Exploring the Nature of Arhopalus ferus (Coleoptera: Cerambycidae: Spondylidinae) Pheromone Attraction.

Cerambycid species of the Spondylidinae subfamily are distributed worldwide and are known for being prolific invaders that infest conifers. In New Zealand, Arhopalus ferus (Mulsant), the burnt pine longhorn beetle, is well-established and requires monitoring at high-risk sites such as ports, airports, and sawmills as part of the requirements to meet pine log export standards set by the New Zealand Ministry of Primary Industries (MPI). Currently, its surveillance relies on traps baited with host volatiles (i.e., ethanol and α-pinene). We used volatile collections from adult beetles, electroantennograms, and field trapping bioassays to identify the pheromones emitted by the burnt pine longhorn beetle A. ferus and their effects on its behaviour. We show that A. ferus males emit mainly (E)-fuscumol and geranylacetone, as well as the minor components, α-terpinene and p-mentha-1,3,8-triene, and that all four compounds elicit a dose-dependent response in antennae of both sexes. Traps baited with the binary combination of geranylacetone plus fuscumol captured significantly more female A. ferus than did unbaited traps in two of three field experiments. α-Terpinene did not affect A. ferus trap catches and effects of p-mentha-1,3,8-triene on trap catch were not determined. Our findings provide further evidence of the use of fuscumol and geranylacetone as aggregation-sex pheromones by longhorn beetles in the Spondylidinae subfamily, and suggest that their deployment in survey traps may improve the efficacy of A. ferus monitoring in New Zealand and elsewhere.

Determining the efficacy of visual inspections at detecting non-biosecurity-compliant goods.

Examination of imported commodities by trained inspectors searching for pest organisms is a common practice that phytosanitary regulatory agencies use to mitigate biosecurity risks along trade pathways. To investigate the effects of target size and color on the efficacy of these visual assessments, we affixed square decals to polystyrene models of mandarins. Sample units of 100 model fruit containing up to 10 marked models were examined by inspectors. Six sizes in six shades of brown were tested across two prevalence levels. The experiment consisted of five inspection rounds where 11 inspectors examined 77 sample units within an allocated time. The probability that decals were detected increased with mark size and color contrast. Smaller, low-contrast marks were mainly missed. The prevalence rate did not affect the detectability. Through the experiment, the false-positive rate dropped from 6% to 3%, whereas false-negative rates were constant throughout. Large, dark targets were readily found with a mean recall of >90%, whereas small, pale marks had a mean recall of 9%. Increased experience made inspectors more competent at recognizing decals, reducing the false positive rate. However, constant false-negative rates indicate that experience did not prevent inspectors from overlooking targets they could not perceive.

Plant acclimation to elevated CO2 affects important plant functional traits, and concomitantly reduces plant colonization rates by an herbivorous insect.

Plants growing under elevated CO2 concentration may acclimatize to this environmental change by modification of chemical, physiological, and/or morphological traits. As a consequence, not only plant functioning but also plant-insect interactions might be altered, with important consequences particularly for agricultural systems. Whereas most studies have focused on the plant acclimation effects of elevated CO2 with regard to crop growth and productivity, acclimation effects on the behavioral response of insects associated with these plants have been largely neglected. In this study, we used a model system comprised of Brussels sprout Brassica oleraceae var. gemmifera and a specialized herbivorous insect, the cabbage aphid Brevicoryne brassicae, to test for the effects of various periods of exposure to an elevated (2× ambient) CO2 concentration on key plant functional traits and on host plant location behavior by the insect, assessed as plant colonization rates. Elevated CO2 had no measurable effect on colonization rates or total plant volatile emissions after a 2-week exposure, but it led to 15 and 26 % reductions in plant colonization rates after 6- and 10-week exposures, respectively. This reduction in plant colonization was associated with significant decreases in leaf stomatal conductance and plant volatile emission. Terpene emission, in particular, exhibited a great reduction after the 10-week exposure to elevated CO2. Our results provide empirical evidence that plants might acclimatize to a future increase in CO2, and that these acclimation responses might affect host plant choice and colonization behavior by herbivorous insects, which might be advantageous from the plant's perspective.

Current and Potential Future Global Distribution of the Raisin Moth Cadra figulilella (Lepidoptera: Pyralidae) under Two Different Climate Change Scenarios.

Global trade facilitates the introduction of invasive species that can cause irreversible damage to agriculture and the environment, as well as stored food products. The raisin moth (Cadra figulilella) is an invasive pest that poses a significant threat to fruits and dried foods. Climate change may exacerbate this threat by expanding moth's distribution to new areas. In this study, we used CLIMEX and MaxEnt niche modeling tools to assess the potential global distribution of the raisin moth under current and future climate change scenarios. Our models projected that the area of suitable distribution for the raisin moth could increase by up to 36.37% by the end of this century under high emission scenario. We also found that excessive precipitation decreased the probability of raisin moth establishment and that the optimum temperature range for the species during the wettest quarter of the year was 0-18 °C. These findings highlight the need for future research to utilize a combined modeling approach to predict the distribution of the raisin moth under current and future climate conditions more accurately. Our results could be used for environmental risk assessments, as well as to inform international trade decisions and negotiations on phytosanitary measures with regards to this invasive species.

