Field Cages Research Articles

The Development and Evaluation of Insect Traps for the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae), Vector of Citrus Huanglongbing.

Simple SummaryCitrus cultivation is affected in many parts of the world because of a devastating disease, huanglongbing (HLB) or citrus greening. In Florida, nearly all commercial citrus is compromised due to HLB, and the disease has spread to other citrus-growing regions of the United States, California and Texas. In California, testing Asian citrus psyllids (ACPs) for the HLB pathogen has been an essential part of integrated pest management. ACP and HLB surveys are essential for disease management in areas where HLB is not widespread. We developed improved ACP traps that can be deployed in the field along with the standard yellow sticky traps. The reusable traps were designed with Rhinoceros computer software and a 3D printer. These traps can be deployed for several months and provide a dynamic sampling mechanism for an improved disease survey strategy. In the present study, ACPs from the 3D-printed traps are collected in a preservative and appear suitable for HLB testing. The evaluation of traps in Florida and California under laboratory, greenhouse, and field conditions indicates that the 3D-printed traps can capture ACPs with about the same efficiency as the sticky traps. They are easy to handle and provide an important field tool for HLB management.Citrus huanglongbing (HLB) is a severe problem for citrus cultivation. The disease management programs benefit from improved field tools suitable for surveying the ACP vector (Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae)) and the associated pathogen. In the present study, we utilize three-dimensional (3D) printers and design tools to develop traps that can capture and preserve ACPs. Three novel, 3D-printed traps were designed and evaluated: stem trap, and cylinder traps 1 and 2. The traps and yellow sticky cards were deployed weekly for 8 months in 2 non-commercial citrus groves in Florida; in California, the traps were evaluated for 12 months in field cages and 4 citrus groves. The stem traps captured lower numbers of ACPs at all experimental sites compared to the cylinder traps. Capture rates in the cylinder traps were comparable to the sticky trap, making the device a viable tool for monitoring field ACPs. The two main advantages of using the reusable 3D traps over standard methods of ACP and HLB surveys include dynamic sampling that can be conducted year-round and the capture of ACPs that can be preserved and tested. Improved trapping may facilitate quick management decisions and mitigate HLB.

Toxicity of Selected Insecticides against Cotton Thrips (Thrips tabaci Lindeman) in Laboratory Bioassays

Investigations on toxicity of insecticides against cotton thrips (Thrips tabaci Lindeman) was carried out at laboratory of Main Cotton Research Station, Navsari Agricultural University, Surat during August to October 2020 through the IRAC leaf dip bio-assay technique. Thrips population from the farmer’s field of Bharuch district were collected and reared at Main Cotton Research Station, NAU, Surat under field cage cover. Leaf dip bio-assays were carried out for the five insecticides viz., fipronil 5 SC, buprofezin 25 SC, diafenthiuron 50 WP, profenophos 50 EC and imidacloprid 17.8 SL with eight concentrations. At recommended rate, diafenthiuron 50 WP at 0.06% and profenophos 50 EC at 0.1% recorded 90.36 and 83.29% mortality of thrips at 72 hours after exposure. Buprofezin 25 SC at 0.05%, imidacloprid 17.8 SL at 0.00445% and imidacloprid 17.8 SL at 0.00445% recorded 79.81, 63.54 and 57.06% mortality of thrips under laboratory bioassay at 72 hours after exposure. The recommended rate of the test insecticides except fipronil 5 SC and imidacloprid 17.8 SL did not show much variation in susceptibility at 72 hours after exposure.

Native, naturalized and commercial predators evaluated for use against Diaphorina citri

Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a key pest of citrus associated with the yet uncurable Huanglongbing (HLB) disease, that is threatening worldwide citrus production. Control of D. citri has hitherto relied on chemical insecticides and on the use of the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). However, use of insecticides is problematic due to environmental and social issues, especially where D. citri is mostly spread in residential areas, and use of T. radiata has resulted in mixed success. Therefore, there is an urgent need to find sustainable and complementary practices to control this pest. Generalist predators, including green lacewings and coccinellids, have been frequently associated to D. citri in field surveys, yet they have rarely been tested. We have tested the predation capability under laboratory, greenhouse and semi-field conditions, of five predators: the green lacewings Chrysoperla comanche (Banks) and C. rufilabris Burmeister (Neuroptera: Chrysopidae), the coccinellids Diomus pumilio Weise and Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae) and the brown lacewing Sympherobius barberi Banks (Neuroptera: Hemerobiidae). All of them were capable of feeding on D. citri and reduce its populations under laboratory conditions, but critical differences emerged in greenhouse and field cages, with some predators (the green lacewings and D. pumilio) being the most effective. We discuss possible ways of utilizing these predators as an additional biological control tool to address current limitations of D. citri control in commercial groves, in residential areas and at the urban-agricultural interface.

