Dominant Predator Species Research Articles

High overlap of zoonotic helminths between wild mammalian predators and rural dogs - an emerging One Health concern?

The concept of One Health emphasizes the interdependence of human, animal and environmental health and is of growing significance, in part owing to the problems related to emerging infectious diseases of wildlife origin. Wild mammalian predators are a potential risk factor for transmission of zoonotic pathogens to domesticated animals and humans. This is especially relevant in rural areas, where transmission of zoonotic pathogens can occur particularly efficiently when free-ranging dogs are present. The main aim of this study was to determine helminth infections among wild mammalian predators and evaluate the overlap between helminth faunas of wild mammals and dogs. Scat samples of predators were collected in coastal areas of Western Estonia and genetic methodology applied for the correct identification of predator species from their scat. Parasitic helminths of mammalian predators in the scat samples were analysed and compared with dog data from a previous study. High helminth prevalence (~90%) was found in dominant predator species in the area, namely the red fox (Vulpes vulpes) and golden jackal (Canis aureus). Moreover, the helminth fauna of both wild species, including potentially zoonotic helminths, overlapped largely with that of rural dogs in the same area. The results, together with the ones from earlier parasitological studies among humans in Estonia, emphasize the potential risk of pathogen transmission from wild mammalian predators to dogs and from dogs to humans, making parasitic diseases of wildlife a One Health concern.

The predator activity landscape predicts the anti‐predator behavior and distribution of prey in a tundra community

AbstractPredation shapes communities through consumptive and non‐consumptive effects. In the latter case, prey respond to perceived predation risk through proactive or reactive risk management strategies occurring at different spatial and temporal scales. The predator–prey space race and landscape of fear concepts are useful to better understand how predation risk affects prey behavioral decisions and distribution. We assessed predation risk effects in a terrestrial Arctic community, where the arctic fox is the main predator of ground‐nesting birds. Using high‐frequency GPS data, we estimated a predator activity landscape corresponding to fox space use patterns and validated with an artificial prey experiment that this predator activity landscape correlated with the predation risk landscape. We then investigated the effects of the fox activity landscape on multiple prey species, by assessing the anti‐predator behavior of a main prey (snow goose) actively searched for by foxes, and the nest distribution of several incidental prey species. We first found that snow geese showed a stronger level of nest defense in areas highly used by foxes, possibly responding with a reactive strategy to variation in predation risk. Then, nests of incidental prey reproducing in habitats easily accessed by foxes had a lower probability of occurrence in areas highly used by foxes, suggesting these birds may use a proactive risk management strategy by shifting their distribution away from risky areas. For incidental prey species nesting in microhabitat refuges difficult to access by foxes, probability of nest occurrence was independent of predation risk in the surrounding area, as they avoid risk at a finer spatial scale. By tracking all individuals of the dominant predator species in our study area, we demonstrated the value of using predator space use patterns to infer spatial variation in predation risk. Overall, we highlight the diversity of risk management strategies in prey sharing a common predator, hence refining our understanding of the mechanisms driving species distribution and community structure.

Predators mitigate the destabilising effects of heatwaves on multitrophic stream communities.

Amidst the global extinction crisis, climate change will expose ecosystems to more frequent and intense extreme climatic events, such as heatwaves. Yet, whether predator species loss-a prevailing characteristic of the extinction crisis-will exacerbate the ecological consequences of extreme climatic events remains largely unknown. Here, we show that the loss of predator species can interact with heatwaves to moderate the compositional stability of ecosystems. We exposed multitrophic stream communities, with and without a dominant predator species, to realistic current and future heatwaves and found that heatwaves destabilised algal communities by homogenising them in space. However, this happened only when the predator was absent. Additional heatwave impacts on multiple aspects of stream communities, including changes to the structure of algal and macroinvertebrate communities, as well as total algal biomass and its temporal variability, were not apparent during heatwaves and emerged only after the heatwaves had passed. Taken together, our results suggest that the ecological consequences of heatwaves can amplify over time as their impacts propagate through biological interaction networks, but the presence of predators can help to buffer such impacts. These findings underscore the importance of conserving trophic structure, and highlight the potential for species extinctions to amplify the effects of climate change and extreme events.

