Pumpkin Fields Research Articles

EPSPS gene amplification confers glyphosate resistance in Palmer amaranth in Connecticut

Abstract A Palmer amaranth biotype (CT-Res) with resistance to glyphosate was recently confirmed in a pumpkin field in Connecticut. However, the underlying mechanisms conferring glyphosate resistance in this biotype is not known. The main objectives of this research were 1) to determine the effect of plant height (10, 20, and 30 cm) on glyphosate resistance levels in CT-Res Palmer amaranth biotype, and 2) to investigate whether the target site–based mechanisms confer glyphosate resistance. To achieve these objectives, progeny seeds of the CT-Res biotype after two generations of recurrent selection with glyphosate (6,720 g ae ha−1) were used. Similarly, known glyphosate-susceptible Palmer amaranth biotypes from Kansas (KS-Sus) and Alabama (AL-Sus) were included. Results from greenhouse dose-response studies revealed that CT-Res Palmer amaranth biotype had 69-, 64-, and 54-fold resistance to glyphosate as compared with the KS-Sus biotype when treated at heights of 10, 20, and 30 cm, respectively. Sequence analysis of the EPSPS gene revealed no point mutations at the Pro106 and Thr102 residues in the CT-Res Palmer amaranth biotype. Quantitative polymerase chain reaction analysis revealed that the CT-Res biotype had 33 to 111 relative copies of the EPSPS gene compared with the AL-Sus biotype. All these results suggest that the EPSPS gene amplification endows a high level of glyphosate resistance in the GR Palmer amaranth biotype from Connecticut. Because of the lack of control with glyphosate, growers should adopt the use of effective alternative preemergence and postemergence herbicides in conjunction with other cultural and mechanical tactics to mitigate the further spread of GR Palmer amaranth in Connecticut.

Diet specialization mediates drivers of Cucurbita herbivory in a semi-arid agroecosystem

Herbivory is a major fitness pressure for plants and a key driver of crop losses in agroecosystems. Dense monocultures are expected to favor specialist herbivorous insects, particularly those who primarily consume crop species; yet, levels and types of herbivory are not uniform within regional cropping systems. It is essential to determine which local and regional ecological factors drive variation in herbivory in order to support functional agroecosystems that rely less on chemical inputs. Crops in the genus Cucurbita host a suite of both generalist and specialist herbivores that inflict significant damage, yet little is known about the relative contribution of these herbivores to variation in herbivory and how local- and landscape-scale Cucurbita resource concentrations, management practices, and natural enemies mediate this relationship. In this study, we tested whether three foundational ecological hypotheses influenced Cucurbita herbivory across 20 pumpkin fields in the semi-arid Southern High Plains Region of Texas. We used generalized linear mixed models and confirmatory path analysis to assess whether the Density-dependent Herbivory Hypothesis, Resource Concentration Hypothesis, or the Natural Enemies Hypothesis, could explain variation in Cucurbita herbivory and insect dynamics in the context of conventional agronomic practices. We found that herbivory increased over time, indicating that herbivores were causing sustained damage throughout the growing season. We also found that fields with higher local Cucurbita resources had lower herbivory, suggesting a resource dilution effect. Natural enemy communities were more abundant and taxonomically rich in sites with greater generalist herbivore abundance, though predator abundance declined over time, indicating that late-season crop fields are most at risk given high herbivory and low natural enemy-based control. Our findings also suggest that while local resource availability may drive the abundance and richness of arthropod communities, additional agronomic and phenological information is needed to anticipate herbivory risk in an agriculturally dominated landscape.

