Evaluation of thiacloprid and clothianidin (neonicotinoids) as alternative to fenthion (organophosphate) for control of Mediterranean fruit fly (Diptera: Tephritidae) in deciduous fruit orchards

Fenthion (organophosphate) was used in Australia to target adults, eggs and larvae of Mediterranean fruit fly (Medfly), Ceratitis capitata Wiedmann (Diptera: Tephritidae) in deciduous fruits. With its removal from use in 2015, clothianidin and thiacloprid (neonicotinoids) were evaluated for any adulticide, ovicide or larvicide (eggs, larvae) activity against Medfly in a series of laboratory and field-cage experiments in peach and nectarine. We included fenthion in all experiments as a positive control. As an adulticide, fenthion had the greatest residual toxicity on fruit, with 7 d old residues killing 44% of adults within 48 h compared to thiacloprid (17%) and clothianidin (30%). When applied as a larvicide to naturally infested peaches, none of the insecticides was 100% effective, though fewest pupae (1.18 ± 0.19 pupae/fruit) (indirect measurement of larval survival) were produced when treated with fenthion, followed by clothianidin (3.40 ± 0.33 pupae/fruit) and thiacloprid (6.88 ± 0.34 pupae/fruit); with 11.35 ± 0.30 pupae/fruit in control (water). In peaches treated 48 h post-infestation, fenthion was most effective in reducing numbers of pupae and adult emergence and with higher percentage of deformed adults, with thiacloprid=clothianidin. In nectarines treated 48 h post-infestation, fenthion was most effective in reducing numbers of pupae and adult emergence as well as with higher percentage of deformed adults, followed by clothianidin. Insecticides were least effective when applied as a preventative 24 h or 7 d prior to infestation, with fenthion more effective than clothianidin. Whilst our study shows that neither clothianidin nor thiacloprid are equivalent to fenthion, they are acceptable substitutes to growers for use for Medfly in deciduous fruits given that fenthion is no longer available to growers in Australia. We recommend that growers incorporate other controls to target the adult stage rather than rely only on new insecticides.     

Suppressing Mediterranean fruit fly (Diptera: Tephritidae) with an attract-and-kill device in pome and stone fruit orchards in Western Australia

Attract-and-kill is a possible alternative to the conventional control of Mediterranean fruit fly (medfly), Ceratitis capitata Wiedemann (Diptera: Tephritidae) with bait or cover sprays of organophosphate insecticides. In this study, we determined if an attract-and-kill device (MagMED^®) could be applied alone at the recommended rate (80 devices/ha), or needed to be combined with other conventional control tactics to suppress medfly in deciduous fruit orchards (apple, nectarine, peach, pear, plum). We also determined if attract-and-kill had any detrimental effects on naturally occurring beneficial insects. Based on an acceptable level of crop loss of 2–5% (the level of crop loss growers can tolerate), attract-and-kill suppressed medfly and reduced crop loss below the acceptable level in orchards with additional controls. Attract-and-kill was most effective when combined with either bait spraying, cover spraying or both. Combining attract-and-kill with cover sprays of fenthion resulted in a drop in crop loss of apples from 2.5% to 0.5%. By combining attract-and-kill with weekly bait sprays and two cover spray applications, crop loss fell from 13.7% to 4.3% in peaches, from 6.3% to 5% in nectarines and from 6.3% to 3.7% in pears. Twice weekly bait spraying was the most effective technique at suppressing medfly, providing acceptable control when applied alone, which further improved by combining with attract-and-kill. By combining attract-and-kill with twice weekly bait spraying crop loss fell from 2% to 1% in nectarines and from 4% to 2% in apples. In laboratory trials, attract-and-kill devices killed 100% of brown lacewings (Micromus tasmaniae Walker) and 94% of transverse ladybeetles (Coccinella transversalis Fabricius) 24 h after contact. However, orchard samples suggest that it may not pose any significant negative impact on naturally occurring beneficials such as Neuroptera, Hymenoptera, Coleoptera, Thysanoptera and Syrphidae in the field.     

