Low Infestation Levels Research Articles

Percent infestation and seed consumption of Centaurea solstitialis L. (Asteracea: Cardueae) by Eustenopus villosus and Larinus curtus (Coleoptera: Curculionidae) in Washington, USA

A 2-year field study (2014–2015) was conducted to determine the levels of Eustenopus villosus (Boheman) and Larinus curtus (Hochhut) infestation and seed consumption of the invasive plant Centaurea solstitialis L. (Asteraceae: Cardueae) in the steppe of southeastern Washington, USA, a marine-modified continental macroclimate. Mature terminal C. solstitialis flowerheads were collected and dissected to determine abundance of each weevil species and level of seed consumption by both species. Data were analyzed by year to assess climatic influences on insect prevalence and feeding activity. Results showed that E. villosus infested 34.2% of the flowerheads in 2014 and 29.9% in 2015. Larinus curtus infested 10.9% in 2014 and 13.7% in 2015. In 2014, 5.8% of the flowerheads were infested by at least one E. villosus and one L. curtus in the same flowerhead and 9.7% in 2015. Eustenopus villosus consumed a higher percentage of total seed production per flowerhead of C. solstitialis than L. curtus (71.4% and 59.8, respectively). Infestation levels of E. villosus and L. curtus in southeastern Washington are lower than in the Mediterranean macroclimates in California and northern Greece. Mean seed consumption was also lower in southeastern Washington compared to northern Greece, with no data specific to California. Lower levels of infestation and seed consumption in southeastern Washington suggests the efficacy of the insect biological controls may be less in more continental macroclimates than in climates with Mediterranean influences.

Barley yield and weed infestation of barley crops depending on the basic soil tillage systems

The study was carried out in a long-term stationary experiment in the period of the 5th grain-fallow crop rotation: bare fallow - winter rye - spring wheat -spring wheat - spring barley (2008-2012). The effect of the long-term use of basic soil tillage systems of various degrees of intensity on the growth of weed vegetation and the yield of spring barley, i.e. the crop that completes the crop rotation, was studied. The experiment was carried out in Tyumen region on the dark-gray forest heavy loamy soil with the use of herbicides - mixtures of anti-dicotyledonous and graminicide preparations. The humus content in the soil layer of 0-20 cm in the fields of crop rotation for a laying period was 4.2-5.0%, with the pH of the salt extract being 6.0-6.4, and the total absorbed bases being 29.4 mg-eq / 100g of soil. During the study period, with various basic tillage systems applied, total weed infestation of barley was 37-75 pieces/m 2 in the spring and 5.2-14.3 pieces/m 2 in the autumn, which corresponded to the medium and low levels of infestation. The technical efficiency of using a mixture of herbicides in the barley field was 83.3%. The best weed control was achieved by moldboard tillage system whereby crops were the cleanest. With all resource-saving tillage systems, infestation was 1.4-2.0 times higher than with moldboard tillage system, mainly due to the growth of miliary weeds (by 60-140%). The highest weed infestation in barley crops before harvest was observed when using a sub-soil tillage system and disk harrowing tillage, which was 105-184% higher than at plowing. It was established that given the complex chemicalization and agrotechnology in grain-fallow crop rotation, the increase in weed infestation with the studied resource-saving tillage systems occurred to a low or medium extent and did not affect weed control or conditions for the formation of the barley yield.

Quick and accurate detection of Sclerotiniasclerotiorum and Phomopsis spp. in soybean seeds using qPCR and seed‐soaking method

