CHAPTER 3 - Mosaics - Evidence from Nigeria - 1
Gerard; Booker; Entwistle; Eguagie
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The Ants of Africa CHAPTER 3 - Mosaics - Evidence from Nigeria - 1 Gerard; Booker; Entwistle; Eguagie |
| Mosaics Introduction | Mosaics Nigeria 2 | Mosaics Nigeria 3 |
Gerard (1967)
This author reviewed 50 years of the applied entomology of Nigerian tree crops. All the work he refers to concerned insect pests and ants are not listed as such. The references to ants, therefore, are limited to reports of early experiments with Oecophylla longinoda as a biological control agent for capsids; the recognition that ant tents, which he refers to as "carton cover (made from soil and plant material" constructed over the mealybug P. njalensis, protected them from insecticides; and how application of insecticides to the trunks of cocoa and citrus would stop species of Crematogaster, Pheidole and Camponotus from tending P. njalensis and various other Homoptera respectively.
As a member of the International Capsid project but based in Nigeria, Booker made an ecological study of the insect and spider fauna of cocoa at CRIN. To judge from the references in Entwistle (1972), his only formal publication was a list of the insects and spiders collected on 9 m² sheets, from 1809 pkd applications to cocoa trees, between July 1966 and May 1968 (Booker, 1968). All the collections were from one of two blocks of cocoa at CRIN (W13/2, about 1 ha planted in 1958, and W18/1, 1.75 ha planted in 1957).
Entwistle (1972, page 480) cited Booker as finding that ants comprised 87% of the total insects. Only 19 species of ant were collected and their abundance was shown as falling into six categories - 1 = one insect per sheet; 2 = one insect per two sheets; 3 = per five sheets; 4 = per ten sheets; 5 = per twenty sheets; and 6 = per forty sheets. Using current taxonomic knowledge and later data on abundance to produce a conversion from the categories to % occurrences as shown, the list was :
From Bolton (1974a, 1982) it seems likely that the two unnamed Cataulacus species were Cataulacus mocquerysi (listed as found by Booker) and either Cataulacus lujae or Cataulacus egenus. The Camponotus rufoglaucus species group may have been the Camponotus species previously known as foraminosus dorsalis.
Although essentially he wrote a review monograph, there is some otherwise unreferenced information on ants in Nigerian cocoa in P.F. Entwistle's book. For instance, he noted that, in relation to the numerical importance of the mealybug, Planococcoides njalensis, and ant attendance, Crematogaster (Sphaerocrema) luctans seemed commoner than Crematogaster striatula. Further, its attendance on Planococcoides njalensis was shared with unidentified members of Crematogaster (Crematogaster) and Crematogaster (Decacrema), the latter being apparently unknown as a tender in Ghana.
As part of an evaluation of the effects of spraying insecticide to control cocoa capsids, Bill Eguagie examined the impact on major ants. Farmers' mature Amelonado cocoa on 4 rectangular plots of 8 ha each were subdivided into four plots. One plot was left as an unsprayed control and each of the other plots were sprayed with either Gamma-BHC, Sevin or Sumithion. All the farms were within a radius of some three km, near Araromi, not far from CRIN (location 15 on the Map of the cocoa growing area). Twenty-eight species of ant were collected, presumably from the four farms but also from other local farms, during an eight-week pre-spraying period (December 1963-February 1964).
The commonest species, and the only ones seen other than sporadically, were Oecophylla longinoda, Tetramorium aculeatum (as Macromischoides aculeatus), and members of the genus Crematogaster (not separately quantified, but including Crematogaster buchneri, Crematogaster clariventris, Crematogaster depressa, Crematogaster nigeriensis (probable correct name for Cr. gabonensis) and Crematogaster gambiensis). The other species are listed in the Species section. All the common species were active throughout the two years of his study, with functioning nests being most common in the rainy season (May-September) than in the dry season. The Oecophylla and Crematogaster workers showed a tendency to be active on the trunk and the ground during the dry season, presumably because food on the trees was then least available. Tetramorium aculeatum, however, was found on the trunks mainly during dispersal, otherwise remaining in the canopy.
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Mosaics - Introduction | Mosaics - Nigeria 2 | Mosaics - Nigeria 3 |
©1998, 2003 - Brian Taylor CBiol FSB FRES 11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K. |
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