This study reports the first successful use of oral feeding dsRNA technique for functional characterization of imaginal disc growth factors (IDGFs) genes (IDGF1, IDGF3_1, IDGF4_0, IDGF4_1, and IDGF6) in melon fly Zeugodacus cucurbitae. Phylogenetic and domain analysis indicates that these genes had high similarity with other Tephritidae fruit flies homolog and contain only one conserved domain among these five genes, which is glyco-18 domain (glyco-hydro-18 domain). Gene expression analysis at different developmental stages revealed that these genes were expressed at larval, pupal, and adult stages. To understand their role in different developmental stages, larvae were fed dsRNA-corresponding to each of the five IDGFs, in an artificial diet. RNAi-mediated knockdown of IDGF1 shows no phenotypic effects but caused mortality (10.4%), while IDGF4_0 caused malformed pharate at the adult stage where insects failed to shed their old cuticle and remained attached with their body, highest mortality (49.2%) was recorded compared to dsRNA-green fluorescent protein (GFP) or DEPC. Silencing of IDGF3_1 and IDGF4_1 cause lethal phenotype in larvae, (17.2%) and (40%) mortality was indexed in Z. cucurbitae. IDGF6 was mainly expressed in pupae and adult stages, and its silencing caused a malformation in adult wings. The developmental defects such as malformation in wings, larval–larval lethality, pupal–adult malformation, and small body size show that IDGFs are key developmental genes in the melon fly. Our results provide a baseline for the melon fly management and understanding of IDGFs specific functions in Z. cucurbitae.

Spodoptera frugiperda has become a major pest in many crops worldwide. The main control strategies are biological and chemical controls. However, pesticides have varying degrees of toxicity to parasitic wasps in the field. To integrate chemical and biological controls, we evaluated the safety of insecticides to Tetrastichus howardi, an important pupal parasitoid of S. frugiperda. This study assessed the toxicity of six major control insecticides (emamectin benzoate, chlorfenapyr, indoxacarb, chlorantraniliprole, bisultap, and lufenuron) to T. howardi based on risk quotient. The results showed that indoxacarb had the lowest risk quotient (RQ = 7.43). Then the side effects of three sublethal concentrations (LC20, LC30, LC40) of indoxacarb were tested using three methods (1. Adult exposure to pesticide residues on the glass tube; 2. Adult exposure to pesticide residues on the host; 3. Larval exposure to pesticides through host exposure). Overall, T. howardi had a lower parasitism rate and emergence rate with the higher pesticide concentrations. Furthermore, among three methods, the adult exposure to pesticide residues on the glass tube was the most efficient in inhibiting the parasitism rate, and impairing the emergence rate and the offspring female/male ratio. This study guides a more scientific and comprehensive application of pesticides and releases natural enemies in the field.

No abstract

Chouioia cunea Yang 1989 is a parasitic wasp and natural enemy of several lepidopteran pests during their pupal stage. In this study, we sequenced and analyzed the mitochondrial genome of C. cunea, and obtained a complete DNA molecule that is 14,930 bp in size with 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), and 22 transfer RNA genes (tRNAs) (GenBank accession number MW192646). All the 13 PCGs started with typical ATN (ATA, ATG, and ATT) and terminated with the stop codon TAA or TAG. Phylogenetic analysis showed that C. cunea formed the sister group with Tamarixia radiata, which belongs to the same family.

Spraying insecticides by unmanned aerial vehicle (UAV) is an effective method to prevent and control Spodoptera frugiperda. This study investigated the influences of different UAV types, spray adjuvants, spray times, maize growth periods, and insecticides on S. frugiperda in three cities, Hainan Province, China. The results showed that at least two times are needed to spray insecticides using UAVs when controlling the S. frugiperda. Both UAVs had a substantially higher control effect and lower cost than artificial spray methods. Oil spray adjuvant Refei was more suitable for both UAVs than Tiancheng to control pests. Chlorantraniliprole had the best control effect of up to 90%. The control effects at the seedling stage and small bell stage of S. frugiperda were 94.3% and 91.3%, respectively. Spraying at 7:00 am and 7:00 pm by UAVof T20 had good control effect on S. frugiperda in three cities.

No abstract

No abstract

The complete mitochondrial genome of Microplitis pallidipes contains 15931 bp, with an A þ T content of 86.5% and consists of 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region (GenBank accession no. MN892396). All of the 22 tRNA genes displayed an usual cloverleaf structure. Gene rearrangement events occurred in this species, there are eight tRNA genes changed their positions or/and directions. 13 PCGs started with ATN. Ten PCGs used the typical stop codon 'TAA' and 'TAG', three PCGs terminated with incomplete stop codons (TA). Phylogenetic analyses within the microgastroid complex were performed based on mitochondrial protein-coding genes.