Pollinator Diversity and Floral Calendar of Forage Resources for Pumpkin, Machakos County, Kenya

The abundance and diversity of bees correlate with the abundance and diversity of forage resources. Pollinator reservoirs in croplands can augment pollination of flowering crops by increasing pollinator diversity and abundance. Therefore, this study provides empirical evidence on the diversity and abundance of alternative forage resources in two landscape classes with pumpkin fields. The study was undertaken in 32 pumpkin farms; 16 for each natural difference vegetation index (NDVI classes). Flowering plants were identified and counted within and around farms at 2 m × 2 m quadrat and 4 m × 50 m belt transect from the middle of the farm towards the exit. Approximately 142 plant species were recorded and their abundance varied between NDVI classes and across months. In the 2 m × 2 m quadrat 6,765 plants were observed in May in low NDVI and 4,399 in medium NDVI were recorded in May. Abundance, diversity and annual floral resource structure for honeybees in low and medium Normalized difference vegetation index (NDVI) classes in Machakos County were determined. The 4 m × 50 m belt transect had the highest numbers of plants (1,434-20,825) and plant species across the months and between NDVI classes. At least 35% of plants remained actively flowering during the sampling period, therefore, can serve as alternative forage sources for pollinators. Our inventory of plants can be used to develop a floral calendar for adoption by farmers for on-farm management of pollinators. The floral calendars will be predictive tools used to detect a correlation between flowering plants, seasons and pollinators.

Acute Toxicity of Commonly used Insecticides to Red Pumpkin Beetle, Aulacophora foveicollis

Acute toxicity of commonly used insecticides viz., fipronil, cyantraniliprole, fluxametamide, phenthoate and thiamethoxam were determined against Red pumpkin beetle, Aulacophora foveicollis collected from the unsprayed pumpkin fields in the orchard of Tamil Nadu Agricultural University, Coimbatore using filter paper disc bioassay method. Based on the LC50 values (ppm) of different insecticides, the order of toxicity was found to be fipronil (6.822) > fluxametamide (11.953) > phenthoate (14.732) > cyantraniliprole (14.793) > thiamethoxam (29.465) at 24 and 48 hours after treatment (HAT). The respective LC95 values were 65.396, 87.077, 42.090, 203.017 and 205.013 against A. foveicollis at 24 HAT and 46.585, 54.242, 37.445, 223.682 and 146.267 at 48 HAT for fipronil, cyantraniliprole, fluxametamide, phenthoate and thiamethoxam, respectively. The study results clearly indicated that the phenyl pyrazole insecticide, fipronil was highly effective against the pumpkin beetle, A. foveicollis.

The microbiome of Riccia liverworts is an important reservoir for microbial diversity in temporary agricultural crusts

BackgroundThe microbiota of liverworts provides an interesting model for plant symbioses; however, their microbiome assembly is not yet understood. Here, we assessed specific factors that shape microbial communities associated with Riccia temporary agricultural crusts in harvested fields by investigating bacterial, fungal and archaeal communities in thalli and adhering soil from different field sites in Styria and Burgenland, Austria combining qPCR analyses, amplicon sequencing and advanced microscopy.ResultsRiccia spec. div. was colonized by a very high abundance of bacteria (1010 16S rRNA gene copies per g of thallus) as well as archaea and fungi (108 ITS copies per g of thallus). Each Riccia thallus contain approx. 1000 prokaryotic and fungal ASVs. The field type was the main driver for the enrichment of fungal taxa, likely due to an imprint on soil microbiomes by the cultivated crop plants. This was shown by a higher fungal richness and different fungal community compositions comparing liverwort samples collected from pumpkin fields, with those from corn fields. In contrast, bacterial communities linked to liverworts are highly specialized and the soil attached to them is not a significant source of these bacteria. Specifically, enriched Cyanobacteria, Bacteroidetes and Methylobacteria suggest a symbiotic interaction. Intriguingly, compared to the surrounding soil, the thallus samples were shown to enrich several well-known bacterial and fungal phytopathogens indicating an undescribed role of liverworts as potential reservoirs of crop pathogens.ConclusionsOur results provide evidence that a stable bacterial community but varying fungal communities are colonizing liverwort thalli. Post-harvest, temporary agricultural biocrusts are important reservoirs for microbial biodiversity but they have to be considered as potential reservoirs for pathogens as well.

