MSc

A study was conducted at the College of Agriculture, Vellayani from
April 2000 to July 2001 to investigate the nature and extent of damage caused
by the sucking pest complex, coconut eriophyid mite (CEM), coconut coreid
bug (CCB) and coconut button mealy bugs (CB M) infesting coconut bunches
and to devise suitable chemical and biological management measures against
them.
CEM, CCB and CBM attack coconut bunches singly or in combinations,
the combined attack of CEM and CCB being the most predominant. The
coconut palms suffered heavy loss due to the combined infestation of" these
pests by way of premature nut fall , varying degrees of damage in retained
nuts, distortion and stunting of nuts and formation of barren nuts. An annual
premature nutfall of 101.5 nuts palm" was observed due to sucking pest
infestation, the share of nut fall due to CEM, CCB and the combined
infestation of CEM and CCB being 35.96 per cent, 36.45 per cent and 27.59
per cent respectively. Maximum nutfall was observed in November. 5.81 nuts
bunch" palm" were rendered barren or stunted due to infestation of button
mealy bugs, singly or in combination with other pests. The infestation of
CEM in retained nuts was more or less uniform all through the year whereas
CCB showed wide fluctuation with maximum infestation in bunches that
opened in November.
A new scoring technique was developed, based on surface damage by
the pests to assess the loss incurred due to combined infestation of CCB and
CEM. Significant negative correlation was observed between surface damage

and nut characteristics like weight of whole nut, weight of dehusked nut,
weight of dewatered nut, volume of nut water and weight of copra. Significant
reduction in the above nut characters was observed in higher scores with high
intensity of surface damage as compared to healthy nuts (Score 1). Reduction
in weight of whole nut, dehuskednut and copra ranged between 17 to 46 per
cent, 13 to 50 per cent and 11 to 53 per cent respectively.
Among the various pesticides evaluated against the sucking pest
complex, neem oil - garlic emulsion (2 %), quinalphos (0.05 %) + wettable
sulphur (0.4 %), endosulfan (0.1 %) + wettable sulphur (0.4 %) and
endosulfan (0.1 %) + neem oil garlic emulsion (2 %) were found to be
effective in reducing the yield loss.
Verticillium suchlasporium (Goddard) and Metarhizium anisopliae
(Metch.) Sorok. were found to be infective to CEM and CCB respectively .
.
Four entomopathogenic fungi Penicillium purpurogenum Stoll., Acremonium
strictum Gams., Fusarium solani (Martius) Sacc. and Paecilomyces varioti
(Bainer) were identified causing natural mortality CEM population and one
fungus, Fusarium moniliforme Wollenw and Reink, to CBM.
Two egg parasitoids viz., Chrysochalcissa oviceps Boucek and Gryon
homeoceri (Nixon), hitherto unknown to parasitise the eggs of CCB were
identified.