Novel Rearing Technique, Developmental Biology, Fecundity and Morphometries of the Brown Cocoa Mirid, Sahlbergella singularis Haglund (Hemiptera: Miridae) in Southwestern Nigeria.


ABSTRACT: The brown cocoa mirid, Sahlbergella singularis Haglund, a major insect pest of cocoa in Nigeria, could cause 80% loss in yield. Fecundity, morphometries and developmental biology of the insect were investigated by a new rearing technique. The first rearing phase involved transfer of 20 day old nymphs collected from field cocoa pod into rearing chamber
equipped with regulated conditions of relative humidity (90 ± 5%) and temperatures (22 – 24°C) while the second phase was carried out oil sleeved pods on the cocoa trees under natural conditions. Each of the life stages was isolated, measured and described. Nymphal instars were separated on the basis of the cast off exuviae. The life cycle from egg to adult lasted an average of 41.1 days while the average egg incubation period was 14.1 days (31.3% of the total developmental time). There were five nymphal instars with total mean duration of 27 days. There were significant differences in the body morphometries of each of the life stages (P<0.05) for body length, abdominal width and antennal length. The sex ratio of male to female was 1:1.03.
The potential fecundity of S. singularis was 42.20 ± 4.96 eggs per female from dissected gravid females whereas the mean actual fecundity from mated females was 37.90 ± 3.09 eggs per female. This study has made available homogenous populations of S. singularis. The indepth knowledge of biology of the pest acquired here will assist in the future development of efficient
and ecologically sound management strategies for its control
Keywords: Sahlbergella singularis, life cycle, body morphometries, fecundity

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