Discovery of insecticide resistance in field-collected populations of the aphid pest, Acyrthosiphon kondoi Shinji.

BACKGROUND: The bluegreen aphid (Acyrthosiphon kondoi) is a worldwide pest of alfalfa, pulses, and other legume crops. An overreliance on insecticides to control A. kondoi has potentially placed populations under selection pressure favouring resistant phenotypes, but to date, there have been no documented cases of insecticide resistance. Recently, Australian growers began reporting that conventional insecticides were failing to adequately control A. kondoi populations, prompting this laboratory-based investigation into whether these populations have evolved resistance. RESULTS: We discovered four A. kondoi populations with moderate resistance (10-40-fold) to three different insecticide groups: organophosphates, carbamates and pyrethroids. However, A. kondoi populations showed no resistance to the butenolide, flupyradifurone. We were unable to identify general metabolic mechanisms using synergist assays (cytochromes P450, glutathione S-transferases, or esterases), indicating that further detailed molecular investigations to characterise the putative resistance mechanism are needed. CONCLUSION: Insecticide-resistant A. kondoi present an emerging challenge to Australian agriculture. Growers require new tools and updated strategies, including access to newer chemistries, to alleviate their reliance on the few insecticides currently registered against A. kondoi. The implications of insecticide resistant A. kondoi for future management, the potential mechanisms of resistance, and future research priorities are discussed. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Periconception and First Trimester Diet Modifies Appetite, Hypothalamic Gene Expression, and Carcass Traits in Bulls.

Nulliparous yearling beef heifers (n=360) were used to evaluate the effects of maternal dietary protein during the periconception and first trimester periods of gestation on postnatal growth, feedlot performance, carcass characteristics, and the expression of genes associated with appetite in the arcuate nucleus of their male progeny. Heifers were individually fed a diet of 1.18g crude protein (CP)/day High protein (HPeri) or 0.62g CP/day Low protein (LPeri) beginning 60days before conception. From 24 to 98days post-conception (dpc), half of each treatment group changed to the alternative post-conception diet and were fed 1.49g CP/day (HPost) or 0.88g CP/day (LPost) yielding four treatment groups in a 2×2 factorial design. From day 98 of gestation, heifers received a common diet until parturition. Calves were weaned at 183days and developed on pasture before feedlot entry. Bulls underwent a 70-day Residual Feed Intake (RFI) feedlot test commencing at 528days of age. Feedlot entry and final body weight (BW), feedlot average daily gain (ADG) and RFI were not different (p>0.05). Progeny of dams that had a change in diet (LPeri/HPost and HPeri/LPost) had 9% higher daily dry matter intake (DMI) during the RFI test (p<0.05) than progeny of dams that received low diet throughout both the peri-conception period and first trimester (LPeri/LPost). Further, mRNA expression of the appetite-stimulating agouti-related protein (AGRP) was increased in the arcuate nucleus of High Peri/LPost bulls (p<0.05). Longissimus dorsi muscle cross sectional area, carcass dressing percentage, and estimated retail beef yield (RBY) were all higher (p<0.05), and rump (P8) fat tended to be lower (p=0.07), for bulls from HPost dams despite no difference in carcass weight (p<0.05). This study is of commercial importance to the livestock industry as specific periods of maternal dietary supplementation may increase feed intake, enhance progeny muscling, and alter fat deposition leading to improvement in efficiency of meat production in beef cattle.

Maternal periconceptional and first trimester protein restriction in beef heifers: effects on maternal performance and early fetal growth.

This study evaluated the effect of protein restriction during the periconception (PERI) and first trimester (POST) periods on maternal performance, physiology and early fetal growth. Yearling nulliparous heifers (n=360) were individually fed a diet high or low in protein (HPeri and LPeri respectively) beginning 60 days before conception. From 24 to 98 days post-conception (dpc), half of each treatment group changed to the alternative post-conception high- or low-protein diet (HPost and LPost respectively), yielding four groups in a 2×2 factorial design with a common diet until parturition. Protein restriction was associated with lower bodyweight subsequent to reduced (but positive) average daily weight gain (ADG) during the PERI and POST periods. During the POST period, ADG was greater in LPeri than HPeri heifers and tended to be greater in LPost than HPost heifers during the second and third trimester. Bodyweight was similar at term. The pregnancy rate did not differ, but embryo loss between 23 and 36 dpc tended to be greater in LPeri than HPeri heifers. Overall, a greater proportion of male fetuses was detected (at 60 dpc 63.3% male vs 36.7% female). Protein restriction altered maternal plasma urea, non-esterified fatty acids, progesterone, leptin and insulin-like growth factor 1 at critical stages of fetal development. However, profiles varied depending on the sex of the conceptus.

