Integrated Management of Aphis craccivora in Cowpea Using Intercropping and Entomopathogenic Fungi under Field Conditions

Cowpea aphid, Aphis craccivora, is a major cowpea pest. Cowpea–cereal intercrop alone does not effectively manage the pest. Use of pesticides in intercrop leads to health and environmental risks. Fungal-based biopesticides offer a better option because they are environment- and consumer-friendly. This study assessed the combined effect of Metarhizium anisopliae ICIPE 62 and cowpea–maize intercrop against A. craccivora under six treatments: (1) untreated cowpea monocrop, (2) untreated cowpea–maize intercrop, (3) cowpea monocrop + ICIPE 62, (4) cowpea–maize intercrop + ICIPE 62, (5) cowpea monocrop + Duduthrin insecticide, and (6) cowpea–maize intercrop + Duduthrin during three seasons (long rainy/cold and dry/short rainy). In the cold and dry season, cowpea–maize intercrop treated with ICIPE 62 recorded the lowest infestation/cowpea damage, whereas the leaf yield was comparable to cowpea monocrop treated with ICIPE 62. In the short rainy season, the cowpea–maize intercrop treated with ICIPE 62 recorded the lowest infestation/damage, whereas leaf yield was similar to cowpea–maize intercrop treated with ICIPE 62 in the cold and dry season. Duduthrin in monocrop and intercrop did not reduce aphid infestation/cowpea damage levels in all the seasons. Although the efficacy of M. anisopliae ICIPE 62-based biopesticide could be affected by seasons, it successfully controlled aphid population in cowpea–maize intercrop under field conditions without affecting aphid-associated natural enemies.Peer Reviewe

Improving Phosphate Rock Use Efficiency In Organic Farming

Between 45 to 81% of the total phosphorus (P) fertilizer applied to soils in sub-Saharan Africa is absorbed in the soil, which among other factors reduce crop yield and contributes to high poverty in the region.  The objective of the study was to assess the effect of different phosphorus rock (PR) management on carrot yields, P recovery and use efficiency.  Different volumes (100, 200, 300, 400, and 500 mLs) of organic (lemon and pineapple) juices and water were used to dissolve 100 g of PR. The available P concentration in the solution was determined using a standard protocol. The solution with the high P concentration as well as powdered PR was each composted with manure and crop residues. Thereafter, a field experiment was set up on Humic andosols and Orthic acrisols to compare the effect of the dissolved PR applied directly with compost, to dissolved PR composted,  powder PR composted, powdered PR applied directly with compost, Triple supper phosphate applied directly with compost, compost and the soil alone (as a control). Our findings showed that lemon juice could release over 65% of the available P from PR and the combined application of the dissolved PR and compost at planting increased P recovery and use efficiency, and carrot yields on both soils as compared to the other treatments

Managing a Transboundary Pest: The Fall Armyworm on Maize in Africa

The fall armyworm (Spodoptera frugiperda J.E Smith) (Lepidoptera: Noctuidae) invaded Africa in 2016, and has since spread to all countries in sub-Saharan Africa, causing devastating effects on mainly maize and sorghum. The rapid spread of this pest is aided by its high reproductive rate, high migration ability, wide host range and adaptability to different environments, among others. Since its introduction, many governments purchased and distributed pesticides for emergency control, with minimal regard to their efficacy. In this chapter, we review efforts towards managing this pest, highlight key challenges, and provide our thoughts on considerations for sustainable management of the pest

Correction: Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) in Cameroon: Case study on its distribution, damage, pesticide use, genetic differentiation and host plants.

[This corrects the article DOI: 10.1371/journal.pone.0215749.]

Visual, vibratory, and olfactory cues affect interactions between the red spider mite Tetranychus evansi and its predator Phytoseiulus longipes

Phytoseiulus longipes Evans (Mesostigmata: Phytoseiidae) is an exotic predator widely used in biological control programs for the red spider mite Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae) in East Africa. However, little is known about the cues mediating this prey/predator interaction. Here, we performed behavioral assays to test the involvement of visual, vibratory, and olfactory cues using a combination of dead/living insects enclosed in either perforated or non-perforated transparent/opaque capsules. We monitored insect responses with a video tracking system and analyzed the data with Ethovision software. Our results showed avoidance behavior of T. evansi in the presence of live P. longipes through visual, vibratory, and olfactory cues. P. longipes was attracted by vibratory and olfactory cues emitted by T. evansi. The composition of volatiles from T. evansi was identified by GC/MS as methyl salicylate (MeSA), linalool, beta-caryophyllene, octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid. Our behavioral assays with predatory mites in a Y-tube olfactometer revealed that among the identified volatiles, only MeSA, linalool, and MeSA + linalool attracted P. longipes. The implications of these findings for the control of T. evansi are discussed