Spatial heterogeneity facilitates carnivore coexistence.

Competitively dominant carnivore species can limit the population sizes and alter the behavior of inferior competitors. Established mechanisms that enable carnivore coexistence include spatial and temporal avoidance of dominant predator species by subordinates, and dietary niche separation. However, spatial heterogeneity across landscapes could provide inferior competitors with refuges in the form of areas with lower competitor density and/or locations that provide concealment from competitors. Here, we combine temporally overlapping telemetry data from dominant lions (Panthera leo) and subordinate African wild dogs (Lycaon pictus) with high-resolution remote sensing in an integrated step selection analysis to investigate how fine-scaled landscape heterogeneity might facilitate carnivore coexistence in South Africa's Hluhluwe-iMfolozi Park, where both predators occur at exceptionally high densities. We ask whether the primary lion-avoidance strategy of wild dogs is spatial avoidance of lions or areas frequented by lions, or if wild dogs selectively use landscape features to avoid detection by lions. Within this framework, we also test whether wild dogs rely on proactive or reactive responses to lion risk. In contrast to previous studies finding strong spatial avoidance of lions by wild dogs, we found that the primary wild dog lion-avoidance strategy was to select landscape features that aid in avoidance of lion detection. This habitat selection was routinely used by wild dogs, and especially when in areas and during times of high lion-encounter risk, suggesting a proactive response to lion risk. Our findings suggest that spatial landscape heterogeneity could represent an alternative mechanism for carnivore coexistence, especially as ever-shrinking carnivore ranges force inferior competitors into increased contact with dominant species.

Population dynamics of Frankliniella occidentalis Pergrande and its predator Orius similis Zheng on common crops and surrounding plants

• Plants surrounding Capsicum annuum fields can provide habitat for predator Orius similis . • Hypericum beanii and Trifolium repens are the important sources of Frankliniella occidentalis on C. annuum . • Zea mays is the potential banker plant of O. similis in C. annuum planting. Frankliniella occidentalis Pergrande is important invasive pests in China, causing damage to agricultural production, and Orius similis Zheng is the dominant predator species of F. occidentalis . A two-year survey was conducted to determine the population density of F. occidentalis and O. similis , on chili ( Capsicum annuum L.) and maize ( Zea mays L.) crops and surrounding weed species, which included white clover ( Trifolium repens L.), St. John's wort ( Hypericum beanii N. Robson), alfalfa ( Medicago sativa L.) and beggarticks ( Bidens pilosa L.) in Kunming, southern China. The activity of F. occidentalis on these 6 host plant species was determined using the quartile method. F. occidentalis mainly damaged plants during their flowering stage. The main activity period of F. occidentalis occurred earlier on H. beanii and T. repens than on C. annuum . The peak activity of F. occidentali s occurred in the middle of May (on T. repens ). During the whole activity period, the highest thrips densities were recorded on H. beanii among all of the sampled host plant species, followed by C. annuum . The lowest density was recorded on B. pilosa . Dynamics of immature F. occidentali s were more irregular than that of adults. The highest density of O. similis was recorded on Z. mays . It was 2.27–26.43-fold (2017) and 2.01–19.09-fold (2018) higher than that on other host plant species. This study showed that F. occidentali s could migrate between C. annuum and surrounding weeds. The weeds were the main source of thrips on C. annuum . The results indicated that Z. mays can be planted around C. annuum fields as a potential banker plant, to attract O. similis to control F. occidentalis on C. annuum , T. repens and B. pilosa . The flowering period of plants and surrounding plant species has a great effect to the population activities of F. occidentalis and predator O. similis on crops.

