Effects of pesticide practices on insect biodiversity in peach orchards

To examine the effects of pesticides on insect biodiversity, a population survey was conducted in conventionally managed, low-input, and organic peach orchards. Pitfall traps were used to sample a total of 6489 insects representing 151 species at seven study sites. Results of a population survey suggest that pesticide application adversely affected insect biodiversity in peach orchards and that the magnitude of the adverse effect might be greater for herbicide application than for insecticide application. The usefulness of carabids and ants as biological indicators of the effects of pesticides was also evaluated. Results suggest that the ant species Tetramorium tsushimae is a good indicator in peach orchards. In contrast, carabids are not suitable indicators.     

Efficiency of Malaise traps and colored pan traps for collecting flower visiting insects from three forested ecosystems

Pan and Malaise traps have been used widely to sample insect abundance and diversity, but no studies have compared their performance for sampling pollinators in forested ecosystems. Malaise trap design and color of pan traps are important parameters that influence insect pollinator catches. We compared pan trap (blue, yellow, white, and red) and Malaise trap catches from forests in three physiographic provinces (Piedmont, Coastal Plain, and Blue Ridge) of the southeastern United States. Similarities in trap performance between sites were observed with blue pan traps being most effective overall. Our results showed that various pollinator groups preferred certain pan trap colors and that adding color to Malaise traps influenced insect pollinator catches. However, pan traps generally caught more pollinators than Malaise traps. Because of their low cost and simplicity, using several colors of pan traps is an effective way to sample relative abundance and species richness of flower-visiting insects.     

Organic versus conventional management in an apple orchard: effects of fertilization and tree-row management on ground-dwelling predaceous arthropods

1 Organic and conventional management of apple orchards may have a different effect on arthropod communities.
2 We conducted a 3-year study to assess the effect of two strategies of fertilizer treatment (organic versus chemical) and three tree-row management systems (straw mulching, tillage and herbicide) on activity-density and biodiversity of epigeic predators. Ground beetles (Carabidae), rove beetles (Staphylinidae), ants (Formicidae) and spiders (Araneae) were sampled monthly with pitfall traps in the same apple orchard during 2003, 2004 and 2005.
3 A total of 4978 individuals were collected. Carabids (56.8% of the total catches) were the most abundant taxonomic group, followed by spiders (20.7%), ants (14.8%) and rove beetles (7.7%). Tree-row management had a greater influence on predator catches than fertilizer treatment. Total predator catches were lower under the mulch. Mulching also reduced carabid abundance, but increased staphylinid catches.
4 Tree row management also had a significant effect on biodiversity parameters. Species richness did not significantly differ among treatments for ants, spiders or the total catches, but was higher on herbicide-treated plots for carabids and on mulched plots for staphylinids. Shannon–Wiener's diversity index was significantly greater in the mulched and herbicide treated plots for total predators and carabids. For staphylinids, this index was significantly greater on the mulched plots. Fertilizer application strategy only influenced the species richness of rove beetles, which was greater in the chemically-treated plots.
5 The results showed that a change from conventional to organic fertilizer treatment of apple trees may be performed without differential effects on predator activity-density or biodiversity. However, a change from herbicide treatment to mulching or mechanical weed control may be significant, depending on the taxonomic group.     

A preliminary study of insect abundance on West Island,Aldabra Atoll,Indian Ocean

• 1 Heath and Rothamsted light traps and a Johnson-Taylor suction trap were used to sample flying insects on Aldabra Atoll.
• 2 The present study extended over two wet seasons. The pattern of relative monthly insect activity resembled the rainfall pattern. Catches were greatest during the months when there was a sudden marked increase in precipitation.
• 3 Lepidoptera dominated light trap catches and Diptera suction trap catches, the total monthly insect numbers therefore reflecting the abundance of these two orders. Hemiptera, Coleoptera and Hymenoptera were also common.
• 4 Predominant families were represented by only a few or even only one dominant species. These species were present throughout the study period although their monthly totals varied considerably, different species dominating the catches during different months.
• 5 The composition and size of catches in the three light traps was affected by the type of light source and surrounding vegetation.
• 6 A comprehensive list of families and selected common species is given with their relative monthly abundance in the light traps.
• 7 Suction trap catches were segregated on an hourly basis to give a broad indication of insect flight periodicity.