Correction: Wang et al. Current and Potential Future Global Distribution of the Raisin Moth Cadra figulilella (Lepidoptera: Pyralidae) under Two Different Climate Change Scenarios. Biology 2023, 12, 435.

In the original publication [...].

Reproduction of Black Soldier Fly (Diptera: Stratiomyidae) Under Different Adult Densities and Light Regimes.

The black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) has been recognized as a promising insect species for sustainable management of organic waste and by-products. Indoor breeding of BSF with artificial lighting has been proved successful, but efforts are still needed to optimize BSF reproductive output. Increasing adult density seems an option to exploit space, whereas decreasing artificial lighting duration may reduce unnecessary power consumption. This study aimed at investigating the effects of adult density (10, 25, and 50 pairs per 30 × 30 × 30 cm cage; i.e., 370, 926, and 1,852 pairs/m3), light regime (8:16, 12:12, and 16:8 [L:D] h), and their possible interactions, on some BSF life history traits relevant to reproduction. The results show that the overall BSF reproductive output increased with increasing adult density but was not affected by light regimes per se. With the highest BSF adult density tested, an average of more than 20,000 neonate larvae were produced from a cage within 10 d. At this density, increasing photoperiod increased neonate production, but also decreased the number of neonates per watt used for artificial illumination. The temporal oviposition patterns, mean individual female reproductive output, mating success, egg hatching rate, and insect survival rate were not affected by adult density or light regime as simple effects. However, the interaction between adult density and light regime was significant for the first oviposition peak, mean individual female reproductive output, and insect survival rate. The possible mechanisms behind our results are discussed.

Mating success of the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), under four artificial light sources.

Larvae of the black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) are promising organisms to be used for organic waste bioconversion. Breeding BSF indoors has been suggested as a cost-effective approach for countries with long winters or low sunlight levels through the year. As the BSF mating is visually mediated, artificial illumination conditions are critical to a successful indoor breeding system. In this study, we tested four different types of artificial light sources for their effects on BSF mating success. They included: (1) a halogen lamp; (2) a combination of a white light-emitting diode (LED) lamp and a fluorescent ultra violet lamp; (3) a metal halide lamp, and (4) a specially designed light-emitting diode (BSFLED) lamp, whose design was based on the specific BSF adult visual spectral sensitivity. We determined the spectra of four artificial light sources, compared their spectral composition in relation to the BSF-visible spectrum, and compared their effects on the mating success of two different BSF colonies. BSFLED was the most energy efficient light source in spectral composition and led to the highest mating success in terms of the percentage of inseminated females and fertile clutches. Thus, BSFLED is the most suitable light source tested in our experiment for breeding BSF indoors. The colony effect and possible light flickering effect on BSF mating success were also detected. The implications of these findings are discussed.

The microbial flora of Aphis gossypii: patterns across host plants and geographical space.

The cotton aphid, Aphis gossypii, has a worldwide distribution and causes damage to numerous economically important crops. The bacterial symbionts associated with cotton aphids, sampled mainly from malvaceous and cucurbitaceous plants within Japan and Australia, were characterised using molecular profiling approaches. The goal was to document the aphid symbionts present and determine if patterns of microbial diversity are consistent with the existence of host plant related cryptic species in A. gossypii. The bacterial profiles of the aphids are diverse and reflect local geography more than host plant use.

Bioconversion of Three Organic Wastes by Black Soldier Fly (Diptera: Stratiomyidae) Larvae.

This study aimed to determine the suitability of several organic waste substrates to be processed by the larvae of the black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae) (BSFL) in a value-added bioconversion system. Three types of organic waste (brewer's waste, solid phase of pig manure, and semidigested grass) were tested and compared with a standard larval diet, broll (wheat middling). Larval survival and growth, chemical composition of the resulting prepupae, conversion ratios of nutrients and waste dry matter, and waste reduction rate were measured. Larval survival was high in all tested substrates. Compared with the larvae fed pig manure or semidigested grass, those fed standard diet or brewer's waste showed shorter development time, higher weight gain, and higher prepupal crude protein and crude fat content. BSFL also reduce more dry matter in the standard diet or in brewer's waste than in the other two substrates. On the other hand, larvae fed semidigested grass took 70 d to complete development and suffered fat loss. Thus, we suggest that brewer's waste is the most suitable substrate among the selected wastes for being processed by BSFL, whereas semidigested grass is an unsuitable substrate. We found that lignin had a significantly negative effect on larval growth, and emphasized the importance of applying lignin-digesting microorganisms to lignin-rich substrates being converted by BSFL. Moreover, a protein:fat:digestible carbohydrate ratio of 2:1:2 was hypothesized to benefit larval development.

