Incidence of natural enemies of Planococcoides njalensis Laing and Planococcus citri Risso in researcher-managed and farmer-managed cocoa farms

Studies were carried out at Tafo in researcher (CRIG)-managed farms and farmer-managed farms to assess the incidence of natural enemies in colonies of Planococcoides njalensis Laing and Planococcus citri Risso, the two most important vectors of the Cocoa Swollen Shoot Virus disease in Ghana. The CRIG farms were sprayed four times with either lindane or propoxur per mirid season, using motorised knapsack sprayers, and weeded at least twice annually, mostly by slashing with cutlass and occasionally by applying herbicides. Control of black pod disease caused by Phytophthora palmivora (Butl.) Butl. was by a combination of cultural practices and chemical control. The peasant farmers partially adopted the CRIG recommendations, spraying unspecified dosages of any available insecticides once or twice annually against mirids, and rarely spraying against the black pod disease. Most weeded once or twice annually while others waited till harvesting time, only to make tracks to trees carrying ripped pods. Mealybug colonies were sampled monthly in both farm types by examining cocoa trees from the base to hand height, brushing observed colonies within this range into glass vials and taking them to the laboratory. Unparasitized adults (females), third instar nymphs and mummies were separated and counted to give an estimate of the colony size. Mummies were kept in vials and observed for the emergence of parasitoids. The monthly incidence of both P. njalensis and P. citri colonies on the farmers' farms and the CRIG farms did not differ significantly. Similarly, the percentages of their colonies free from natural enemies in the two farm types did not differ significantly, and the differences in the incidence of parasitoids, and also of predators, in colonies of the two vectors in the two farm types were not significant. These results are discussed in terms of agrochemical usage and the efficiency of the natural enemies in the control of mealybug vectors of CSSV. (Journal of the Ghana Science Association: 2001 3(3): 45-51

Current levels of incidence of parasitism and predation in Planococcus citri Risso (Homoptera: Pseudococcidae) in Ghanaian Cocoa (Theobroma cacao L.) farms

From August 1988 to January 1997, natural enemies were reared from 335 colonies of Planococcus citri Risso (Homoptera: Pseudococcidae) sampled for 87 months from 225 randomly selected cocoa farms in the six cocoa-growing regions in Ghana. A total of 20,408 P. citri individuals was recorded, comprising adult females, third instar nymphs and mummified individuals harbouring parasitoids. Observed predators were larvae of Coccodiplosis coffeae Barnes (Diptera: Cecidomyiidae), nymphs and adults of Hyperaspis egregia Mader and Scymnus (Pullus) sp. (Coleoptera: Coccinellidae), as well as an unidentified lepidopteran. Twelve parasitic Hymenoptera were also reared, including Aenasius abengourouii (Risbec), Leptomastix dactylopii Howard, Anagyrus beneficians Compere, Tropidophryne melvillei Compere, Anagyrus amoenus Compere and Chryptochetum (Lestophonus) spp. Also recorded were a hyperparasitoid, Cheiloneurus carinatus Compere, parasitising Coc. coffeae , Xyphigaster pseudococci Risbec and six rare, undetermined parasitoids. Coccodiplosis coffeae was the commonest parasitoid, occurring throughout the year and infesting 72.8% of the P. citri colonies. Parasitism levels were generally low, the highest mean being 4.6 ± 2.6% for Aen. abengouroui . Simultaneous parasitism by more than one species was common and this gave rise to mean monthly parasitism levels ranging from 0.8 to 4.5%. Aenasius abengourouii , Ana. amoenus and H. egregia are being reported for the first time in P. citri on cocoa in Ghana, and the recovery of L. dactylopii suggests its establishment in the country, where it was introduced in 1949. Entre août 1988 et janvier 1997, nous avons élevé les ennemis naturels de 335 colonies de Planococcus citri échantillonnées pendant 87 mois dans 225 fermes de cacaoyers choisies au hazard au Ghana. Vingt milles, quatre cent-huit individus de P. citri ont été dénombrés, comprenant des adultes femelles, des larves de troisième stade, et des individus momifiés. Les prédateurs observés ont été des larves de Coccodiplosis coffeae Barnes (Diptera: Cecidomyiidae), des larves et des adultes d' Hyperaspis egregia Mader et Scymnus (Pullus) sp. (Coleoptera: Coccinellidae), ainsi que des Lépidoptères inconnus. Douze Hyménoptères parasitoïdes ont été élevées, comprenant Aenasius abengouroui (Risbec), Leptomastix dactylopii Howard, Anagyrus beneficians Compere, Tropidophryne melvillei Compere, Anagyrus amoenus Compere et Chryptochetum (Lestophonus) spp. On a observé aussi Cheiloneurus carinatus Compere, Xyphigaster pseudococci Risbec et six parasitoides inconnus. Coccodiplosis coffeae a été le plus commun, présent pendant toute l'année et infestant 72,8 % des colonies. Les niveaux de parasitisme ont été bas; le plus haut a été de 4,6 ± 2,6% chez Aen. abengouroui . Le multiparasitisme, causé par plus d'une espèce de parasitoide, a été commun, comprise entre 0,8 et 4,5 % de parasitisme moyen mensuel. Cet article est le premier à rapporter la présence de Aen. abengouroui , Ana. amoenus et H. egregia sur P. citri sur des cacaoyers au Ghana, ainsi que l'etablissement de L. dactylopii dans le pays, où il a été introduit en 1949