     

Using insect traps to increase weaver ant (Oecophylla longinoda) prey capture

Weaver ants (Oecophylla spp.) are managed in plantations to control insect pests and are sometimes harvested as a protein‐rich food source. In both cases, the amount of insect prey caught by the ants is imperative for returns, as more prey leads to more effective biocontrol and to a higher production of ants. Malaise‐like traps placed in trees may catch flying insects without catching ants, as ants may use pheromone trails to navigate in and out of the traps. Thus, ants may increase their prey intake if they are able to extract insects caught in traps. In a mango plantation in Tanzania, we estimated the amount of insects caught by simple traps (cost per trap = 3.9 USD), and whether Oecophylla longinoda was able to collect insects from them. On average, a trap caught 110 insects per month without catching any weaver ants. The number of insects found in traps with ant access was 25% lower than in control traps (ants excluded), showing that ants were able to gather prey from the traps. Ant activity in traps increased over time, showing that prey extraction efficiency may increase as ants customize to the traps. The prey removed from traps by ants constituted 5% of the number of prey items collected by O. longinoda under natural conditions (without traps), potentially increasing to 14% if ants learn to extract all insects. Thus, prey intake may be increased with 5–14% per 3.9 USD invested in traps. These numbers increased to 38 and 78%, respectively, when light was used to attract insects during night time. Combining ant predation with insect trapping is a new approach potentially building increased returns to ant biocontrol and to ant entomophagy.     

Optimising coloured pan traps to survey flower visiting insects

Colour is an important attractant for many flower-visiting insects (anthophiles). Consequently, coloured pan trapping is an efficient technique that can be easily and cost-effectively used to quantitatively sample assemblages of anthophiles. However, colour preferences of anthophiles is an important source of bias that needs to be considered in pan trap surveys. By drawing sub samples comprised of different colour combinations from a database of pan trap surveys in the lowlands of the Cape Floristic Region, we examine the effects of colour on pan trap catches and determine which combinations of colours might provide better estimates of diversity when sampling with multi-colour sets of pan traps. Pan trap catches included the major groups of anthophiles in the region (Coleoptera, Diptera and Hymenoptera), but butterflies (Lepidoptera) were strongly under-represented. Colour played an important role in determining the species richness and composition of pan trap catches, with colour sets that included high reflectance yellow and white generally having catches with the highest species richness. While all colour combinations provided reasonable estimates of proportional species richness, proportional abundance of taxa varied among different colour sets, and did not accurately reflect actual proportions of different taxa in the entire dataset. For comparative biodiversity surveys and assessments we recommend the use of high reflectance colours such as white and yellow traps, while for full inventory surveys, it may be necessary to include other colours to catch rarer species that are excluded by the high reflectance colours alone.     

Entomofauna associated to horticultural crops under organic and conventional practices in Córdoba, Argentina

Farming practices and the addition of chemical synthetic substances in conventional agroecosystems are detrimental mainly to natural enemies of phytophagous insects, diminishing the natural regulation of pest insects. On the other hand, in organic agriculture, biological processes and care of the environment are favoured, hence an increase in insect biodiversity is predicted in this type of systems. In this work, abundance, richness of insects and proportion of functional groups were compared through a single quantitative sampling of insects in horticultural crop fields, three under organic and three under conventional management practices. Insect species richness, total and for guilds (phytophagous and entomophagous insects) were significantly higher in organic orchards, and also was the abundance of entomophagous insects. Richness and abundance of all insect orders (with exception of Homoptera abundance), were higher in orchards under organic management, being significative the differences for richness of Coleoptera and richness and abundance of Hymenoptera. Similar tendencies were observed in data obtained through sweep net in weeds. These results suggest that organic practices increase the diversity of species, particularly that of natural enemies.     