Disease Transmission Ability and Pattern of Deltocephalus menoni (Hemiptera: Cicadellidae) Vector of Sugarcane White Leaf Disease

Sugarcane White Leaf Disease (WLD) is one of the most devastative phytoplasma disease which cause substantial losses to the sugar cane industry in Sri Lanka. Leaf hopper Deltocephalus menoni (Hemiptera: Cicadellidae) is the locally-identified vector of WLD. Disease transmission proficiency of the vector, is a key factor to consider in disease management. Therefore, the present study was conducted to find out the ability of males, females and nymphs of D. menoni in transmitting the WLD and to determine the level of persistency of D. menoni in WLD phytoplasma (WLDP) transmission. To determine the percentage WLD transmission by virulified D. menoni males, females, and nymphs were introduced to one-month-old healthy potted plants in insect proof field cages for a one week period. Test plants were maintained until WLD symptom development. In estimating the WLD transmission pattern of D. menoni, virulified one-day- old adult females were introduced to the healthy sugarcane plants allowing them to feed on healthy plant for 24h period. Then they were recollected and introduced to another set of healthy sugarcane plants. Above procedure was repeated in 24h frequency for 13 days. Test plants were maintained in insect proof field cages for three-month period. The Presence of WLDP in the tested-plants was confirmed by PCR with WLDP specific SPP1/SPP2 primers. Under local conditions, female and male adults, 2nd and 4th instar nymphs were capable of transmitting the WLDP to the healthy plants in a rate of 55.5, 44.5, 22.2 and 33.3% respectively. The transmission efficiency of females is comparatively highthan that of adult male insects. Adult female of D. menoni was capable to transmit the disease from just after acquisition of the WLDP up to maximum of 11 days. Results imply that D. menoni is incapable to propagate the WLDP within its body and circulative transmission dose not occurred within the insect. D. menoni is an efficient vector in secondary transmission of the WLD and it is a semi-persistent vector. Due to semi-persistent nature of the vector, the management practices are vital to prevent rapid spread of this disease in sugarcane plantations.

Integrated control of the mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae) in Australian cotton with insecticides and naturally occurring beneficial arthropods

AbstractInsecticidal treatment options based on putative integrated pest management (IPM) compatible active ingredients spirotetramat, sulfoxaflor and buprofezin were evaluated for efficacy against first and second instar (small) and large (third instar and adult) cotton mealybugs, Phenacoccus solenopsis. Four field evaluations were conducted at the Department of Agriculture and Fisheries (Queensland) research station facilities at Kingaroy (KRS) and Emerald (ERS) in 2016 and 2017. Two ‘insecticide evaluations’ included treatment options with different rates of active ingredients and adjuvants, aimed at validating efficacy results obtained in previous glasshouse evaluations. The other two ‘IPM evaluations’ were designed to test the compatibility of selected insecticidal active ingredients with naturally occurring beneficial arthropods through differential exclusion by means of large field cages configured to be either partially open or fully closed to regulate access. Spirotetramat gave consistent and commercially acceptable (≥80%) control of large and small mealybugs at the highest rate of 96 g in these insecticide evaluations. The addition of crop oil to spirotetramat as a tank mix partner significantly enhanced efficacy, as documented previously in glasshouse evaluations. Sulfoxaflor provided equivalent control of large and small mealybugs but only at the ERS site. The overall control efficacy of buprofezin was equivalent to spirotetramat and sulfoxaflor at the ERS site but inferior to both at the KRS site. In the IPM evaluations, the abundance of predatory arthropods and their potential contribution to overall mortality was generally low. Parasitism contributed significantly to overall mortality among treatments over time and was independent of cage status (closed or open). Large mealybugs were equitably distributed between the upper (terminal) and lower sections of the cotton plant canopy in both ERS evaluations whereas in the KRS evaluations the distribution was biased towards the lower section. The importance of pest distribution within the crop canopy in the context of insecticide efficacy is discussed. The results of this study confirm the importance of spirotetramat, sulfoxaflor and buprofezin as key insecticidal platforms that will give growers and crop managers the flexibility and confidence to implement sustainable, multi‐pest IPM strategies in Australian cotton.