Cheetah communication at scent-marking sites can be inhibited or delayed by predators

Scent-marking is a way for individuals to indirectly communicate; however, the information is not exclusive to a single species and can be informative to a whole community. Prey or competitively inferior species can use scent-marks from predators/dominant species to avoid interactions. Cheetahs are a subordinate member of the large carnivore guild in Africa, yet olfactory communication in this guild has yet to be explored. We explore whether intraguild or intraspecific communication is occurring at cheetah scent-marking sites as well as whether dominant predator avoidance by cheetah occurs in response to predator presence or predator scent-marking. We recorded cheetah behaviour with video recording camera traps at cheetah scent-marking sites where a ‘landscape of fear’ was provided through natural predator presence or manipulated cues of predator presence. We found that cheetah took longer to return to scent-marking sites when a lion or a leopard was the previous species to visit the site. Moreover, cheetah increased the amount of time that they spent sniffing at scent-marking sites when another predator, as opposed to a cheetah, was the previous visitor. Finally, we noted that females never visited a scent-marking site after a predator was present nor when a predators’ scent-mark was present. Our results demonstrate that cheetahs use scent-marking sites for intraspecific communication, but also obtain intraguild information at these sites. Dominant predators can inhibit or at least delay important intraspecific communication around estrous events that occurs between cheetah at scent-marking sites, a novel form of interference competition. Competition occurs between species, and dominant species deprive subordinate species from key resources. Individuals are able to avoid the cost of direct interactions with competitors by using cues (both direct and indirect) such as scents to assess such risks. Using video recording cameras at cheetah scent-marking sites, we provide novel insight into how dominant predator species shape cheetah behaviour through the use of avoidance by cheetah to the presence of dominant predators. Scent-marking sites are important to cheetah communication around reproduction opportunities and territory maintenance; however, dominant predator species’ cues blocked female reproductive signalling at the sites and delay male visitation. This serves as a novel form of interference competition for cheetah, but we suggest that cheetahs maintain communication through the use of multiple sites.

Assessing trophic flexibility of a predator assemblage across a large estuarine seascape using blood plasma stable isotope analysis

The northcentral Gulf of Mexico (nGoM) encompasses a range of environments that support a speciose predatory assemblage. Large predatory species are often viewed as trophically-analogous, sharing similar isotopic niches. To investigate the regional and seasonal isotopic variability of a predator assemblage across the coastal waters of the nGoM (Louisiana, Mississippi, and Alabama), we analyzed the stable isotopes of carbon, nitrogen, and sulfur using a fast turnover tissue, blood plasma, for seven dominant predator species. Carbon, nitrogen, and sulfur isotope values varied regionally, with a significant interaction between region and season for nitrogen and sulfur. Species' isotopic niches varied regionally, as well as seasonally, leading to varying levels of isotopic niche overlap among species. Blacktip sharks Carcharhinus limbatus and Atlantic sharpnose sharks Rhizoprionodon terraenovae in particular demonstrated flexibility in their isotopic relationships, whereas blacknose sharks C. acronotus maintained a more consistent isotopic niche regardless of region or season. No biologically significant overlap was observed for blacknose sharks, bull sharks C. leucas, or spinner sharks C. brevipinna, suggesting that these species occupy distinct isotopic space. Overlap calculations using two isotopes (carbon and nitrogen) produced markedly higher overlap versus three isotopes (carbon, nitrogen, and sulfur), which demonstrates that predatory roles may be oversimplified when using only carbon and nitrogen. These findings highlight the value of examining seasonal variation in trophic roles using fast turnover tissues and provide the first triple-isotope characterization of a common predatory assemblage in the northcentral Gulf of Mexico.

Cellular basis of anti‐predator adaptation in a lizard with autotomizable blue tail against specific predators with different colour vision

AbstractJuveniles of numerous lizard species have a vividly blue‐coloured tail that likely serves to deflect predator attacks toward the autotomizable tail rather than the lizard's body. The shades of blue colour in the tails of juvenile Plestiodon latiscutatus lizards vary across populations, most notably among those island populations with different predator assemblages. Here, we determine if this intraspecific variation is associated with the differences in colour vision capabilities of lizard predator species. If associated, it would be evidence for local adaptation of tail colour phenotype – natural selection is maximizing the conspicuousness of the tail to the dominant predator species to increase the chance of successfully deflecting attacks. We also use transmission electron microscopy (TEM) to determine the proximate cellular mechanisms that produce the shades of blue in different populations. We revealed that lizard tails with vivid blue reflectance evolved in communities with either weasel or snake predators, two groups of animals with the ability to detect blue wavelengths. However, lizard tail UV reflectance was much higher in populations with only snake predators; that snakes can detect UV, yet weasels cannot, suggests that high UV reflectance is an adaptation to increase tail conspicuousness specifically to snake predators. Finally, a cryptic brown tail evolved independently on the islands where birds are the primary lizard predator. We suggest that because birds have keen visual acuity; a brown, camouflaged phenotype is more advantageous. We also determined through TEM that the thickness of light reflecting platelets in iridophores, and densities of iridophores and xanthophores, predicted the wavelengths and intensity of light reflected by the lizard tail. For example, blue coloration was produced by selective reflection of short wavelengths of light by the thin light reflecting platelets of the iridophore. Greater iridophore density increased light reflectance, while greater xanthophore density decreased light reflectance.

