Yellow Pan Research Articles

APHID SURVEILLANCE IN POTATO FIELDS: IMPLICATIONS FOR VIRUS MANAGEMENT AND TUBER QUALITY

Aphids are the most common and effective carriers of plant viruses. The transmission of potato viruses is primarily linked to the activity of winged aphids. This study monitored migratory aphids in a seed potato field during 2020 and 2021, utilizing yellow water pan traps placed at varying distances from the field edge (20, 50, and 80 meters) to gather spatial and temporal data on the activity of winged aphids within the seed potato field. Throughout the monitoring period, 922 aphids from 65 species were identified in 2020, while 2,508 aphids from 84 species were recorded in 2021. In both years, the highest number of aphids was collected from the trap positioned at the edge of the potato crop at 20 meters. Regarding the total abundance of vector aphid populations and species, in 2021 higher values were recorded than in 2020: 1227 vector aphids from 20 species in 2021 compared with 528 vector aphids from 17 species. In comparison to 2020, the level of virus infection in the tested material was highest in 2021 across all varieties, with the most significant increases noted for the PVM and PVY viruses. Aphids play a significant role as viral vectors in potatoes, impacting tuber quality by transmitting several damaging viruses, most notably the potato virus Y (PVY) and potato leafroll virus (PLRV). These viruses, can lead to a range of quality issues in the tubers, such asstarch and dry matter content.

Diversity of cereal pests (wheat and barley) grown in arid climate in Ziban region (provence of Biskra- southeastern Algeria)

This study investigated cereal pests (wheat and barley) grown in southeastern Algeria's arid climate. Using three sampling techniques (yellow pan traps and Pitfall traps, a comprehensive collection of insect specimens was obtained, comprising 2526 individuals taxonomically classified into 20 distinct species, 15 genera, ten families, and six orders. Homoptera and according to quantitative analysis, Thysanoptera was the most dominant taxa, with six and four occurrences, respectively. In contrast, the dominant species were Mayetiola destructor (Say 1817) (Diptera, Cecidomyiidae) with 412 specimens, Rhopalosiphum maidis (Fitch 1856) (Homoptera, Aphididae) with 404 specimens then Oulema melanopa (Linné 1758) (Coleoptera, Chrysomelidae) with 342 specimens. The observed and expected species richness diversity parameters were comparatively more significant in the cereal ecosystem cultivated in the El Outaya location than in the Sidi Okba location. (Kruskal–Wallis, df = 3, P = 0.019). The results obtained from the Generalised Linear Models (GLM) indicated a statistically significant variation in species richness across the different sites and crops (wheat and barley) (df = 3, Mean Square = 47.70, F = 3.58, P = 0.020).While there were very significant differences in the average number of individuals per species (N/S ratio) (df = 3, mean square = 22.08, F = 5.526, P = 0.002). Species richness extrapolation revealed that diversity is anticipated as the number of individuals captured increases, however, at a slower rate as the sampled population increases. The species distribution showed that some insect species are found at all phenological stages and all sampling sites.

Blue Vane and Pan Traps Are More Effective for Profiling Multiple Facets of Bee Diversity in Subtropical Forests.

The choice of trap in entomological surveys affects the composition of captured insects, though previous comparative studies have been limited in the types of composition measured, and the effects of environmental context. We assessed the sampling bias of several traps commonly used in pollinator monitoring: blue, yellow, and white pan traps, and blue vane traps, towards different taxonomic and functional groups and their efficiency in measuring taxonomic, phylogenetic, and functional diversity. Analyses were performed in monoculture and mixed forests to understand the environmental context of trap efficiency. We found that blue pan traps generally outperformed other types in bee capture and exhibited a preference for Halictidae bees. Blue pan traps yielded the highest species richness and phylogenetic diversity, while blue vane traps captured the highest functional richness. Bias differences were frequently detected in mixed forests compared with monoculture forests. We also found the combination of blue vane and pan traps consistently correlated highest with a complete survey among two-method combinations. Based on our findings, we recommend a combination of blue vane and pan traps to obtain a more comprehensive bee collection in an efficient manner. Additionally, it is crucial to consider habitat type when designing bee trapping protocols to ensure an accurate representation of bee communities.

