Animals use signals to coordinate a wide range of behaviors, from feeding offspring to predator avoidance. This poses an evolutionary problem, because individuals could potentially signal dishonestly to coerce others into behaving in ways that benefit the signaler. Theory suggests that honest signaling is favored when individuals share a common interest and signals carry reliable information. Here, we exploit the opportunities offered by bacterial signaling to test these predictions with an experimental evolution approach. We show that: (1) reduced relatedness leads to the relative breakdown of signaling, (2) signaling breaks down by the invasion of mutants that show both reduced signaling and reduced response to signal, (3) the genetic route to signaling breakdown is variable, and (4) the addition of artificial signal, to interfere with signal information, also leads to reduced signaling. Our results provide clear support for signaling theory, but we did not find evidence for previously predicted coercion at intermediate relatedness, suggesting that mechanistic details can alter the qualitative nature of specific predictions. Furthermore, populations evolved under low relatedness caused less mortality to insect hosts, showing how signal evolution in bacterial pathogens can drive the evolution of virulence in the opposite direction to that often predicted by theory.
Bioassays (at generation 1, G1) using fipronil, spinosad, indoxacarb, and Bacillus thuringiensis toxins Cry1Ac and Cry1Ca with a newly collected field population of Plutella xylostella (L.) from farmers fields in the Cameron Highlands, Malaysia, indicated a resistance ratio of approximately 400-, 1,170-, 330-, 2,840-, and 1,410-fold, respectively, compared with a laboratory-susceptible population of P. xylostella (ROTH). At G3, the field-derived population was divided into two subpopulations, one was selected (G3 to G7) with fipronil (fip-SEL), whereas the second was left unselected (UNSEL). Bioassays at G8 found that selection with fipronil gave a resistance ratio of approximately 490 compared with UNSEL and approximately 770 compared with ROTH. The resistance ratio for fipronil, spinosad, indoxacarb, Cry1Ac, and Cry1Ca in the UNSEL population declined significantly by G8. Logit regression analysis of F1 reciprocal crosses between fip-SEL (at G8) and UNSEL indicated that resistance to fipronil in the fip-SEL population was inherited as an autosomal, incompletely recessive (D(LC) = 0.37) trait. At the highest dose of fipronil tested, resistance was completely recessive, whereas at the lowest dose it was incompletely recessive. A direct test of monogenic inheritance based on a backcross of F1 progeny with fip-SEL suggested that resistance to fipronil was controlled by a single locus. The fip-SEL population at G8 showed little change in its response to spinosad and indoxacarb compared with G1, whereas its susceptibility to Cry1Ac and Cry1Ca increased markedly over the selection period. This suggests that there may be some low level of cross-resistance between fipronil, spinosad, and indoxacarb.
Helicoverpa armigera (Hub.) is a destructive pest of the tomato (Lycopersicon esculentum Mill) crop in Pakistan. Although insecticides are the primary management strategy used to control H. armigera, most of them are not effective due to considerable toxic residual effects on the fruits. Nonetheless, H. armigera is rapidly evolving resistance against the available pesticides for its management. This situation calls upon the need of alternative management options against the pest. Different plant extracts have been suggested as a viable, environment-friendly option for plant protection with minimal side effects. Furthermore, the plant extracts could also manage the insect species evolving resistance against pesticides. This study evaluated the efficacy of different plant extracts (i.e., Neem seed, turmeric, garlic and marsh pepper) against H. armigera. Furthermore, the impact of the plant extracts on growth and yield of tomato crop was also tested under field conditions. The results revealed that all plant extracts resulted in higher mortality of H. armigera compared to control. Similarly, the highest plant height was observed for the plants treated with the plant extracts compared to untreated plants. Moreover, the highest tomato yield was observed in plants treated with plant extracts, especially with neem seed (21.013 kg/plot) followed by pepper extract (19.25 kg/plot), and garlic extract 18.4 kg/plot) compared to the untreated plants (8.9 kg/plot). It is concluded that plant extracts can be used as eco-friendly approaches for improving tomato yield and resistance management of H. armigera.
The fall armyworm (Spodoptera frugiperda) is one of the most destructive pests of corn. New infestations have been reported in the East Hemisphere, reaching India, China, Malaysia, and Australia, causing severe destruction to corn and other crops. In Puerto Rico, practical resistance to different mode of action compounds has been reported in cornfields. In this study, we characterized the inheritance of resistance to chlorantraniliprole and flubendiamide and identified the possible cross-resistance to cyantraniliprole and cyclaniliprole. The Puerto Rican (PR) strain showed high levels of resistance to flubendiamide (RR50 = 2,762-fold) and chlorantraniliprole (RR50 = 96-fold). The inheritance of resistance showed an autosomal inheritance for chlorantraniliprole and an X-linked inheritance for flubendiamide. The trend of the dominance of resistance demonstrated an incompletely recessive trait for H1 (♂ SUS × ♀ PR) × and an incompletely dominant trait for H2 (♀ SUS × ♂ PR) × for flubendiamide and chlorantraniliprole. The PR strain showed no significant presence of detoxification enzymes (using synergists: PBO, DEF, DEM, and VER) to chlorantraniliprole; however, for flubendiamide the SR = 2.7 (DEM), SR = 3.2 (DEF) and SR = 7.6 (VER) indicated the role of esterases, glutathione S- transferases and ABC transporters in the metabolism of flubendiamide. The PR strain showed high and low cross-resistance to cyantraniliprole (74-fold) and cyclaniliprole (11-fold), respectively. Incomplete recessiveness might lead to the survival of heterozygous individuals when the decay of diamide residue occurs in plant tissues. These results highlight the importance of adopting diverse pest management strategies, including insecticide rotating to manage FAW populations in Puerto Rico and other continents.
