Fruit Infestation Levels Research Articles

Tephritid Fruit Fly Species Composition, Seasonality, and Fruit Infestations in Two Central African Agro-Ecological Zones.

Bactrocera dorsalis and several Africa-native Ceratitis species are serious constraints to fruit production in sub-Saharan Africa. A long-term trapping and fruit collection study was conducted (2011-2016) in two contrasting agro-ecological zones (AEZs) of Cameroon to determine fruit fly species composition, seasonality, attraction to various lures and baits, and fruit infestation levels. Ten tephritid species from genera Bactrocera, Ceratitis, Dacus, and Perilampsis were captured in traps. Bactrocera dorsalis was the most dominant of the trapped species and persisted throughout the year, with peak populations in May-June. Ceratitis spp. were less abundant than B. dorsalis, with Ceratitis anonae dominating in the western highland zone and Ceratitis cosyra in the humid forest zone. Methyl eugenol and terpinyl acetate captured more B. dorsalis and Ceratitis spp., respectively than Torula yeast. The latter was the most effective food bait on all tephritid species compared with BioLure and Mazoferm. Bactrocera dorsalis was the dominant species emerging from incubated fruits, particularly mango, guava, and wild mango. Four plant species-I. wombolu, Dacryodes edulis, Voacanga Africana and Trichoscypha abut-were new host records for B. dorsalis. This study is the first long-duration and comprehensive assessment of frugivorous tephritid species composition, fruit infestations, and seasonality in Central Africa.

The predation impact of ruby-throated hummingbird, Archilochus colubris, on spotted-wing drosophila, Drosophila suzukii, in raspberry, Rubus idaeus

Hummingbirds require arthropods in their diet and may consume 2000 small insects per day, including drosophilids, when nesting. In New York, we investigated the use of feeders to attract Ruby-throated Hummingbirds, Archilochus colubris (Linnaeus, 1758), into red raspberry, Rubus idaeus L., to encourage predation of the spotted-wing drosophila, Drosophila suzukii Matsumura. We investigated whether fly populations and fruit infestation would be reduced in the half of the field with feeders compared to the half without. Over four years, 2015–2018, 81% of 266 hourly observations of hummingbird behavior found they were occupying the field when utilizing the feeders, supporting opportunities for predation on D. suzukii. In 2016 to 2018, when maximal hummingbird sightings were reached, significant reductions in D. suzukii trap counts and fruit infestation levels were obtained in some weeks in the half of the field provided with feeders at a density of 62 feeders/hectare. Compared to the half without feeders, the final tally of cumulative trap counts and fruit infestation levels were lower in the half of the field treated with feeders in all years. In comparing two paired commercial raspberry fields (in 2020), one with feeders at a density of 151 feeders/hectare and the other without feeders, presence of feeders significantly reduced trap counts in most weeks during the fruiting season. No Ruby-throated Hummingbirds were observed in the commercial field without feeders. Hummingbirds may protect fruit from D. suzukii when they are encouraged with feeders to visit and occupy raspberry plantings. The presence of hummingbirds in raspberry fields has the potential to contribute to a D. suzukii integrated management program and reduce the reliance on pesticides.

What is the level of fruit infestation by pulp-feeding insects? An overview of their meaning and measurement

What is the level of fruit infestation by pulp-feeding insects? An overview of their meaning and measurement

Within-Canopy Distribution of Stenoma catenifer (Lepidoptera: Elachistidae) Infestation in Avocado Orchards

Native to the neotropics, the avocado seed moth Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) is a specialist pest of the family Lauraceae and considered one of the most important pests of avocados worldwide. However, little is known regarding its spatial distribution within a single tree. Therefore, we designed a study to evaluate the effects of canopy height and aspect (i.e., side of the tree) on fruit infestation by S. catenifer larvae in avocados. The study was conducted in three commercial organic avocado orchards located in São Paulo, Brazil. At each orchard, 40 fruit from 30 random trees were sampled weekly from October 2017 through February 2018, evaluating the number of fruits infested by S. catenifer larvae at three tree heights (bottom, middle, and top). In addition, fruits on the ground were also sampled. We also evaluated the effect of the side of the tree where the fruits were collected, i.e., whether they were on the side facing the east (sunrise) or the west (sunset). Within the avocado canopy, the level of fruit infestation by S. catenifer larvae was significantly higher at the top of the trees than in the middle and bottom. Fruit on the ground had lower levels of infestation than those on the tree canopy. The level of fruit infestation was also higher on the side of avocado trees facing the east (sunrise). Understanding the within-tree distribution of S. catenifer will help to better target monitoring and control activities against this pest in avocados.

