Chemical residue trends for Australian and New Zealand wool

Textile consumer trends towards improved product safety and high environmental standards have significantly influenced regulators in key consumer markets. The apparel wool industry sector has responded to regulators, and for three decades the Australia and New Zealand wool industries have managed advancements in ectoparasiticides and improved sheep treatments targeting high environmental, animal health and welfare standards leading to safe wool products. Australian and New Zealand chemical residue data from greasy wool have been consolidated and analysed for organophosphate, synthetic pyrethroid, insect growth regulator, neonicotinoid, macrocyclic lactone and spinosad active. Trend analysis has been applied to time domain data to evaluate advancements in ectoparasiticide technology after revising environmental, animal health and welfare standards. Analysis shows impacts from technology improvement, regulatory change and compliance by sheep farmers meeting or exceeding published European Union residue limits for regulated ectoparasiticides namely organochlorine, organophosphate, synthetic pyrethroid and insect growth regulators. Implications from advancements in ectoparasiticide technology, industry management and regulatory measures, include healthy sheep growing in clean pastoral environments with evidence of reduced wool residue levels which complement high and rising proportions of Australian and New Zealand wool fibre meeting European Union Ecolabel criteria.

Validation of the method for evaluating the efficacy of food baits against pharaoh ant colonies

The validation of the method for testing the effectiveness of food baits against colonies of the Pharaoh ant using experiments with commercially produced and laboratory-prepared sugar baits containing insecticides from different chemical groups was carried out. We studied baits based on boron compounds (boric acid and sodium tetraborate), neonicotinoids (thiamethoxam, imidacloprid, and acetamiprid), oxadiazines (indoxacarb), phenylpyrazoles (fipronil), carbamates (methomyl), pyrroles (chlorfenapyr) amidinohydrazones (hydramethylnon), avermectins (abamectin), and insect growth regulators (pyriproxyfen). The proposed algorithm for conducting experiments covers the whole variety of active ingredients of insecticides used in baits. The verification of several dozen products intended for the elimination of colonies of the Pharaoh ant has shown that most of the products are suitable for the requirements for efficacy indices. Keywords: Pharaoh ant, insecticidal baits.

Insecticide resistance to insect growth regulators, avermectins, spinosyns and diamides in Culex quinquefasciatus in Saudi Arabia

Background Culex quinquefasciatus is not only a biting nuisance but also an important vector of fatal diseases. In Saudi Arabia, management measures to control this mosquito and thereby prevent associated disease transmission have focused on insecticides. Nevertheless, information on the resistance status of C. quinquefasciatus is insufficient, especially concerning insecticides containing novel classes of insecticides. Methods We evaluated six insecticides belonging to four classes of insecticides (insect growth regulators [3], avermectins [1], diamides [1] and spinosyns [1]) for toxicity and resistance in eight C. quinquefasciatus populations (from Ishbiliya, Al-Masfa, Al-Masanie, Al-Washlah, Al-Nakhil, Irqah, Al-Suwaidi and Al-Ghanemiya) following World Health Organisation protocols. Results Resistance status ranging from susceptibility/low resistance to high resistance, in comparison with the susceptible strain, was detected for cyromazine in the eight C. quinquefasciatus populations: Ishbiliya (resistance ratio [RR] = 3.33), Al-Masfa (RR = 4.33), Al-Masanie (RR = 3.67), Al-Washlah (RR = 2.33), Al-Nakhil (RR = 5.33), Irqah (RR = 7.00), Al-Suwaidi (RR = 21.33) and Al-Ghanemiya (RR = 16.00). All C. quinquefasciatus populations exhibited a high level of resistance to diflubenzuron (RR = 13.33–43.33), with the exception of Al-Nakhil which exhibited moderate resistance (RR = 10.00). Susceptibility/low resistance to high resistance was observed for triflumuron in the eight C. quinquefasciatus populations: Ishbiliya (RR = 0.50), Al-Ghanemiya (RR = 3.00), Al-Suwaidi (RR = 10.00), Al-Masfa (RR = 5.00), Al-Masanie (RR = 10.00), Al-Nakhil (RR = 5.00), Irqah (RR = 5.00) and Al-Washlah (RR = 15.00). Susceptibility/low resistance was assessed for abamectin, chlorantraniliprole and spinosad in all C. quinquefasciatus populations, with RR ranges of 0.25–3.50, 0.17–2.19, and 0.02–0.50, respectively. However, the population collected from Irqah showed high resistance to chlorantraniliprole (RR = 11.93). Conclusions The detection of widespread resistance to insect growth regulators in C. quinquefasciatus highlights an urgent need to establish integrated vector management strategies. Our results may facilitate the selection of potent insecticides for integrated vector management programmes for C. quinquefasciatus. Graphical Abstract

