Activity of Selected Formulated Biorational and Synthetic Insecticides Against Larvae of Helicoverpa armigera (Lepidoptera: Noctuidae).

This work studied 17 insecticides belonging to nucleopolyhedrovirus (NPV), Bacillus thuringiensis (Bt kurstaki and Bt aizawai), benzoylureas (insect growth regulators [IGRs]), carbamates, organophosphates, spinosyns, and diamides against larvae of Helicoverpa armigera (Hübner), invasive species in the South American continent. Larvae of different instars were fed for 7 d with untreated or insecticide-treated diets. Mortality was recorded daily for 7 d, and surviving larvae were individually weighed on the seventh day. The NPV and Bt insecticides caused 100% mortality of first-instar larvae and first-instar and second-instar larvae, respectively. However, both NPV and Bt-based products caused low mortality of third-instar larvae and did not kill older larvae. The IGR lufenuron was highly effective against all three ages of larvae tested, whereas teflubenzuron and triflumuron produced maximum 60% mortality of second-instar larvae and lower than 50% to older larvae. Thiodicarb, chlorantraniliprole, indoxacarb, chlorpyrifos, and chlorfenapyr, irrespective of tested age, caused 100% mortality of larvae, with the last two insecticides reaching 100% mortality within 2 d of feeding on the treated diet. Flubendiamide caused lower mortality but significantly affected the weight of surviving larvae, whereas neither spinosad nor methomyl produced significant mortality or affected the weight of larvae. Based on the results, the age of H. armigera larvae plays an important role in the recommendation of NPV and Bt insecticides. Furthermore, there are potential options between biological and synthetic insecticides tested against H. armigera, and recording larval size during monitoring, in addition to the infestation level, should be considered when recommending biological-based insecticides to control this pest.

Description of the immatures of Scaptocoris carvalhoi Becker (Hemiptera: Cydnidae).

Nymphs and adults of the burrower bug Scaptocoris carvalhoi Becker feed on vegetal sap of their host plants through the roots, and little is known on the morphology and biology of its immature stage. Therefore, we aimed to characterize the immatures of S. carvalhoi by describing the egg and the morphology of each instar. Eggs of S. carvalhoi have a smooth chorion surface without visible micropylar processes. The presence of five instars was confirmed by the coefficient of determination (R (2) > 0.95) and by the growth constant (K between 1.2 and 1.6). Nymphs have an elliptical body and fossorial scythe-like forelegs. The tarsi are absent as in adults, and the prototarsal insertion region becomes visible only in the fourth instar. Nymphs from first to fourth instar of S. carvalhoi showed the presence of 1 + 1 trichobothria in urosternites III to VII, close to the anterior margin and inside the spiracles; besides these trichobothria, fifth instars presented 1 + 1 pre-trichobothria in urosternites III to V located posteriorly, almost in the row of spiracles close to the posterior margin of the urosternites. This is the first detailed morphological record of immatures belonging to Scaptocoris.