Aphid (Hemiptera: Aphididae) species composition and potential aphid vectors of plum pox virus in Pennsylvania peach orchards

Plum pox, an invasive disease recently identified in Pennsylvania stone fruit orchards, is caused by the aphid-transmitted Plum pox virus (genus Potyvirus, family Potyviridae, PPV). To identify potential vectors, we described the aphid species communities and the seasonal dynamics of the dominant aphid species within Pennsylvania peach orchards. Aphids were trapped weekly in 2002 and 2003 from mid-April through mid-November within two central Pennsylvania orchards by using yellow and green water pan traps. In total, 42 aphid species were identified from both orchards over 2 yr. Within orchards, actual species richness ranged from 24 to 30 species. The Abundance Based Coverage Estimator predicted species richness to range from 30 to 36 species, indicating that trap catches were identifying most aphid species expected to occur in the orchard. Three species, Rhopalosiphum maidis (Fitch), Aphis spiraecola Patch, and Myzus persicae (Sulzer), were consistently dominant across locations and years. Orchard-trapped populations of these three species peaked in a similar chronological sequence each year. As expected, trap color influenced the total number and distribution of the predominate species collected. However, the same dominant species occurred in both yellow and green traps. Based on the seasonal population dynamics reported here and on published vector efficacy studies, the most probable significant PPV vector was identified as A. spiraecola. If the PPV pathogen escapes current quarantine or if subsequent reintroductions of PPV occur, these data will be useful for developing plum pox management strategies.     

Attraction of Bactrocera dorsalis (Diptera: Tephritidae) and nontarget insects to methyl eugenol bucket traps with different preservative fluids on Oahu Island, Hawaiian Islands

Attraction of oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), and nontarget insects to preservative fluids ethylene glycol antifreeze, propylene glycol antifreeze, or mineral oil in bucket traps that contained captured decaying male oriental fruit flies, a male lure (methyl eugenol), and a toxicant (DDVP vapor insecticidal strip) were compared with dry control traps. Significantly (P < 0.05) greater numbers of B. dorsalis were captured in propylene glycol antifreeze traps than in other attractant trap types. Among attractant trap types with lowest negative impacts on nontarget insects, control traps captured significantly lower numbers of three species and one morphospecies of scavenger flies, one species of plant-feeding fly, and one species each of sweet-and lipid-feeding ants. Mineral oil traps captured significantly lower numbers of two species of scavengers flies and one morphospecies of plant-feeding fly, and one species of sweet-feeding ant. Because of the fragile nature of endemic Hawaiian insect fauna, the propylene glycol antifreeze bucket trap is best suited for use in environments (e.g., non-native habitats) where endemic species are known to be absent and mineral oil traps are more suited for minimizing insect captures in environmentally sensitive habitats.     

Visual Responses of Adult Asian Citrus Psyllid (Hemiptera: Liviidae) to Colored Sticky Traps on Citrus Trees

The effects of five differently-colored sticky traps in capturing adult Diaphorina citri were evaluated in citrus orchards. Trap catches of D. citri were monitored fortnightly on blue, green, red, white and yellow sticky cards placed on three citrus varieties during D. citri active flight period from April to July in south Texas. Evaluation of mean trap catches of each color by repeated measures analysis of variance produced three separate groups: yellow traps caught significantly more D. citri adults than the other four traps; red and green traps caught significantly more D. citri than blue and white traps, which were not significantly different. Although the number of adult psyllid captured on all trap types significantly increased with time during the trapping period, the performance of traps did not change with time. Trap catches were also significantly influenced by the citrus species; traps placed on lemon trees captured more D. citri than those placed on sweet orange and grapefruit, suggesting that plant preference exhibited by D. citri may influence the performance of traps. The ratio of trap reflectance between the 680 to 700 nm and the 450 nm was significantly correlated with total trap catches in all host species studied. Thus, this index was a good indicator of the attractiveness of adult D. citri to colored traps. Additionally, we compared the reflectance values of young versus mature flush shoots of the three host plants used in this study as related to densities of D. citri recorded in colored traps. We discussed the importance of visual cues in the host finding behavior of adult D. citri.     