Indirect transfer of pyriproxyfen to European honeybees via an autodissemination approach

The frequency of arboviral disease epidemics is increasing and vector control remains the primary mechanism to limit arboviral transmission. Container inhabiting mosquitoes such as Aedes albopictus and Aedes aegypti are the primary vectors of dengue, chikungunya, and Zika viruses. Current vector control methods for these species are often ineffective, suggesting the need for novel control approaches. A proposed novel approach is autodissemination of insect growth regulators (IGRs). The advantage of autodissemination approaches is small amounts of active ingredients compared to traditional insecticide applications are used to impact mosquito populations. While the direct targeting of cryptic locations via autodissemination seems like a significant advantage over large scale applications of insecticides, this approach could actually affect nontarget organisms by delivering these highly potent long lasting growth inhibitors such as pyriproxyfen (PPF) to the exact locations that other beneficial insects visit, such as a nectar source. Here we tested the hypothesis that PPF treated male Ae. albopictus will contaminate nectar sources, which results in the indirect transfer of PPF to European honey bees (Apis mellifera). We performed bioassays, fluorescent imaging, and mass spectrometry on insect and artificial nectar source materials to examine for intra- and interspecific transfer of PPF. Data suggests there is direct transfer of PPF from Ae. albopictus PPF treated males and indirect transfer of PPF to A. mellifera from artificial nectar sources. In addition, we show a reduction in fecundity in Ae. albopictus and Drosophila melanogaster when exposed to sublethal doses of PPF. The observed transfer of PPF to A. mellifera suggests the need for further investigation of autodissemination approaches in a more field like setting to examine for risks to insect pollinators.

Effects of Insect Growth Regulators on Mortality, Survival, and Feeding of Euprosterna elaeasa (Lepidoptera: Limacodidae) Larvae

The potential of insecticides that affect the growth and insect development to control Euprosterna elaeasa was evaluated. Fenoxycarb, methoxyfenozide, pyriproxyfen, and tebufenozide were assessed against E. elaeasa larvae for toxicity, survivorship, and feeding inhibition in the laboratory, and mortality in semifield conditions. Concentration–mortality bioassays demonstrated that insect growth regulators (IGRs) have a lethal effect on this insect, with pyriproxyfen (LC50 = 0.141 g L−1) being the most effective, followed by fenoxycarb (LC50 = 0.199 g L−1), methoxyfenozide (LC50 = 0.233 g L−1), and tebufenozide (LC50 = 0.259 g L−1). The survival rate was 99.8% in the control group, compared to 44.6%, 42.9%, 42.2%, and 39.5% in insects treated with pyriproxyfen, fenoxycarb, methoxyfenozide, and tebufenozide, respectively. IGRs caused feeding inhibition in E. elaeasa larvae 3 h after exposure. Furthermore, mortality in semifield conditions was similar to the results found in the laboratory. Our findings suggest that fenoxycarb, methoxyfenozide, pyriproxyfen, and tebufenozide are effective against E. elaeasa and, therefore, we confirm the potential of these IGRs for the control of this pest.