Pumpkin and watermelon production constraints and management practices in Uganda

BackgroundWatermelons and pumpkins are cultivated in Uganda for their leaves, fruits, and seeds, thereby contributing to food, nutrition and income security. However, there is limited research and information on constraints affecting their production. This study assessed the current production constraints for watermelons and pumpkins, management practices, sources of production inputs to guide research and decision making in production of these crops.MethodologyWatermelon and pumpkin fields totalling 105 located in 28 districts from nine sub-regions of Uganda were surveyed. Purposive sampling was conducted based on the importance and availability of watermelon and pumpkin fields in the sub-regions using a questionnaire administered to farmers on different practices, management strategies, and current production constraints. Data were analysed to determine the relationship between the source of seed, sale of their produce, constraints, and control measures of biotic constraints in the different sub-regions.ResultsPumpkins and watermelons were grown by 85.7% and 14.3% of respondent farmers, respectively. The constraints as ranked by the farmers were pests, diseases, drought, high transport and labour costs. Bacterial wilt, downy mildews, anthracnose powdery mildews and virus diseases in this order were the most common and important disease constraints.The whitefly (Bemisia tabaci, Gennadius), order hemiptera family aleyrodidae, aphids (Myzus Persicae, Sulzer), order hemiptera family aphidadae, melon fly (Bactrocera cucurbitae, Coquillett), order diptera family tephritidae and cutworm (Agrotis ipsilon, Hufnagel), order lepidoptera family noctuidae, were reported as the most limiting pests of watermelon and pumpkin production. Mixing of several agrochemicals was observed in watermelon fields coupled with gross lack of knowledge of proper usage or purpose of these chemicals may result in pesticide resistance, health and environmental hazards.ConclusionPests, diseases, and drought constitute the main constraints affecting watermelon and pumpkin cultivation in Uganda. Whereas weeding using hand hoes is the most common method of weed control, application of ash was the main strategy for pest management in pumpkin, while in watermelons, pheromone traps and pesticides were frequently used.

Wild bumble bee colony abundance, scaled by field size, predicts pollination services

AbstractAlthough bee visitation rate to flowers is often used to assess both pollination services and bee abundance, the abundance of social species needs to be assessed by quantifying the number colonies instead of the number of foraging individuals. Because accurately quantifying the number of wild bee colonies can be difficult, the relationship of visitation rates provided by foragers and the abundance of colonies contributing those foragers from the surrounding landscape is poorly documented for social species. Here, we use genetic methods and statistical inference to estimate the abundance of wild colonies of Bombus impatiens in the surrounding landscape providing foragers to 30 commercial pumpkin (Cucurbita pepo) fields over 4 yr across a 13,000‐km2 area in Pennsylvania, USA. We show that the abundance of wild colonies in the surrounding landscape providing foragers per field (colony abundance per field) ranges from 291 to 829 colonies per field. Furthermore, colony abundance per field has been stable across years, counties, and field size, resulting in a dilution of foragers from the available colonies across larger fields. Wild colony abundance, when scaled by field size, by expressing colony abundance on a per hectare basis, is predictive of visitation rate. Thus, we document the relationship of wild colony abundance per hectare to visitation rate at a level that provides sufficient pollination to a highly pollinator‐dependent crop. As expected, genetic differentiation among sampled populations is essentially non‐existent across different fields or regions, suggesting a panmictic population. Although many Bombus species are in decline, we document abundant and genetically resilient wild populations of B. impatiens associated with a mass‐flowering crop under current agricultural practices and provide baseline information needed to monitor these wild populations at a time when they face similar stressors implicated in the decline of congenerics.

Evaluation of Tarsonemus bilobatus and Podosphaera xanthii as suitable resources for Proprioseiopsis mexicanus in cucurbit systems in the Southeast USA.

