Distribution and damage characteristics of an emerging insect pest of cashew, Plocaederus ferrugineus L. (Coleoptera: Cerambycidae) In Nigeria: A preliminary report

Among the numerous insect pests infesting cashew in Nigeria, the cashew trunk and root borer, Plocaederus ferrugineus L. (Coleoptera: Cerambycidae) is fast becoming the most dreaded because itsinfestation results in the sudden death of the tree within weeks. Observations at Ochaja in 1999/2000 and at Ibadan in 2005 of “sudden death” of mature cashew trees within few weeks of infestation were indications of emergence of new pest of cashew in Nigeria, which needs urgent investigation. Frass and gum exudates were collected from the trunk base of dead plants before they were cut down andexhumed carefully from the soil. Soil samples were collected from beneath the excavated roots. The bored holes on the trunk and roots were excised to expose their frass and gum contents. Both the frassand gum exudates collected from the base of the cashew trunk and those from excised trunk and roots together with the soil samples from beneath the excavated roots were thinly spread out in thelaboratory to search for the various life stages of the beetles. Brief description of the beetle’s life stages and parts of the infested/dead stands were made. The rate of infestation of cashew trees at Ibadan was18.13%, resulting in a death rate of 1.88% of trees, while the infestation rate at Ochaja was 13.3% with a death rate of 6.38%. The eggs were conspicuously absent at the time of this assessment as they had all emerged and developed into larvae, pupae and adults. The control of the pest at advanced stage of the larval development was very difficult; hence control measures were recommended to be initiated at early stage of infestation. Strict cultural practices gave desired results

Laboratory Culture Technique for Cephonodes hylas Linnaeus (Lepidoptera: Sphingidae)

Cephonodes hylas (L) is a major Lepidopterous defoliator insect pest that is responsible for 50-70% yield loss of robusta coffee in Nigeria. The biology of the pest was not fully understood due to paucity of information on its rearing in captivity. In addition, on eclosion, the young adults have undeveloped gonads and they require feed before maturation of their gonads. A new laboratory culture technique for this pest is therefore, discussed in this study. Eight cages were initially screened in the laboratory for rearing the insects. Subsequently, four concentrations (5, 10, 20 and 25%) of three sources of sugar; table cane sugar, analytical sucrose and honey were tested for their suitability for raising adults C. hylas under laboratory conditions in the chosen muslin cage with a feeding platform. The moths fed actively on the diets and lived longer than when starved. It was also confirmed that the adults require food for maturation of the gonads. A mean longevity of 14days/adult was attained with the 25% sucrose as against 4 days when starved (given water only) while a mean fecundity of 957 viable eggs/ female was obtained compared to an average of 132 eggs/female in the wild population of the insect. No egg was recorded for the starved moth. The 10% commercial cane sugar solution was adjudged best diet for laboratory rearing of adult C. hylas. Keywords: Laboratory; Culture/Rearing; Diet; Cephonodes hyla

Evaluation of the toxicity of Actara 25 WG for the control of the cocoa mirid Sahlbergella singularis Hagl. (Hemiptera: Miridae) in Nigeria

In Nigeria, the brown cocoa mirid Sahlbergella singularis is responsible for over 30% yield loss in cocoa. Insecticides still remain a very important component among the strategies for effective controlof major insect pests of cocoa in Nigeria. The Cocoa Research Institute of Nigeria (CRIN) has the “National Mandate” to evaluate and recommend new insecticides for use on cocoa in Nigeria. Themortality rates of mirids on exposure to the various concentrations (0.01, 0.013, 0.015 and 0.02%) of Actara 25 WG increased with period of exposure of the mirids in the laboratory. Both Actara and theStandard Miricide were similar at 0.020% concentration as both gave a 100% kill of mirids at the 90th min. No mortalities were recorded in control cages throughout the exposure period. The insecticide didnot produce any adverse side effects on cocoa seedlings and mature plants sprayed with the various concentrations over the years. The relative toxicity of the insecticide at the four different concentrationsto adult mirids, 24 h after the first field treatment application, was 93.3, 82.4, 81.8 and 100% adult mortality, respectively. In the case of the nymphal mirids, percentage mortality was 89.6, 81.5, 86.8 and94.3% for the various concentrations, respectively. The population of both the adult and nymphal mirids crashed to almost zero (0) in most cases suggesting about 100% mortality 24 h after the secondspraying on the residual mirid populations. Mirid numbers remained so low until the third spray application after which it was unnecessary to spray the sub-plots, thereafter. Spraying of mature andfruiting cocoa farms at application rate of 0.015% was found adequate and recommended taking into consideration the impact of the product on the environment and for economic reasons