Area-wide management of fruit flies (Diptera: Tephritidae) in the Central Burnett district of Queensland,Australia

Queensland fruit fly, Bactrocera tryoni (Froggatt), is the most serious pest of the native tephritid species in Australia and a significant market access impediment for fruit commodities from any area where this species is endemic. An area-wide management (AWM) program was implemented in the Central Burnett district of Queensland with the aim of improving fruit fly control and enhancing market access opportunities for citrus and other fruits produced in the district. The primary control measures adopted in the AWM system included bait spraying of commercial and non-commercial hosts and the year-round installation of male annihilation technology (MAT) carriers in both orchards and town areas. The MAT carrier used consisted of a dental wick impregnated with 1 ml cue-lure [4-(4-acetoxyphenol)-2-butanone] and 1 ml Malathion 500 EC in a plastic cup. The application of these control measures from 2003 to 2007 resulted in overall suppression of fruit fly populations across the entire district. Male trap catches at the peak activity time were reduced by 95% and overall fruit fly infestation in untreated backyard fruit of town areas reduced from 60.8% to 21.8%. Our results demonstrate remarkable improvement in fruit fly control and economic benefit to the Central Burnett horticulture. Therefore, commercial growers are continuing the AWM program as a long-term, industry funded activity, to provide an additional layer of phytosanitary security for market access of fruit commodities from this district.     

我国南方实蝇类害虫概述

实蝇(fruit fly)是水果和蔬菜类作物的重要害虫。本文对我国南方(海南、广东、广西、云南、贵州、四川、重庆、湖南、湖北、福建)实蝇种类、分布范围、寄主(诱剂)进行总结。据不完全统计,我国华南地区采集(诱捕)的实蝇已达18属97种,其中海南21种,广东15种,广西30种,云南59种。同时,就主要实蝇在我国的分布特征及实蝇科昆虫的鉴定和分类上的一些问题进行简要论述。     

Improvement of bait sprays for the control of Bactrocera oleae (Diptera: Tephritidae)

The control of the olive fruit fly Bactrocera oleae (Gmelin) is based on insecticides that are usually applied as bait sprays. Large-scale field experiments were conducted in the Kolymvari region of Crete (Greece) to evaluate the efficacy of several bait spray solutions against the fly that were applied at the recommended spraying volume per hectare (or 300 ml per treated tree), compared applications at volumes reduced by two and three fold (150 and 100 ml, respectively). The trophical attractant (hydrolysed protein at 75% w/w) that was used was mixed with alpha-cypermethrin, thiacloprid, thiacloprid + deltamethrin or dimethoate, and these formulations were tested during three successive summers (2012–2014) according to European Plant Protection Organisation (EPPO) standards. The products were alternated with one another over time in the experimental plots. The results indicated that all of the bait spraying solutions of the tested products were effective against B. oleae at all of the doses tested and resulted in significantly lower olive fly populations compared with the standard recommended dose, which was indicated by the fly catches in the nets of McPhail traps within the experimental plots. The percentages of live infestations of B. oleae were very low (<2%, except in 2013 due to a very low olive fruit yield), as was the number of applications each year, which was 6–7 and did not differ among treatments. The benefits of this concept in the management of the pest and potential future improvements of the method are discussed.     