Tritrophic relationships involving tarsonemids and predatory phytoseiids are common in a variety of agroecosystems, but due to the wide range of diets in both families, it is necessary to understand what food resources they are consuming to determine potential impact on crops. We investigated a frequent association of cucurbit powdery mildew (Podosphaera xanthii), Tarsonemus bilobatus, and Proprioseiopsis mexicanus in watermelon and pumpkin fields to determine whether P. mexicanus is consuming either or both of the other organisms. We also examined developmental and reproductive capability of P. mexicanus on these diets. If P. mexicanus is an effective predator of T. bilobatus, it may also be useful in controlling pest tarsonemids, such as broad mites. Proprioseiopsis mexicanus either starved or escaped from arenas rather than consume P. xanthii. When consuming T. bilobatus, P. mexicanus females developed from larva to adult in ca. 3days. On this diet, the preoviposition period was ca. 2days and P. mexicanus laid 1.7 eggs/day. These results are comparable to some of the higher-quality non-prey resources investigated in the literature. Starved female P. mexicanus consumed 6.5T. bilobatus of mixed stages in 1h. This study provides support for further research into the importance of non-pest tarsonemids as a resource to maintain the presence of generalist predatory mites as an early-intervention natural enemy. Further work should examine the efficacy of P. mexicanus as a natural enemy of economically important pest tarsonemids.

Survival of Xanthomonas cucurbitae in Different Crop Rotations, Plant Debris, and Weeds in Pumpkin Fields

This study was conducted to evaluate the effectiveness of crop rotation in managing Xanthomonas cucurbitae, the causal agent of Xanthomonas leaf spot, in pumpkin fields. The study was conducted using ‘Howden’ pumpkin, a susceptible pumpkin cultivar, at four sites with no history of cucurbit production. All sites were planted with pumpkins in the first year of crop rotations. The disease developed at all four sites. In a 3-year rotation with nonhost crops, the severity of Xanthomonas leaf spot in pumpkin plots was significantly (P < 0.05) lower than those of plots in the 2-year rotation with nonhost crops and continuous pumpkin production. Furthermore, X. cucurbitae was recovered from pumpkin plant debris 15 months after harvesting pumpkins in commercial fields, and the pathogen was viable. X. cucurbitae was also isolated from asymptomatic weeds in pumpkin fields. In a greenhouse inoculation of weeds with X. cucurbitae, however, Xanthomonas leaf spot developed only on leaves of burcucumber (Sicyos angulatus) and velvetleaf (Abutilon theophrasti) weeds. In the infested soil with X. cucurbitae, the bacterium was not recovered after 15, 42, and 56 days at 22, 12, and 4°C, respectively. The results showed that crop rotation alone does not provide adequate protection of pumpkin plants against X. cucurbitae.

Population Abundance of Insect Trapped on Different Colours of Sticky Trap in Pumpkin (Cucurbita moschata) Field

A study was conducted to attract insects using different colours of sticky trap in pumpkin (Cucurbita moschata) field. Sticky trap was chosen as it is one of a method to estimate the insect population density in field as it requires a low cost and less skilled labour. Four different colours of sticky traps (i.e. red, white, blue and yellow) were used to determine the insect population abundance at the pumpkin field. All the traps were installed at the height of 100 cm at a random of 1 ha of pumpkin plot with five replicates for each colour and the insect samples were collected weekly for three months (October-December 2019). Overall, a total of 13,052 insects were collected throughout 11 weeks of sampling. The results showed that the percentage of insect population abundance recorded the highest was on week eight (15.01%) whilst the least abundance of insects trapped was on week one (2.28%). The most attractive colour to attract insects was significantly the yellow colour (44.34%) followed by blue (20.12%) and white (19.15%) whilst the lowest insect trapped was on red colour (16.40%). A total of nine insect orders recorded were; Diptera, Hemiptera, Coleoptera, Hymenoptera, Lepidoptera, Orthoptera, Blattodea, Isoptera and others. Diptera was the most abundant of insect’s order trapped in the yellow trap with 3427 individuals and followed by Hemiptera order (1022 individuals). Whilst the Isoptera order was the least number of insects caught on a red colour trap with only one individual. In conclusion, our findings showed that the yellow sticky trap colour is the most attractive to attract insects of C. moschata compared to other colours. Therefore, this study could provide essential knowledge that may be useful for the future ecological survey of insects of C. moschata.