Differences in sampling efficiency of each insect order in yellow pan traps with installation of flight interception windows

AbstractTo monitor insect diversity and community changes, it is necessary to select traps with a high sampling efficiency. We examined the effects of a flight interception window on a small yellow pan trap (flight interception pan; FIP). Our results showed that fewer Hymenoptera individuals were captured by the FIP than by the non‐FIP (NFIP) traps. Fewer Aculeata, Diptera and Hemiptera individuals were captured by the FIP than by the NFIP traps, whereas more Coleoptera individuals were captured by the FIP than by the NFIP traps. The flight interception window did not affect the Aculeata species composition. Considering the labor involved in attaching windows and the reduced ease of trap transport and setting, the NFIP traps are better for sampling Hymenoptera, Diptera and Hemiptera, whereas the FIP traps are better for sampling Coleoptera.

One-step TaqMan® RT-qPCR detection of sugar beet-infecting poleroviruses in Myzus persicae from yellow water pan traps opens up new possibilities for early risk assessment of virus yellows disease

Virus yellows disease (VY) is a major threat to sugar beet production in Europe. Beet chlorosis virus (BChV) and beet mild yellowing virus (BMYV) are of particular economic importance and are both persistently transmitted by the aphid vector Myzus persicae. As part of integrated pest management strategies, M. persicae influx into sugar beet fields is recorded weekly using yellow water pan traps. To date, only ELISA and RT-PCR assays have been described for BChV and BMYV detection in individual aphids. In this study, we describe for the first time two one-step TaqMan® RT-qPCR assays designed for the specific detection of BChV and BMYV in M. persicae after 7d incubation in water pan trap medium. Both viruses were reproducibly detected in individual aphids. After 7d incubation in trap medium, both viruses were reproducibly detected in individual aphids, as well as in one viruliferous aphid in a pool of 99 non-viruliferous aphids. Significant correlations can be shown between different mixing ratios of viruliferous to non-viruliferous aphids and Ct values of total RNA templates, allowing the percentage of viruliferous aphids in yellow water pan traps to be estimated using a standard curve. The described methodology provides a high sensitivity combined with a high sample throughput and can be used, after evaluation in the field, for practical monitoring, risk modelling and development of decision support systems for VY.

Wild Bee Conservation in Viticulture: Effects of Semi-Natural Habitats, Organic Management, and Fungicide Reduction.

In agricultural landscapes, the removal of semi-natural habitats (SNH) and the intensive use of pesticides contribute to declines of biodiversity, including crop pollinators such as bees (Hymenoptera: Apoidea). However, effects of pesticide use and landscape characteristics on bees have rarely been studied together. In this study, we investigated how SNH in the surrounding landscape, organic and conventional management, and the reduction of fungicides affect wild bee diversity in 32 vineyards in southwest Germany. We used yellow pan traps to sample bees in a crossed design of management (organic vs. conventional) and fungicide use (reduced in fungus-resistant grape varieties vs. regular) along a gradient with increasing proportions of SNH in the surrounding landscape. Higher proportions of SNH influenced species composition of bees and increased the abundance and richness of above-ground-nesting species. Organic vineyards had a 49% higher abundance of bees compared to conventional vineyards. The reduction of fungicides did not affect bee diversity nor abundance. The absence of a response to fungicide intensity suggests that the benefit of organically managed vineyards to wild bees was through differences in their vegetation management, which is in line with the positive response of bees to SNH in the surrounding landscape. Synthesis and applications: Our study underlines that the local provision of diverse vegetation in vineyards and the landscape-scale provision of suitable SNH are key factors for wild bee conservation in viticulture.