Pest behaviour insights from quarantine surveillance of male Queensland fruit fly,Bactrocera tryoni (Froggatt) (Diptera: Tephritidae)

Fruit flies (Diptera: Tephritidae) are a major problem for Australia's $6.9 billion horticultural industry. Bactrocera tryoni (Froggatt) is the most significant fruit fly pest in the eastern states of Australia. Catches of male B. tryoni from cuelure-baited Lynfield surveillance traps in towns bordering the Fruit Fly Exclusion Zone in New South Wales, Australia, from November to May in 2001/2002–2007/2008 were analysed with respect to year, town, property type (urban/rural), and tree species/crop varieties in which the trap was placed (tree type). Average catches of all traps were highest in 2007/2008 and lowest in 2003/2004, and showed an overall positive correlation with rainfall (P < 0.05). More B. tryoni males were caught in Wagga Wagga and Lockhart than in other towns. There were no significant differences in catches of B. tryoni between urban and rurally located traps. With respect to tree type, traps placed in pomefruit trees caught significantly more flies than those in citrus, stonefruit, or nonfruit trees, with no significant differences among the latter three tree groups. Within the pomefruit group, traps in apples (Malus domestica Borkh.) and pears (Pyrus spp.) caught significantly more flies than those in cotoneasters (Cotoneaster spp). Within the citrus group, traps in orange trees (Citrus × sinensis (L.) Osbeck) caught significantly more flies than those in mandarin trees (Citrus reticulata Blanco). No significant differences were detected in catches between any members of the stonefruit group. Within the nonfruit group, traps placed in kurrajongs (Brachychiton populneum (Schott & Endl.) R. Br.) caught significantly more flies than those placed on other tree species in the group. This study demonstrates that although surveillance programs conducted to establish and/or maintain area freedom from specific pests may not provide balanced datasets, careful analysis of the results of such programs can provide valuable insights into the behaviour of the species in question.     

Complementary physical and chemical treatments as an alternative to fungicide use to control postharvest decay incidence and fruit quality of Montenegrina tangerines

Heat treatments affect the germination and development of pathogens and enhance the ability of fruits to resist infection after harvest. In the present work, the effects of heat, in combination with other alternative decay control methods, were studied on ‘Montenegrina’ tangerines along with the effects on the cuticular surface of the fruit. Different treatment combinations using hot water (60 °C), brushing, and immersion in chloride dioxide, imazalil, sodium bicarbonate, and hand-applied carnauba wax were used. The tangerines were then put in cold storage for 20 days at 5 °C and retrieved to ambient conditions for 7 more days. Fruit samples were analyzed for total soluble solids, titratable acidity, epidermal color, weight loss, and decay incidence; an analysis of fruit surface was done through scanning electron microscopy. Heat treatments significantly reduced the number of tangerines with decay symptoms and enhanced the efficacy of the tested products. Carnauba wax significantly increased the number of rotten fruits, exerting a protective effect on the fungi by covering their structure. Sodium bicarbonate in combination with heat exerted a good control on decay incidence. The heat treatments partially removed the hyphae and spores of pathogens on the surface and also melted the cuticular waxes that cover stomata and cracks, reducing possible entry points for pathogens.     

Review of grapes Vitis sp. as an occasional host for Queensland fruit fly Bactrocera. tryoni (Froggatt) (Diptera: Tephritidae)

The recognition of grapes as a host of Queensland fruit fly Bactrocera tryoni (Froggatt) (Qfly) has been inconsistent across Australian states due to the variable nature of reports. Here the current state of knowledge is reviewed. Grapes are not a preferred Qfly host and attacks are infrequent. Infestations were reported to be more common in coastal and subtropical areas or in periods of high rainfall associated with the low availability of preferred hosts. Egg survival appears to be low, although larval survival may be considerably higher. This review has identified a range of literature referring to grapes as a host of Qfly. A review of overseas literature also indicates that grapes are a host for several other fruit fly species.     