Susceptibility of the Non-Targeted Crustacean Eurytemora affinis to the Endocrine Disruptor Tebufenozide: A Transcriptomic Approach

Copepods are zooplanktonic crustaceans ubiquitously widespread in aquatic systems. Although they are not the target, copepods are exposed to a wide variety of pollutants such as insect growth regulators (IGRs). The aim of this study was to investigate the molecular response of a non-targeted organism, the copepod Eurytemora affinis, to an IGR. Adult males and females were exposed to two sub-lethal concentrations of tebufenozide (TEB). Our results indicate a sex-specific response with a higher sensitivity in males, potentially due to a differential activation of stress response pathways. In both sexes, exposure to TEB triggered similar pathways to those found in targeted species by modulating the transcription of early and late ecdysone responsive genes. Among them were genes involved in cuticle metabolism, muscle contraction, neurotransmission, and gametogenesis, whose mis-regulation could lead to moult, locomotor, and reproductive impairments. Furthermore, genes involved in epigenetic processes were found in both sexes, which highlights the potential impact of exposure to TEB on future generations. This work allows identification of (i) potential biomarkers of ecdysone agonists and (ii) further assessment of putative physiological responses to characterize the effects of TEB at higher biological levels. The present study reinforces the suitability of using E. affinis as an ecotoxicological model.

Alternative Use of the Insecticide Diofenolan on Musca domestica (Diptera: Muscidae): A Morphological and Ultrastructural Investigation

Musca domestica Linnaeus (Diptera: Muscidae), a relevant synanthropic pest, is the most frequent dipteran species in farms and waste landfills. Insect Growth Regulators (IGR), insecticides with species-specific toxicity and low health and environmental impact, are known to act mostly on larval stages but may induce sterility in adults. We investigated the effects of diofenolan, an IGR analogue of juvenile hormone, on M. domestica, with special attention to female reproductive ability (egg-laying and hatching), and ovarian and ovariole morphology, using optical and transmission electron microscopy. We also tested the interactions between diofenolan and the activity of corpora allata, endocrine gland producing juvenile hormone required for ovarian development, by morphological and ultrastructural investigations. The results show that diofenolan negatively affects the reproductive ability of M. domestica, causing extensive morphological alterations in ovaries and ovarioles. In treated females, ovarioles showed nine different morphotypes that could be arranged into three “transformation paths”, and these alterations were able to reduce egg-laying. The effects of diofenolan on corpora allata, investigated at the optical and ultrastructural level in M. domestica, showed extensive alterations of the nuclei, cytoplasms, and mitochondria, strongly suggesting a rapid transition of the gland from inactivity to degeneration. The sterilizing effects of diofenolan in M. domestica are very interesting for integrated pest management programs within sustainable defence strategies against this relevant and annoying pest.

Effect of insect growth regulators on two german cockroach strains and pharaoh ants

When eating poisoned baits based on 0.1–1.0 % pyriproxyfen, within 6 weeks killed up to 50 % of German cockroaches of the S-NIID strain, and 12 % of cockroaches of the OBN strain. The resulting oothecae turned out to be defective and the second generation of cockroaches did not hatch. Morphological changes consisted were in the deformation of the wings (rudimentary, curved, twisted) and in the inability of the larvae to transform into adults. In experiments with an alternative food, similar results were obtained, females formed more oothecae, but the emergence of new generation larvae was not recorded. The consumption of pyriproxyfen-based baits by Pharaoh ant led to the elimination of colonies. A significant decrease in brood number was recorded at 3–6 weeks, and complete death of brood was observed at 6–8 weeks in all treated colonies. The absence of brood can be explained by both mortality as a result of developmental disorders and the cessation of egg laying by queens. Keywords: insect growth regulators, German cockroach, Pharaoh ant, pyriproxifen, hydroprene.