Anticarsia gemmatalis Hübner, 1818 (Lepidoptera) is a major pest of soybean in the Brazil. It is known that the reduction of proteolytic activity by the ingestion of protease inhibitors reduces digestion and larval development of the insects. Control via inhibition of the digestive enzymes necessitates deeper knowledge of the enzyme kinetics and the characterization of the inhibition kinetics of these proteases, for better understanding of the active centers and action mechanisms of this enzyme. Trypsin-like proteases found in the gut of Anticarsia gemmatalis were purified in a p-aminobenzamidine agarose column. Kinetic characterization showed KM 0.503 mM for the L-BApNA substrate; Vmax= 46.650 nM s-1; Vmax/[E]= 9.256 nM s-1 mg L-1 and Vmax/[E]/KM= 18.402 nM s-1 mg L-1 mM. The Ki values for the inhibitors benzamidine, berenil, SKTI and SBBI were 11.2 µM, 32.4 µM, 0.25 nM and 1.4 nM, respectively, and all revealed linear competitive inhibition. The SKTI showed the greatest inhibition, which makes it a promising subject for future research to manufacture peptide mimetic inhibitors.

Root-knot nematodes (RKN - Meloidogyne spp.) are one of the most serious threats to carrot production worldwide. In Brazil, carrots are grown throughout the year, and economic losses due to RKN are reported. Since little is known on the distribution of RKN species in carrot fields in Brazil, we collected plant and soil samples from 35 fields across six states. Based on the morphology of perineal patterns, esterase phenotypes and species-specific PCR, three Meloidogyne species were identified: 60% of the fields were infested with Meloidogyne incognita, M. javanica was reported in 42.9% of the areas, whereas M. hapla was detected in 17.1% of carrot fields. Mixed populations were reported in 20% of the areas with a predominance of M. incognita + M. javanica. The combination of morphological, biochemical, and molecular techniques is a useful approach to identify RKN species.

Resistance to neurotoxic insecticides in populations of the coffee leafminer Leucoptera coffeella | InTechOpen, Published on: 2016-03-02. Authors: Daianna P. Costa, Flávio L. Fernandes, Flávia M. Alves, et

The management of Meloidogyne incognita often depends on chemical nematicides, which pose environmental and health risks. This study investigated the potential of bacterial strains isolated from uncultivated native soil as biocontrol agents and plant growth-promoting rhizobacteria (PGPR) in tomato plants artificially infected with this nematode. Fifteen strains were screened in vitro for nematicidal and ovicidal activity, and four promising strains (307, GB16, GB24, and GB29) were selected for greenhouse trials. All strains reduced the nematode reproduction factor and the number of nematodes/g of root. Strains 307 and GB24 showed the highest reductions, 61.39 and 57.24%, respectively. Despite some positive physiological trends, Bacillus spp. did not promote a significant increase in plant growth. Metabolomic analysis revealed that the strains produced a wide range of primary metabolites with potential nematicidal activity. All strains also secreted proteases and chitinases, enzymes linked to nematode cuticle degradation. Preliminary identification based on the 16S rRNA gene and phylogenetic analysis grouped the four strains into the Bacillus subtilis group (strains GB16, GB29 and 307) or Bacillus cereus group (strain GB24); however, genome sequencing will be required in future studies. Overall, strains 307 and GB24 demonstrated strong biocontrol potential, supporting their use as sustainable and complementary alternatives to chemical nematicides.

The effects of four extracts of Hortia oreadica Groppo (Rutaceae) on the biological parameters, nutritional indices, and activity of digestive enzymes of Anticarsia gemmatalis Hübner [1818] (Erebidae) were evaluated. Newly hatched caterpillars were subjected to extracts from H. oreadica extracted with hexane (HE), dichloromethane (DE), dichloromethane fractionated with ethyl acetate (DEAE) and dichloromethane fractionated with dichloromethane (DDE) at concentrations 0, 100, 500 and 1000 μg ꞏ ml–1. The results showed that treatments significantly increased the cumulative mortality rate of A. gemmatalis and that HE 100 μg ꞏ ml–1 was the most effective, causing 92% of insects’ deaths. The period of larval development was significantly shorter with treatments HE 100 and 500 μg ꞏ ml–1 and longer with DEAE (all concentrations). The pupal weight was lower in the treatments HE 1000 μg ꞏ ml–1 and in all doses tested of the DEAE treatment. The morphological integrity of pupae and adults was not affected. The lowest values of relative food consumption rate, relative metabolic rate, and relative growth rate were observed in the HE 100 μg ꞏ ml–1 treatment. In most treatments, there was a reduction in the activity of total proteases, serine and cysteine proteases, and amylase. The results suggest that the HE extract of H. oreadica is the most efficient in controlling A. gemmatalis, due to the presence of deterrent metabolites that affect the insect’s digestion and nutrition and consequently promote adverse effects on its development and mortality.