Host suitability of three avocado cultivars (Persea americana Miller: Lauraceae) to oriental fruit fly (Bactrocera (invadens) dorsalis (Hendel) (Diptera: Tephritidae))

The oriental (invasive) fruit fly Bactrocera (invadens) dorsalis (Hendel) (Diptera: Tephritidae) has invaded Africa and is currently established in over 30 countries and has caused in massive fruit losses. Avocado (Persea americana Miller) is among the fruit with which the pest is associated. The aim of the study was to determine the host status of a ‘black-skinned’ cultivar “Hass” and two ‘green-skinned’ cultivars “Pinkerton” and “Fuerte” to B. (invadens) dorsalis. In the laboratory study conducted in Kenya in 2012 and 2013, punctured and unpunctured recently-harvested fruit were exposed to sexually-mature fruit fly in ‘no-choice’ experiments. B. (invadens) dorsalis readily developed in the punctured fruit but not in the uncompromised fruit (fruit not damaged by insects or handling). This result was confirmed in Tanzania in 2013 where flies were introduced to unpunctured fruit. In the field studies the fruit of each cultivar were caged in situ with flies for 72 h. On dissection only fruit damaged by false codling moth (Thaumatotibia leucotreta (Meyrick)) were found to harbor B. (invadens) dorsalis. In the light of these results the risk imposed for “Hass”, “Pinkerton” and “Fuerte” by B. (invadens) dorsalis is negligible under standard export conditions. The findings of this study and the implications to regional and international trade are discussed.     

Effect of Pichia membranaefaciens on ROS metabolism and postharvest disease control in citrus fruit

The yeast Pichia membranaefaciens has antagonistic effects against a wide range of phytopathogenic fungi that cause postharvest fruit decay. This work evaluated the effects of P. membranaefaciens on the reactive oxygen species (ROS) metabolism and disease control in harvested citrus fruit (Citrus sinensis L. Osbeck). The lesion diameter caused by Penicillium italicum and Penicillium digitatum on citrus fruit was remarkably reduced when the fruit was point-inoculated or dipped in a suspension of P. membranaefaciens at 1 × 10⁸ CFU mL⁻¹. The application of P. membranaefaciens on citrus fruit enhanced the activity of superoxide dismutase, ascorbate peroxidase, and glutathione reductase, as well as the levels of hydrogen peroxide, the superoxide anion and glutathione, but inhibited the decreasing ascorbic acid content. Furthermore, catalase activity was decreased by the same treatment. These results indicated that yeast treatment induced the synthesis of antioxidant enzymes which might have antagonistic effects against postharvest green and blue mold infection in citrus fruit.     

Effect of temperature on the developmental time,survival of immatures and adult longevity of Aganaspis daci (Hymenoptera: Figitidae), a natural enemy of Ceratitis capitata (Diptera: Tephritidae)

Longevity, developmental time and offspring survival of parasitoid wasps are decisive in their effective performance as biocontrol agents. Optimum temperature range determines parasitoid survival, development and reproduction. Thus, controlling this abiotic factor is a key to the success of pest management programs. Adult longevity, developmental time from egg to adult and survival of immatures of Aganaspis daci were assessed in the laboratory under different constant temperatures; adult longevity without hosts, but with the provision of water and honey, and developmental time and survival of immatures from host pupae, whose larvae had been exposed to parasitoids. Results showed that longevity depended on temperature decreasing in the range 15–20 °C (36 – 25 days), but was lower in the range 25–35 °C (10 – 7 days). Regarding developmental time from egg to adult and survival of immatures, our results showed that 20 and 25 °C are the most suitable temperatures. At 15 and 30 °C mortality of the immature stages was very high (>90%) or developmental time to adult was very slow (>3 months). Immatures did not survive at 35 °C. We found no significant differences in developmental time to adult or survival of immatures between 20 and 25 °C. The sex ratio of parasitoid progeny was female biased at 25 °C; the proportion of females increased at all cases with temperature. The t_o and K for total development were 8.5 °C and 500 DD, respectively. Our findings provide some guidance for future inundative or inoculative field releases of this parasitoid for the management of Ceratitis capitata in Spain.     