AbstractSeed‐borne pathogenic fungi can cause serious damage to soybean crops by reducing the germination, vigour and emergence of the seeds. Special attention should be paid to pathogen detection in seeds to prevent its introduction in disease‐free areas. Considering the importance of rapid and successful diagnosis of seed‐borne pathogenic fungi in soybeans, this study evaluated a method to detect Sclerotinia sclerotiorum and Phomopsis spp. in seeds using quantitative polymerase chain reaction (qPCR). Naturally infested samples were subjected to detection using qPCR and blotter test, and the findings were compared. Using soybean seeds soaked in water, both pathogens were detected at an infestation level up a 0.0625% (one infected seed out of 1,599 healthy seeds) by qPCR. This technique allowed the detection of 300 fg of S. sclerotiorum and 30 fg of Phomopsis spp. DNA in the seed samples. Phomopsis spp. was detected in 40.7% of the evaluated seed batches (81 batches) and S. sclerotiorum was detected in 32.1% of the evaluated batches, although most of the seeds had low infestation levels. It was up to 28.5 times more efficient to use qPCR rather than blotter test to detect pathogens with a low incidence of occurrence in soybean seeds. If routinely used to test healthy seeds, qPCR would contribute to reducing soybean losses due to diseases as well as decreasing the costs required to control those diseases.

A model of insect control with imperfect treatment

Insecticide spraying of housing units is an important control measure for vector-borne infections such as Chagas disease. However, some vectors may survive treatment, due to imperfect spraying by the operator or because they hide deep in the cracks or other places, and re-emerge in the same unit when the effect of the insecticide wears off. While several mathematical models of this phenomenon have been previously described and studied in the literature, the model presented here is more basic than existing ones. Thus it is more amenable to mathematical analysis, which is carried out here. In particular, we demonstrate that an initially very high spraying rate may push the system into a region of the state space with low endemic levels of infestation that can be maintained in the long run at relatively moderate cost, while in the absence of an aggressive initial intervention the same average cost would only allow a much less significant reduction in long-term infestation levels.

Response of Arabica Coffee Cultivars to Competition from Beggarticks

ABSTRACT: The goal of this study was to analyze the response of Arabica coffee cultivars grown under three levels of Bidens pilosa (beggarticks) interference. At 30 days after transplanting (DAT) of 14 Arabica coffee cultivars into 11 L pots, beggarticks was seeded in the pots and soon after emergence, three levels of weed infestation were established: none, low (two plants per pot), and high (five plants per pot). Treatments were arranged in a 14 × 3 factorial scheme under a completely randomized design, with four replicates. Coffee plant growth was evaluated at both weed emergence and blossoming (90 DAT) when the experiment was completed. Regardless beggarticks infestation levels, significant effects of cultivars occurred on almost all the coffee growth variables. Specifically, the Arabica coffee cultivars Arara, Asa Branca, and Bourbon Amarelo exhibited greater values for root, leaf, shoot, and whole plant dry matter when compared with the other cultivars. The Arabica coffee cultivars presented lower leaf area increments, and also lower leaf, shoot, and whole plant dry matter accumulation when grown under either low or high infestation levels (between which there were no statistical differences, p>0.05) in comparison with that under the weed-free treatment. However, there were no significant interactions between Arabica coffee cultivars and weed infestation levels for those crop growth variables. We conclude that all Arabica coffee cultivars tested were equally susceptible to B. pilosa competition in this phase of crop implantation.

Tick infestations correlates at a Falkland Islands Black-browed Albatross colony

The tick Ixodes uriae is an ectoparasite widely distributed among seabirds throughout circumpolar regions, usually associated with seabird colonies. Nevertheless, potential effects of infestations, especially in chicks, are not well documented. In this article, we studied factors associated with probability and intensity of infestations in Black-browed Albatross Thalassarche melanophrys nestlings in a colony at the Falklands Islands. We compared the body measurements, physiological parameters, distance to other nests and position inside the colony between infested and non-infested 40 Black-browed Albatross nestlings. Ticks were present in 60% of the nestlings with a mean number per nestlings of 1.47. None of the 12 analysed blood parameters but LDH (Lactate dehydrogenase) showed significant differences between infested and not infested nestlings. Nestlings infected showed significant higher level of LDH than those without ticks. The number of ticks found on each nestling was positively and significantly correlated with their LDH blood levels. Tarsus length (as a proxy of age) and distance to the nearest nest showed a significant effect, with younger nestlings with closer nests showing higher probability to be infected. These variables also affect intensity of infestation. No effects of nutritional condition (butyrate or urea levels) or body condition (residuals of cubic root of mass/tarsus length regression) on probability or intensity of infestation were found. Both small anaemias and tick scars would explain the different values of LDH between infected/non-infected chicks. The low level of infestation found in our colony could be the cause of a non-detectable effect of the presence of ticks on nestling body condition and other blood parameters related to metabolism of fat or protein.