Physical wetland characteristics influence amphibian community composition differently in constructed wetlands and natural wetlands

Wetlands provide critical habitat for a diverse group of organisms and provide important ecosystem services. Despite this, most natural wetlands have been lost to anthropogenic activities, and as a result, wetland construction is common mitigation practice. Therefore, examination of constructed wetland viability in replacing the function of lost wetlands is vital. Our primary objectives were to compare amphibian communities of shallow and deep constructed wetlands to natural wetlands and to identify which wetland characteristics affect species composition. All wetlands were hydrologically isolated and fishless; natural wetlands had an ephemeral hydrology, and constructed wetland hydrology varied from ephemeral to permanent. Overall, constructed wetlands did not sufficiently replicate natural wetlands with respect to the amphibian community. However, two of our constructed wetlands had a drying period and exhibited communities more similar to natural wetlands. Hydroperiod and canopy closure were indicators of amphibian community composition. Many species observed in natural wetlands were rare in shallow constructed and absent in deep constructed wetlands. Additionally, dominant predator species (primarily Lithobates catesbeianus, Lithobates clamitans, and Notophthalmus viridescens) associated with permanent water were more abundant in constructed wetlands. Water depth, pH, and emergent vegetation were lower in natural wetlands. These data influenced land managers to revise construction methods and to renovate deep constructed wetlands by creating gradual slopes, decreasing maximum depth to 20cm or less, maintaining canopy cover, and decreasing soil compaction to attempt replication of natural wetland hydrology.

Pesticide-mediated displacement of a phytoseiid predator, Neoseiulus womersleyi, by another phytoseiid predator, N. californicus (Acari: Phytoseiidae).

Neoseiulus womersleyi and N. californicus are two predators that are frequently used to control spider mites in fruit-tree orchards. Neoseiulus womersleyi used to be the dominant predator species in Japan, but since the 1990s in central and southwestern Japan, N. californicus populations have been increasing and have displaced populations of N. womersleyi. We previously observed the same phenomenon under laboratory conditions when these species were released at a 1:1 ratio, and attributed the displacement to asymmetrical intraguild predation. However, the ratio in fruit-tree orchards could be different from 1:1. Therefore, we hypothesized that differential susceptibilities to pesticides might accelerate species displacement of N. womersleyi by N. californicus, even if the ratio between these two species was extremely skewed in favor of N. womersleyi and no species displacement occurred otherwise. We examined the effects of 21 pesticides on egg-to-adult and adult survivorship in N. womersleyi and N. californicus. Among these pesticides, two neonicotinoids (acetamiprid and imidacloprid) had much severer effects on N. womersleyi than on N. californicus and thus could possibly account for the species displacement. When the two species were released onto leaf arenas at an N. californicus: N. womersleyi ratio of 1:9 in the absence of insecticide, no displacement was observed. However, just after acetamiprid or imidacloprid application, the proportion of N. californicus increased, causing N. californicus to displace N. womersleyi. Our results indicate that displacement in predator complexes of fruit-tree orchards could be due to different degrees of pesticide susceptibility.