Pan Trapping and Malaise Trapping: A Comparison of Bee Collection Techniques in Subalpine Meadows

Public lands, managed for multiple uses such as logging, mining, grazing, and recreation, also support vital environmental services like wild bee pollination. A trending decline in wild bees has heightened interest in documenting these key pollinators in their native habitats. Accurate assessment of pollinator community diversity is crucial for population monitoring and informing land management practices. In this study, we evaluate the efficiency of Malaise traps and pan traps in sampling wild bees over three growing seasons in subalpine meadow communities in central Utah. Sixteen trapping sites were established, each with a Malaise trap and an array of blue, white, and yellow pan traps, nine at each site. Weekly collections were made through summer months and a comparison of their effectiveness in capturing bee abundance and species richness was made. Malaise traps captured significantly greater abundance of bees on average, though this was species-dependent. Malaise traps were especially effective at capturing Bombus spp. and larger species. Pan traps were generally more effective with smaller species such as Hylaeus spp. White pan traps outperformed yellow and blue pan traps in terms of abundance and only yellow pan traps in terms of richness. Both methods contributed unique species to the overall collection effort, suggesting that a combination of trapping methods provides a more comprehensive understanding of bee communities. Species accumulation curves indicate that species existing within the community went unencountered in our samples and that more time or perhaps additional methods could aid in best describing the entire community.

Diversity and Relative Abundance of Insect Pests and Natural Enemies in Organic Rice

A study was conducted to decipher diversity and relative abundance of insect pests, hemipteran predators and hymenopteran parasitoids in organic rice transplanted at the research farm of the Indian Institute of Rice Research, Rajendranagar, Hyderabad during Rabi, 2020. Yellow pan traps, visual count, yellow sticky traps, sweep net and D-net methods were used for collecting insect specimens. A total of 543 insect pest individuals belonging to 12 families, 678 Hemipteran predators belonging to 9 families and 2193 parasitoids of 10 families were collected. The most abundant families among insect pests, predators and parasitoids were Cicadellidae, Miridae and Eulophidae with a relative abundance of 32.41, 81.56 and 72.55%, respectively. Shannon weiner index of insect pests, predators and parasitoids was 1.81, 0.72 and 0.99 respectively. Further, Margelef diversity index of insect pests, predators and parasitoids was 1.75, 1.23 and 1.43, respectively. Furthermore, the Pielou’s eveness index was 0.73, 0.33 and 0.40, respectively. Visual count for pests, yellow sticky traps for predators and parasitoids were adjudged the most effective methods of collection.

Conostigmus nankunensis (Hymenoptera: Ceraphronoidea), a new species from China with a long facial sulcus.

A new species of the megaspiline genus Conostigmus Dahlbom with a distinct facial sulcus is described and figured from material collected in yellow pan traps. Conostigmus nankunensis Qian and Wang sp. nov., is the fifth species of Conostigmus described from China.

Manipulating the community structure of arthropods in rice fields with floral resources plants

Abstract Conservation biological control encourages natural enemies to suppress target pests through manipulation of environmental factors that influence natural enemy survival and effectiveness, including microclimates, availability of food for adults and alternative prey, and shelter from adverse environmental conditions. This study aimed to identify selective flowering plants that could be used to manipulate the arthropod community structure in rice fields. Three rice fields (a field without resources of flowering plants, a field with vegetable crop, and a field with ornamental plant) were used in this experiment. The flowering plants included Helianthus sp., Catharanthus roseus, and Cosmos sulphureus while the vegetable plants included eggplant, cucumber, and long beans. Arthropod recording was carried out by direct observation and yellow pan traps from 14 to 98 days after planting. We recorded 33,728 arthropods representing 153 species in 68 families, 13 orders, and 2 classes. The presence of flowering plant significantly affects abundance, species richness, diversity index, and evenness of arthropods both in dry and wet seasons. The rice field surrounded with ornamental plants or vegetables showed the lowest abundance of phytophagous arthropods, the highest abundance of parasitoid and predatory arthropods. Therefore, vegetable crops such as cucumber, long beans and eggplant have great opportunities as refugia in rice fields.