Standard Protocol for Screening Conventional Insecticides at the Cocoa Research Institute of Ghana for Mired Control

Mirids, (Sachlbergella singularis Hagl, and Distantiella theobroma (Dist), are the most important insect pests of cocoa in West Africa and their current control relies primarily on conventional insecticides. Insecticides have, for over six decades, had very beneficial effects on cocoa cultivation in Ghana. The success of mired control operation depends on, among others, the type of insecticide, the equipment used to apply them and timing. Consumers worldwide detest pesticide contaminated food products. The Cocoa Research Institute of Ghana (CRIG), therefore, routinely screens all insecticides submitted by manufacturers for mired control with all the aim of identifying environmentally friendlier compounds and to address consumer concerns about pesticide residues. This paper reports on the five stages that an insecticide passes through before it is recommended for use on cocoa in Ghana. The stages include a laboratory screening, a cage spray test, a small-scale, researches- managed field trial, a large-scale, researcher and farmer-managed field trial, as well as a trial for taint test and residue analysis. We hope the presentation will go a long way to allay the fears of consumers and environmentalists on the safety of chemical control of cocoa mirids in Ghana. Journal of the Ghana Science Association Vol. 9 (2) 2007: pp. 117-12

Evaluation of karate EC, cyperdim EC, and confidor SL for the control of Helopetis schoutedeni reuter (hemiptera: Miridae) on cashew in Ghana

Cashew (Anacardium occidentale L.) has become a very important non-traditional tree crop in Ghana, with increasing area of cultivation and nut yield. An important threat to the sustained production of the crop is the cashew mosquito, Helopeltis schoutedeni. Petri dishes laboratory bioassay was carried out with different rates of Karate, Cyperdim and Confidor on the 5th instar nymphs and adults of H. schoutedeni, to determine a suitable insecticide and its minimum effective dosage to control this insect. Field experiments were also conducted to determine the efficacy and persistence of Karate and Cyperdim on H. schoutedeni. In the laboratory bioassay, Karate and Cyperdim were found suitable with minimum effective dosages as 0.010% and 0.102% active ingredient (a.i.), respectively. The mean corrected mortality recorded for the minimum effective dosages of the two insecticides on the 5th instar nymphs and adults was more than 95% in the bioassay. The persistence tests indicated that, one day after insecticide application, both Karate and Cyperdim gave 100% kill. Seven days after treatment, only the Cyperdim killed more than 95% of the insect. From 14 days after treatment, there was a marked reduction in the percentages killed and the differences were no longer significant between the two insecticides, although the Cyperdim still gave higher per cent kill. From the results, either Karate or Cyperdim can be used in the case of a massive invasion of a cashew farm by the pest, to knock them off. But on prophylactic basis Cyperdim would be a better choice as it showed longer persistence than Karate. Journal of Science and Technology(Ghana) Vol. 27 (1) 2007: pp. 1-