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Maize (Zea mays L.) production is constrained in Ghana by declining soil fertility, erratic rainfall and the recent fall armyworm invasion. We hypothesised that adopting push-pull farming practices would reduce infestation and damage of maize by fall armyworm, while increasing maize yield. We conducted field experiments at two sites over two cropping seasons to evaluate the effects of spatial arrangements of push-pull companion crops on fall armyworm infestations and grain yield of maize. The experiment was arranged in a split-plot design with variety (Abotem and Opeaburo) as the main plot and fall armyworm treatment options (1 row maize and 1 row Desmodium [conventional push-pull]; three maize rows before one row of Desmodium [modified push-pull]; synthetic chemical and no treatment [control]) as a subplot. Results showed that, regardless of location or maize variety, both conventional and spatially modified push-pull companion cropping significantly reduced fall armyworm infestations under all seasons, as compared with the control. The push-pull companion cropping systems reduced the mean maize damage score of fall armyworm by 168%, compared with the control. Additionally, both conventional and spatially modified push-pull companion cropping significantly increased maize grain and biomass yield by 46.80% and 51.11%, respectively, irrespective of the maize variety compared with the control. The mean damage score, biomass and grain yield of conventional push-pull and modified push-pull were not significantly different. The fall armyworm infestation was decreased by 14.61% in the major season compared with the minor cropping season. This study provides novel evidence of the effectiveness of push-pull farming practice in reducing fall armyworm infestation and damage, and in increasing maize yield in Ghana, which has a different ecosystem to East Africa, where push-pull was developed. Further, it provides critical evidence of the effectiveness of a spatial modification of the push crop in relation with the main crop against the fall armyworm.

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a highly polyphagous plant pest that can severely impact yields of several agricultural crops. Understanding the economic impact and management thresholds for FAW across a variety of crop commodities is crucial for effective management. Evaluating the peer-reviewed and grey literature, we compiled global data on: (1) yield losses reported as a result of FAW infestations, (2) the relationship between FAW pressure/density and reported yield loss, and (3) current known economic injury levels, economic thresholds and action thresholds. We identified 71 references that reported yield losses from FAW infestation, with a total of 888 separate yield loss entries. The majority of research quantifying yield losses and the relationship between pest pressure and yield has focused on maize, sorghum, and cotton, with some evidence for sweet corn, bermudagrass, and rice. Yield loss varied between management strategies, with genetically modified and/or insecticide treated crops typically retaining higher yields. Most studies investigating the relationship between FAW density and yield loss across different crops have focused on early and mid FAW larval instars and on vegetative through to reproductive plant growth stages, with minimal research on both late larval instars and on plant seedlings. Economic thresholds were not reported in the literature. The reporting of economic injury levels and action thresholds varied significantly both between and within crops, highlighting the need for a standardised approach when measuring FAW pressures or densities that elicit management responses.

The oriental (invasive) fruit fly Bactrocera (invadens) dorsalis (Hendel) (Diptera: Tephritidae) has invaded Africa and is currently established in over 30 countries and has caused in massive fruit losses. Avocado (Persea americana Miller) is among the fruit with which the pest is associated. The aim of the study was to determine the host status of a ‘black-skinned’ cultivar “Hass” and two ‘green-skinned’ cultivars “Pinkerton” and “Fuerte” to B. (invadens) dorsalis. In the laboratory study conducted in Kenya in 2012 and 2013, punctured and unpunctured recently-harvested fruit were exposed to sexually-mature fruit fly in ‘no-choice’ experiments. B. (invadens) dorsalis readily developed in the punctured fruit but not in the uncompromised fruit (fruit not damaged by insects or handling). This result was confirmed in Tanzania in 2013 where flies were introduced to unpunctured fruit. In the field studies the fruit of each cultivar were caged in situ with flies for 72 h. On dissection only fruit damaged by false codling moth (Thaumatotibia leucotreta (Meyrick)) were found to harbor B. (invadens) dorsalis. In the light of these results the risk imposed for “Hass”, “Pinkerton” and “Fuerte” by B. (invadens) dorsalis is negligible under standard export conditions. The findings of this study and the implications to regional and international trade are discussed.

The entomopathogenic fungus Metarhizium anisopliae (Ma) and the predatory mite Phytoseiulus longipes (Pl) are both potential biocontrol agents of the tomato spider mite Tetranychus evansi. The combination of the two agents may enhance biological control of T. evansi if there is no antagonistic effect. Here, we evaluated the effect of combining the application of Ma and Pl in the control of T. evansi under screenhouse and field conditions on tomato crops. The acaricide abamectin was included as a control. Spray applications of Ma and abamectin, and release of Pl in the screenhouse significantly reduced mite population density among motile (P