Variations in the relative abundance of hemipteran species in different seasons and stages of rice growth depending on weather variations

Rompin has played an active role in Malaysia's rice production for several decades. However, it also faces a threat, particularly from the hemipteran insect pests. There is limited documentation on the abundance of these insects and their relationship with climatic factors. Therefore, this study aimed to determine the abundance of hemipterans in different growth stages and to understand the effects of climatic factors on their population in rice fields. The study was conducted in farmers' rice fields in Rompin, Pahang, Malaysia, during the main and off-season rice planting. Sweep nets, yellow sticky traps, and yellow pan traps were utilized in each plot. Trapped insects were identified based on the rice planting seasons and growth stages. The trends of climatic factors such as rainfall, temperature, light intensity, and wind speed were analysed and correlated with insect abundance. A total of 23,023 individuals belonging to eight families and eleven species of the hemipteran order were recorded. Nine of these species were pests, namely Leptocorisa oratorius, Recilia dorsalis, Nephotettix virescens, N. nigropictus, Amaurochrous dubius, Nilaparvata lugens, Sogatella furcifera, Nezara viridula, and Scotinophara coarctata. The remaining two species were predators, Cyrtorhinus lividipennis and Polytoxus fuscoviftatus. R. dorsalis, N. lugens, S. furcifera, and A. dubius were found in significantly higher numbers and exceptionally high during rice's late vegetative and early reproductive stages. The maximum temperature significantly increased during the main season, while wind speed increased dramatically during the off-season. Wind speed significantly correlated with N. virescens, S. furcifera, L. oratorius, and A. dubius. On the other hand, rainfall exhibited a significant correlation with L. oratorius. Various pest species and their high populations in this study pose a significant threat to plants due to their preferences for different plant parts and strata.

Diversity and community structure of predators in surjan (polyculture) and lembaran (monoculture) paddy fields

Predator diversity decreases because of low ecosystem quality in modern agriculture that applies monoculture systems. However, polyculture systems in paddy fields can improve biodiversity, including pests, natural enemies, and microorganisms. Surjan is a local polyculture farming practice that originated in Yogyakarta. This farming practice consists of raised beds for cultivating palawija or horticultural crops and sunken beds for rice cultivation. Surjan farming may have an impact on predatory diversity and abundance, although this has not been studied. To address this issue, research was carried out to investigate the diversity, abundance, and structure of the community of predators in the paddy fields of surjan (polyculture) and lembaran (monoculture). The field experiment was conducted in three pairs, surjan and lembaran, in Panjatan District, Kulon Progo Regency, Yogyakarta Special Region, Indonesia. In each field, five random plots arranged in a cross pattern were used to collect a sample of predators. Several traps, including sweeping, pitfall traps, yellow adhesive traps, and yellow pan traps, were used to determine the abundance and diversity of predators. Results showed that species diversity, abundance, species composition, and biodiversity index in surjan farming were significantly improved compared to lembaran farming. Ceratopogonidae and Formicidae were the most abundant families in both surjan and lembaran farming, although they are more abundant in surjan. It can be concluded from the study that surjan farming could improve ecosystem quality by implementing predators for pest management.

Assessment of biodiversity and seasonal dynamics of spiders in maize crops of Punjab, Pakistan

Spiders contribute significantly to natural pest control in agriculture. Here, we investigated the biodiversity, population dynamics and predatory activities of spiders in the maize-growing districts (Kasur and Lahore) of Punjab, Pakistan during 2018–2019. Various collecting methods including pitfall and yellow pan traps, manual hand-picking, beat sheet, and sweep nets were used to collect spiders on a biweekly basis. The collected 12,894 individuals represented 45 different species, 27 genera, and 13 families. The major families recorded were Araneidae (32.92%), Lycosidae (20.43%) and Salticidae (11.12%) comprising >64% of the overall abundance. Neoscona theisi (Araneidae) was found to be most dominant species (11.61%). Moreover, the species Macracantha hasselti (Araneidae) and Atypena formosana are reported for the first time from Pakistan. Besides, the estimated species diversity from both districts was 97%. The Margalef's index was highest in Kasur (D = 5.08) and lowest in Lahore (D = 4.95). The values of the Shannon-Wiener and species evenness indices were similar in Kasur and Lahore suggesting similar diversity levels and an even distribution. Spider abundance was highest in April and lowest in June and July. These findings will help to develop effective Integrated Pest Management strategies in maize growing areas across the world.

