The cytochrome P450 gene Cyp6a2 from Drosophila melanogaster is located on the right arm of chromosome 2 at position 43A1-2 and comprises two exons separated by a 69-bp intron. Phenobarbital treatment of flies leads to a rapid increase in the level of CYP6A2 mRNA and to an increased production of the CYP6A2 protein. DNA from the Cyp6a2 promoter region was functional when linked to a luciferase reporter gene and transfected into D. melanogaster Schneider cells. Moreover, a dose-dependent induction of luciferase activity by phenobarbital indicated that elements necessary for phenobarbital induction are located within 428 bp of the translation start site. Heterologous expression of the CYP6A2 protein in lepidopteran cells infected with a Cyp6a2-recombinant baculovirus was observed by Western blotting of cell lysates and by spectral characterization of the reduced-CO complex of the P450. The CYP6A2 protein produced in this system metabolized aldrin and heptachlor to their epoxides and metabolized the insecticide diazinon by desulfuration to diazoxon and by oxidative ester cleavage to 2-isopropyl-4-methyl-6-hydroxypyrimidine. Metabolism in lysates of cells infected with recombinant baculovirus was greatly enhanced by the addition of purified housefly NADPH cytochrome P450 reductase and cytochrome b5. These results show that CYP6A2 catalyzes the metabolism of organophosphorus insecticides and they implicate Cyp6a2 overexpression in metabolic resistance. The Cyp6a2 gene appears to be a suitable model for a genetic analysis of the phenobarbital induction process.

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In order to examine the conservation of the mechanism of cyclodiene insecticide resistance between species we cloned a cDNA from the yellow fever mosquito Aedes aegypti homologous to the resistance gene Rdl m Drosophda. In D melanogaster. resistance to cyclodienes and picrotoxinin is caused by a single amino acid substitution (alanme to serine) in the putative channel lining of a y-aminobutyic acid gated chlortde ion channel. We report that the mosquito gene not only shows high homology to that of Drosophila but also that resistant strains display substitution of the same amino acid. The sigmficance of thts result in relation to the evolution of pesticide resistance, the use of Drosophila as a model insect for resistance studies and the potential use of this gene as a selectable marker in the genetic transformatton of non-Drosophilids is discussed

Two well-described elements of the immune response of insects include encapsulation of metazoan parasites (blood-cell-mediated) and the production of antibacterial peptides (humoral and/or cellular). However, the possible functional interrelationship between cellular encapsulation and antibacterial responses, and the extent to which the two components may be co-regulated, are poorly understood. We used a novel approach involving strains of Drosophila resistant (R) or susceptible (S) to the wasp parasitoid Leptopilina boulardi to study the expression of three genes involved in the antibacterial response: Dorsal-related immunity factor (Dif), Cecropin (CecA1) and Diptericin (Dip). Both S and R strains produced high levels of all antibacterial transcripts upon bacterial injection. However, when parasitized the R strain showed no induction whilst the S strain did. This lack of antibacterial transcript induction in the parasitized R strain not only clarifies the separation of these two types of immune response but also raises the fascinating possibility of a link in their genetic regulation.

Plants expressing Cry proteins from the bacterium, Bacillus thuringiensis (Bt), have become a major tactic for controlling insect pests in maize and cotton globally. However, there are few Bt vegetable crops. Eggplant (Solanum melongena) is a popular vegetable grown throughout Asia that is heavily treated with insecticides to control the eggplant fruit and shoot borer, Leucinodes orbonalis (EFSB). Herein we provide the first publicly available data on field performance in Asia of eggplant engineered to produce the Cry1Ac protein. Replicated field trials with five Bt eggplant open-pollinated (OP) lines from transformation event EE-1 and their non-Bt comparators were conducted over three cropping seasons in the Philippines from 2010–2012. Field trials documented levels of Cry1Ac protein expressed in plants and evaluated their efficacy against the primary target pest, EFSB. Cry1Ac concentrations ranged from 0.75–24.7 ppm dry weight with the highest in the terminal leaves (or shoots) and the lowest in the roots. Cry1Ac levels significantly increased from the vegetative to the reproductive stage. Bt eggplant lines demonstrated excellent control of EFSB. Pairwise analysis of means detected highly significant differences between Bt eggplant lines and their non-Bt comparators for all field efficacy parameters tested. Bt eggplant lines demonstrated high levels of control of EFSB shoot damage (98.6–100%) and fruit damage (98.1–99.7%) and reduced EFSB larval infestation (95.8–99.3%) under the most severe pest pressure during trial 2. Moths that emerged from larvae collected from Bt plants in the field and reared in their Bt eggplant hosts did not produce viable eggs or offspring. These results demonstrate that Bt eggplant lines containing Cry1Ac event EE-1 provide outstanding control of EFSB and can dramatically reduce the need for conventional insecticides.