A comparison of monitoring systems used for Ceratitis species (Diptera: Tephritidae) in South Africa

For 16 years a bucket-type trap known as the Sensus fruit fly trap has been used to monitor three fruit fly pest species Ceratitis capitata, Ceratitis rosa and Ceratitis cosyra in South African fruit industries. The relative efficiencies of lures sold for monitoring fruit flies with the Sensus trap in South Africa were determined in field experiments where laboratory-reared C. capitata, C. rosa and C. cosyra were released in a mango orchard within a few metres of Sensus traps containing either Capilure (trimedlure or tert-butyl 4 (or 5) -chloro-2-methylcyclohexane carboxylate), Ceratitislure (protein hydrolysate plus β-caryophyllene) or Questlure (protein hydrolysate plus plant extracts). When using 12-day-old flies, Capilure caught 3 times more C. capitata males than C. rosa males and this difference was more extreme when 3-day-old flies were released. Ceratitislure caught significantly more 12-day-old C. cosyra males than 12-day-old C. capitata males, but the difference was reversed when 3-day-old flies were compared. Questlure showed the least differences between species and age but recovered the lowest proportion of released species. Further comparisons were conducted in an orchard with wild flies using other known attractants in larger yellow Probodelt bucket traps. Capilure caught more male C. capitata than BioLure Fruit Fly 3-component, but BioLure 2-component (trimethylamine and ammonium acetate) was more effective than Questlure for C. capitata females. The 3-component lure was also more effective than both Capilure and Questlure for male and female C. rosa, respectively. Ceratitislure was the most effective lure for male C. cosyra flies and BioLure 3-component was more effective than Ceratitislure and Questlure for female C. cosyra flies. The intervention threshold of 4 flies/trap/week previously used in citrus with Capilure for C. rosa was lowered to 2 C. rosa/trap/week when using the Sensus trap due to the lower sensitivity of this trap-lure combination found for C. rosa in this study. The 3-component lure, or the 2-component combination of trimethylamine and ammonium acetate in a ratio of 1:8 in the Sensus trap capsule, would be more effective for both sexes of all three Ceratitis species than the Questlure that is currently being used.     

Status of Bactrocera invadens (Diptera: Tephritidae) in Mango-Producing Areas of Arba Minch,Southwestern Ethiopia

Bactrocera invadens, the Asian fruit fly, was first reported in Kenya in 2003, and it spread fast to most tropical countries in Africa. To our knowledge, there is no detailed data on the fruit damage and status of fruit flies in Arba Minch and elsewhere in Ethiopia. Hence, information on the species composition and pest status of the fruit fly species is urgent to plan management strategies in the area. Fruit flies were captured using male parapheromone-baited traps. Matured mango (Mangifera indica) fruits were collected from randomly selected mango trees and incubated individually in cages (15 by 15 by 15 cm) with sandy soil. B. invadens was the predominant (96%; 952 of 992) captured species and the only fruit fly species emerging from mango fruits incubated in the laboratory. The mean number of adult B. invadens emerging per mango fruit was 35.25, indicating that the species is the most devastating mango fruit fly in the area. The loss due to this species would be serious if no management strategies are implemented.     

Evaluation of three ground release methods for sterile Queensland fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae)

The sterile insect technique has been in use for more than 50 years. Release techniques vary considerably from country to country. The release of sterile Queensland fruit fly in Australia continues to progress since its initial trials in the 1960’s. Three ground release methods (adult tub, adult chilled and pupal bucket) for sterile Queensland fruit fly were evaluated in the field. The recapture rate from the adult tub release method is significantly better than the other two methods. Adult chilled release had the lowest recapture rate but was not significantly different from the pupal bucket release. All methods could have been improved. 98.8% of recaptured flies were trapped within 600m of the release points. The dispersal distance was compared with other species.     

Screening of different citrus rootstocks and citrus-related species for resistance to Phyllocnistis citrella (Lepidoptera: Gracillariidae)

Nine citrus-related species and 349 citrus rootstocks were evaluated under either field or laboratory conditions for resistance to the citrus leafminer, Phyllocnistis citrella (Stainton). Field results confirmed the widespread susceptibility of citrus to the leafminer. Only 0.9% of the trees checked during one growing season escaped damage by flushing once early in the season. Laboratory assays showed that differences among citrus rootstocks existed, but levels of resistance detected were not high enough to establish a breeding program. Contrary to these results, two citroids, Murraya koenigii (L.) Sprengel and Glycosmis pentaphylla (Retzius) Corrêa, exhibited antibiotic effects against first instar larvae and may provide a source of pest-resistance genes for breeders.     