Measuring Daphnia life history in the wild: The efficacy of individual field cages.

Life‐history studies are often conducted in a laboratory environment where it is easy to assay individual animals. However, factors such as temperature, photoperiod, and nutrition vary greatly between laboratory and field environments, making it difficult to compare results. Consequently, there is a need to study individual life histories in the field, but this is currently difficult in systems such as Daphnia where it is not possible to mark and track individual animals. Here, we present a proof of principle study showing that field cages are a reliable method for collecting individual‐level life‐history data in Daphnia magna. As a first step, we compared the life history of paired animals reared outside and inside cages to test the hypothesis that cages allow free flow of algal food resources. We then used a seminatural mesocosm setting to compare the performance of individual field cages versus glass jars refilled with mesocosm water each day. We found that cages did not inhibit food flow and that differences in life histories between three clones detected in the jar assays were also detectable using the much less labor‐intensive field cages. We conclude that field cages are a feasible approach for collecting individual‐level life‐history data in systems such as Daphnia where individual animals cannot be marked and tracked.

Thermal history of alfalfa leafcutting bees affects nesting and diapause incidence.

Variable spring temperatures may expose developing insects to sublethal conditions, resulting in long-term consequences. The alfalfa leafcutting bee, Megachile rotundata, overwinters as a prepupa inside a brood cell, resuming development in spring. During these immobile stages of development, bees must tolerate unfavorable temperatures. In this study, we tested how exposure to low temperature stress during development affects subsequent reproduction and characteristics of the F1 generation. Developing male and female M. rotundata were exposed to either constant (6°C) or fluctuating (1 hday-1 at 20°C) low temperature stress for 1week, during the pupal stage, to mimic a spring cold snap. Treated adults were marked and released into field cages, and reproductive output was compared with that of untreated control bees. Exposure to low temperatures during the pupal stage had mixed effects on reproduction and offspring characteristics. Females treated with fluctuating low temperatures were more likely to nest compared with control bees or those exposed to constant low temperature stress. Sublethal effects may have contributed to low nesting rates of bees exposed to constant low temperatures. Females from that group that were able to nest had fewer, larger offspring with high viability, suggesting a trade-off. Interestingly, offspring of bees exposed to fluctuating low temperatures were more likely to enter diapause, indicating that thermal history of parents, even during development, is an important factor in diapause determination.

Grass-like plants release general volatile cues attractive for gravid Anopheles gambiae sensu stricto mosquitoes

BackgroundUnderstanding the ecology and behaviour of disease vectors, including the olfactory cues used to orient and select hosts and egg-laying sites, are essential for the development of novel, insecticide-free control tools. Selected graminoid plants have been shown to release volatile chemicals attracting malaria vectors; however, whether the attraction is selective to individual plants or more general across genera and families is still unclear.MethodsTo contribute to the current evidence, we implemented bioassays in two-port airflow olfactometers and in large field cages with four live graminoid plant species commonly found associated with malaria vector breeding sites in western Kenya: Cyperus rotundus and C. exaltatus of the Cyperaceae family, and Panicum repens and Cynodon dactylon of the Poaceae family. Additionally, we tested one Poaceae species, Cenchrus setaceus, not usually associated with water. The volatile compounds released in the headspace of the plants were identified using gas chromatography/mass spectrometry.ResultsAll five plants attracted gravid vectors, with the odds of a mosquito orienting towards the choice-chamber with the plant in an olfactometer being 2–5 times higher than when no plant was present. This attraction was maintained when tested with free-flying mosquitoes over a longer distance in large field cages, though at lower strength, with the odds of attracting a female 1.5–2.5 times higher when live plants were present than when only water was present in the trap. Cyperus rotundus, previously implicated in connection with an oviposition attractant, consistently elicited the strongest response from gravid vectors. Volatiles regularly detected were limonene, β-pinene, β-elemene and β-caryophyllene, among other common plant compounds previously described in association with odour-orientation of gravid and unfed malaria vectors.ConclusionsThe present study confirms that gravid Anopheles gambiae sensu stricto use chemical cues released from graminoid plants to orientate. These cues are released from a variety of graminoid plant species in both the Cyperaceae and Poaceae family. Given the general nature of these cues, it appears unlikely that they are exclusively used for the location of suitable oviposition sites. The utilization of these chemical cues for attract-and-kill trapping strategies must be explored under natural conditions to investigate their efficiency when in competition with complex interacting natural cues.Graphical abstract