Field Trials on Land Gastropods Infesting some Ornamental Plants at Kafr El-Sheikh Governorate

Land molluscs became one of the most serious pests attacking many plants including ornamental plants. Occurrence of certain land gastropods associated with some ornamental plants at Kafr EL-Sheikh Governorate was conducted. Results revealed that the land snails, Eobania vermiculata and Succinea putris and the land slug Deroceras reticulatum were recorded on the tested plants. E vermiculata was the predominant species while the other identified gastropods showed lower infestation levels. Therefore ,the seasonal abundance of the predominant snail, E vermiculata was studied and results showed that the population of E vermiculata was increased during spring months (171.99 snails/ 1/2 m2) as compared to summer and autumn(149,34 and 59,33),respectively whereas the infestation was the least during winter (40.67 snails/ 1/2 m2). Malabar was superior among the tested plants since it attracted the highest number of snails with mean of (5.68 ± 1.56) snails/ 1/2 m2 followed by Hlibiscus, basil, kockia, DustyMiller, Manitoka and Royal palm, respectively. Both of Pricharida and Duranta were the least attractive to snails. Concerning the efficacy of certain pesticides against E vermiculata under field conditions, Data revealed that Agrinate was more toxic to snails than the other pesticides, since it achieved the highest reduction percentage of snail population of (69.03 ± 7.2 ) % followed by Vicarb with reduction of (55.87 ± 6.8)% while Uphold was the least in this respect with reduction percentage of (25.41±2.6)%.

Effect of configuration of calyx in cowpea flowers on infestation by spotted pod borer, Maruca vitrata (Fab.) (Lepidoptera: Crambidae)

Twenty cowpea accessions were evaluated for resistance to the spotted pod borer, Marucavitrata in the Department of Agricultural Entomology, College of Horticulture, KeralaAgricultural University, Thrissur. The calyxes of the flowers were examined and the accessionswere categorized into two groups, partially free (major portion of the sepals free, the basalportion tight) and semi tight (major portion of the sepals tight, only the tip free). Significantvariation was observed in terms of damage to cowpea flowers due to spotted pod borer. Thehighest extent of flower damage (50.39 %) was recorded in case of Bhagyalakshmy.Categorization of the different accessions on the basis of the configuration of calyx indicatedthat EC 100092, Palakkadanthandanpayar, TVX – 944, EC 300039, IC 20645 and IC 52110 hadsemi tight calyx characterized by tight sepals with tips alone being free. All these accessionshad consistently low levels of infestation ranging from zero to 3.16 per cent. The accessions C– 152, Kanakamony, PKM – 1, Anaswara, IC 20431, Sreya, Hridya, Mysore local, IC 52105,Kashikanchan, Vellayani Jyothika, Malika, Bhagyalakshmy and Lola had major portion ofsepals free with their basal portion tight. Hence, they were grouped as partially free. Freesepals would provide the first instar borer larvae some extent of concealment as well as enableit to bore into the flower more easily. Tight calyx, thus, could possibly have a deterrent effecton the first instar larvae entry.

Effect of configuration of calyx in cowpea flowers on infestation by spotted pod borer, Maruca vitrata (Fab.) (Lepidoptera: Crambidae)