Application of oviposition deterrent compounds for the control of olive fruit fly, Bactrocera oleae Rossi. (Dip. Tephritidae) control

Olive Fruit Fly Bactrocera oleae Rossi (Dip.: Tephritidae) which reduces the quantity and quality of olive products and oil, is considered as the most serious olive pest in the world, also in Iran. The present study was conducted in the Roudbar olive Research Station in Guilan, Iran between 2015 to 2017 regarding the efficiency of several oviposition deterrent compounds to reduce olive fruit fly damage. The treatments included kaolin 5% (Sepidan®), kaolin 4% (Sepidan®), kaolin 5% (Sepidan®)+ copper hydroxide, kaolin 4% (Sepidan®)+ copper hydroxide, copper hydroxide, and water as control. The experiment was performed in a (CRBD). Spraying was done three times a year. First, at the time of the pit hardening of the olive fruit, which was in late June. Second, with the activity onset of the second generation of the pest in early September and third with the appearance of the third generation of pests in early October. As a result, kaolin 5% + copper hydroxide had the highest oviposition deterrents effect on the olive fruit fly. In the first year of the study, the lowest level of total fruit infestation in this compound was 5.00 ± 1.46. In the second year, it was 5.00 ± 1.26. In the third year, the total fruit infestation was 2.42 ± 1.04 for kaolin 5% + copper hydroxide and 2.85 ± 1.22 for copper hydroxide which showed the lowest level of infestation of fruits. The results showed that copper hydroxide alone or combined with kaolin 5% with at least two sprays is recommended for controlling B. oleae and reducing the fruit damage.

Can Mating Disruption Be a Possible Route to Control Plum Fruit Moth in Mediterranean Environments?

Simple SummaryGrapholita funebrana is a main pest of plum throughout the Palearctic region. The management of this pest is generally carried out with chemical insecticides. In this study we investigated the suitability of the mating disruption as alternative method of control of this pest. Experiments were carried out in organic plum orchards during 2012 and 2014. Trap catches and fruit sampling were carried out to estimate the efficacy of this technique in reducing males catch and fruit infestation. The results indicated that the males caught in traps placed in the treatment plots was always significantly lower than untreated plots. The chemical analysis of the pheromone emission from the dispenser, carried out by solid-phase micro-extraction followed by gas chromatography, indicated an optimal duration of these tool for at least 60 days of field exposure. Fruit sampling evidenced that pheromone treatment significantly reduced fruit infestation, but not economic damage, particularly on the cultivar for which a high susceptibility to the moth infestation is known.Control of the plum fruit moth, Grapholita funebrana Treitschke (Lepidoptera: Tortricidae), has been mainly based on the use of chemical insecticides, which can cause undesirable side effects, leading to a growing interest towards alternative sustainable strategies. The aim of this study was to evaluate the effect of the mating disruption technique on G. funebrana infestation in plum orchards, by comparing the number of male captures in pheromone-baited traps, and evaluating the damage to fruits in plots treated with the pheromone dispersers and in control plots. The study was carried out in 2012 and 2014 in three organic plum orchards, on the cultivars Angeleno, Friar, President and Stanley. To evaluate the pheromone emission curve of the dispensers from the openings to the end of the trials, a chemical analysis was carried out by solid phase micro-extraction followed by gas chromatography, followed by mass spectrometry. In all years and orchards the mean number of males caught in traps placed in the treatment plots was always significantly lower than untreated plots. Pheromone emission from the dispensers was highest at the opening, and was still considerable at 54 days of field exposure, while it significantly decreased after 72 days of field exposure. Cultivar was confirmed to be an essential factor in determining the fruit infestation level. Pheromone treatment significantly reduced fruit infestation, but not economic damage.

