Seasonal Abundance and Spatial Pattern of Distribution of Liriomyza trifolii (Diptera: Agromyzidae) and Its Parasitoid on Bean and Squash in South Florida

American serpentine leafminer, Liriomyza trifolii, is a polyphagous insect pest that feeds on a wide range of vegetable and ornamental plants around the world. To develop an effective IPM program, information on the seasonal field distribution and population dynamics of leafminer and its parasitoids is very important. Therefore, seasonal abundances and spatial distributions of, L. trifolii on snap bean and squash were studied during four crop growing periods between 2013 to 2015 in Homestead, Florida. The mean numbers of mines, larvae, pupae, emerged adults, and parasitoids on snap bean were highest at 2 weeks after planting during all four growing periods. Whereas, the mean numbers of mines, larvae, pupae, emerged adults, and parasitoids on squash were highest at 3 weeks after planting during all four growing periods. L. trifolii distributions tended to be aggregated on snap bean at 2 weeks after planting during most of growing periods but had uniform distributions on squash at 2 weeks after planting during most of growing periods. Similar results were seen on the distribution of leafminer parasitoids on both bean and squash.

Assessing the effects of a novel biostimulant to enhance leafminer resistance and plant growth on common bean

The leafminer Liriomyza trifolii is one of the major insects that affect Phaseolus vulgaris production worldwide. Novel and safe biobased stimulator compound (BSTC) with micronutrient-amino acid chelated compounds was developed from natural compounds and was used for foliar spray of P. vulgaris. Treated plants showed significantly increased in quality and productivity as well as significant reduction in leafminer infestation by close the tunnel end resulting in larvae suffocation and death. BSTC contains chemical composition that has important function in inducing immunity and resistance against insects, enhance plant growth and production. Also, HPLC showed that the assembled BSTC is rich in nucleobases than yeast extract (> 56 fold). Aminochelation zinc enhanced the rate of absorption of nutrient compounds and could participate in safe biofortification strategy. The expression of plant defense related genes under BSTC treatment revealed strong correlations between the transcription rates of defense related genes. Based on binding energies and interacting residues of six vital insect proteins, the best-docked complexes was obtained with disodium 5′-inosinate, delphinidin 3-glucoside and hyperoside. Obtained findings indicate that the foliar application of BSTC can enhance plant growth and productivity, uptake of important elements, expression of defense related genes and inhibit insect essential genes.

Transcriptome analysis reveals gene expression differences in Liriomyza trifolii exposed to combined heat and abamectin exposure

Liriomyza trifolii is an invasive pest of horticultural and vegetable crops that possesses robust competitive advantages that enable it to replace closely-related species. High temperatures often occur concomitantly with insecticide usage during L. trifolii outbreaks. In this study, we compared the transcriptomes of L. trifolii exposed to high temperature (40 °C T40), insecticide (LC50 of technical grade abamectin, I50) and combined high temperature and abamectin exposure (IT5040, I50 followed by T40; and TI4050, T40 followed by I50). RNA-seq generated and revealed 44,633 unigenes with annotation data; these were compared with COG and KEGG databases for functional classification and enrichment analysis. Compared with the I50 treatment, COG classification indicated that ‘post-translational modification, protein turnover, chaperones’ was enriched in the IT5040 treatment. In the TI4050 treatment, ‘carbohydrate transport and metabolism’ was the most abundant group. The most enriched KEGG pathways in the TI4050 and IT5040 treatments were ‘longevity regulating pathway - multiple species’ and ‘protein processing in endoplasmic reticulum’, respectively. Subsequent annotation and enrichment analyses indicated that stress-related genes such as CYP450s and HSPs were differentially expressed in the I50 vs. TI4050 or I50 vs. IT5040 treatment groups. Three commercial insecticide formulations were also used to further verify the expression of selected differentially-expressed genes. This study will be conductive to consider the temperature effect on insecticide tolerance in L. trifolii, and provides a framework for improving the application efficiency of insecticides in hot weather, which will ultimately reduce the overuse of pesticides.

Comparative Study Between ATOMES Novels, NOVOSECT SC21®, ATO BED BUG® and NEO-BOOST® as a Bio-organic Solution in Managing Tomato Open Field Plantation in Hrajel Area in Lebanon

The increasing use of chemical insecticides has adversely effected the environment and increased insect resistance. Biopesticides have been noticed the potential to be an excellent alternative to chemicals to reduce the negative impacts to human health and the environment. Tomato (Lycopersicon esculentum) is the second most important vegetable crop worldwide due to its nutritional importance. The effect of NOVOSECT SC21® (0.5 L/200 L), ATO BED BUGS® (1 L/200 L) and NEO-BOOST® (1 kg/200 L) against Tuta absoluta, Liriomyza trifolii and Alternaria solani was studied. A complete randomized block design (CRBD) was used with three replications, three treatments and one control in Hrajel area in Lebanon in the summer of 2020. We evaluated the level of infestation and larval mortality level of Tuta absoluta, Liriomyza trifolii and Alternaria solani infection 24, 48 and 72 hr after the application. Results showed that NOVOSECT SC21® (Mix of metabolites of the Bacillus F.D. 777) was the most efficient in decreasing the infestation and inducing larval mortality level of T. absoluta and L. trifolii and the fungal infection induced by A. solani with significant difference with time, followed respectively by ATO BED BUGS® and finally NEO-BOOST®.

Seasonal Abundance and Spatial Pattern of Distribution of Liriomyza trifolii (Diptera: Agromyzidae) and Its Parasitoid on Bean and Squash in South Florida

ABSTRACTAmerican serpentine leafminer, Liriomyza trifolii, is a polyphagous insect pest that feeds on a wide range of vegetable and ornamental plants around the world. To develop an effective IPM program, information on the seasonal field distribution and population dynamics of leafminer and its parasitoids is very important. Therefore, seasonal abundances and spatial distributions of, L. trifolii on snap bean and squash were studied during four crop growing periods between 2013 to 2015 in Homestead, Florida. The mean numbers of mines, larvae, pupae, emerged adults, and parasitoids on snap bean were highest at 2 weeks after planting during all four growing periods. Whereas, the mean numbers of mines, larvae, pupae, emerged adults, and parasitoids on squash were highest at 3 weeks after planting during all four growing periods. L. trifolii distributions tended to be aggregated (1 < b/β) on snap bean at 2 weeks after planting during all four growing periods but had uniform (1 > b/β) distributions on squash at 2 weeks after planting during all four growing periods. Similar results were seen on the distribution of leafminer parasitoids on both bean and squash.