Field phenology of emerald ash borer (Coleoptera: Buprestidae) parasitoids in New York State.

Emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), has caused extensive mortality of ash across North America. Biological control offers a potential long-term management option, allowing for long-term survival of ash. Careful monitoring of populations of biocontrol agents is necessary to understand their relative impacts. Understanding the emergence and flight phenology of these species allows for the optimization of monitoring schemes and improves our understanding of host-parasitoid interactions. We used yellow pan trapping data to assess the adult phenology of both EAB and its associated native and introduced parasitoids in 3 New York counties. We monitored 2 introduced larval biocontrol agents, Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) and Spathius galinae Belokobylskij & Strazanac (Braconidae), for 3-4 years post-release, as well as the native parasitoid Phasgonophora sulcata Westword (Chalcididae). Results indicate a single discrete emergence event for both EAB and P. sulcata in all monitored counties, which is consistent with previously reported results. Our results also suggest there are 4 generations per year of T. planipennisi and 3 generations of S. galinae in the monitored counties. We recorded an additional generation of T. planipennisi that had not previously been reported in New York, and both T. planipennisi and S. galinae appeared to emerge earlier than previously documented.

Diversity of wasps (Hymenoptera) in alfalfa (Medicago sativa L.) farms in Basrah Governorate, Southern Iraq.

Studies on the diversity of parasitoid wasps in agroecosystems exemplify the first stage of recognizing the best species to be used in biological control programs. There is an increased effort to recognize the diversity of pests in agroecosystems, but information on agricultural environments in Iraq is still unknown. This study is interested in the diversity of wasps in a cultivated area in Basrah governorate and the identification of dominant species for potential application in biological control studies. Samples were collected from alfalfa farms between January and December 2020 using two insect collection methods: sweep nets and yellow pan traps in four stations in Basrah governorate. This paper confirms that there is a high diversity of wasp species in agricultural environments. During this study, 18 wasp species were recorded for the first time in Iraq. Gronotoma micromorpha recorded the highest annual relative abundance value of 26.5%, while Chalcis biguttata recorded the lowest relative abundance of 0.89% in most agricultural environments. Numerous studies on G. micromorpha indicate that it is a parasitoid of Liriomyza species (Diptera). Thus, this species may be an important agent in the biological control of this pest.

First record of Apanteles hemara (N.) on Leucinodes orbonalis Guenée and biodiversity of Hymenoptera parasitoids on Brinjal.