Effect of the olive fruit size on the parasitism rates ofBactocera oleae(Diptera: Tephritidae) by the figitid waspAganaspis daci(Hymenoptera: Figitidae), and first field releases of adult parasitoids in olive grove

SummaryThe olive fruit flyBactrocera oleae(Rossi) (Diptera: Tephritidae) is the major pest of olives worldwide. The figitid wasp,Aganaspis daci(Hymenoptera: Figitidae), is a larval-prepupal endoparasitoid of fruit fly species, and it was found to successfully parasitize medfly larvae in field-infested figs in Greece. To assess the potential ofA. dacias a biological control agent againstB. oleae, we studied the effect of olive fruit size on parasitism rates ofA. dacion 2ndand 3rdinstar larvae ofB. oleae, by using fruit of different size (cultivar ‘Chalkidikis’) and wild olive fruit. In addition, we conducted releases ofA. dacifemales in a pilot olive grove in Volos, Magnesia. From July to October, we released 200A. dacifemales/0.1 ha/week, followed by olive fruit sampling to estimate olive fruit infestation levels and the parasitism rates ofA. daci. Laboratory trials revealed that fruit size and larvae instar were predictors of parasitism success ofA. daci, with parasitism rates higher for small-size fruit of the cultivar “Chalkidikis” and the 3rdinstar larvae ofB. oleae. In field trials, noA. daciadults emerged from the olive fly infested fruit.

On a poorly known tritrophic interaction: fruit-infesting Rhagoletotrypeta pastranai Aczél (Diptera: Tephritidae) and its parasitoid Utetes anastrephae (Viereck) (Hymenoptera: Braconidae) in Celtis ehrenbergiana (Klotzsch) Liebm. (Rosales: Cannabaceae) fruits

We present information on a poorly known native tritrophic interaction involving Celtis ehrenbergiana (Klotszch) Liebm. (Cannabaceae), the fruit fly Rhagoletotrypeta pastranai Aczel (Diptera: Tephritidae), and its parasitoid Utetes anastrephae (Viereck) (Hymenoptera: Braconidae) from Buenos Aires, Argentina. Insects were collected from 70 trees and 950 fruits and immatures were reared in the laboratory. The fruit fly accounted for 41.8% of all pupae (59 out of 141 pupae), whereas the parasitoid accounted for 32.6% of fruit fly pupae (46 braconids out of 141 pupae). Fruit infestation levels by the fruit fly ranged between 0 and 191 pupae/100 g of fruit (mean = 53.3 ± 55.3 pupae/100g of fruit), and percentage infestation levels ranged between 0 and 100% (mean = 18.2 ± 32.1%). Most parasitoid adults emerged after 1-2 months, whereas most fruit fly adults emerged after a 12-mo diapause period. Our results show that both insects are common and abundant at our study area and, despite being non-economically important, highlight the need of studying poorly known species to gain a better insight into the ecology of biotic interactions with ultiple interactors

Population Dynamics of Spotted Wing Drosophila (Drosophila suzukii (Matsumura)) in Maine Wild Blueberry (Vaccinium angustifolium Aiton).

A long-term investigation of D. suzukii dynamics in wild blueberry fields from 2012–2018 demonstrates relative abundance is either still increasing or exhibiting periodicity seven years after the initial invasion. Relative abundance is determined by physiological date of first detection and air temperatures the previous winter. Date of first detection of flies does not determine date of fruit infestation. The level of fruit infestation is determined by year, fly pressure, and insecticide application frequency. Frequency of insecticide application is determined by production system. Non-crop wild fruit and predation influences fly pressure; increased wild fruit abundance results in increased fly pressure. Increased predation rate reduces fly pressure, but only at high abundance of flies, or when high levels of wild fruit are present along field edges. Male sex ratio might be declining over the seven years. Action thresholds were developed from samples of 92 fields from 2012–2017 that related cumulative adult male trap capture to the following week likelihood of fruit infestation. A two-parameter gamma density function describing this probability was used to develop a risk-based gradient action threshold system. The action thresholds were validated from 2016–2018 in 35 fields and were shown to work well in two of three years (2016 and 2017).