Efficiency of Three Egg Parasitoid Species on Fall Armyworm (Lepidoptera: Noctuidae) in Laboratory and Field Cages

Abstract Egg parasitoids are the most used natural enemies in biological control of Spodoptera frugiperda (J.E. Smith), a pest of gramineous plants native to the Americas that recently invaded Africa and some countries of Asia. Although Trichogramma pretiosum (Riley) is one of the main species used against this pest, there are other species with equal or greater parasitism potential. The objective of this work was to compare, in laboratory and in field cages, the parasitism of Telenomus remus Nixon, Trichogramma atopovirilia (Oatman and Platner), and T. pretiosum on S. frugiperda eggs. Telenomus remus and T. atopovirilia reached the highest percentages of parasitism in laboratory (>70%) which did not differ statistically from each other. Trichogramma pretiosum had the lowest percentage of parasitism (29%) of the three. In the field cage assays, Te. remus parasitized 30% of the S. frugiperda egg masses, and T. pretiosum parasitized about 7.5% of the egg masses. These results underscore the importance of adequate selection of egg parasitoids for their use in biological control programs by augmentation against S. frugiperda.

Does body size influence mating success? A morphometric study of two Anastrepha (Diptera: Tephritidae) fruit fly species.

Male mating success depends on various traits and factors, and correctly identifying these traits can be key in the context of pest management. For tephritid pests, controlled through the sterile insect technique (SIT) traits, such as male size, can be manipulated through mass-rearing procedures. Thus, it is particularly important to understand whether male size can favor mating success. Here, we evaluated mating success of males of different sizes in Anastrepha ludens and Anastrepha obliqua, two species controlled through SIT. For both species, a morphometric analysis was performed of mated and unmated mass-reared and wild males in field cages. In both A. ludens and A. obliqua, wild females did not discriminate their mates based on male size and mated more frequently with wild males regardless of size. For mass-reared males, we found no evidence of an advantage of the large males compared to small males in mating success. However, we did find differences between the morphometric traits of mass-reared and wild males. In A. ludens, traits associated to mating success were Face Width (FW), Head Width (HW), Thorax Length (TL) and Wing Length (WL), and for A. obliqua were FW, HW, WL and WW (Wing Width). Overall, FW and TL were more consistent predictors of mating success. In conclusion, female choice seems to suggest multivariate selection, confirming that overall body size (expressed as pupal diameter, which is highly correlated with weight) is not a decisive factor in male mating success in these two species. However, morphological traits such as FW, HW, TL, WL and WW may be relevant in mating preference of wild female.

Growth inhibition in cucumber (Cucumis sativus L.) induced by Epilachna chrysomelina fabricius (Coleoptera: Coccinellidae)

Studies were conducted in screen and field cages on growth inhibition and fruit damage by Epilachna chrysomelina on cucumber. Six population densities (0, 1-, 2-, 3-, 4- and 5-pairs) of the beetle was introduced into separate cages containing 3-weeks old cucumber seedlings and arranged in Completely Randomised Design (CRD) with three replicates. Increased E. chrysomelina density resulted in increased number of days to 50% fruiting in both experiments. Fruit initiation was delayed by 12 days and 7 days in the screen and field caged cucumber respectively at the 5-pairs population density while the number of fruits produced was significantly lower (p < 0.05) as beetle population increased per cage. Regression analysis in both experiments showed that vine length, functional leaf area and number of cucumber produced were a linear function of E. chrysomelina population density. Chi-square (χ2) analysis revealed that the models obtained in both experiments were similar for the parameters tested.

Pre-release dietary supplements of methoprene and raspberry ketone increase field abundance of sterile Queensland fruit flies (Diptera: Tephritidae).

