Decline in soil health is a serious worldwide problem that decreases complexity and stability of agricultural ecosystems, commonly making them more prone to outbreaks of herbivorous insect pests. ...Potato (Solanum tuberosum L., Solanaceae) and onion (Allium cepa L., Amaryllidaceae) production is currently characterized by high soil disturbance and heavy reliance on synthetic inputs, including insecticides. Evidence suggests that adopting soil conservation techniques often (but not always) increases mortality and decreases reproductive output for the major insect pests of these important vegetable crops. Known mechanisms responsible for such an effect include increases in density and activity of natural enemy populations, enhanced plant defenses, and modified physical characteristics of respective agricultural habitats. However, most research efforts focused on mulches and organic soil amendments, with additional research needed on elucidating effects and their mechanisms for conservation tillage, cover crops, and arbuscular mycorrhizae.
Heavy soil disturbance and reliance on synthetic inputs, including insecticides, are typical of potato and onion farming. Adopting soil conservation techniques creates unfavorable environments for insect herbivores, including the major pests of these important crops. Known mechanisms responsible include increases in density and activity of natural enemies, enhanced plant defenses, and modified physical characteristics of agricultural habitats. However, most research focused on mulches and organic soil amendments. Additional research is needed on conservation tillage, cover crops, and arbuscular mycorrhizae.
While the functions of vacuolar processing enzymes (VPE) in plant responses to pathogens are now better established, their possible roles against insect herbivores need validation. Inspired by an ...observation that
βVPE
and
δVPE
represent the most highly upregulated transcripts in leaves of
Solanum bulbocastanum
and its backcross progenies that were highly resistant to the phloem-feeding green peach aphids (
Myzus persicae
), we used a reverse genetic approach in Arabidopsis to investigate whether T-DNA insertion mutants for specific
βVPE
and
δVPE
loci would exhibit compromised defenses at the whole-plant, physiological, and molecular levels. We hypothesized that impaired expression of
VPE
genes would lead to hyper-susceptibility if
VPE
-mediated processes were essential for basal defenses, given that Arabidopsis is naturally susceptible. Compared to the wild-type,
βvpe
and
δvpe
mutants exhibited an early onset of leaf curling and necrosis, rapid aphid population build-up, and significant physiological tissue injuries as a result of herbivory. This indicates that basal defenses were compromised by the loss-of-functions of either
VPE
-encoding gene.
VPE
co-expression networks were comprised of genes involved in sucrose metabolism and transport (
AtSUC5
,
AtSUS3
, and invertases), efflux and oxidative detoxification proteins, and modulators of gene-for-gene-type disease response linked to sucrose metabolism (
AtSWEET13
and
AtSWEET15
). These results suggest that
VPEs
play a role in basal defenses by mediating mechanisms of detoxification and metabolite availability in host tissues to counteract the rapid depletion caused by the phloem sucker. These processes might be important as first line of defense to delay the progression of perturbations caused by herbivory.
Undesirable growth of potato (Solanum tuberosum L.) crop under an excessive N fertilizer application is the main obstacle presently. This research was conducted to investigate the response of ...different potato cultivars; Russet Burbank, Shepody, and Superior, and its qualitative characteristics under a series of N rates. Six rates of N fertilization (0–280 kg ha−1) were applied on 11 sites in a randomized complete block design, with four replications. Sites with ≥30 g kg−1 of soil organic matter (OM) produced total tuber yield, marketable yield, and tuber weight per plant 39.5, 45.2, and 54.9%, respectively, higher than sites with ≤30 g kg−1 of OM. Tubers specific gravity increased by 0.18% in the sites with ≥30 g kg−1 of OM. The total tuber yield for the three cultivars was maximized at 168 kg N ha−1. Marketable specific gravity, starch, and dry matter content were achieved by applying 168 and 112 kg N ha−1 at ≤30 and ≥30 g kg−1 of OM sites, respectively. Russet Burbank produced a higher yield than Shepody and Superior cultivars significantly, but there was no significant difference among them regarding specific gravity. Excessive N application (>168 kg ha−1) decreased potato tuber production and quality.
Mineral oil is a product used to reduce PotatoVirusY transmission in potato fields. However, there is little information available about other effects that oil may have on insect pests of potato.To ...better understand how mineral oil affects potato pests, we performed a series of experiments testing the effects of oil on mortality, behavior, and development of potato aphids, Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae), green peach aphids, Myzus persicae (Sulzer) (Hemiptera: Aphididae), and Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). All three species showed negative behavioral responses to oil-treated potato foliage. Oil treatment also increased aphid mortality. Colorado potato beetle mortality was not affected, but developing on oil-treated potato plants resulted in prolonged development and smaller adults. Additionally, oil acted synergistically with the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae); Colorado potato beetle larvae were killed more rapidly when sprayed with both products compared with when sprayed with B. bassiana alone. Based on these results, mineral oil has the potential for expanded use in potato IPM programs.
Potato aphid, Macrosiphum euphorbiae (Thomas), is a highly mobile aphid species that dominates aphid communities in Maine potato fields and may contribute to virus transmission between potato plants. ...We studied effects of simulated rain, wind, mechanical raking, fungicide application, reflective mulch, and predator lady beetle, Harmonia axyridis (Pallast) on the interplant movement of wingless adult potato aphids in greenhouse experimental arenas that imitated small segments of a potato field. The number of aphids dispersing from the central plant in the arena after a tested perturbation was recorded. Experiments were repeated with 3- to 4-wk-old plants with nonoverlapping canopies and with 4- to 5-wk old plants with canopies overlapping within rows. Aphids moved between potato plants even when canopies did not overlap and without any environmental perturbations. However, more aphids moved between larger plants with overlapping canopies. Rain significantly encouraged aphid movement between plants with nonoverlapping canopies. Wind, rain, and mechanical raking significantly encouraged aphid movement between plants with overlapping canopies. Regardless of canopy overlap, most aphids moved within the rows of potato plants. However, there was also considerable movement between the rows, even though the aphids had to walk over bare soil.
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