The dynamics of the jellyfish joyride: mathematical discussion of the causes leading to blooming

Dramatic increases in jellyfish populations, which lead to the collapse of formally healthy ecosystems, are repeatedly reported from many different sites. Because of their devastating effects on fish populations, understanding of the causes for such bloomings are of major ecological as well as economical importance. Based on a previous work, we set up a two‐dimensional predator–prey model for the fish–jellyfish interactions by taking fishery as well as environmental conditions into account. It assumes the fish as the dominant predator species. By totally analytic means, we completely classify all equilibria in terms of existence and non‐linear stability and give a description of this system's non‐linear global dynamics. We analytically study the non‐equilibrium dynamics and detect homoclinic, Andronov–Hopf, and Takens–Bogdanov bifurcations as well as the non‐existence of periodic and homoclinic orbits in certain relevant regions of the phase space. A hereby found, and analytically rigorously stated, funnel phenomenon gives rise to a mathematical explanation of jellyfish blooming beyond the typical one in terms of large‐amplitude limit cycles based on the well‐known Rosenzweig–MacArthur equations. Also, we illustrate the plethora of bifurcation scenarios by numerical results. Copyright © 2015 John Wiley & Sons, Ltd.

Shift in microhabitat use as a mechanism allowing the coexistence of victim and killer carnivore predators

It has been suggested that spatial heterogeneity is key to the coexistence at local spatial scales of subordinate and dominant predator species by allowing the former to shift to more protective habitats when the risk of intraguild predation exists. Here, we show how the smaller carnivore Egyptian mongoose (Herpestes ichneumon) may coexist on a local scale with its intraguild pre- dator, the Iberian lynx (Lynx pardinus), by using places with different microhabitat character- istics. We expect that mongooses living within lynx home ranges will use denser and more protective habitats when active in order to di- minish their risk of being killed by lynx com- pared to those living in areas similar in vege- tation and prey availability but where lynx are absent. The scrubland cover of points used by mongooses outside lynx areas, and that of points located within lynx areas but not used by mongooses, were significantly lower than, or similar to, cover of points used by mongooses within lynx areas. The probability of finding mon- goose tracks was constant across levels of scrubland cover when lynx were absent, but more mongoose tracks were likely to be found in thicker scrubland within lynx areas, especially if these areas were intensively used by lynx. This result agrees with the hypothesis on shifts in microhabitat use of subordinate carnivores to prevent fatal or risky encounters with dominant ones.

Field responses of predaceous arthropods to methyl salicylate: A meta-analysis and case study in cranberries

Methyl salicylate (MeSA) is a herbivore-induced plant volatile that has shown potential in attracting natural enemies. Here, we conducted a meta-analysis to evaluate the magnitude of natural enemy response to MeSA in the field, and tested its attractiveness to insect predators in commercial cranberry bogs. Eighteen experiments from 14 publications were used in the meta-analysis, resulting in 91 total observations. Of these, 41 documented significant attraction and the magnitude of this attraction response was not significantly different across predator and parasitoid taxa. Insect predators were monitored in cranberries using MeSA (PredaLure)-baited and unbaited yellow sticky traps. MeSA-baited traps caught greater numbers of adult hoverfly, Toxomerus marginatus, lady beetles, and green lacewings compared with unbaited traps. In another field experiment, predator abundance was monitored using traps placed near the MeSA lure (0m), as well as at 2.5, 5, and 10m away from the lure. Adult T. marginatus, the dominant predator species, showed a clear attraction to the point source but not to the other distances. In complementary studies we showed that MeSA emissions from PredaLures dropped quickly soon after deployment in the field but remained relatively high for over 4weeks; flowering, but not vegetative, vines were a primary source of MeSA in cranberries; and, exposure to PredaLures triggered elevated MeSA emissions from vegetative vines. In conclusion, we find strong evidence that insect predators are broadly attracted to MeSA in agricultural fields, including cranberries; yet, whether this behavior can be manipulated to improve biological control needs further investigation.

Distribution and Habitat Preference of Carabidae and Staphylinidae (Coleoptera) in an Orange Orchard and a Forest Fragment

ABSTRACT A survey of Carabidae and Staphylinidae (Coleoptera) was conducted in a forest fragment and an orange orchard located in the Gaviao Peixoto municipality, Sao Paulo State, Brazil to identify dominant predator species that may be important in the biocontrol of orange pests. Beetles were captured by pitfall traps arranged along 2 parallel transects 200 m long, placed across the orchard/forest boundary, extending 100 m into each habitat. The Shannon-Wiener diversity and Bray-Curtis similarity indices were calculated for both habitats, and habitat preference of abundant species were investigated by analysis of variance. Carabids comprised 91% and 86% of the beetles observed in the fragment and orchard, respectively. Abaris basistriata Chaudoir, Athrostictus sp.1, Tetracha brasiliensis (Kirby), Pseudabarys sp. 1, Selenophorus seriatoporus Putzeys, Selenophorus sp.4, and the staphylinid Xenopygus sp.2 were the dominant species. There was no significant increase or decrease in carabid and staphylinid spe...