Population variation in the intensity of fruit infestation and pre-dispersal seed predation in Yucca schidigera (Asparagaceae) by its obligate pollinator

Variation in the occurrence and the intensity of pre-dispersal seed predation can help understand ecological and evolutionary dynamics of plant populations. Pre-dispersal seed predation can vary in intensity, resulting in costs that differ in magnitude among populations. We examined variation in the cost of pre-dispersal seed predation across nine Yucca schidigera populations, by quantifying yucca moth infestation, damage on fertile seeds and seed mass in 650 fruits sampled from 73 Yucca plants. We recorded Tegeticula mojavella larvae on 100% of the Y. schidigera plants. Across populations, mean infestation rates ranged from 2.9 to 6.11 larvae per fruit. Despite slight variation in the level of fruit infestation, predation on mature seeds differed among the nine populations, ranging from 10 to 26%. Mean seed mass and germination rate differed among populations, but the effect of larvae infestation on these traits was not significant. Altogether, our results demonstrate that infestation and pre-dispersal seed predation by yucca moths differ significantly across populations of Y. schidigera. Variable ratios of seed predation result in different costs across plant populations, despite experiencing similar infestation ratios. It seems that, regardless of its spatial distribution, the interaction between Y. schidigera and T. mojavella is dependent on local ecological factors that regulate oviposition and seed predation.

Infestation of Wild Fruit byDrosophila suzukiiSurrounding Maine Wild Blueberry Fields1

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is an invasive vinegar fly that attacks a large variety of soft fruits including wild blueberries in Maine. Wild blueberry fields in Maine are commonly surrounded by woodland edges that contain wild fruit. These edges are important refugia as they provide the fly with needed shade and moisture during the hottest parts of the day. The wild fruit in these wooded edges are also potential alternative hosts for D. suzukii. We surveyed wild fruit along blueberry fields to determine the types of fruit present and measured D. suzukii infestation levels in surveyed fruit. We also measured the number of adult D. suzukii along field edges and the level of infestation in the wild blueberry crop. Drosophila suzukii was found in nine out of seventeen surveyed wild fruit species along field edges. Our results suggest a correlation between wild fruit infestation levels and adult fly densities in the crop fields. Blueberry fields with higher levels of wild fruit infestation also showed higher levels of adult D. suzukii trap captures in the commercial blueberry fields. These wild fruit hosts may allow D. suzukii to increase its population abundance prior to moving into commercial blueberry fields.

Seasonality of the Mediterranean Fruit Fly (Diptera: Tephritidae) on Terceira and Sao Jorge Islands, Azores, Portugal.

Population dynamics studies are very important for any area-wide control program as they provide detailed knowledge about the relationship of Medfly [Ceratitis capitata (Wiedemann)] life cycle with host availability and abundance. The main goal of this study is to analyse seasonality of C. capitata in Terceira and Sao Jorge Islands (Azores archipelago) using field and laboratory data collected during (2010–2014) CABMEDMAC (MAC/3/A163) project. The results from Sao Jorge Island indicate significantly lower male/female ratio than on Terceira Island. This is an important finding specially regarding when stablishing the scenario parameters for a sterile insect technique application in each island. The population dynamics of C. capitata are generally linked with host fruit availability and abundance. However, on Terceira Island fruit infestation levels are not synchronized with the trap counts. For example, there was Medfly infestations in some fruits [e.g., Solanum mauritianum (Scop.)] while in the nearby traps there were no captures at the same time. From this perspective, it is important to denote the importance of wild invasive plants, on the population dynamics of C. capitata, as well important to consider the possibility of having different densities of traps according to the characteristics of each area in order to improve the network of traps surveillance’s sensitivity on Terceira Island.