The termicidal effects of Chlorpyrifos 48 EC, Endosulfan 35 EC, Dichlorvos 1000 EC and Diazinon 600 EC against termites in South-West Nigeria

Studies were carried out at the Cocoa Research Institute of Nigeria, Ibadan to determine the efficacy of four insecticides (Chlorpyrifos 48 EC, Endosulfan 35 EC, Dichlorvos 1000 EC and Diazinon 600 EC) ontermites (workers and soldier castes). The results showed that for both topical and residual action tests, worker caste mortality rates ranging from 70 to 100% were recorded for Chlorpyrifos, Endosulfan,Dichlorvos and Diazinon at 0.063, 0.125, 0.25 and 0.5% treatment levels within 120 min after exposure (MAE). For the soldier caste, the mortality rate was between 10 and 70% at the same treatment levelswithin the same time interval. However, the insecticide concentrations had very low fumigant action against the termites (workers and soldiers) when exposed to different concentrations of their fumes. There was no mortality recorded in any of the control petridishes. A higher mortality of the soldier caste was recorded for the topical application (10 to 70%) than the residual application, which gave a better kill of the workers caste (90 to 100%) 120 MAE. The high death rate of the workers might be due to the fact that they were generally more active during foraging and thus more susceptible to the effects of theinsecticide either by contact or systemic actions. The fact that the workers have a lower surface area and body weight than the soldiers might have also contributed to their higher vulnerability to theinsecticides. The application of these insecticides at 0.25% active ingredient is adjudged the best due to the high mortality rate achieved. Also the application at 0.25% will help to maintain cost effectiveness ofthese insecticides and minimize environmental pollution, toxicity and phytotoxicity problems associated with pesticides

Evaluation of the toxicity of Actara 25 WG for the control of the cocoa mirid Sahlbergella singularis Hagl. (Hemiptera: Miridae) in Nigeria

In Nigeria, the brown cocoa mirid Sahlbergella singularis is responsible for over 30% yield loss in cocoa. Insecticides still remain a very important component among the strategies for effective controlof major insect pests of cocoa in Nigeria. The Cocoa Research Institute of Nigeria (CRIN) has the “National Mandate” to evaluate and recommend new insecticides for use on cocoa in Nigeria. Themortality rates of mirids on exposure to the various concentrations (0.01, 0.013, 0.015 and 0.02%) of Actara 25 WG increased with period of exposure of the mirids in the laboratory. Both Actara and theStandard Miricide were similar at 0.020% concentration as both gave a 100% kill of mirids at the 90th min. No mortalities were recorded in control cages throughout the exposure period. The insecticide didnot produce any adverse side effects on cocoa seedlings and mature plants sprayed with the various concentrations over the years. The relative toxicity of the insecticide at the four different concentrationsto adult mirids, 24 h after the first field treatment application, was 93.3, 82.4, 81.8 and 100% adult mortality, respectively. In the case of the nymphal mirids, percentage mortality was 89.6, 81.5, 86.8 and94.3% for the various concentrations, respectively. The population of both the adult and nymphal mirids crashed to almost zero (0) in most cases suggesting about 100% mortality 24 h after the secondspraying on the residual mirid populations. Mirid numbers remained so low until the third spray application after which it was unnecessary to spray the sub-plots, thereafter. Spraying of mature andfruiting cocoa farms at application rate of 0.015% was found adequate  and recommended taking into consideration the impact of the product on the environment and for economic reasons

The Integrated Management Of An Emerging Insect Pest Of Cashew: A Case Study Of The Cashew Root And Stem Borer, Plocaederus ferrugineus In Ibadan, Nigeria

Sudden death of mature cashew trees at the Cocoa Research Institute of Nigeria (CRIN), Ibadan, southwestern Nigeria, a tropical humid ecology, necessitated an urgent study to unravel the cause and evolve an integrated management strategy for the control of the problem. Morphometric examination of the adult insect recovered from dying cashew trees revealed that, Plocaederus ferrugineus (cashew root and stem borer) was the pest responsible for the sudden death and Spondias mombin (purple mombin) was identified as an alternative preferred host plant of this pest. Phytosanitation practices like removing infested-dead cashew trees and alternate host plant (Spondias mombin) was carried out. This phytosanitary practice was also recommended to other cashew growers in the region. Application of coal tar–kerosene mixture in ratio 1:2 to healthy trees within infested plots gave 100% prophylactic efficacy at twelve months after treatment. Chemical control using Propoxur (a carbamate) and physical control by poking of holes created by the borer using a wire and killing of the insect both gave 98% success rate each. With mode of damage to cashew and about 25% trees infestation per hectare recorded so far, the cashew root and stem borer, P. ferrugineus can now be classified as one of the most economically important insect pests of cashew in Nigeria