Factors affecting nest predation on forest songbirds in North America

Nest predation is an important factor in the ecology of passerines and can be a large source of mortality for birds. I provide an overview of factors affecting nest predation of passerines in North America with the goal that it may provide some insight into the ecology and management of woodland birds in the United Kingdom. Although several factors influence productivity, nest success is perhaps the most widely measured demographic characteristic of open‐cup‐nesting birds, and nest predation is usually the largest cause of nest failure. The identity of predator species, and how their importance varies with habitat and landscape factors, must be known for managers and scientists to design effective conservation plans and place research on nest predation in the appropriate context. Recent studies using video surveillance have made significant contributions to our understanding of the relative importance of different predator taxa in North America. Spatial and temporal variation in nest predation can be better understood when landscapes are placed in a biogeographical context and local habitat and nest‐site effects are placed in a landscape context. Low productivity resulting from high nest predation is one of several potential causes of bird population declines in North America and the UK. Although the ‘forest fragmentation paradigm’ from the eastern US may not apply directly to the UK, thinking about avian demographics from a multiscale perspective, and consideration of factors affecting nest predation with knowledge of the dominant predator species, may provide insight into population declines.

In-Field Monitoring of Beneficial Insect Populations in Transgenic Corn Expressing a Bacillus thuringiensis Toxin

In 1998 and 1999, field studies were conducted near Rosemount, MN to assess the potential impact of transgenic sweet corn, transformed to express the Cry1Ab toxin from Bacillus thuringiensis Berliner var kurstaki (i.e., Bt corn), on several beneficial insects, including predatory coccinellids, chrysopids and anthocorids. Beneficial insects in both Bt and in non-Bt sweet corn were also monitored in field cages in 1999. Plants were visually sampled for beneficial insects by arbitrarily selecting 3 consecutive plants from each plot or 6 plants/cage. Rank transformed data were analyzed using the Kruskal-Wallis test, which indicated no significant within-year differences in the overall density of beneficial insect populations between Bt and non-Bt sweet corn. Coleomegilla maculata (DeGeer) was the dominant predator species detected in 1998 and 1999. A significant trend (P < 0.05) was found for C. maculata larvae in open plots, with non-Bt treatments having higher C. maculata levels than Bt. Also, C. maculata larval and adult densities, for caged plots, showed a significant trend for higher counts in the in non-Bt corn. No additional differences in species diversity of beneficial insects were detected using Hills N1. Neither Hippodamia convergens Guérin-Ménville, Adalia bipunctata (L.), nor Coccinella septempunctata L. were observed during 1999. Although our test detected significant trends for higher densities of C. maculata in non-Bt corn, the results also suggest that longer-term in-field studies with higher sample sizes are needed to further characterize what may be relatively subtle population effects in the field.

Biology of Typhlodromus bambusae (Acari: Phytoseiidae), a predator of Schizotetranychus nanjingensis (Acari: Tetranychidae) injurious to bamboo in Fujian, China

Abstract Typhlodromus bambusae Ehara is a dominant predator species associated with the spider mite Schizotetrany-chus nanjingensis Ma & Yuan on the giant bamboo (Phyllostachys pubscens) in Fujian, China. In the field, increased densities of T. bambusae were associated with reduced densities of S. nanjingensis on bamboo leaves. Laboratory studies at 22–30°C on a diet of S. nanjingensis showed that females of T. bambusae completed a full egg-egg cycle in 7.5 days and mated females laid an average of 3.2 eggs per female per day. The number of female prey consumed by predator females increased with prey density very fast initially at prey densities of ≤5 but levelled off as prey density was further increased. Prey handling time was over 40% shorter and the rate of successful attack was twice higher at 28–30°C than at 22–24°C. When fed the pollen of Luffa cylindrica or eggs and larvae of Tyrophagus putrescentiae, T. bambusae females could not survive to layeggs.However,predator females readily attacked female...

