Bob Du

Ethyl formate (EF) is an environmentally friendly fumigant with strong potential as a methyl bromide (MB) alternative for pre-export quarantine disinfestation of agricultural produce. This study evaluated the synergistic effect of EF combined with 10 % carbon dioxide (CO₂) to enhance penetration and toxicity against Pseudococcus jackbeardsleyi in pineapple. Insect mortality was significantly influenced by EF concentration, treatment temperature, and developmental stage. At 25 °C, fumigation with 60 mg L−1 EF + 10 % CO₂ for 3 h achieved 99.9968 % mortality of the most tolerant stage. Comparable efficacy was obtained at 20 °C and 15 °C with 90 mg L−1 and 110 mg L−1 EF, respectively, representing an approximate 30 % reduction in EF concentration compared to EF alone. Large-scale confirmatory trials validated complete control of over 100,000 individuals at each temperature. Post-fumigation assessments showed no significant differences in fruit firmness, weight loss, total soluble solids (TSS), or titratable acidity (TA) during cold storage. EF-alone treatments, however, led to elevated respiration rates and greater color variation (ΔE) during shelf-life, while EF + CO₂ mitigated these effects. The combined treatment effectively stabilized physiological and visual quality. These findings indicate that EF + 10 % CO₂ is a highly effective phytosanitary treatment for P. jackbeardsleyi in pineapple, ensuring both quarantine security and postharvest quality. This strategy enables rapid and shelf-life-preserving pest control for fresh produce, supporting safer and more sustainable export practices.

Fungi can degrade grain quality, produce harmful mycotoxins, and hinder germination in the post-harvest stage, resulting in significant economic losses. Ethyl formate (EF) is an efficient and eco-friendly fumigant for controlling pest insects in grains, horticulture, and quarantine treatments. However, there is a lack of research on the antifungal activity of EF and its degradation products on barley seeds. In this study, fifteen fungal species, predominantly Alternaria infectoria, were isolated and identified from seven Australian barley samples. Efficacy results indicated that EF significantly inhibited fungal growth at a commercial concentration of 2.4 mmol/L, except for Penicillium sp. 2, Fusarium chlamydosporum, and Rhizopus arrhizus. To control these EF-tolerant fungal species, the EF concentration was increased to 5 mmol/L, which achieved a 100% inhibition rate. The degradation product of EF, formic acid, effectively inhibited all EF-tolerant fungi, requiring only 0.08 mmol/L in the in vitro study. There were no significant differences in vigor and germination rates in barley treated with EF at concentrations of 2.5, 3.7, and 5 mmol/L. Additionally, EF treatments led to a significant increase in the barley root length from an average of 9.1 cm in the control group to 13.2, 13. 6, and 12.3 cm at 2.5, 3.7, and 5 mmol/L. The findings suggest that EF could be a suitable alternative fumigant to safeguard grain from fungal infestation, particularly in the context of advancing agricultural practices and improving seed germination quality. The degradation compound, formic acid, may contribute significantly to the overall antifungal function of ethyl formate fumigation, particularly in high-humidity environments.

The fatty acid composition of Western Australian commercial pasteurised milk was profiled using gas chromatography-mass spectrometry (GC–MS). A total of 31 fatty acids (FA) were identified in the milk samples. The majority of FA were medium-chain fatty acids (MCFA) with 6–13 carbon atoms and long-chain fatty acids (LCFA) with 14–20 carbon atoms. The results of principal component analysis (PCA) showed significant differences in the levels of MCFA and LCFA in the different milk samples. The levels of MCFA and LCFA ranged from 10.09 % to 12.12% and 87.88% to 89.91% of total FA, respectively. C10:0 and C12:0 were the major components of MCFA comprising 3.46% and 4.22% of total FA, while C16:0 and C18:1 (cis 9-octadecenoic acid) represented the majority of LCFA with the levels of 26.18% and 23.34% of total FA, respectively. This study provides new insight into the FA composition of Western Australian pasteurised milk and differences in FA profiles which influence human health.

The traditional manual sampling method for detecting stored grain insect pests is labor-intensive and time-consuming, often yielding non-representative samples. However, to achieve more accurate monitoring, it is necessary to understand the distribution patterns of different insect pests within grain silo and their correlation with monitoring and sampling data. This study aimed to assess the population density and distribution of Sitophilus oryzae (rice weevil) in bulk wheat grain to predict insect dynamics effectively. Utilizing a probe trap in a wheat silo, adult insects were tracked across different population densities. The traps recorded captured pests, alongside temperature and humidity data. The correlation analysis revealed that rice weevils were active throughout the silo but less prevalent at the bottom, with the highest distribution near the upper surface. Temperature and humidity significantly influenced their activity, particularly within the 22 °C to 32 °C range. Higher population densities correlated with increased relative humidity, impacting weevil activity. Trapping data aligned with overall population density changes in the silo. This study will provide an accurate assessment of the population density of adult rice weevils in grain silos based on temperature changes in the upper part of the grain silo.