Twenty cowpea accessions were evaluated for resistance to the spotted pod borer, Marucavitrata in the Department of Agricultural Entomology, College of Horticulture, KeralaAgricultural University, Thrissur. The calyxes of the flowers were examined and the accessionswere categorized into two groups, partially free (major portion of the sepals free, the basalportion tight) and semi tight (major portion of the sepals tight, only the tip free). Significantvariation was observed in terms of damage to cowpea flowers due to spotted pod borer. Thehighest extent of flower damage (50.39 %) was recorded in case of Bhagyalakshmy.Categorization of the different accessions on the basis of the configuration of calyx indicatedthat EC 100092, Palakkadanthandanpayar, TVX – 944, EC 300039, IC 20645 and IC 52110 hadsemi tight calyx characterized by tight sepals with tips alone being free. All these accessionshad consistently low levels of infestation ranging from zero to 3.16 per cent. The accessions C– 152, Kanakamony, PKM – 1, Anaswara, IC 20431, Sreya, Hridya, Mysore local, IC 52105,Kashikanchan, Vellayani Jyothika, Malika, Bhagyalakshmy and Lola had major portion ofsepals free with their basal portion tight. Hence, they were grouped as partially free. Freesepals would provide the first instar borer larvae some extent of concealment as well as enableit to bore into the flower more easily. Tight calyx, thus, could possibly have a deterrent effecton the first instar larvae entry.

PM 9/26 (1) National regulatory control system for Globodera pallida and Globodera rostochiensis

Specific scopeThis Standard describes a national regulatory control system for Globodera pallida and Globodera rostochiensis.

The effect of rearing history and aphid density on volatile‐mediated foraging behaviour of Diaeretiella rapae

1. Parasitoid females foraging for hosts rely on cues derived from the insect host, the host plant and/or their interaction, and all of these can be learned during the immature and adult stages.2. The present study investigated the importance of rearing history on foraging behaviour of Diaeretiella rapae, an endoparasitoid often associated with aphids feeding on brassicaceous plant species.3. Parasitoids were reared on one of the four possible combinations, comprising two brassicaceous host plant species, Brassica nigra or Raphanus sativus, and two aphid species Brevicoryne brassicae or Myzus persicae. These parasitoids were tested in a Y‐tube olfactometer and given the choice between volatiles emitted by an aphid‐infested plant (25 or 100 aphids per plant) and an uninfested control plant. The parasitoid's responses were compared when offered: (i) the same plant–aphid combination as the one on which it had been reared; (ii) the same host plant infested with the alternative aphid species; or (iii) an alternative plant with the alternative aphid species.4. Aphid density did affect the behavioural responses to the various odour sources, but rearing history did not. Diaeretiella rapae only preferred aphid‐induced to non‐induced plant volatiles at low aphid infestation level, whereas they did not discriminate between volatiles at high aphid infestation level.5. It is concluded that aphid‐induced volatiles of brassicaceous plants play an important role during host habitat location, but seem less important for parasitoids to locate the aphid host itself. The data are discussed in the light of manipulation of host plant defences by aphids.

The resilience of Triatoma dimidiata: An analysis of reinfestation in the Nicaraguan Chagas disease vector control program (2010-2016).

BackgroundThe control of Triatoma dimidiata, a major vector of Chagas disease, was believed to eliminate Trypanosoma cruzi transmission in Central America. This vector was known for its ability to repeatedly reinfest human dwellings even after initial insecticide spraying. Current vector control programs assume that community-based surveillance can maintain low levels of infestation over many years, despite a lack of evidence in the literature to corroborate this assumption. This study aims to evaluate long-term reinfestation risk in the Nicaraguan vector control program from 2010 to 2016.MethodsWe collected data from a cohort of 395 houses in Pueblo Nuevo, Nicaragua. Primary data were collected through a field survey to assess post-intervention levels of T. dimidiata house infestation in 2016, two years after the large-scale insecticide spraying. We obtained secondary data from the records about past infestation levels and control activities between 2010 and 2015. Multilevel mixed-effects logistic regression analyses were used to identify factors associated with post-intervention house infestation.ResultsThe control program effectively reduced the infestation level from 2010 to 2014. Community-based surveillance was introduced in 2013; however, post-intervention infestation in 2016 had nearly reached pre-intervention levels in rural villages. Post-intervention house infestation was positively associated with poor wall construction, roofing tiles piled in the peri-domestic areas or the presence of dogs. Interestingly, the odds of post-intervention house infestation were one-fifth less when villagers sprayed their own houses regularly. Past infestation levels and the intensity of government-led insecticide spraying did not explain post-intervention house infestation.ConclusionsThe vector control program failed to offer sustained reductions in T. dimidiata house infestation. This experience would suggest that community-based surveillance is an insufficient approach to suppressing T. dimidiata house infestation over many years. This study provides evidence to suggest that control policies for T. dimidiata should be reconsidered throughout Central America.