Bacillus thuringiensis Berliner (Bt) crystal (Cry) toxins are expressed in various transgenic crops and are also used as sprays in integrated pest management and organic agricultural systems. The diamondback moth (Plutella xylostella L.) is a major worldwide pest of crucifer crops and one that has readily acquired field resistance to a broad range of insecticides.
Introduction: This is a proto-type product which is based on Frankincense essential oil and hydrosol. Methods: Three oleo gum resin species, namely; Boswellia carterii (BC), Boswellia frereana (BF), and Commiphora myrrha (CM) of Burceraceae family were extracted for their essential oil by hydro-distillation. They were screened for their poten-tial of anti-cariogenic activity by in-vitro experimental study of two main bacterial species (Streptococcus mutans and Lactobacillus spp), which are considered the main cause of dental and mouth diseases. Results: Methanol and acetone extracts of the three plants inhibited the growth of the bacteria. However, BF-methanol extract shows the greatest inhibition followed by BC and CM respectively. Hence, the obtained result encourages proceeding further thorough investigation to benefit the positive outcomes of these plant extracts in terms of introducing new potential antimicrobial formulations, such as mouth wash which can be used for mouth cleansing and protection from the diseases such as mouth ulcers, gingivitis, sinusitis, glandular fever and brucellosis as well as dental caries. This result can be converted to Boswellia Mouthwash Essential Oil (BosMEO) and Boswellia Mouthwash Hydrosol (BosMoHy) based products. This new plant extract product can be exploited for further research for its potential used as moth infection natural treatments such as mouth ulcers, gingivitis, sinusitis, glandular fever, brucellosis as well as respi-ratory problem. It is free of synthetic chemicals, organic, natural, plant based, and halal with no major health side effects. Conclusion: Plant-based product which is free from synthetic chemicals and with minimal side effects will satisfy its quality efficiency.
Red Palm Weevil (RPW), Rhynchophorus ferrugineus is a lethal pest which has been described as a serious pest that reduces the production of coconut tree and other major cultivated palms. RPW infestation was initially detected by Department of Agriculture (DOA) in 2007 in all eight Terengganu districts. Rhu Tapai plantation area is one of the highly infested areas in Terengganu. Until now, limited reports on population abundance of this lethal pest have been discussed particularly in Rhu Tapai. Therefore, a study on population abundance is a must in order to understand the population dynamic of RPW which will be the first step of its control strategy. A total of 12 traps were installed and synthetic pheromones (P028 Ferrolure+) were used in attracting the RPW adults. Overall, 81 individuals of RPW were successfully collected after 16 weeks of pheromone trapping (3rd September until 28th November 2018). The trend of weekly RPW captured was eventually decreasing from Week 1 to Week 16 but showed a sudden increment in Week 10. Pandan cultivar plot captured the highest number of adult RPW compared with Mawa cultivar plots. Result showed no significant difference between RPW sexes percentage of sexes which was 53% of male and 47% of female (1:1 ratio) (U= 0.143, p > 0.05). Daily rainfall and temperature significantly reduced the trapping efficiency (R²rainfall = 0.142, p = 0.145; R²temperature = 0.0858; p = 0.258). These results will be the baseline information for future study regarding control management strategy using pheromone-based mass trapping system.
Due to problems with chemical control, there is increasing interest in the use of microsporidia for control of lepidopteran pests. However, there have been few studies to evaluate the susceptibility of exotic species to microsporidia from indigenous Lepidoptera.