Global declines in insect abundance are of significant concern. While there is evidence that climate change is contributing to insect declines, we know little of the direct mechanisms responsible for these declines. Male fertility is compromised by increasing temperatures, and the thermal limit to fertility has been implicated as an important factor in the response of insects to climate change. However, climate change is affecting both temperature and hydric conditions, and the effects of water availability on male fertility have rarely been considered. Here we exposed male crickets
Teleogryllus oceanicus
to either low or high‐humidity environments while holding temperature constant. We measured water loss and the expression of both pre‐ and postmating reproductive traits. Males exposed to a low‐humidity environment lost more water than males exposed to a high‐humidity environment. A male's cuticular hydrocarbon profile (CHC) did not affect the amount of water lost, and males did not adjust the composition of their CHC profiles in response to hydric conditions. Males exposed to a low‐humidity environment were less likely to produce courtship song or produced songs of low quality. Their spermatophores failed to evacuate and their ejaculates contained sperm of reduced viability. The detrimental effects of low‐humidity on male reproductive traits will compromise male fertility and population persistence. We argue that limits to insect fertility based on temperature alone are likely to underestimate the true effects of climate change on insect persistence and that the explicit incorporation of water regulation into our modeling will yield more accurate predictions of the effects of climate change on insect declines.
The thermal limit to fertility has been implicated as a factor in the response of insects to climate change. However, climate change is also affecting hydric conditions. We demonstrate strong effects of hydration stress on mating behavior and male fertility that will adversely affect insect reproduction under climate change.

The often complex cocktails of hydrocarbon compounds found on the cuticles of insects can serve both naturally and sexually selected functions, contributing to an individual's ability to withstand water loss and attract mating partners. However, whether natural and sexual selection act synergistically or antagonistically on a species' cuticular hydrocarbon (CHC) profile remains unclear. Here, we examined the ontogeny of the CHC profile in a species of cricket, Teleogryllus oceanicus, while manipulating humidity during development. We predicted that juvenile crickets should produce only those compounds that contribute to desiccation resistance, while those compounds contributing specifically to male attractiveness should be produced only at sexual maturity. Further, if attractive CHCs come at a cost to desiccation resistance as predicted by some models of sexual selection, then males reared under low humidity should be constrained to invest less in attractive CHCs. Crickets reared under low humidity produced more long-chain methyl-branched alkanes, alkenes and alkadienes than did crickets reared under high humidity. The abundance of n-alkanes was unaffected by humidity treatment. Sexual dimorphism in the CHC profile was not apparent until adult emergence and became exaggerated 10 days after emergence, when crickets were sexually mature. Males produced more of the same compounds that were increased in both sexes under low humidity, but the humidity treatment did not interact with sex in determining CHC abundance. The data suggest that CHC profiles which protect crickets from desiccation might have synergistic effects on male attractiveness, as there was no evidence to suggest males trade-off a CHC profile produced in response to low humidity for one associated with sexual signalling.

Insects rely on lipids as an energy source to perform various activities, such as growth, flight, diapause, and metamorphosis. This study evaluated the role of lipids in phosphine resistance by stored-grain insects. Phosphine resistant and susceptible strains of the two main stored-grain insects, Tribolium castaneum and Rhyzopertha dominica, were analyzed using liquid chromatography-mass spectroscopy (LC-MS) to determine their lipid contents. Phosphine resistant strains of both species had a higher amount of lipids than susceptible stains. Significant variance ratios between the resistant and susceptible strains of T. castaneum were observed for glycerolipids (1.13- to 53.10-fold) and phospholipids (1.05- to 20.00-fold). Significant variance ratios between the resistant and susceptible strains of R. dominica for glycerolipids were 1.04- to 31.50-fold and for phospholipids were 1.04- to 10.10-fold. Glycerolipids are reservoirs to face the long-term energy shortage. Phospholipids act as a barrier to isolate the cells from the surrounding environment and allow each cell to perform its specific function. Thus, lipids offer a consistent energy source for the resistant insect to survive under the stress of phosphine fumigation and provide a suitable environment to protect the mitochondria from phosphine. Hence, it was proposed through this study that the lipid content of phosphine-resistant and phosphine-susceptible strains of T. castaneum and R. dominica could play an important role in the resistance of phosphine.