Adult aquatic insects: Potential contributors to riparian food webs in Australia's wet–dry tropics

Abstract Changes in the abundance and biomass of aquatic and terrestrial aerial insects with distance (mid‐stream, 0, 10–15 and 160 m) from lowland streams were examined across the dry season landscape in Kakadu National Park, northern Australia. Malaise traps and sticky intercept traps were used to sample the insects at four streams, spaced over an area of 1650 km². Malaise and intercept catches were dominated by Diptera (flies and midges), both numerically and by biomass. Chironomid midges were the most abundant taxon, making up 43.4 and 51.0% of the malaise and intercept trap catches, respectively. However, most chironomids were small (less than 3 mm body length), contributing 34.9% to intercept trap biomass, but only 5.2% in malaise traps. Ceratopogonid midges and caddisflies (Trichoptera) accounted for most of the remaining adult aquatic insects. Major terrestrial components were Diptera and Hymenoptera in malaise traps and Coleoptera and Diptera in intercept traps. The total abundance and biomass of insects were much greater over streams and along the water's edge than in riparian (10–15 m) and savanna (160 m) habitats primarily because of the presence of large numbers of adult aquatic insects. The abundance and biomass of terrestrial insects in malaise traps showed no relationship with distance, but intercept trap catches suggested slightly greater abundances over the water and at the water's edge. The great abundance of aquatic insects relative to terrestrial insects close to streams suggests that they have the potential to be an important component of the diets of riparian insectivores, and predation may be an important pathway by which aquatic nutrients and energy are moved into terrestrial food webs.     

Effects of habitat type and trap placement on captures of bark (Coleoptera: Scolytidae) and longhorned (Coleoptera: Cerambycidae) beetles in semiochemical-baited traps

Two studies were conducted to determine the effect of habitat selection and trap placement on catches of Scolytidae and Cerambycidae (Coleoptera) in northeastern U.S. forests. In a nonreplicated case study, four habitat types--closed canopy hardwood stand, closed canopy conifer stand, a low-intensity thinned Pinus strobus L. stand, and a high-intensity thinned P. strobus stand--were surveyed using alpha-pinene, ethanol, ipsenol, ipsdienol, and lanierone. Average trap catches, species richness, and the number of unique species captured were all highest in at least one of the thinned habitats. A second experiment that was replicated evaluated the placement of traps in relation to habitat patches. Semiochemical-baited traps (alpha-pinene and ethanol) were placed under a closed canopy forest, along an edge, and in a clearing and tested for effects on Scolytidae and Cerambycidae trap catches. Abundance and species richness were generally higher in the closed canopy and edge placements compared with traps in the open area. The highest number of unique species were captured in the edge and clearing.     

The role of odour and visual cues in the pan-trap catching of hoverflies (Diptera: Syrphidae)

Coloured pan traps are frequently used to attract and catch insects, such as in the monitoring of populations of beneficial insects in classical or conservation biological control. They are also used in the evaluation of the recovery of insect populations after disturbance and in many other situations where an estimate of relative insect numbers is required. However, the fact that traps may be visible to the insects over a considerable distance can influence the interpretation of catch data. This difficulty may arise, for example, if traps along a transect can attract insects from some or all of the other transect positions. This study compared the effect of different coloured traps on attraction and catch of hoverflies. The hypothesis was that completely yellow traps would attract hoverflies from a distance, while traps that were green outside and yellow inside would catch fewer flies because only those from above or near the trap can see the yellow stimulus. A subsidiary hypothesis was that rose water would enhance hoverfly capture rates. For the two main hoverfly species captured, Melanostoma fasciatum (Macquart) and Melangyna novaezelandiae (Macquart), significantly more individuals were caught in completely yellow traps than in yellow and green or in completely green traps. Moreover, the addition of rose water increased the number of hoverflies caught significantly. It is suggested that if a measure of hoverfly numbers relating to a particular distance along a transect is required, consideration should be given to the ability of hoverflies to see yellow traps from a distance. The use of traps that are green outside would more accurately reflect the local abundance of hoverflies. If higher trap catches of hoverflies are needed for statistical purposes, rose water can enhance catches.     