Dormant season foliar sprays of broad-spectrum insecticides: An effective component of integrated management for Diaphorina citri (Hemiptera: Psyllidae) in citrus orchards

Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a global pest of citrus and vector of Candidatus Liberibacter, a bacteria that causes huanglongbing or greening, a devastating disease of citrus. Mature citrus trees are dormant in winter and produce most new shoots in spring, followed by sporadic canopy growth in summer and fall. Young shoots are required for oviposition and nymphal development, but adults can survive and overwinter on hardened leaves. Surviving adults reproduce in spring shoots and their progeny are probably responsible for a large portion of disease spread as they disperse to search for food. Therefore, foliar sprays of broad-spectrum insecticides applied to mature trees in winter were evaluated in a commercial citrus orchard as tactic to reduce pest populations and insecticide use in spring and summer when beneficial insects are most active. A single spray of chlorpyrifos (2.8 kg a.i. ha⁻¹) in January 2007 reduced adult psyllids an average of 10-fold over six months compared to untreated trees. The following year, differences with the untreated control averaged 15-fold for over five months following a single spray of chlorpyrifos, fenpropathrin (0.34 kg a.i. ha⁻¹), or oxamyl (1.12 kg a.i. ha⁻¹) applied in January. Spiders, lacewings and ladybeetles were equally abundant during the growing season in both treated and untreated trees both years (P = 0.05). Thus foliar sprays of broad-spectrum insecticides before spring growth suppressed D. citri for five to six months, with no detectible impact on key natural enemies. This tactic has been widely adopted to control the psyllid in Florida, in some cases area-wide. Additional sprays during the growing season should be based on scouting and targeted at adults before anticipated new flush.     

Sequential sampling plans for estimating density of glassy-winged sharpshooter, Homalodisca vitripennis (Hemiptera: Cicadellidae) on citrus

The glassy-winged sharpshooter, Homalodisca vitripennis (Germar), is a serious pest of grapes and other crop and ornamental plants mainly through its role as a vector of the bacterium Xylella fastidiosa Wells. Citrus harbors large populations of this insect throughout much of the year in areas where the pest is problematic and improved understanding of the population dynamics and management of H. vitripennis on citrus may be key to its management in the broader agricultural landscape. In turn, the study of population dynamics and the development of management strategies require effective and efficient sampling methods. Within-tree sampling distribution studies revealed that adults and nymphs were more abundant and less variable in the upper strata of citrus trees (>1.5 m). They occurred in greater numbers on the southern quadrants of trees but relative variability did not differ due to cardinal direction. We developed and validated several fixed-precision sequential sampling plans for estimating the density of nymphs and adults of H. vitripennis using a pole bucket sampling method. Based on validation from resampling of independent data sets, Green’s sequential sampling model, based on the Taylor’s power law, provided the best overall performance in terms of providing mean density estimates with levels of precision equal to or better than the desired precision over a range of possible insect densities. Average sampling costs varied from about 21 to 189 min for a desired precision of 0.25 depending on insect density and whether the goal is to sample nymphs, adults or both stages combined. Further, the sampling plans developed on orange trees were robust, being equally effective on orange and lemon trees and on trees treated or not with insecticides.     