Wild Bee Visitation Rates Exceed Pollination Thresholds in Commercial Cucurbita Agroecosystems.

Wild bees supply sufficient pollination in Cucurbita agroecosystems in certain settings; however, some growers continue to stock fields with managed pollinators due to uncertainties of temporal and spatial variation on pollination services supplied by wild bees. Here, we evaluate wild bee pollination activity in wholesale, commercial pumpkin fields over 3 yr. We identified 37 species of bees foraging in commercial pumpkin fields. Honey bees (Apis mellifera L. [Hymenoptera: Apidae]), squash bees (Eucera (Peponapis) Say, Dorchin [Hymenoptera: Apidae]), and bumble bees (Bombus spp., primarily B. impatiens Cresson [Hymenoptera: Apidae]) were the most active pollinator taxa, responsible for over 95% of all pollination visits. Preference for female flowers decreased as distance from field edge increased for several bee taxa. Visitation rates from one key pollinator was negatively affected by field size. Visitation rates for multiple taxa exhibited a curvilinear response as the growing season progressed and responded positively to increasing floral density. We synthesized existing literature to estimate minimum 'pollination thresholds' per taxa and determined that each of the most active pollinator taxa exceeded these thresholds independently. Under current conditions, renting honey bee hives may be superfluous in this system. These results can aid growers when executing pollination management strategies and further highlights the importance of monitoring and conserving wild pollinator populations.

Bacterial communities in the gut of wild and mass-reared Zeugodacus cucurbitae and Bactrocera dorsalis revealed by metagenomic sequencing

BackgroundInsect pests belonging to genus Bactrocera sp. (Diptera: Tephritidae) pose major biotic stress on various fruits and vegetable crops around the world. Zeugodacus and Bactrocera sp. are associated with diverse bacterial communities which play an important role in the fitness of sterile insects. The wild populations of melon fly, Zeugodacus cucurbitae (Coquillett) and Oriental fruit fly, Bactrocera dorsalis (Hendel) were collected from pumpkin and mango fields, respectively. The laboratory populations of Z. cucurbitae and B. dorsalis were mass-reared on bottle gourd and sweet banana, respectively. Bacterial communities present in the gut of wild and mass-reared mature (~ 12 days old) and newly emerged (< 1 h after emergence) male and female adults of Z. cucurbitae and B. dorsalis were assessed. We used Illumina HiSeq next-generation sequencing of 16S rRNA gene to profile the gut bacterial communities of wild and mass-reared mature and newly emerged Z. cucurbitae and B. dorsalis adults.ResultsWe found diverse bacterial composition in the gut of wild and mass-reared Z. cucurbitae (ZC) and B. dorsalis (BD) with varied relative abundance. Few taxonomic groups were common to both the species. The most dominant phyla in all samples of Z. cucurbitae and B. dorsalis adults were Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. The phylum Proteobacteria occurred more in wild Z. cucurbitae (~ 87.72%) and B. dorsalis (~ 83.87%) as compared to mass-reared Z. cucurbitae (64.15%) and B. dorsalis (~ 80.96%). Higher relative abundance of Phylum Firmicutes was observed in mass-reared fruit fly than wild adults. Cyanobacteria/Chloroplast and Actinobacteria were also present with very low relative abundance in both wild as well as mass-reared melon fly and Oriental fruit fly. Enterobacteriaceae (61.21%) was dominant family in the gut of both wild and mass-reared adults. Providencia and Lactococcus were dominant genera with varied relative abundance in wild as well as in mass-reared mature and newly emerged fruit fly adults of both species. Some of the genera like Morganella and Serratia were only detected in mass-reared mature and newly emerged Z. cucurbitae and B. dorsalis adults. Principal Coordinate Analysis (PCoA) showed that fruit fly adult samples were grouped based on species and age of the adults while no grouping was observed on the basis of sex of the adult fruit fly.ConclusionsThe gut bacterial communities associated with wild and mass-reared mature and newly emerged adults of Z. cucurbitae and B. dorsalis showed variation that depends on species and age of the insects. Understanding the gut microbiota of wild and mass-reared Z. cucurbitae and B. dorsalis using high throughput technology will help to illustrate microbial diversity and this information could be used to develop efficient mass-rearing protocols for successful implementation of sterile insect technique (SIT).