THE COMPARISON OF SUCTION TRAP, STICKY TRAP and TOW-NET FOR THE QUANTITATIVE SAMPLING OF SMALL AIRBORNE INSECTS

The sticky trap and stationary aerial 'tow-net' catch insects which alight or fly on to them or are blown against them by the wind. It would be expected that such traps would be inefficient in light winds or in calm weather; and even though their efficiency should increase with stronger winds, errors of unknown magnitude may occur not only in estimations of density and of proportions of species in the air, but also with comparisons of actual catches. These errors are due to unknown degrees of weighting as the traps sample by means of a variable wind from a changing population density. The suction trap, on the other hand, samples a constant quantity of air in all relevant wind-speeds and does not appear to suffer so seriously from these disadvantages. It also works efficiently in perfectly calm weather when maximum densities of insects are often in the air.
The performances of the three traps in the field operating over a range of wind-speeds are described. Particular attention has been paid to aphids, for which the sticky trap and tow-net are generally used and for which the suction trap was primarily designed. Density estimates of these insects in winds below about 3 m.p.h. are much larger when calculated from suction trap catches as compared with estimates from sticky trap and tow-net catches. There is reason for the belief that the suction trap is neither attractive nor repellent to aphids to a significant extent, and that it catches these insects at random by virtue of its air stream alone; weighting of catches due to variable quantities of air being sampled does not occur. It is considered, therefore, that the suction-trap values of density are likely to be the more accurate ones. Sampling of other small insects is also discussed.     

紫胶虫蜜露对地表蚂蚁多样性的影响

2009年12月至2010年5月,采用陷阱法在云南省墨江县雅邑乡调查了紫胶林地表蚂蚁群落多样性,分析了紫胶虫蜜露对地表蚂蚁多样性的影响.结果表明:紫胶虫蜜露资源的有无及变动对地表蚂蚁群落物种组成、多度及多样性均产生影响.在紫胶林样地共采集蚂蚁标本4953头,隶属5亚科23属34种,在对照样地共采集蚂蚁标本2416头,隶属5亚科20属30种;紫胶林地表蚂蚁相对多度、物种丰富度(S)及ACE估计值均高于对照样地,地表蚂蚁常见种和指示种均与对照样地不同,表明放养紫胶虫改变了地表蚂蚁群落结构;紫胶虫成虫期蜜露分泌量高于幼虫期,其地表蚂蚁相对多度、S及ACE估计值也高于幼虫期,且两阶段的蚂蚁常见种和指示种显著不同.     

Slippery or sticky? Functional diversity in the trapping strategy of Nepenthes carnivorous plants

The pitcher-shaped leaves of Nepenthes carnivorous plants have been considered as pitfall traps that essentially rely on slippery surfaces to capture insects. But a recent study of Nepenthes rafflesiana has shown that the viscoelasticity of the digestive fluid inside the pitchers plays a key role. Here, we investigated whether Nepenthes species exhibit diverse trapping strategies. We measured the amount of slippery wax on the pitcher walls of 23 taxa and the viscoelasticity of their digestive liquid and compared their retention efficiency on ants and flies. The amount of wax was shown to vary greatly between species. Most mountain species exhibited viscoelastic digestive fluids while water-like fluids were predominant in lowland species. Both characteristics contributed to insect trapping but wax was more efficient at trapping ants while viscoelasticity was key in trapping insects and was even more efficient than wax on flies. Trap waxiness and fluid viscoelasticity were inversely related, suggesting the possibility of an investment trade-off for the plants. Therefore Nepenthes pitcher plants do not solely employ slippery devices to trap insects but often employ a viscoelastic strategy. The entomofauna specific to the plant's habitat may exert selective pressures, favouring one trapping strategy at the expense of the other.     