Determination of Human Parasitic Infestation on Fruits and Vegetables Sold in Ekpoma Markets, Edo State, Nigeria

Fruits and vegetables commonly brought for sale in markets within Ekpoma in Esan West Local Government Area of Edo State were screened for human parasites in medical laboratory science department Research and diagnostic laboratory in College of Medicine, Ambrose Alli University, Ekpoma, Edo State. Two hundred and fifty (250) samples of seven different vegetable types which include cabbage, carrot, spinach, pumpkin, cucumber tomatoes and waterleaf and two different types of fruits which are pineapple and garden egg were obtained in three different markets within Ekpoma and screened using centrifugation method (Simple Sedimentation) and Floatation method. Cysts, ova, larvae and trophrozoites of intestinal Protozoa and helminthes were recovered. 106 (42.4%) of the samples were positive for different species of parasites. The parasites implicated were <em>Entamoeba coli</em> 21 (20.5%), <em>Entamoiba histolytica</em> 11 (10.4%), 4(3.6%), <em>Giardia lablia</em> 4 (3.6%), <em>Hymenolepis nana</em> 1 (0.9%), <em>Trichuris trichiura</em> 2 (1.9%), <em>Ascaris lumbricoides</em> 12 (11.3%), Hookworm 14 (13.2%), <em>Strongyloides stercoralis</em> 34 (32.1%), <em>Gastrodiscoides hominis</em> 1(0.9%) <em>and Faciola species</em> 1 (0.9%). <em>Strongyloides</em>. <em>stercoralis</em> with 34 (32.1%) of the positive cases has the highest occurrence, while <em>H. nana</em>, <em>G. hominis</em> and <em>Faciola species</em> with1 (0.9%) had the least occurrences. The study also showed that water-leaf with 83.3% infestation rate has the highest parasitic infestation, while cucumber with 0 (0.0%) has zero infestation. Spinach was found to have the highest multiple parasitic infestation of seven (7) species, whereas, cucumber had none. Infestation of different vegetables and fruits by various species of parasites was statistically significant (p<0.05; X² = 108.41). The infestation of medical important parasites and non-medical important parasites that were recovered in this project was found to be statistically significant (p<0.05; X = 9.845). Results from this current study however show high level of fruit and vegetables infestation with intestinal parasites and also indicate a great risk of acquiring intestinal parasites by eating improperly processed fruits and vegetables, but it can be excluded from the cycle of transmission of parasitic infections by properly and hygienically prepared fruits and vegrtables before consumption and proper waste management.

Limits to the host range of the highly polyphagous tephritid fruit fly Anastrepha ludens in its natural habitat.

Anastepha ludens (Diptera: Tephritidae) is a highly polyphagous fruit fly that is able to develop in a wide range of hosts. Understanding the limits of this pest's host range could provide valuable information for pest management and plant breeding for pest resistance. Previous studies have shown that guavas (Psidium guajava (Myrtaceae) L.), are not attacked under natural conditions by A. ludens. To understand this phenomenon, guavas were exposed to natural infestation by A. ludens and to other fruit fly species that infest guavas in nature (Anastrepha striata Schiner, Anastepha fraterculus (Wiedemann), Anastepha obliqua (Macquart)). Once the susceptible phenological stage of guavas was determined, fruit infestation levels were compared between A. ludens and A. striata. Choice and non-choice tests were performed under field-cage conditions. Under field conditions, guavas were susceptible to A. striata and A. fraterculus attack all the way from when fruit was undeveloped to when fruit began to ripen. No infestation by A. ludens was recorded under natural conditions. Similar results were obtained when forced exposures were performed, indicating that unripe guavas were preferred by A. striata over ripe fruit, and that infestation rates were higher at early fruit maturity stages. Under forced oviposition conditions, A. ludens larvae were unable to develop in unripe guavas but did so in fully ripe fruit. However, A. ludens fitness parameters were dramatically affected, exhibiting reduced survival and reduced pupal weight compared to conspecifics that developed in a natural host, grapefruit. We confirm that P. guajava should not be treated as a natural host of this pestiferous species, and suggest that both behavioral aspects and the fact that larvae are unable to adequately develop in this fruit, indeed represent clear limits to A. ludens's broad host range.