Overhead sprinkler irrigation affects pollinators and pollination in pumpkin (Cucurbita maxima)

Cucurbits are monoecious plants and most of them depend on pollinators for fruit set. However, studies suggest that pumpkin and squash fields are pollination deficient. Pollinator limitation, suboptimal flower sex ratio, and exploitative competition between invasive ants and bees are a few major suggested reasons for this. Pumpkin flowers have a corolla cup and secrete nectar throughout anthesis, which make them attractive to bees. In south India, honey bee (Apis cerana) is the major pollinator of pumpkin flowers. Like pollinators, water is also a limiting factor for growth and production of flowers in pumpkin. It has been suggested to use overhead sprinklers to irrigate and fertilize pumpkin fields. We hypothesized that the sprinkler affects the visitation characteristics of foraging bees in flowers and pollination, and so, we performed an experiment to test this. For this reason, we recorded pollinator visits on staminate and pistillate flowers for 15 min and poured water in the flower cups and examined the water retention time and the visitation characteristics of pollinators in both staminate and pistillate flowers, and fruit set in pistillate flowers. Water remained inside the staminate and pistillate flower cups until the flower senescence. Honey bees entered and foraged nectar/pollen in flowers during the waterless condition. In water-filled flowers, honey bees hovered around or landed only on the corolla and did not forage floral resources or contact the reproductive parts. As a consequence, none of the water-filled flowers developed fruits. Therefore, the overhead sprinkler irrigation, despite cover a large area effectively, may not be an appropriate irrigation method for pumpkin during flowering period.

Physicochemical and microbiological characteristics of honey obtained through sugar feeding of bees.

This study was planned to characterize the physicochemical and antioxidant properties, and microbiological quality of honey obtained from the sandbar pumpkin field. In this study, four sugar supplemented and one control (without sugar fed) honey sample was used. Results revealed that all samples exhibited appropriate maturity considering their low moisture content (~ 19%) and high total solids (~ 80%) and TSS (~ 79%). Total acidity (< 40meq/kg) and pH (~ 4.5) directed the absenteeism of detrimental fermentation. Ash (~ 0.29%) and electrical conductivity (~ 700µS/cm) were reasonable and distinctive of dark yellowish-brown honey, which is buttressed by color attributes. Reducing sugars, glucose, fructose, and sucrose values ranged from 68.98 to 75.82%, 26.01 to 33.84%, 34.93 to 38.70%, and 1.74 to 5.96%, respectively. Proline (~ 400mg/kg), HMF (< 40mg/kg) and diastase action (~ 14° Gothe) were found within accepted limits, and also possesses good antioxidants in terms of total phenol (~ 160mg GAE/100g), total flavonoid (4.67-6.25mg CE/100g), and DPPH-RSA (30.65-35.97%). Themicrobial study revealed that the total viable count ranged between 33.33 and 27.66CFU/g, while yeasts and mold count varied between 14.33 and 12CFU/g. Principle component analysis (PCA) results revealed that all the studied parameters could be used effectively to discriminate the honey sample. The overall results signpost a new information regarding the quality i.e. processing, maturity, freshness and composition of honey obtained from the sandbar pumpkin field.

Using host-associated differentiation to track source population and dispersal distance among insect vectors of plant pathogens.