Potato Insect Control, 1985

Abstract Potatoes were planted on 9 May in So. Deerfield, MA. Fertilizer (700 lb. 10N:10P2O3:10K2O/acre) was broadcast and incorporated prior to planting. An additional 700 lb/acre was side dressed on 26 Jun. Soil type was a fine sandy loam with a pH of ca. 5.3. The land was rotated from corn and no other potato crops were planted within 0.5 miles. Hence, Colorado potato beetle (CPB) pressure was moderate. Treatment blocks were replicated 4 times in a randomized complete block design. Each plot consisted of two 30-ft rows with a 3-ft fallow area between each plot. Treatments were applied with C02 pressurized sprayers at 40 psi with a delivery rate of ca. 65 gal/acre. Applications were made on 3, 11 and 17 Jul. In one treatment, Alsystin 4F at 0.5 lb (AI)/acre was applied on 3 and 11 Jul, and on 17 Jul, Alsystin 4F at 0.25 lb (AI)/acre plus Monitor 4 at 0.5 lb (AI)/acre was applied. CPB densities were assessed on 3 Jul and 4-5 days after treatment by counting adults and larvae on 10 primary stalks in each plot. Green peach aphids (GPA) were sampled on 29 Jul by counting those found on 10 terminal leaflets from lower leaves. Predators were assessed on 29 Jul by counting individual larvae, pupae and adults per 10 stalks. Coleomegilla maculata was the dominant predator species. Because densities of individual species were not high, predator numbers were pooled. Each plot was rated for defoliation on a scale from 1 (0-20%) to 5 (80-100%). Potato leafhopper (PLH) damage was assessed by ranking damage from 1 (no damage) to 3 (severe). Due to their clumped distribution, CPB and GPA counts were transformed by log(x = 1); means reported here are back transformed. No effects from blocking were observed for CPB.

Potato Insect Control, 1985

Abstract Potatoes were planted on 9 May in So. Deerfield, MA. Fertilizer (700 lb 10N:10P2O5:10K2O/acre) was broadcast and incorporated prior to planting. An additional 700 lb/acre was sidedressed on 26 Jun. Soil type was a fine sandy loam with a pH of ca 5.3. The land was rotated from corn, and no other potato crops were planted within 0.5 miles; therefore, Colorado potato beetle (CPB) pressure was moderate. Treatment blocks were replicated 4 times in a randomized complete block design. Each plot consisted of 2 30-ft rows with a 3 ft fallow area separating each plot. Insecticides were applied with C02 pressurized sprayers at 40 psi, with a delivery rate of ca. 65 gal/acre. Applications were made on 3, 11, and 17 Jul. Temik 15G (3.0 lb (AI)/acre) was applied at planting, and Temik 15G (2.0 lb (AI)/acre) at plant emergence. For this reason, the pre-counts (3 Jul) for these two treatments were significantly lower than all the other treatments. Because Kryocide 8F was not available for the first generation applications, a separate trial, adjacent to the trial area at a location where first generation CPB larval counts were still high, was carried out on 18 Jul (Kryocide 8F and control). The mean number of larvae per ten stalks before treatment was 83.4 for the control and 88.8 for the Kryocide 8F plots. After treatment (22 Jul), the control had 94.5 larvae/10 stalks; the Kryocide treatment had 14.3 larvae/10 stalks. CPB densities were determined on 3 Jul (before treatment) and 4-5 days after treatment by counting adults and larvae on 10 primary stalks in each plot. Green peach aphids (GPA) were sampled on 29 Jul by counting those found on 10 terminal leaflets from lower leaves. Predators were assessed on 29 Jul by counting individual larvae, pupae and adults per 10 stalks. Coleomegilla maculata was the dominant predator species. Because densities of individual species were not high, predator numbers were pooled. Each plot was rated for defoliation on a scale from 1 (0-20%) to 5 (80-100%). Potato leafhopper (PLH) damage was assessed by ranking damage from 1 (no damage) to 3 (severe).