The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 1: mortality rates and sources of variation.

Petroleum spray oils (PSOs) kill insect pests on contact, and the composition of modern PSOs is substantially different from the ones introduced earlier. The effects of direct application of a new nC24 PSO on the cotton aphid, Aphis gossypii Glover, were therefore determined. This covered not only aphid mortality rates but also the way in which the oils affected aphid behaviour at the time of contact with the oil. Direct application of the nC24 oil proved to be highly effective in controlling A. gossypii at a range of concentrations between 1 and 10% v/v. The oil killed cotton aphids quickly, with most of the mortality occurring within the first 10 min of spraying. The fast killing action of the oils prevented any behavioural responses by the aphids. Aphids killed by the oils became flaccid and their legs and antennae extended horizontally relative to the body axis. With time, their cuticle became very shiny and began to darken. The quick death of the aphids suggested a contact mode of action of the oils, an interpretation supported by the lack of any negative effect on aphids not initially reached by the oils. However, those aphids not hit by the oils, but that subsequently encountered oil-treated areas when they moved elsewhere, also died, indicating that the oil deposits are also toxic to the aphids. The mode of action of the oil thus seems to be versatile, and the means by which it kills the aphids may be more complex than anoxia, which is the widely claimed mechanism attributed to PSOs. This oil now needs to be tested for any possible indirect effects on the cotton aphid (e.g. through its host-plant acceptance behaviour). The implications of the present findings for cotton aphid control and assessment of PSO efficacy in the field are discussed.

The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 2: indirect effects of oil deposits.

The primary mode of action of petroleum spray oils (PSOs) on pest insects is through direct contact. Indirect effects are, however, also possible, and deposits of the oils may influence pest populations by killing insects and/or by influencing their behaviour. The indirect effects of deposits of a new nC24 oil against the cotton aphid, Aphis gossypii Glover, were therefore determined. The effects of oil deposits on the acceptance of cotton as host plant by the aphids were assessed, as well as aphid mortality rates and their success in the establishment of colonies. The efficacy of deposits of a heavier oil (nC27) was also evaluated. Deposits of PSO were toxic to A. gossypii and remained effective until 8 days after spraying. Mortality decreased with time, so that, the older the deposit, the lower was the mortality. Significantly higher aphid mortalities were achieved on younger leaves than on mature ones. Thus, leaf age proved a significant factor in the efficacy of the deposits. Consecutive prophylactic applications (at 9 day intervals) did not have a cumulative effect, and their killing power proved to be independent of one another. Thus, applying the oil prior to aphid infestations would confer only minimal protection. The mortality inflicted by the deposits was not improved by increasing the molecular mass of the oil used (nC27 oil), but the toxic life of the oil deposit was increased. Oil deposits did not deter alates from landing on oil-sprayed plants. Oil deposits did, however, affect subsequent alate and nymphal survival, and thus the establishment of aphid colonies. The impact that the oils could have on the longer-term development of aphid populations in the field was thus demonstrated. First- and second-instar nymphs were the most susceptible life stages, with > 50% mortality compared with < 10% for the other stages. These nymphs did not show the typical signs of oil-induced mortality observed in aphids killed by direct oil applications, which suggests an alternative mode of action to that of the directly applied oil. Anoxia does not seem to be involved in either process, and alternative modes of action of the oil deposits are discussed. The implications of these findings for cotton aphid control are also considered, primarily in relation to the timing and frequency of oil application.

Sorption and desorption characteristics of methyl bromide during and after fumigation of pine (Pinus radiata D. Don) logs.

BACKGROUND: The sorption and desorption characteristics of methyl bromide (MB) were determined during and after fumigation of recently harvested pine (Pinus radiata D. Don) logs. The effects of dose (48 or 120 g m-3 ), degree of bark cover (0, 50 or 100%) and end-grain sealing (sealed or unsealed) on sorption and desorption were determined over time. RESULTS: Sorption of MB was proportional to the dose applied and dependent on the amount of end-grain sealed. After 16 h, an average of 70.7 ± 2.5% of the initial concentration remained in the treated space when end-grains were sealed, whereas only 47.3 ± 2.5% remained when unsealed. During aeration, MB was released from logs, initially ranging from 2.8 to 8.8 g · h m-3 , depending on the treatment. The rate of desorption quickly decreased during aeration. CONCLUSION: The surface area of a log is the most important factor influencing MB sorption and desorption rates, with greater surface area resulting in greater (de)sorption rates. Sorption data can now be combined with insect toxicity data to estimate a minimum effective dose of MB for further evaluation, while desorption data can be combined with fumigant plume modelling to assess worker safety. © 2016 Society of Chemical Industry.