Field margins and cropping system influence diversity and abundance of aphid natural enemies in <i>Lablab purpureus</i>

Obanyi, Janet N.; Ogendo, Joshua O.; Mulwa, Richard M. S.; Nyaanga, Jane G.; Cheruiyot, Erick K.; Bett, Philip K.; Belmain, Steven R.; Arnold, Sarah E. J.; Nash‐Woolley, Victoria C.; Stevenson, Philip C.

doi:10.1111/jen.13125

Cited by 3 publications

(1 citation statement)

References 70 publications

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“…Field borders (AKA eld margins) are often left uncultivated by farmers, thereby engendering places for spontaneous growth of vegetation and consequent sheltering of invertebrates and small-vertebrates (Marshall and Moonen 2002;Aschwanden et al 2007; Anderson et al 2013;Mkenda et al 2019a;Obanyi et al 2023). Nevertheless, the formation of these vegetational segments at the borders is seldom intentional, and more often it is actually due to the challenges of maneuvering properly the agricultural machinery close to those borders (especially when close to fenced borders).…”

Section: Introductionmentioning

confidence: 99%

Agricultural intensification affects communities of plants and arthropods in field borders and their potential to engender biological control

Saldanha,

Carvalho,

Machado

et al. 2024

Preprint

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In agriculture, spontaneous field border vegetation can engender several benefits, including mitigating soil erosion, increasing carbon retention, conserving pollinators, and promoting biological control. The extension of these benefits can, however, often depend on the context of location and time. As for biological control, field borders can promote natural enemy conservation if the plants therein can provide adequate resources (e.g. shelter, alternative food, microclimate). In the context of location, field borders can be adjacent to areas with varying degrees of agricultural intensification, including fields with annual crops, perennial crops, or forest areas. While many studies have investigated how field borders can influence arthropod communities in adjacent crops, the opposite direction of effect (i.e. how crop areas can influence adjacent field borders) remains an underexplored topic. Therefore, in this three-season study we selected vegetated field borders next to annual crops, perennial crops, and forest areas, to study their communities of spontaneous plants (weeds) and arthropods as well as their potential to engender biological control. In general, our results show that the community composition of plants and arthropods was affected by land use type and season. Furthermore, field border vegetation next to areas with higher level of agricultural intensification (i.e. annual or perennial crops) harbored more herbivores, flowers and natural enemies; although some of these results were season dependent. Lastly, field borders next to annual or perennial crop areas engendered stronger biological control of aphids; possibly due to the alternative food (herbivores/aphids and flowers) provided by the plants therein. Taken altogether, our results reinforce the importance of preserving spontaneous field border vegetation, especially in areas under intensive agriculture management.

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Section: Introductionmentioning

confidence: 99%

Agricultural intensification affects communities of plants and arthropods in field borders and their potential to engender biological control

Saldanha,

Carvalho,

Machado

et al. 2024

Preprint

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Flowering margins support natural enemies between cropping seasons

Obanyi,

Ogendo,

Mulwa

et al. 2024

Front. Agron.

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IntroductionPopulations of natural enemies of insect pests are declining owing to agricultural intensification and indiscriminate use of pesticides, and this may be exacerbated in agricultural systems that clear all margin plants after the cropping season for other uses such as fodder. Retaining a diversity of non-crop flowering vegetation outside the cropping season may support more resilient and effective natural pest regulation.MethodsWe tested the potential for non-crop vegetation to support natural enemies in fields across two locations after harvesting the primary crops of lablab and maize.ResultsA total of 54 plant species were recorded across the sites in Kenya with 59% of them being annuals and 41% perennials. There was a significant seasonal variation in plant species richness (ANOVA: F1, 16 = 33. 45; P< 0.0001) and diversity (ANOVA: F1, 16 = 7.20; P = 0.0511). While time since harvesting was a significant factor influencing the overall abundance of natural enemies (ANOVA: F2, 1,133 = 8.11; P< 0.0001), they were generally higher in abundance in locations with margin plants or where a diversity of margin plants was observed.DiscussionThese findings demonstrate that flowering plants in agricultural systems offer refuge and alternative food for natural enemies and potentially other beneficial insects between cropping seasons. The conservation of natural enemies between crops may lead to more effective natural pest regulation early in the following crop, thus reducing reliance on insecticides application.

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Lablab (Lablab purpureus L.) genotypes and field margin vegetation influence bean aphids and their natural enemies

Karimi,

Nyaanga,

Mulwa

et al. 2024

Front. Insect Sci.

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Lablab (Lablab purpureus L.) is an important food and livestock feed legume that can also enhance soil fertility. However, its production is limited by insect pests, notably the black bean aphid (Aphis fabae). The present field study was conducted to determine the difference in the contribution of lablab genotypes and natural field margin vegetation (FMV) to the abundance and diversity of natural enemies and the damage, incidence, and abundance of bean aphids. Eighteen lablab genotypes were planted in the presence or absence of FMV in a randomized complete block design experiment replicated four times. Data on aphid abundance, incidence, and severity of damage were collected at four growth stages of the crop. Lablab genotypes significantly influenced aphid incidence, suggesting some level of tolerance to aphid colonization. Findings showed that lablab genotypes were a significant influence on natural enemy species richness with no statistical difference for abundance and natural enemy species diversity. However, the genotypes did not vary significantly in their influence on the number of aphid natural enemies. FMV was associated with low bean aphid damage. Overall, the presence or absence of FMV did not influence the number of natural enemies caught on the crop. This concurs with recent work that shows a similar number of natural enemies with field margin plants but may reflect the reduced number of pest insects. Cropping seasons influenced aphid abundance and damage severity, with the populations developing at the early stages of lablab development and decreasing as the crop advanced. This pattern was similar both in the presence or absence of FMV. The findings of this study highlight the important contribution of crop genotype together with the presence of field margin species in the regulation of aphids and their natural enemies in lablab.

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Field margins and cropping system influence diversity and abundance of aphid natural enemies in Lablab purpureus

Cited by 3 publications

References 70 publications

Agricultural intensification affects communities of plants and arthropods in field borders and their potential to engender biological control

Agricultural intensification affects communities of plants and arthropods in field borders and their potential to engender biological control

Flowering margins support natural enemies between cropping seasons

Lablab (Lablab purpureus L.) genotypes and field margin vegetation influence bean aphids and their natural enemies

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