Ground beetle (Coleoptera: Carabidae) assemblages in conventional and diversified crop rotation systems

Ground beetles (Coleoptera: Carabidae) are important in agro-ecosystems as generalist predators of invertebrate pests and weed seeds and as prey for larger animals. However, it is not well understood how cropping systems affect ground beetles. Over a 2-yr period, carabids were monitored two times per month using pitfall traps in a conventional chemical input, 2-yr, corn/soybean rotation system and a low input, 4-yr, corn/soybean/triticale-alfalfa/alfalfa rotation system. Carabid assemblages were largely dominated by a few species across all cropping treatments with Poecilus chalcites Say comprising >70% of pitfall catches in both years of study. Overall carabid activity density and species richness were higher in the low input, 4-yr rotation compared with the conventionally managed, 2-yr rotation. There were greater differences in the temporal activity density and species richness of carabids among crops than within corn and soybean treatments managed with different agrichemical inputs and soil disturbance regimes. Detrended correspondence analysis showed strong yearly variation in carabid assemblages in all cropping treatments. The increase in carabid activity density and species richness observed in the 4-yr crop rotation highlights the potential benefits of diverse crop habitats for carabids and the possibility for managing natural enemies by manipulating crop rotations.     

Comparison of pheromone-mediated mating disruption and conventional insecticides for management of tufted apple bud moth (Lepidoptera: Tortricidae)

Large-plot studies were used to compare pheromone-mediated mating disruption and conventional insecticide applications for management of tufted apple bud moth, Platynota idaeusalis (Walker), in North Carolina in 1993 and 1994. Pheromone trap catches were reduced in mating disruption blocks, and traps placed in the lower stratum of the canopy had a higher level of trap capture reduction compared with traps placed in the upper stratum. First-generation tufted apple bud moth exposure to either pheromones for mating disruption or insecticides affected second generation pheromone trap catches in the lower and upper canopy. More second generation male moths were caught in pheromone traps placed in the upper compared with the lower canopy in blocks treated with pheromones for mating disruption during the first generation, whereas the opposite was true in blocks treated with insecticides during the first generation. Despite reduced trap catches in pheromone-treated blocks, egg mass densities were not reduced in these blocks compared with insecticide-treated blocks. Furthermore, fruit damage was not significantly different between mating disruption blocks and conventionally treated blocks in orchards with relatively low populations of tufted apple bud moth, but damage was greater in mating disruption blocks in orchards with higher moth densities.     

农田景观格局对南疆枣园传粉昆虫群落多样性的影响

[目的]明确新疆南疆地区农田景观格局对枣园传粉昆虫群落多样性的影响.[方法]2019和2020年在新疆阿克苏地区共选取29个试验站点,通过陷阱诱集法获取中心枣园内传粉昆虫多样性数据,调查中心枣园周围半径2 000 m范围内土地使用信息,建立枣园传粉昆虫群落指数与景观变量之间的线性混合模型,使用基于赤池信息准则的多模型推...     

Optimization of traps for live trapping of Pine Wood Nematode vector Monochamus galloprovincialis

The pine sawyer beetle Monochamus galloprovincialis, a secondary pest of pines in Europe and North Africa, has become important as it was identified as the vector in Europe of Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD). An effective trapping system is needed, not only for monitoring the insect vector but also for direct control of its population. Trapping may also provide key information on the nematode load carried by the beetles, allowing early detection of infections, provided that captured beetles remain alive within the trap. Highly effective attractants have been developed in recent years that are commonly used in combination with diverse standard trap designs. In this study, several trap designs were developed and compared to commercial standard models in order to determine which designs maximized the number of attracted insects actually caught and the proportion of them remaining alive. In total, 12 trap designs were evaluated in five field experiments carried out in France, Spain and Portugal. Teflon coating applied to the whole trap and extended, ventilated collecting cups resulted in a significant improvement of trap performance. These modifications led to significant increases of pine sawyer catches, up to 275%, when applied to multiple‐funnel or black cross‐vane traps, compared to standard designs. Furthermore, a significant proportion of the captured beetles remained alive within the trap. These findings have been used to develop new commercial traps (Econex Multifunnel‐12^® and Crosstrap^®; Econex, Murcia, Spain) available to forest managers. A model for insect survival within the trap was also fitted. Elapsed time between consecutive samplings, mean relative humidity and maximum radiation were the three most significant variables. Thus, traps should provide a suitable sample of live insects if sun exposure of the trap is minimized and a reasonable sampling schedule is implemented.