Spatial analyzes of triatomine infestation indices and their association to the actions of a Chagas disease program and environmental variables during a 5-year intervention period

Vector control of Chagas disease in the past decades has been mainly based on chemical control. Fundación Mundo Sano is implementing an Integral Chagas Program in a rural area of the Argentinean Gran Chaco Region since 2002. The objective of this study was to analyze both, temporal and spatial variation of infestation indices and their relation to the actions of the Program and environmental variables as land and vegetation cover changes, during a 5 year intervention period (2010–2014).Triatoma infestans infestation data from five rural localities from the Province of Santiago del Estero (Argentina) was analyzed in order to detect spatial aggregation. Differences in control effectiveness were observed between the peridomicile and intradomicile: infestation indices were higher in the peridomicile, recurrent infestation was present only in the peridomicile while low level infestation clusters were absent in the peridomicile. Cluster zones with low intradomestic infestation had larger proportions of bare soil and thin vegetation. In contrast, cluster zones with high intradomestic infestation had higher forest vegetation proportions and smaller cultivated area proportions.Spatial statistics analysis detected differences in cluster patterns between intra and peridomestic infestation suggesting that control actions should be based on geographical areas and not on political units. This work brings together different approaches to analyze infestation levels at the fine spatial scale, which could be used as a base for risk spatial stratification.

Evaluation of some integrated management approaches against flower thrips and pod borers of mungbean (Vigna radiata L.)

Efficacy and profitability of different management packages comprising white sticky trap, biopesticide and synthetic insecticides were evaluated against flower thrips and pod borers of mungbean at Pulses Research Center, Ishurdi, Pabna, Bangladesh during two consecutive seasons of kharif-1, 2015 & 2016. All the treatments significantly reduced flower infestation by thrips and pod borer infestation. The highest percentage of flower infestation and thrips population reduction was observed in installing white sticky trap + spraying of chlorfenapyr (Intrepid 10 SC) + spraying with emamectin benzoate (Proclaim 5 SG) followed by farmers practice, i.e. spraying imidacloprid (Imitaf 20 SL). Again, the highest pod borer infestation reduction was found in installing white sticky trap + spraying azadirachtin (Bio-neem plus 1EC) + spraying with spinosad (Success 2.5 SC) treated plots followed by installing white sticky trap + spraying chlorfenapyr (Intrepid 10 SC) + spraying with emamectin benzoate (Proclaim 5 SG). The highest grain yield was obtained from installing white sticky trap + spraying chlorfenapyr (Intrepid 10 SC) + spraying with emamectin benzoate (Proclaim 5 SG), but the highest return came from farmers practice (spraying Imidacloprid). This might be due to the higher cost of Intrepid 10 SC and Proclaim 5 SG reduced the return as well as benefit. Therefore, considering the efficacy and benefit, it is seen that the evaluated IPM package could not be profitable against low level infestation of flower thrips and pod borer infestation. It could be profitable that areas where serious out break of flower thrips and pod borer occurs.Jahangirnagar University J. Biol. Sci. 7(1): 55-64, 2018 (June)

Intraguild interactions between two biological control agents in citrus fruit: implications for biological control of medfly

