ester, vamidothion, injected into the trunks of
infested trees are capable of producing nearly 100% mortality
among the mites. When such programmes are done near the end
of the rainy season which is associated with little probability for
the dispersal of mite, permanent control might be achieved. In
the long run, eradication of the mite is possible through this for-
mat. Finally, to eliminate the possibility of crop residues, control
measures should be executed as outlined.



References
 1. Griffith, R.1982. The development of a programme for the control of the
coconut mit, Eriophyesguerreronis, Keifer, in the coconut groves of the island of St.
Vincent, W.E.: Ministry of Agriculture, Lands and Food Protection, Trinidad and
Tobago. p. 11.
 2. Julia, J.F., and D. Mariau. 1979. Nouvelles recherches en Cote-d'Ivoire sur
Eriophyes guerreronis K., acarien ravageur des noix du cocotier. Oleagineux
34(4):;181-187.


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