This study investigated the principal leaf protein (rubisco) solubilization and in vitro ruminal enzyme activity in relation to the molecular structure of proanthocyanidins extracted from leaves of Anogeissus pendula and Eugenia jambolana. Six proanthocyanidin fractions were extracted by 50% (v/v) methanol–water followed by 70% (v/v) acetone–water and then distilled water from leaves of A. pendula (AP) and E. jambolana (EJ) to yield EJ–70, EJ–50, EJ–DW, AP–70, AP–50 and AP–DW. Fractions were examined for their molecular structure and their effects on sheep ruminal enzymes and solubilization of rubisco in vitro. All fractions significantly (p < 0.05) inhibited the activity of ruminal glutamic oxaloacetic transaminase and glutamic pyruvic transaminase. The fractions AP–50 and EJ–50 significantly inhibited the activity of the R-cellulase enzyme. Most of the fractions inhibited R-glutamate dehydrogenase activity (p < 0.05) by increasing its concentration, while protease activity decreased by up to 58% with increasing incubation time and concentration. The solubilization of rubisco was observed to be comparatively higher in A. pendula (16.60 ± 1.97%) and E. jambolana (15.03 ± 1.06%) than that of wheat straw (8.95 ± 0.95%) and berseem hay (3.04 ± 0.08%). A significant (p < 0.05) increase in protein solubilization was observed when wheat straw and berseem hay were supplemented with A. pendula and E. jambolana leaves at different proportions. The efficiency of microbial protein was significantly (p < 0.05) greater with the supplementation of leaves of A. pendula in comparison to E. jambolana. The overall conclusion is that the proanthocyanidins obtained from E. jambolana exhibited greater inhibitory activities on rumen enzymes, whereas A. pendula recorded higher protein solubilization. Thus, PAs from A. pendula and E. jambolana appear to have the potential to manipulate rumen enzyme activities for efficient utilization of protein and fiber in ruminants.

The use of shipping containers for cargo transportation has the potential to transport insect pests from infested to non-infested areas. Fumigation is required as an appropriate biosecurity measure to exterminate insect pests. Fumigation trials were conducted in a 20 ft general purpose (GP) shipping container. Four species of mixed-age cultures, Lasioderma serricorne (F.), Sitophilus oryzae (L.), Trogoderma variabile (Ballion), and Rhyzopertha dominica (F.) were used for bioassays. Ninety g m−3 of ethyl formate + nitrogen formed non-flammable ethyl formate fumigant formulation was released into the container. The fumigation yielded sufficient concentration × time (Ct) products at a range of 437.54–449.19 g h m−3 in the container for exterminating all life stages. Ethyl formate left no residue in treated drinks. This study demonstrated that on site generation of a non-flammable ethyl formate and nitrogen fumigant can be achieved and this new application technology ensures that ethyl formate distributes evenly in the container within 30 min after application and with a variation of <3%. The research further demonstrated that an ethyl formate + nitrogen application can be used as a pre-shipment treatment for controlling all the stages of insect pests in a shipping container. After a fumigation holding period and ventilation of 15 min, ethyl formate was successfully removed from the container at 0.5–35ppm in different locations. The levels of ethyl formate in the workspace were <0.5 ppm during application, fumigation, and aeriation, which is about 5% of the 100 ppm level for ethyl formate.

The psocid Liposcelis entomophila (Enderlein) is a nuisance pest of stored products, owing to its high reproduction capability. While vitellogenin receptor (VgR) is an important carrier for the uptake of vitellogenin (Vg) into developing oocytes, the identification and function of VgR in psocids remain unexplored currently. This study identified and characterised the full-length cDNA of L. entomophila vitellogenin receptor (LeVgR). The results revealed that LeVgR is 5916 bp long; encodes 1811 amino acid residues, and belongs to the low-density lipoprotein receptor (LDLR) gene superfamily. LeVgR was expressed exclusively in the ovary, first transcribed in 4th-instar nymphs, and then the transcript level increased gradually from adult emergence, reached the highest level in 13-day-old female adults, and gradually declined in 15- to 23-day-old female adults with slight fluctuations. Feeding with dsLeVgR disturbed the normal expression pattern of LeVgR, leading to a decrease in egg count and hatchability and inhibited ovary maturation. These results suggest that VgR is critical for the uptake of Vg into oocytes and plays a vital role in female reproduction. Furthermore, VgR may be an important potential target to disrupt insect reproduction for pest management by oral delivery of dsRNA.