Small, mobile insects are notoriously challenging to track across landscapes and manage in agricultural fields. However, genetic differentiation among insect populations and host plants acquired through host‐associated differentiation could be exploited to infer movement within crop systems and damage potential. Although many insects exhibit host‐associated differentiation, management strategies for insect vectors of plant pathogens assume a homogenous population. Nevertheless, phenotypic changes derived from host‐associated differentiation could manifest in altered behavior or physiology affecting the likelihood of vector–pathogen–plant interactions, or the subsequent efficiency of pathogen transmission. We used SNPs to assess genotypic structure and host‐associated differentiation in the cowpea aphid, Aphis craccivora Koch (Hemiptera: Aphididae). To do so, we sampled A. craccivora across the Midwestern United States. from two host plants, alfalfa (Medicago sativa) and black locust (Robinia pseudoacacia)—putative source populations for winged migrants. Simultaneously, we sampled winged A. craccivora landing in pumpkin fields where they transmit viruses. Structure analyses supported host‐associated differentiation by identifying two major genotypic groups: an alfalfa group containing a single multilocus genotype and a locust group containing all others. Winged locust‐group aphids landed at a much greater magnitude within focal fields during year 2 than year 1, while those in the alfalfa group remained fairly consistent. Spatial autocorrelation analyses indicated locust‐group aphid movement was characterized by small‐scale dispersal during year 2, likely originating from populations within 10 km. We also detected strong temporal differences in colonization from the two host plants. Early in the summer, most winged aphids (79.4%) derived from the locust group, whereas late in the summer more (58.3%) were from the alfalfa group. Because early crop growth stages are more susceptible to damage from aphid‐vectored viruses, these data implicate locust as the more important source and illustrate how host‐associated differentiation can be used to track dispersal and inform management of heterogeneous pest populations.

Interactive effects of local and landscape factors on farmland carabids

AbstractAs a result of migration and spillover from noncrop habitats, predacious insects in agricultural fields respond locally to adjacent field margins and on a larger spatial scale to habitats in the surrounding landscape. However, the relative importance of local and landscape effects and their possible interactions have rarely been studied. We studied carabids in 18 pumpkin fields bordered by different field margins, along a gradient from simple to structural rich landscapes. Carabids were caught in pitfall traps along transects from the adjoining semi‐natural habitat towards the field centre. Although estimated species richness generally increased towards the field edges, carabid abundance increased towards adjacent woody margins and other crop fields. By contrast, abundance decreased towards adjacent herbaceous margins. Estimated carabid species richness in organically managed fields increased with increasing landscape heterogeneity, whereas this effect was absent in conventional fields. However, estimated species richness did not differ between organic and conventional fields. The differential response of carabid abundance to distance from the field edge in accordance with the type of field margin may explain the variability of patterns reported in the literature. The results of the present study show that both local and landscape parameters must be taken into account to promote carabids as natural enemies of crop pests.

Heavy-weight Crop Harvesting Robot - Controlling Algorithm

The Japanese agriculture is facing serious concerns such as labor shortage. The agricultural robotic systems can be an answer for this issue because it can increase the working efficiency. Currently, there are various kinds of agricultural robots in the world but most of them have developed based on a modified system from current agricultural machinery such as tractor and combine harvester. In some agricultural fields such as pumpkin field, modification of current platforms doesn’t meet the requirements of smart agriculture. In this regard, this study presents the development of a controlling algorithm for a harvesting robot specifically for heavy-weight crops. This robotic system composed of a robotic arm, an end effector, and a control algorithm which installed on a robot tractor. The objective of this research is to develop a control algorithm that can (1) approach to the position of pumpkin precisely, (2) grasp pumpkin properly without damage, and (3) transport pumpkin to the truck. The Denevit-Hartenberg methodology has used for forward and inverse kinematics. Two types of experiments were conducted in a laboratory to find the accuracy and repeatability of the system. The results showed that positioning accuracy in x and y direction and repeatability of the developed system were 4.85, 4.15, and 5.23 mm, satisfied to harvest pumpkin. The positioning error of end effector was almost 5mm respectively.