Species-specific primers for Zoophthora radicans and Pandora bluckii were developed. To achieve this, partial sequences of DNA that encode for rRNA, more specifically, the ITS region (rDNA-ITS) were obtained from different isolates and analysed. Seven Z. radicans isolates (four from P. xylostella, and three from other lepidopteran hosts) and one P. blunckii isolate (from P. xylostella) were used. These isolates were selected based on PCR-RFLP patterns obtained from 22 isolates of P. blunckii and 39 isolates of Z. radicans. All P. blunckii isolates were from the same host (P. xylostella); 20 isolates were from Mexico, one from the Philippines, and one from Germany. The Z. radicans isolates were more diverse in geographical origin (Mexico, Kenya, Japan, New Zealand, Australia, Taiwan, Philippines, Malaysia, Uruguay, France, USA, Poland, Indonesia, Switzerland, Israel, China, and Denmark) and host origin (Lepidoptera, Hemiptera, Hymentoptera, and Diptera). Using conventional PCR, each pair of species-specific primers successfully detected each species of fungus from DNA extracted from infected host larvae either single- or dual-inoculated with both fungal species. The PCR-RFLP analysis also showed that Z. radicans was genetically more diverse than P. blunckii, although only a limited number of P. blunckii isolates from one country were considered. There was no direct relationship between genetic diversity and host or geographical origin. The relationship between genetic variation within both fungal species and host specificity or ecological adaptation is discussed.
We sequenced and annotated the complete mitochondrial genome (mitogenome) of Bactrocera diaphora (Diptera: Tephtitidae), which is an economically important pest in the southwest area of China, India, Sri Lanka, Vietnam and Malaysia. This mitogenome is 15 890 bp in length with an A + T content of 74.103%, and contains 37 typical animal mitochondrial genes that are arranged in the same order as that of the inferred ancestral insects. All protein-coding genes (PCGs) start with a typical ATN codon, except cox1 that begins with TCG. Ten PCGs stop with termination codon TAA or TAG, whereas cox1, nad1 and nad5 have single T-- as the incomplete stop codon. All of the transfer RNA genes present the typical clover leaf secondary structure except trnS1 (AGN) with a looping D-arm. The A + T-rich region is located between rrnS and trnI with a length of 946 bp, and contains a 20 bp poly-T stretch and 22 bp poly-A stretch. Except the control region, the longest intergenic spacer is located between trnR and trnN that is 94 bp long with an excessive high A + T content (95.74%) and a microsatellite-like region (TA)13.
A field population of Plutella xylostella from Malaysia (SERD4) was divided into five sub-populations and four were selected (G2-G5) with the Bacillus thuringiensis insecticidal crystal (Cry) toxins Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da. Bioassay at G6 gave resistance ratios of 88, 5, 2 and 3 for Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da respectively compared with the unselected sub-population (UNSEL-SERD4). The Cry1Ac-selected population showed little cross-resistance to Cry1Ab, Cry1Ca and Cry1Da, (3-, 2- and 3-fold compared with UNSEL-SERD4), whereas the Cry1Ab-SEL sub-population showed marked cross-resistance to Cry1Ac (40-fold), much greater than Cry1Ab itself. In contrast, the Cry1Ca- and Cry1Da-SEL sub-population showed little if any cross-resistance to Cry1Ac and Cry1Ab. The mode of inheritance of resistance to Cry1Ac was examined in Cry1Ac-selected SERD4 by standard reciprocal crosses and back-crosses using a laboratory insecticide-susceptible population (ROTH). Logit regression analysis of F1 reciprocal crosses indicated that resistance to Cry1Ac was inherited as an incompletely dominant trait. At the highest dose of Cry1Ac tested, resistance was recessive, while at the lowest dose it was almost completely dominant. The F2 progeny from a back-cross of F1 progeny with ROTH were tested with a concentration of Cry1Ac that would kill 100% of ROTH. The mortality ranged between 50 and 95% in seven families of back-cross progeny, which indicated that more than one allele on separate loci were responsible for resistance to Cry1Ac.
Introduction: Even though exclusive breastfeeding prevalence has increased from 19.3% in 2006 to 47.1% in 2016, this practice was slightly higher in urban areas (48.3%) compared to rural area (45.1%) in Malaysia. National Plan of Action for Nutrition of Malaysia III has set an indicator to achieve at least 70% exclusive breastfeeding by 2025. Therefore this study is to identify predictors that influenced exclusive breastfeeding practice in rural areas. Methods: This cross-sectional study was conducted in six rural health clinics in Hulu Langat District, Selangor among moth- ers with youngest child aged 6-48 months old. Respondents were selected through systematic random sampling. Validated self-administered questionnaire was used to assess sociodemographic factors, maternal factors, external factors and child’s factors. Mother’s height and weight was measured and body mass index was calculated. Data were analyzed using SPSS version 23. Multivariate logistic regression was used to determine the predictors for ex- clusive breastfeeding practice. Results: Response rate was 96% with a total of 311 mothers participated in this study. More than half of the mothers exclusively breastfed (52.4%). The predictors for exclusive breastfeeding were Malay ethnicity (AOR=3.951, 95% CI: 1.374-11.358), having tertiary education (AOR=2.401, 95% CI: 1.100-5.241) and positive attitude toward breastfeeding (AOR=7.755, 95% CI: 1.382-43.502). Conclusion: Prevalence of exclusive breastfeeding was higher in this study than the national level. Programme planners should pay special attention to Chinese and Indian ethnicities, mothers with lower level of education and negative attitude in order to improve breastfeeding practice among rural mothers.