The sterile insect technique (SIT) is a sustainable pest management tool based on the release of millions of sterile insects that suppress reproduction in targeted populations. Success of SIT depends on survival, maturation, dispersal, and mating of released sterile insects. Laboratory and field cage studies have demonstrated that dietary supplements of methoprene and raspberry ketone (RK) promote sexual maturation of adult Queensland fruit fly, Bactrocera tryoni (Froggatt), and may hence shorten the delay between release and maturity in the field. We investigated the effects of methoprene and RK dietary supplements on field abundance of sexually mature sterile Q-flies relative to untreated flies fed only sugar and yeast hydrolysate before release at 2 d of age. Compared with untreated flies, more methoprene- and RK-treated flies were recaptured in cuelure traps to which only sexually mature males are attracted. At distances of 100 and 200 m from the release point, recapture rates were higher for methoprene- and RK-treated flies than for untreated flies, but at 300 m recapture rates were low and were similar for treated and untreated flies. Rainfall, relative humidity, wind speed, and wind direction did not affect recapture rates, but temperature was positively correlated with recapture rates for all treatments. There was a strong correlation between the number of sterile and wild flies caught in traps, indicating co-location in the field. Dietary supplements of methoprene and RK can substantially increase abundance of sexually mature sterile male Q-flies in the field following release as 2-d-old immature adults.

Pollinators and plant nurseries: how irrigation and pesticide treatment of native ornamental plants impact solitary bees.

A key conservation goal in agroecosystems is to understand how management practices may affect beneficial species, such as pollinators. Currently, broad gaps exist in our knowledge as to how horticultural management practices, such as irrigation level, might influence bee reproduction, particularly for solitary bees. Despite the extensive use of ornamental plants by bees, especially little is known about how irrigation level may interact with insecticides, like water-soluble neonicotinoids, to influence floral rewards and bee reproduction. We designed a two-factor field cage experiment in which we reared Megachile rotundata (Fabricius) (Hymenoptera: Megachilidae) on containerized ornamental plants grown under two different irrigation levels and imidacloprid treatments (30% label rate dosage of a nursery formulation or an untreated control). Lower irrigation was associated with modest decreases in nectar volume and floral abundance in untreated plants, whereas irrigation did not affect plants treated with imidacloprid. Furthermore, higher irrigation decreased the amount of imidacloprid entering nectar. Imidacloprid application strongly reduced bee foraging activity and reproduction, and higher irrigation did not offset any negative effects on bees. Our study emphasizes the impact of a nursery neonicotinoid formulation on solitary bee foraging and reproduction, while highlighting interactions between irrigation level and neonicotinoid application in containerized plants themselves.

The Type I interferon antiviral gene program is impaired by lockdown and preserved by caregiving

Previous research has linked perceived social isolation (loneliness) to reduced antiviral immunity, but the immunologic effects of the objective social isolation imposed by pandemic "shelter in place" (SIP) policies is unknown. We assessed the immunologic impact of SIP by relocating 21 adult male rhesus macaques from 2,000-m2 field cage communities of 70 to 132 other macaques to 2 wk of individual housing in indoor shelters. SIP was associated with 30% to 50% reductions in all circulating immune cell populations (lymphocytes, monocytes, and granulocytes), down-regulation of Type I interferon (IFN) antiviral gene expression, and a relative up-regulation of CD16- classical monocytes. These effects emerged within the first 48 h of SIP, persisted for at least 2 wk, and abated within 4 wk of return to social housing. A subsequent round of SIP in the presence of a novel juvenile macaque showed comparable reductions in circulating immune cell populations but reversal of Type I IFN reductions and classical monocyte increases observed during individual SIP. Analyses of lymph node tissues showed parallel up-regulation of Type I IFN genes and enhanced control of viral gene expression during juvenile-partnered SIP compared to isolated SIP. These results identify a significant adverse effect of SIP social isolation on antiviral immune regulation in both circulating immune cells and lymphoid tissues, and they suggest a potential behavioral strategy for ameliorating gene regulatory impacts (but not immune cell declines) by promoting prosocial engagement during SIP.

Host-searching capacity of the fruit fly parasitoid Diachasmimorpha longicaudata (Ashmead) as a measure for evaluating quality in mass rearing

ABSTRACT The host-searching capacity of the parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) was evaluated in field cages with Anastrepha ludens (Loew)-infested mangoes. The main objective was to determine whether the data collected from these evaluations could be analysed to obtain useful quality indicators of mass reared adult parasitoids. Landing and oviposition activities of female parasitoids on infested fruit increased at higher densities of larvae and with more extended time of infested fruit exposition. Physical characteristics of the fruits did not influence the search. Females positively arrested on infested fruit, and their response was significantly related to the number of larvae per fruit. At a density of 1–40 larvae per fruit, 5–8 parasitoid females were found landing on the fruit, with 1–2 females ovipositing every 15 minutes for 2 hours, resulting in percentages of parasitism between 30 and 56%. The mass-reared parasitoids showed a competitive response similar to that determined for wild parasitoids. The evaluation procedure is practical and inexpensive, allowing it to be applied for quality assessment in mass rearing of D. longicaudata.