The brinjal fruit and shoot borer (BFSB), Leucinodes orbonalis Guenée (Lepidoptera: Crambidae), is a very detrimental pest that causes significant economic losses to brinjal crop worldwide. Infested brinjal fruits were collected from vegetable fields located at the ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, India, during two consecutive seasons (2021-2022). The larvae of the pest were brought to the laboratory and reared under controlled conditions of 25 ± 0.5 °C and 70 ± 5% relative humidity, for the emergence of parasitoids. In addition, the survey of Hymenoptera parasitoids in brinjal was conducted utilizing a sweep net and yellow pan trap over the course of two seasons. The results reveal that five parasitoid species were emerged from L. orbonalis viz., Apanteles hemara Nixon, 1965, Bracon greeni Ashmead 1896 (Hymenoptera: Braconidae), Goryphus nursei (Cameron, 1907), Trathala flavoorbitalis (Cameron, 1907) (Hymenoptera: Ichneumonidae) and Spalangia gemina Boucek 1963 (Hymenoptera: Spalangiidae). Out of these, A. hemara and S. gemina were documented as new occurrences in Delhi. Additionally, A. hemara was recorded for the first time as a parasite on L. orbonalis. Trathala flavoorbitalis was observed during both seasons and exhibited higher parasitism reaching 15.55% and 18.46% in July and August 2022, respectively. However, the average parasitism (%) recorded by A. hemara, B. greeni, G. nursei, T. flavoorbitalis and S. gemina was 3.10%, 1.76%, 1.10%, 9.28% and 1.20% respectively. Furthermore, the findings showed a significant (p ≤ 0.01) strongly positive correlation between fruit infestation (%) by L. orbonalis and parasitism (%). The survey indicates the presence of a broad group (19 families and 60 species) of Hymenoptera parasitoids in the brinjal crop ecosystem in Delhi which could be valuable in biological control. In light of these results, this study revealed that A. hemara and other parasitoids identified in this study alongside T. flavoorbitalis would be ideal biocontrol agents within the integrated pest management (IPM) program of BFSB in Delhi.

The comparison of species diversity and abundance of insect natural enemies in the domesticated species of cotton using the yellow pan trap method.

India is the world's largest cotton producer and the only country that grows all four cultivated cotton species. There have been very few studies on the diversity and abundance of natural enemies of cotton insect pests in these cultivated cotton species. Therefore, the current study (2016-2018) was conducted to assess the diversity and abundance of natural enemies that cultivated cotton species harbour. Phule Dhanwantari, Suraj, Suvin, RCH-2, and DCH-32 were the five genotypes used in the study, each with a distinct genetic background. Using the adiv 2.0.1 and vegan R packages, we identified significant differences in natural enemies in terms of species diversity, richness, evenness, and abundance. Analysis of Similarity (ANOSIM) and Non-metric Multidimensional Scaling (NMDS) indicated substantial differences in the natural enemy community structure among the examined genotypes. A total of 17,279 natural enemies were collected and identified across genotypes from seven predatory families and five parasitoid families. The percentage share of these natural enemy families across genotypes and years, in descending order, is Coccinellidae (28.23%) < Tachinidae (19.23%) < Braconidae (12.68%) < Chrysopidae (11.65%) < Chalcididae (9.41%) < Aphelinidae (6.33%) < Pentatomidae (3.29%) < Ichneumonidae (2.37%) < Syrphidae (2.33%) < Vespidae (1.81%) < Asilidae (1.79%) < Geocoridae (0.89%). Coccinellidae, Tachinidae, Braconidae, Chrysopidae, Chalcididae, and Aphelinidae are the six major families that account for more than 85% of all recorded natural enemies. These six families have a higher percentage share in Phule Dhanwantary (90%) compared to the other genotypes. The conservation and better utilization of these natural enemies are crucial for the ecological and safe management of insect pests in the cotton ecosystem.

The diversity of aerial insect in coffee agroforestry, Dampit and Purwodadi district East Java Indonesia

Coffee is one of the export commodities in Indonesia. East Java is one of the largest Coffee supplies with land that is widely spread, such as in Malang and Pasuruan Regencies. The agroforestry system is applied in coffee cultivation, the system has different management from plantations for example the use of shade trees which will affect the structure of aerial insect diversity. Aerial insects play an important role in maintaining the balance of the ecosystem. The research objective was to determine the diversity and dominance of aerial insects in coffee agroforestry in East Java. The research method is exploratory, taking aerial insects using a yellow pan trap. The abiotic factors observed were light intensity, wind speed, temperature and humidity, and data analysis with past 4.03 program. The results of the study found 407 individuals in Dampit coffee agroforestry and 470 individuals in Purwodadi coffee agroforestry. The diversity and dominance index values were found to be the highest in Dampit coffee agroforestry. From the results of the analysis of abiotic factors, it is found that temperature and humidity in Dampit coffee agroforestry have higher values while wind speed and sunlight intensity of Purwodadi coffee agroforestry have higher values. The differences in the number and types of insects as well as the differences in the diversity and dominance index obtained, explained that the two study sites had differences in abiotic factors and shade trees.