Suppression of green peach aphid (Myzus persicae) (Sulz.), citrus mealybug (Planococcus citri) (Risso), and two spotted spider mite (Tetranychus urticae) (Koch.) attacks on tomatoes and cucumbers by aqueous extracts from vermicomposts

Vermicomposts are produced through interactions between earthworms and microorganisms in the breakdown of organic wastes. Aqueous extracts were prepared in commercial brewing equipment (Growing Solutions Inc.) from vermicomposts processed from pre-consumer food waste. The ratio of vermicompost to water was 1 to 5 v:v to produce a 20% aqueous solution. The effects of soil drenches at dilutions of 20%, 10%, and 5% vermicompost extracts, were compared with those of deionized water, in the suppression of green peach aphids, mealybugs, and two spotted spider mites attacking tomatoes and cucumbers, in greenhouse cage experiments.     

Investigating phenotypic structures and allelochemical compounds of the fruits of Momordica charantia L. genotypes as sources of resistance against Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae)

Plant resistance is an important component of integrated management of the melon fruit fly, Bactrocera cucurbitae (Coquillett) owing to difficulties associated with its chemical control. Various biophysical traits including fruit length, fruit diameter, fruit toughness, number of the longitudinal ribs, height of the longitudinal ribs, number of small ridges, depth of small ridges and pericarp thickness, and biochemical traits including total chlorophyll, pH, tannin, flavanol, phenol, ash and silica contents of fruit were studied on six genotypes of bitter gourd (Momordica charantia L.) in relation to resistance against B. cucurbitae under field conditions in Pakistan. Faisalabad-long and Col-II were the most resistant whereas Chaman and Col-Vehari were the most susceptible among the tested genotypes. Fruit length, fruit diameter, number of the longitudinal ribs and number of small ridges had significant positive correlations whereas fruit toughness, depth of small ridges, height of the longitudinal ribs and pericarp thickness had significant negative correlations with the percent fruit infestation and larval density. Maximum variation in fruit infestation and larval density was explained by fruit toughness (63.4 and 49.2% respectively) followed by fruit diameter (23.2 and 22.4% respectively) and number of the longitudinal ribs (8.2 and 11.6% respectively) whereas the remainder of the physical traits explained <2.0% variation in fruit infestation. Total chlorophyll and pH were lowest in resistant and highest in susceptible genotypes whereas tannin, flavanol, phenol, ash and silica contents were highest in resistant and lowest in susceptible genotypes. Tannin and flavanol contents explained 96.5% of the total variation in fruit infestation and 97.7% of the total variation in larval density whereas rest of the biochemical traits explained <0.2% variation in fruit infestation.     

Identifying an Optimal Screen Mesh to Enable Augmentorium-Based Enhanced Biological Control of the Olive Fruit Fly Bactrocera oleae (Diptera: Tephritidae) and the Mediterranean Fruit Fly Ceratitis capitata (Diptera: Tephritidae)

The augmentorium is a cost-effective screened enclosure designed to receive fruits infested with insect pests, retain the pests inside but let their natural enemies escape to enhance biological control of pest populations. Screen selection is critical to ensure that an augmentorium is effective for a particular system. Here we tested five types of screens with a mini-augmentorium design and measured the escape of four insect species under laboratory conditions: the pests olive fruit fly Bactocera oleae (Rossi) (Diptera: Tephritidae) and Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), and the parasitoids Psyttalia lounsburyi (Silvestri) (Hymenoptera: Braconidae) and Psyttalia ponerophaga (Silvestri) (Hymenoptera: Braconidae). The sex ratio of insects that escaped the screens was compared to the sex ratio of insects that could not escape. Results showed that one screen type (‘crystal mesh’) was the best for the purpose of designing a functional augmentorium: it retained 90% of B. oleae adults and 100% of C. capitata adults while letting 72% of Psyttalia lounsburyi adults and 94% of P. ponerophaga adults escape. The other screen types tested were suboptimal, either because they let too many flies freely escape or because they retained too many parasitoids. Sex ratio was almost always similar for insects that managed to escape the screens and insects that were retained, except for P. ponerophaga and the screen type ‘light mesh’. These results are promising for the development of a functional augmentorium against the olive fruit fly and further implementation against Mediterranean fruit fly.