Aphids and their enemies in pumpkin respond differently to management, local and landscape features

Natural enemies of agricultural pests can be limited by high farming intensity and the scarcity of important resources such as flowers and alternative prey. Thus, organic farming and the presence of seminatural habitats adjacent to crop fields or in the surrounding landscape may enhance pest control. However, studies in vegetable crops investigating combined effects of field management, adjacent habitats and landscape complexity are still rare. We measured natural field densities of aphids and their enemies in 18 pumpkin fields in Southwest Germany. Increasing flower abundance in field margins tended to decrease aphid densities and significantly increased densities of natural enemies, especially of lady beetles, parasitoids, lacewings and aphid gall midges. Organic management and landscape complexity (measured as proportion of agriculture in 1kmradius) had no clear effect on pest control. Our results indicate that abundant flower resources in field margins are the most promising tool to enhance natural aphid control in pumpkin.

When herbicides don't really matter: Weed species composition of oil pumpkin (Cucurbita pepo L.) fields in Hungary

Oil pumpkin is a major emerging alternative crop with several unresolved weed management questions in central-eastern Europe, one of the focal regions of oil pumpkin production worldwide. This study aims to assess the importance of three groups of factors: environment, non-chemical management (all management excluding herbicides), and chemical weed management, in determining the weed species composition of oil pumpkin crops in Hungary. We surveyed the weed flora of 180 oil pumpkin fields across the country, along with 32 background variables. Applying a minimal adequate model consisting of 18 terms with significant net effects, 30.8% of the total variation in weed species data could be explained. Most variation in species composition was determined by environmental factors, with climatic conditions (precipitation and temperature) being most influential. The net effects of seven non-chemical management variables (preceding crop, N and P fertilisers, seeding rate, crop cover, cultivating tillage, and manual weed control), and two herbicides (S-metolachlor and linuron) were also significant. Variation partitioning demonstrated the dominance of environmental factors, and it also showed that non-chemical management practices accounted for five times more variance than herbicides. Within non-chemical management, the relative impact of cultural variables was nearly five times larger than that of mechanical weed management. Among the abundant weeds, Chenopodium polyspermum and Ambrosia artemisiifolia were positively associated with precipitation, Datura stramonium and Hibiscus trionum correlated with higher temperature, and Chenopodium album favoured larger potassium content of the soil. High seeding rate and crop cover suppressed Amaranthus retroflexus, cultivating tillage reduced Ambrosia artemisiifolia and Setaria pumila, while conspicuous tall weeds like Abutilon theophrasti and Chenopodium album were most vulnerable to manual weed control. Although the short stature of pumpkin with its poor weed-suppressive ability could unfavourably influence the results of some cultural practices, our findings suggest that the weed vegetation of oil pumpkin fields can be efficiently managed also with environmentally benign methods.

Invasive ant (Anoplolepis gracilipes) disrupts pollination in pumpkin

Yellow crazy ant (Anoplolepis gracilipes (F. Smith); “YCA”) is known for its aggressive predatory ability and ability to exert exploitation competition on both native and other invasive ants via floral nectar. We argue that YCA invasion can exert both interference and exploitation competition on legitimate pollinators. In pumpkin fields (Cucurbita maxima L.) of south India, YCA infested the flowers, particularly the pistillate flowers, for nectar foraging. Pumpkin is a honey bee-mediated cross-pollinated monoecious plant that produces disproportionately very few pistillate flowers. We hypothesize that YCA presence in the flowers can affect the visitation rate and foraging time of honey bees in the flowers, the fruit set in pumpkins, and can exert predatory pressure on the honey bees if the bees linger in ant-colonized flowers. Both YCA and honey bees preferred to forage on the limited pistillate flowers in the plants. After colonizing the flowers, YCA did not retreat for hours, even upon disturbance by competitors, such as honey bees. Both the visitation frequency and the foraging time of honey bees were drastically reduced in ant-colonized flowers, and none of the ant-colonized flowers developed into fruits, suggesting that the YCA exert both an ecological and evolutionary pressure on pumpkin. The ants preyed upon about 17% of the honey bees that lingered in ant-colonized flowers, and the time the bees spent foraging predicted the fate of the bees. Exploitation competition exerted by the YCA on pumpkin may have far-reaching consequences for the pollination and productivity of this cash crop.