Development of an effective dose of cypermethrin for managing eggplant shoot and fruit borer (Leucinodes orbonalis)

A study was conducted in the experimental farm of Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh during November 2012 to April 2013 in order to find out an effective dose of cypermethrin insecticide (that is commonly used in Bangladesh) against Eggplant Shoot and Fruit Borer (ESFB). Including control there were five treatments were used to measure the effectiveness of the particular insecticide based on fruit infestation, total yield and also benefit - cost ratio. Among the different treatments Ripcord (cypermethrin) 10 EC @ 1 ml/l of water sprayed after observing 5% level of fruit infestation and repetition of the same at 15 days interval (T3) performed the best in respect of marketable yield (30.55 t/ha), reduction of fruit infestation over control (77.54%) and also the benefit cost ratio (8.14).

Seasonal population fluctuations ofBactrocera invadens(Diptera: Tephritidae) in relation to mango phenology in the Lake Victoria Crescent, Uganda

Introduction. Timing of management practices requires an understanding of pest population dynamics in given cropping systems. Our study was designed to establish the population trends of B. invadens in mango orchards and to determine if population fluctuations were reflected in fruit infestation levels during changes in mango phenology. Materials and methods. Bactrocera invadens flies were trapped weekly from February 2011 to November 2012, using methyl eugenol and DDVP (dichlorvos) insecticidal strips. Trapping was done in three mango orchards in the Luweero district of Uganda’s Lake Victoria Crescent. Mango fruit samples were incubated for the retrieval of puparia to calculate positivity (proportion of fruits infested) and fruit infestation indices (number of puparia per kg of fruit) for each stage of fruit maturity. Results. Mean trap catches of adult B. invadens varied significantly over the months (range : ~11 flies per trap per day (FTD) to over 590 FTD; P £ 0.0001). During each year, infestations peaked during June-July and January-February. Trap catches were higher in the major fruiting season compared with the minor fruiting season and were the highest when mango was at the physiological maturity and ripe stages. Fruit infestation and positivity were highest for fruit at the physiological maturity and ripe stages and lowest at the fruit set stage. Discussion. Our findings show that B. invadens is present year-round and all stages of mango fruit development are susceptible to attack. Thus, control measures should be implemented throughout the year and preferably started at fruit set to lessen fruit fly population build-up and damage to fruits.

Field type, trap type and field-edge characteristics affectRhagoletis mendaxcaptures in lowbush blueberries

Blueberry maggot, Rhagoletis mendax Curran (Diptera: Tephritidae), is the most important pest of blueberries in eastern North America. Insecticide use in fruit-bearing lowbush blueberry fields could be reduced with management strategies focused on vegetative fields. Fly distribution and fruit infestation levels were assessed where fruit-bearing and vegetative fields adjoin and along forested edges of vegetative fields. Along adjoining edges, immature female flies were captured in fruiting fields and mature females in vegetative fields throughout the season. Male fly captures and fruit infestation levels were greater at 5 m than at 30 m from the edge. Along forested edges, fly captures were best predicted by densities of ripe lowbush blueberries and large coniferous trees. Maggot infestation level in lowbush blueberries was best predicted by blueberry density and small deciduous trees. Bunchberry, Cornus canadensis L., was the only non-crop host in which blueberry maggot was found. We have shown that relatively high numbers of flies occur in vegetative fields and at edges of fruiting fields. Ripe blueberries and certain vegetation in forested edges affect fly distribution and probably maintain populations. These results may help to predict where controls for blueberry maggot should be targeted and suggest that management strategies focused on vegetative fields and field edges may be worthwhile.