AbstractThe parasitoid wasp Spalangia cameroni and the predatory beetle Pseudoophonus rufipes have long been studied for use as biological control agents against the Mediterranean fruit fly Ceratitis capitata, particularly in citrus fruit orchards. Nevertheless, these two species of natural enemies, when competing for a common resource, may experience intraguild predation (IGP) interactions. These possible interactions, affecting parasitism and predation, have been evaluated in the present work, under laboratory conditions, through potential changes in functional response. Regarding host/prey density, both natural enemies, when acting alone, showed a type II functional response. Nevertheless, due to IGP, S. cameroni, in the presence of P. rufipes, showed a higher fertility rate and a type III functional response. The parasitism behaviour of S. cameroni was affected by the presence of the predator, reducing the host handling time. Conversely, the parasitism rate of S. cameroni did not vary in the presence of P. rufipes but the degree of superparasitism decreased and led to an increased fertility rate and an increasingly female‐biased sex ratio. Meanwhile, the predatory efficiency of P. rufipes was not affected by the presence of S. cameroni but discrimination between parasitised and unparasitised pupae of C. capitata, with a preference for the latter, was reported for this predator species. Our results suggest that in biological control programmes, the use of only one of these species is recommended at low infestation levels, whilst at high densities of the pest, the combination of both natural enemies seems to be the most appropriate strategy.

Models of Disease Vector Control: When Can Aggressive Initial Intervention Lower Long-Term Cost?

Insecticide spraying of housing units is an important control measure for vector-borne infections such as Chagas disease. As vectors may invade both from other infested houses and sylvatic areas and as the effectiveness of insecticide wears off over time, the dynamics of (re)infestations can be approximated by [Formula: see text]-type models with a reservoir, where housing units are treated as hosts, and insecticide spraying corresponds to removal of hosts. Here, we investigate three ODE-based models of this type. We describe a dual-rate effect where an initially very high spraying rate can push the system into a region of the state space with low endemic levels of infestation that can be maintained in the long run at relatively moderate cost, while in the absence of an aggressive initial intervention the same average cost would only allow a much less significant reduction in long-term infestation levels. We determine some sufficient and some necessary conditions under which this effect occurs and show that it is robust in models that incorporate some heterogeneity in the relevant properties of housing units.

Levantamento da fauna de macroinvertebrados associados à macrófitas aquáticas

In aquatic ecosystems, the presence of macrophytes offers survival conditions for colonization of macroinvertebrates. This study aimed to characterize the fauna of macroinvertebrates associated with Pistia stratiotes L. (Araceae), in the Capivaras Lagoon, located inside the Baguaçu Ecological Park, in the municipality of Araçatuba, and to relate them to the physical and chemical parameters of the water. The sampling of P. stratiotes was in three points; the samples were sorted and later identified. It was observed a high density of Oligochaeta and Chironomidae larvae in the three points sampled, which may be related to the higher capacity of these organisms tolerate adverse environmental conditions, such as the low concentration of oxygen dissolved in the water obtained in the physical-chemical analyzes. The small lake has a history of pollution and currently suffers from low levels of oxygenation and infestation of P. stratiotes forming a long "rug" enclosed throughout its cover. Considering find solutions to recover the integrity of the environment and,, mainly, to recover the oxygenation of the water, it is suggested more investigations in the area, in several areas and the drainage of the inlet and outlet water channel of the lagoon, beyond the drainage of input and output of water of the lagoon, to improve the rapid circulation, avoiding the establishment of large banks of aquatic macrophytes.

Deployment of organic farming at a landscape scale maintains low pest infestation and high crop productivity levels in vineyards

Abstract Organic farming is a promising way to reduce pesticide use but increasing the area under organic farming at the landscape scale could increase pest infestations and reduce crop productivity. Examining the effects of organic farming at multiple spatial scales and in different landscape contexts on pest communities and crop productivity is a major step in the ecological intensification of agricultural systems. We quantified the infestation levels of two pathogens and five arthropod pests, the intensity of pesticide use and crop productivity in 42 vineyards. Using a multi‐scale hierarchical design, we unravelled the relative effects of organic farming at both field and landscape scales from the effects of semi‐natural habitats in the landscape. At the field scale, pest communities did not differ between organic and conventional farming systems. At the landscape scale, increasing the area under organic farming did not increase pest infestation levels. Three out of seven pest taxa were affected both by local farming systems and the proportion of semi‐natural habitats in the landscape. Our findings revealed that the proportion of semi‐natural habitats reduced pest infestation for two out of seven pest taxa. Organic vineyards had much lower treatment intensities, very similar levels of pest control and equal crop productivity levels. Synthesis and Applications. Our results clearly indicate that policies promoting the development of organic farming in conventional vineyard landscapes will not lead to greater pest and disease infestations but will reduce the pesticide treatment intensity and maintain crop productivity. Moreover, the interactions between semi‐natural habitats in landscape and local farming practices suggest that the deployment of organic farming should be adapted to landscape contexts.