BIOCHEMICAL AND PATHOLOGICAL EFFECTS ON THE MALE RAT HEPATIC TISSUE AFTER EXPOSURE TO 900MHZ ELECTROMAGNETIC FIELD DURING ADOLESCENT PERIOD

The aim of this study was to employ biochemical analysis and histopathological techniques to investigate the effects of the application of a 900-megahertz electromagnetic field during adolescence on the rat liver. 24 male Sprague Dawley rats aged 21 days were randomly divided into electromagnetic field, sham and control groups. No procedure was performed on the control group rats. Electromagnetic field group rats were exposed to a 900-megahertz electromagnetic field in an electromagnetic field application cage (1 hours/day, every day for 25 days). The sham group rats were placed in the same electromagnetic field cage without exposure to electromagnetic field. At the end of the experiments, the livers were removed. The livers were used for histopathological evaluation (light, electron and immunofluorescence microscopy) and biochemical analyses. Biochemical analyses revealed increased lipid peroxidation and glutathione values while catalase and superoxide dismutase values were decreased in electromagnetic field group. Electron microscopy evaluations identified necrotic hepatocytes with numerous cytoplasmic and mitochondrial vacuoles in electromagnetic field group sections. We also observed an enlarged endoplasmic reticulum and loss of mitochondrial matrix, in addition to the presence of vacuoles. Also, loss of inner and outer mitochondrial membrane integrity was observed. Light microscopy evaluations revealed sinusoidal capillary dilatation and degeneration in hepatocytes with cytoplasmic swelling, vacuolar degeneration and pyknotic nuclei in electromagnetic field group sections. Deterioration in the integrity of the collagen fibers was also present around the vena centralis. Additionally, electromagnetic field had no effect on body weight. Therefore, we conclude that continuous 900-megahertz electromagnetic field treatment may cause changes in oxidative stress biomarkers and the morphology of the adolescent rat liver.

Canopy distribution and microclimate preferences of sterile and wild Queensland fruit flies

Insects tend to live within well-defined habitats, and at smaller scales can have distinct microhabitat preferences. These preferences are important, but often overlooked, in applications of the sterile insect technique. Different microhabitat preferences of sterile and wild insects may reflect differences in environmental tolerance and may lead to spatial separation in the field, both of which may reduce the control program efficiency. In this study, we compared the diurnal microhabitat distributions of mass-reared (fertile and sterile) and wild Queensland fruit flies, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). Flies were individually tagged and released into field cages containing citrus trees. We recorded their locations in the canopies (height from ground, distance from canopy center), behavior (resting, grooming, walking, feeding), and the abiotic conditions on occupied leaves (temperature, humidity, light intensity) throughout the day. Flies from all groups moved lower in the canopy when temperature and light intensity were high, and humidity was low; lower canopy regions provided shelter from these conditions. Fertile and sterile mass-reared flies of both sexes were generally lower in the canopies than wild flies. Flies generally fed from the top sides of leaves that were lower in the canopy, suggesting food sources in these locations. Our observations suggest that mass-reared and wild B. tryoni occupy different locations in tree canopies, which could indicate different tolerances to environmental extremes and may result in spatial separation of sterile and wild flies when assessed at a landscape scale.

Evaluation of Mass Trapping Devices for Early Seasonal Management of Ceratitis Capitata (Diptera: Tephritidae) Populations

Mass trapping is an environmentally safe alternative to insecticide application for the Mediterranean fruit fly management. The selection of effective trap-attractant combinations for monitoring and mass trapping control remains challenging. The current study explored the attractiveness of trapping devices during spring (early season) and summer (late season) in field cage trials. Five trapping devices were assessed: (a) the commercially available Decis® trap, (b) Tephri trap baited with Biodelear, (c) Tephri trap baited with BioLure, (d) International Pheromone McPhail trap (IPMT) baited with Biodelear, and (e) IPMT baited with BioLure. On a test day, 100 adults (50 males and 50 females) were released in each field cage wherein traps were placed individually. Trap captures were recorded at hourly intervals from 10:30 am to 5:30 pm. Our results showed that Tephri traps baited either with BioLure or Biodelear captured the most adults under low temperatures. Efficacy of Tephri traps baited with BioLure were higher than that of other trap-attractant combinations at high temperatures. Adult captures in Decis® trap were low during both seasons. More males than females were captured at low temperatures. Both efficacy and female selectivity of trapping devices are related to prevailing temperature regimes during spring and summer under semi-field conditions.