Effect of breed, age, season and region on sperm morphology in 11,387 bulls submitted to breeding soundness evaluation in Australia.

This study reports the distribution of sperm morphology defects by breed, age, season and region of 11,387 bulls in 500 herds in Australia and near Pacific Islands during annual BBSE. Bull location was divided into 4 broad climatic regions based upon temperature, vegetation and climatic risk. Taking into account the impact of age, season, region, and breed there were differences between breeds in both percent morphologically normal sperm and in some individual categories of sperm abnormality (P < 0.001). Independent of breed, season and region, proximal droplets were significantly increased in bulls less than 20 months of age. This is the first study to comprehensively collect data from this wide geographical area and compare sperm morphology profiles among the Bos indicus and Bos taurus breeds. The findings of this study will act as a guide for veterinary practitioners and cattle breeders in the proportion of bulls that can be expected to pass the PNS test, by breed, age and region, based on a robust data set.

Correction: Gestational Dietary Protein Is Associated with Sex Specific Decrease in Blood Flow, Fetal Heart Growth and Post-Natal Blood Pressure of Progeny.

[This corrects the article DOI: 10.1371/journal.pone.0125694.].

The influence of peri-conception and first trimester dietary restriction of protein in cattle on meat quality traits of entire male progeny.

Primiparous Santa Gertrudis heifers were used to evaluate the effects of gestational dietary protein content on meat quality traits of 20month old bull progeny (n=40). At -60d before AI, heifers were randomly allocated to HIGH or LOW protein diet (HPERI and LPERI). From 24dpc, half of each treatment group changed to an alternative post-conception HIGH or LOW protein diet (HPOST and LPOST). LPERI and LPOST diets resulted in higher shear force of the semitendinosus muscle than HPERI (P=0.053) and HPOST (P=0.003), respectively. Heat-soluble collagen in the semitendinosus muscle was lower (P=0.019) for LPERI than HPERI. Collagen and tenderness of the longissimus muscle were not affected by dam nutrition (P>0.05). Color, pH, sarcomere length, cooking loss, compression values, desmin and troponin-T degradation, fiber type, intramuscular fat and polyunsaturated fatty acid content were not affected by dam nutrition during the peri-conception and first trimester gestational period (P>0.05).

Gestational dietary protein is associated with sex specific decrease in blood flow, fetal heart growth and post-natal blood pressure of progeny.

STUDY OVERVIEW: The incidence of adverse pregnancy outcomes is higher in pregnancies where the fetus is male. Sex specific differences in feto-placental perfusion indices identified by Doppler assessment have recently been associated with placental insufficiency and fetal growth restriction. This study aims to investigate sex specific differences in placental perfusion and to correlate these changes with fetal growth. It represents the largest comprehensive study under field conditions of uterine hemodynamics in a monotocous species, with a similar long gestation period to the human. Primiparous 14 mo heifers in Australia (n=360) and UK (n=180) were either individually or group fed, respectively, diets with differing protein content (18, 14, 10 or 7% crude protein (CP)) from 60 d prior to 98 days post conception (dpc). Fetuses and placentae were excised at 98 dpc (n = 48). Fetal development an median uterine artery blood flow were assessed monthly from 36 dpc until term using B-mode and Doppler ultrasonography. MUA blood flow to the male feto-placental unit increased in early pregnancy associated with increased fetal growth. Protein restriction before and shortly after conception (-60 d up to 23 dpc) increased MUA diameter and indices of velocity during late pregnancy, reduced fetal heart weight in the female fetus and increased heart rate at birth, but decreased systolic blood pressure at six months of age. CONCLUSION AND SIGNIFICANCE: Sex specific differences both in feto-placental Doppler perfusion indices and response of these indices to dietary perturbations were observed. Further, maternal diet affected development of fetal cardiovascular system associated with altered fetal haemodynamics in utero, with such effects having a sex bias. The results from this study provide further insight into the gender specific circulatory differences present in the fetal period and developing cardiovascular system.