Surveys for Stenoma catenifer (Lepidoptera: Elachistidae) and Associated Parasitoids Infesting Avocados in Perú

Surveys for Stenoma catenifer Walsingham, the avocado seed moth, and its associated larval parasitoids were conducted in the Departments of Junín, Huánuco, Cusco, and Madre de Dios in Perú. Fruit infestation levels in some areas ranged from 0 to 58%, and parasitism of S. catenifer larvae in Junín and Huánuco was 23%. Five species of hymenopteran parasitoid in two families, Braconidae (Apanteles sp., Hypomicrogaster sp., and Chelonus sp.) and Ichneumonidae (Pristeromerus sp. and Xiphosomella sp.), were reared from larvae, and one species of tachinid fly (Chrysodoria sp.) emerged from pupae. The dominant larval parasitoid, a gregarious Apanteles sp., accounted for 55% of parasitized hosts. Branch and twig tunneling by S. catenifer larvae in a commercial Hass avocado orchard was observed in Cusco. The field attractiveness of the sex pheromone of S. catenifer was demonstrated with 73% of monitoring traps deployed in three departments (Junín, Huánuco, and Cusco) catching male moths. Approximately 55% of avocado fruit sourced from the Province of Chanchamayo (Junin) and purchased at the Mercado Modelo de Frutas in La Victoria, in central Lima were infested with larvae of S. catenifer. Infested avocado fruit sold at this market could represent a potential incursion threat to coastal Hass avocado production regions in Perú that are reportedly free of this pest.

Influence of walnut cultivar on infestation by Rhagoletis completa: behavioural and management implications

The walnut husk fly, Rhagoletis completa Cresson (Diptera: Tephritidae), has recently invaded Switzerland, Austria, Germany, and France, probably crossing the alpine divide after its initial introduction into Italy. Here, the susceptibility of 36 walnut [Juglans regia L. (Juglandaceae)] cultivars to attack by R. completa was studied in an experimental orchard in Switzerland. Walnut cultivars differed significantly in infestation rates; cultivars that produced large, heavy fruit harboured significantly more larvae than cultivars that produced smaller fruit. Pupal weight was significantly influenced by cultivar, but not by any of the physical properties that we measured. For individual fruit within a cultivar, pupal weight was weakly related to fruit weight and infestation level. Adult longevity was correlated with pupal weight and appeared to be favoured in flies that developed in large-fruit cultivars. The longevities of adults recovered from different cultivars differed significantly. The shortest longevity was recorded for flies recovered from Geisenheim 1049 (39.2 ± 2.80 days) and the longest for flies recovered from Sheinovo (68.8 ± 21.75 days). Differences in diapause length were also highly significant and varied between 167 ± 5.1 (Esterhazy III) and 257.4 ± 8.21 days (Mayette). These results suggest that (1) across and within cultivars, walnut husk flies prefer to infest (i.e., they develop better in) large, heavy fruit, and (2) offspring that develop in large fruit are likely to accrue fitness advantages over the offspring of females using smaller fruit. Our results provide the basis for subsequent studies on resource defence by males, as they enable a prediction of which type of fruit males should defend more vigorously.

Use of intercrops and antifeedants for management of eggplant shoot and fruit borer Leucinodes orbonalis (Lepidoptera: Pyralidae)

The impact of vegetational diversity through intercrop and the application of antifeedants were assessed for their ability to reduce the infestation of shoot and fruit borer Leucinodes orbonalis Guen. on eggplant. Intercropping with coriander and fennel reduced the fruit damage to 12–15% compared with the plots with eggplant monoculture. Total yield of intercropped eggplant was significantly higher than the eggplant monoculture yield. Coriander and fennel were found to be equally effective in reducing infestation by L. orbonalis. Neem seed kernel extract (4%) and the neem-based product Neemarin® were found to be more effective in controlling L. orbonalis than ash dust and were lower than the untreated control. The fruit infestation level in the neem treatments (either of them) was 15–16% less than the untreated check. The interaction of intercrop and antifeedant showed that coriander-intercropped eggplant along with foliar spray of Neemarin® significantly reduced fruit damage. In a multiple choice chamber, orientation of female moths to eggplant was significantly reduced in the presence of fennel or coriander. With 38.9 and 37.1 per female, the extent of egg-laying by L. orbonalis on eggplant associated with fennel or coriander, respectively, was significantly less than on sole eggplant (48.4/female).