Establishment of the biological control agent Hypocosmiapyrochroma for Dolichandraunguis‐cati (Bignoniaceae) is limited by microclimate

AbstractCat's claw creeper, Dolichandra unguis‐cati (Bignoniaceae), a perennial woody vine native to tropical America, is a target for biological control in Australia and South Africa. The cat's claw creeper leaf‐tying moth Hypocosmia pyrochroma (Lepidoptera: Pyralidae) from tropical South America was released as a biological control agent for cat's claw creeper in Australia from 2007 to 2010. A total of 2,277 adults, 837 pupae and 77,250 larvae were released at 40 sites in Queensland and New South Wales. Releases were made mostly in open fields (85%), and at limited sites (15%) in insect‐proof cages erected over naturally occurring cat's claw creeper infestations in the field. Sampling was conducted annually in spring and autumn to monitor the establishment and dispersal of H. pyrochroma. Establishment of H. pyrochroma was first noticed in 2012 at three release sites and since then the number of established sites has increased to 80 in 2020. Establishment was evident on both ‘short‐pod’ and ‘long‐pod’ forms of cat's claw creeper and was more widespread in sites where releases were made within insect‐proof field cages (50%) than in sites with open field releases (9%). The moth was active from late spring to late autumn with peak larval activity in late summer. To date, all field establishments have been in areas predicted by a CLIMEX model as climatically suitable but restricted mostly to riparian environment (93% of establishment), where the moth has continued to spread from 1.5 to 23 km from release sites. In contrast, there is the only limited establishment and spread in non‐riparian corridors, highlighting the role of microclimate (riparian) as a limiting factor for establishment and spread. Future efforts will focus on redistribution of the agent to river/creek systems where the moth is currently not present.

Herbivory of a biocontrol agent on a native plant causes an indirect trait‐mediated non‐target effect on a native insect

Abstract Identifying food web linkages between biocontrol agents of invasive plants and native species is crucial for predicting indirect non‐target effects. Biocontrol insects can integrate into food webs within recipient habitats and influence native insects through apparent competition (altering shared natural enemies) or density‐mediated exploitation competition (changing density of native plants). However, whether and how trait‐mediated exploitation competition (modifying native plant chemicals and volatiles profiles) can produce indirect non‐target effects remains largely overlooked, despite plant phenotypic responses to insect herbivory being common and widely documented. The flea beetle Agasicles hygrophila was introduced into China for management of alligator weed Alternanthera philoxeroides, but it also attacks the native congener sessile joyweed Alternanthera sessilis, which may cause indirect non‐target effects on the native tortoise beetle Cassida piperata that also feeds on sessile joyweed. Here, we examined the relationships among abundances of the flea beetle and tortoise beetle, and coverage of sessile joyweed in the field. Then, we investigated the impact of flea beetle herbivory on tortoise beetle development and oviposition, as well as on sessile joyweed primary metabolites and leaf volatiles. Tortoise beetle abundance was not related to sessile joyweed coverage, but they were less abundant on plants with more flea beetles in the field survey, and produced fewer offspring on plants with more prior flea beetle damage in the field cage experiment. Tortoise beetle development was inhibited by prior flea beetle herbivory in bioassays in enemy‐free conditions and they preferred to oviposit on sessile joyweed that had experienced little or no flea beetle damage. Flea beetle herbivory decreased sessile joyweed foliar glucose and protein, and substantially changed its leaf volatile blend. Synthesis. Our results show that the flea beetle has major indirect non‐target effects on the tortoise beetle through trait‐mediated exploitation competition, rather than apparent competition or density‐mediated exploitation competition. Our results demonstrate a new example for indirect non‐target effects of biocontrol agents. Furthermore, our results indicate that minor brief negative impacts of biocontrol agents on non‐target plants might propagate to higher trophic levels and such negative impacts can strengthen with increasing intensity of the direct non‐target effect.