In Kenya, Thrips tabaci Lind., is an important constraint to onion production. The current strategy to use synthetic pesticides is inadequate and unsustainable. An isolate of Metarhizium anisopliae (Metsch.) Sorok. with high pathogenicity to legume thrips, Megalurothrips sjostedti , and western flower thrips, Frankliniella occidentalis , was tested in field trials as a potential alternative for control of onion thrips. Weekly and bi-weekly applications of the fungus M. anisopliae and bi-weekly spray of the chemical insecticide dimethoate (Rogor ® 50) were compared for 3 seasons. M. anisopliae was applied at the rate of 1×10 11 conidia ha −1 and dimethoate was applied at the recommended rate of 17.5 g a.i. ha −1 . In all the trials, thrips density and damage were significantly lower in the fungal and chemical insecticide treatments compared with the untreated control. Onion bulb yield did not differ significantly among the treatments during the first season trial. However, in the second season trial, dimethoate-treated plots provided the greatest bulb yield (17 metric tons ha −1 ) and in the third season trial, M. anisopliae applied weekly recorded the highest yield (24 metric tons ha −1 ). With the exception of spiders, densities of nontarget organisms were higher in plots treated with M. anisopliae than in dimethoate-treated plots. The results indicate the potential of using M. anisopliae for the control of T. tabaci while protecting biodiversity in the onion agroecosystem.

The ovicidal activity of eight isolates of entomopathogenic hyphomycetes was evaluated in the laboratory against Maruca vitrata and Clavigralla tomentosicollis . At a concentration of 1×10 8 conidia ml −1 , four isolates ( Beauveria bassiana CPD 3 and 10, and Metarhizium anisopliae CPD 5 and 12) were found to be highly pathogenic to eggs of M. vitrata , achieving 89–100% mortality. At a given concentration, three isolates ( B. bassiana CPD 9 and M. anisopliae CPD 5 and 12) were highly pathogenic to eggs of C. tomentosicollis , achieving 91–94% mortality. These isolates also caused high larval and nymphal mortality (94–100% in M. vitrata and 91–100% in C. tomentosicollis ). M. anisopliae CPD 5 and 12 were selected for testing in cage experiment based on their high pathogenicity to both insect species. Spray application of the fungus in cages at two concentrations, 1×10 6 and 1×10 8 conidia ml −1 , was found to significantly reduce the number of emerging borers and bugs. The percentage of pods and seeds damaged was significantly lower in fungal-treated cages than in the control cages. Grain yield per plant also was significantly higher in fungal-treated cages than in the control cages. However, CPD 5 was superior in protecting cowpea plants at a lower inoculum concentration than CPD 12.

Field experiments were conducted at Mbita, western Kenya for two seasons to evaluate the potential of the entomopathogenic fungus, Metarhizium anisopliae (Metsh.) Sorokin, for biological control of the legume flower thrips, Megalurothrips sjostedti (Trybom), on cowpea. An ultra-low-volume (ULV) oil/aqueous formulation and a high-volume (HV) aqueous formulation of conidia were applied three times each at two concentrations of 1 × 10 11 and 1 × 10 13 conidia ha −1 . Compared with the untreated controls, both formulations significantly reduced thrips populations and plant damage in both seasons. Adult insects collected from fungal-treated plots and reared in the laboratory showed a high mortality due to mycosis. Flower and pod production was significantly higher in treated plots compared to the control plots. HV formulation was superior to ULV formulation in reducing thrips population and plant damage, and in increasing flower and pod production. During the first season, plots treated with HV formulation at 1 × 10 13 conidia ha −1 produced yields that were significantly higher than other treatments. No significant difference in grain yield was found between the fungal-treated plots and the synthetic insecticidal treatment during the second season. The results of these experiments suggest that M. anisopliae is a potential candidate for the management of M. sjostedti on cowpea.

We utilized two waves of data collected from a sample of mango farmers in Meru County in Kenya to evaluate the impact of Integrated Pest Management (IPM) strategy for controlling fruit flies in mango-production. We specifically explored the effect of five IPM practices including parasitoids (p) and Metarhizium anisopliae-based biopesticides (biop), orchard sanitation (os), spot spray of food bait (fb) and male annihilation technique (mat) on three outcome indicators: farmer pesticide expenditure, farm-level mango fruit yield losses and profit. We fitted difference-in-difference and household fixed effects regression models that account for unobserved heterogeneity across households. Our estimates differentiated the impact of the different IPM components, in comparison to farmers' practices as a control group. The descriptive statistics of the study show that application of the IPM strategy resulted in a 48% average increase in mango net income compared to the previous season irrespective of the IPM combination component used. The extent of improvement in net income, however, varied across treatments; treatments posfb and posmatfb registering the greatest improvements whereas the pos treatment generated the smallest increase in net income. The study findings further show mango yield losses due to fruit fly infestation reduced by an average of 19% among the IPM users. We also found a reduction in expenditure on pesticides, albeit across all the households. Regression model estimates show that, except for IPM combinations posbiop and pos, farmers using the rest of the IPM practices recorded significantly higher incomes from mango compared to their counterparts in the control group. We also noted that although average expenditure on pesticides decreased across all mango farmer households, the reduction was comparable between the treated and control farmer households. Our findings however, show significant decreases in mango damage due to fruit fly infestations among all farmers using the different IPM treatments. Our study recommends combinations of affordable and easy to apply and maintain IPM strategies that could yield significant impact on mango fruit fly control.