The additional benefit of residual spraying and insecticide-treated curtains for dengue control over current best practice in Cuba: Evaluation of disease incidence in a cluster randomized trial in a low burden setting with intensive routine control.

BackgroundAedes control interventions are considered the cornerstone of dengue control programmes, but there is scarce evidence on their effect on disease. We set-up a cluster randomized controlled trial in Santiago de Cuba to evaluate the entomological and epidemiological effectiveness of periodical intra- and peri-domiciliary residual insecticide (deltamethrin) treatment (RIT) and long lasting insecticide treated curtains (ITC).Methodology/Principal findingsSixty three clusters (around 250 households each) were randomly allocated to two intervention (RIT and ITC) and one control arm. Routine Aedes control activities (entomological surveillance, source reduction, selective adulticiding, health education) were applied in the whole study area. The outcome measures were clinical dengue case incidence and immature Aedes infestation. Effectiveness of tools was evaluated using a generalized linear regression model with a negative binomial link function.Despite significant reduction in Aedes indices (Rate Ratio (RR) 0.54 (95%CI 0.32–0.89) in the first month after RIT, the effect faded out over time and dengue incidence was not reduced. Overall, in this setting there was no protective effect of RIT or ITC over routine in the 17months intervention period, with for house index RR of 1.16 (95%CI 0.96–1.40) and 1.25 (95%CI 1.03–1.50) and for dengue incidence RR of 1.43 (95%CI 1.08–1.90) and 0.96 (95%CI 0.72–1.28) respectively. The monthly dengue incidence rate (IR) at cluster level was best explained by epidemic periods (Incidence Rate Ratio (IRR) 5.50 (95%CI 4.14–7.31)), the IR in bordering houseblocks (IRR 1.03 (95%CI 1.02–1.04)) and the IR pre-intervention (IRR 1.02 (95%CI 1.00–1.04)).ConclusionsAdding RIT to an intensive routine Aedes control programme has a transient effect on the already moderate low entomological infestation levels, while ITC did not have any effect. For both interventions, we didn’t evidence impact on disease incidence. Further studies are needed to evaluate impact in settings with high Aedes infestation and arbovirus case load.

A Potential Repellent Against the Coffee Berry Borer (Coleoptera: Curculionidae: Scolytinae)

The coffee berry borer, Hypothenemus hampei (Ferrari), continues to pose a formidable challenge to coffee growers worldwide. Because of the cryptic life habit of the insect inside coffee berries, effective pest management strategies have been difficult to develop. A sesquiterpene, (E,E)-α-farnesene, produced by infested coffee berries has been identified as a potential repellent against the coffee berry borer both in laboratory bioassays and a field experiment in Hawaii. Various laboratory bioassays revealed significantly lower levels of infestation in berries treated with different concentrations of the (E,E)-α-farnesene. A field experiment in Hawaii resulted in up to 80% decreased coffee berry borer captures in traps containing a standard 3:1 methanol:ethanol attractant and a bubble cap formulation of (E,E)-α-farnesene compared to traps with just the attractant. (E,E)-α-farnesene was still active 19 wk after installation in the coffee plantation, based on 59% lower insect captures in traps containing the attractant + (E,E)-α-farnesene (1,737 insects) compared to traps containing the attractant (4,253 insects). The easy to install bubble caps are a welcome contrast with other pest management strategies that require spraying. The placement of (E,E)-α-farnesene in bubble caps in coffee plantations when coffee berries first become susceptible to infestations (ca. 90 d post-flowering) might result in lower infestation levels throughout the season, and consequently, increased yields and profits.