Monitoring of coccinellid (Coleoptera) presence and syrphid (Diptera) species diversity and abundance in southern California citrus orchards: implications for conservation biological control of Asian citrus psyllid and other citrus pests

Abstract The abundance and diversity of three taxa of citrus pest predators, syrphids (Diptera), coccinellids (Coleoptera), and chrysopids (Neuroptera) and their association with flowering weed species in commercial citrus orchards in southern California were investigated. The occurrence and frequency of adult predators were determined with vertical yellow sticky traps and by performing 3 min visual counts on flowering weeds from May through November 2021. Syrphid abundance peaked in June and September, with the dominant species being Allograpta obliqua (Say), Toxomerus marginatus (Say), and Paragus tibialis (Fallen). Peak collections of coccinellids occurred in May, June, and September on sticky traps and during September and October in flowering weedy plants. Peak flowering of weed species occurred during May and declined sharply over summer into fall (June–November). The efficacy of yellow 355 mL glycol pan traps, yellow 1774 mL water pan traps, and yellow sticky traps orientated either horizontally or vertically with respect to capturing key natural enemies was evaluated in 2021 and 2022. Significantly more syrphids were captured on the horizontal yellow sticky traps than on the vertical yellow sticky traps or the yellow pan traps filled with glycol or water. Coccinellids were most frequently captured on vertical yellow sticky traps and yellow water pan traps. Numbers of chrysopids captured in all studies were not significant, which was most likely attributable to their nocturnal behavior. Collectively these results suggest that syrphid and coccinellid activity in southern California citrus orchards displayed two seasonal peaks, one in spring and the other in the fall. In the context of future conservation biological control, insectary plantings in spring (April–June) and fall (September–October) would be most beneficial to these predators and would coincide with population peaks of a key citrus pest, Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae).

Trophic impacts of a rolled‐rye cover crop on the lettuce aphid (Nasonovia ribisnigri) and associated insect fauna in cultivated Histosols

AbstractCultivated peatland (Histosol) in Southern Québec (Canada) is a rapidly declining non‐renewable resource used to grow most Canadian lettuce (Lactuca sativa L., Asteraceae). Rolled‐rye (Secale cereale L., Poaceae) cover crop is one of the conservation practices proposed to reach a more sustainable lettuce production, but the overall impact on the agroecosystem remains poorly studied in Histosols. We assessed multiple effects of rolled‐rye cover crop on the trophic chain associated with the lettuce aphid, Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae), a major pest of lettuce. During one growing season and through two consecutive lettuce crops, we monitored in situ the impacts of rolled‐rye cover crop on insect fauna and lettuce quality. We used visual scouting and yellow pan traps to assess plant colonization by N. ribisnigri, its natural enemies, and alternative prey. Exclusion cage experiments were also conducted to measure aphid fitness and population growth. Under greenhouse conditions, following cover crop removal, we examined potential lingering effects of rye within the soil on lettuce plants and N. ribisnigri. In situ experiments showed that rolled‐rye cover crop has the potential to inhibit N. ribisnigri field colonization and recruit natural enemies and alternative prey in the first lettuce crop. Rye also reduced aphid fitness as well as lettuce foliar amino acid concentration and weight. For the second lettuce crop, an almost 50% reduction in N. ribisnigri abundance was observed with the use of rolled‐rye cover crop. In greenhouse experiments, no persistent effect of rye was observed on the quality of lettuce grown with soil collected under a cover crop, nor on the fitness of aphids inoculated on these lettuces. This study highlights the diversity of trophic effects rolled‐rye cover crop may have on lettuce production in Histosols and the potential of rolled‐rye cover crop as a cultural practice to reduce aphid populations. Mechanisms at play while underlining agronomic challenges regarding proper rye termination must be further explored to maintain high‐performing lettuce yields.