RESUMEN

BACKGROUND: The invasion of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) into the New World has made it possible for this pest to hybridize with a native American species, H. zea (Boddie), under natural conditions. We investigated the viability and development of hybrids of these two Helicoverpa species. We reared the parental species and evaluated crosses between H. armigera males and H. zea females and vice versa, two intercrosses between hybrids, and eight backcrosses between hybrids and parental species. We estimated the length of immature stages, fecundity, survival, sex ratio, and heterosis. RESULTS: Although hybridization occcurred, with heterosis during the development of immatures, reproductive incompatibilities also were observed between the parental species and between hybrids from subsequent crosses. The interspecific crosses between hybrids and backcrosses confirmed the possibility of introgression events and their perpetuation in field populations. The results indicate that hybridization events are favored at high population levels, while at low population levels the 'species identities' will be maintained. CONCLUSIONS: The possibility of interspecific gene flow and its perpetuation through successive crosses and backcrosses suggests several recommenations for management. Populations of both species should be maintained at an equilibrium level to reduce the chance of interspecific crosses, which are presumably more likely to occur during pest outbreaks. The existence of hybridization and resistance to different active pesticide ingredients should be monitored. All practices related to managing the resistance of these pests to chemical and biological insecticides should be systematized to reduce the chance of selecting for resistant individuals.

Asunto(s)

Mariposas Nocturnas , Zea mays , Animales , Femenino , Humanos , Vigor Híbrido , Hibridación Genética , Masculino , Mariposas Nocturnas/genética , Control de Plagas

RESUMEN

Plant cell and tissue responses to the attack of mining herbivores may be diagnosed by anatomical and histochemical analyses, herein investigated regarding the mining activity of Phyllocnistis hemera larvae in the leaf lamina of Daphnopsis fasciculata. The larva enters the leaf lamina through the adaxial epidermis, and feeds on palisade parenchyma cells. A healing tissue is produced after the larva passes, and its cells are reactive to histochemical tests for lignins and pectins. At first, the leaf mine is composed of a channel that is limited by palisade parenchyma cell wall fragments. Later, it is filled with a regenerative tissue constituted by isodiametric cells recruited from the spongy parenchyma, which fills up the mine channel. The cells differentiated inside the mine, regenerated the damage caused to leaf tissues, and may isolate the mine from the entrance of pathogens. Daphnopsis fasciculata is capable of reconstructing mesophyll tissues, which involves the totipotency of parenchyma cells and enables an important strategy for plant recovering after the attack of mining parasites.

Asunto(s)

Lepidópteros , Thymelaeaceae , Animales , Hábitos , Herbivoria , Larva , Hojas de la Planta

RESUMEN

Larvae of most clearwing moths (Lepidoptera, Sesiidae) are endophagous borers of many angiosperms, including their fruits, stems, and roots. Their localized feeding may lead to swellings on those plant parts, but whether the structures produced should be considered true galls is still controversial. In this study we describe a peculiar sesiid moth, Neospheciacecidogena sp. nov. whose larvae induce unusual, external galls on Cayponiapilosa (Vell.) Cogn. (Cucurbitaceae) in the Atlantic Forest of southernmost Brazil. The adults, egg, larva, pupa and the gall are described and illustrated based on light and scanning electron microscopy. Galls are cylindrical and unilocular; they are induced individually on axillary buds of the C.pilosa stem. Unlike larvae of other sesiids, those of N.cecidogena sp. nov. lack abdominal pseudopodia, and show reduced stemata and chaetotaxy. Pupation occurs inside the gall, after having overwintered in the last larval instar. A maximum likelihood tree constructed based on mitochondrial DNA (COI) sequences showed that N.cecidogena sp. nov. is monophyletic and has an average distance of 13% to species of Melittia. The genera Neosphecia Le Cerf, 1916 stat. rev., Premelittia Le Cerf, 1916 stat rev., and Melittina Le Cerf, 1917 stat. rev. are restored from synonyms of Melittia Hübner, 1819 ["1816"].

RESUMEN

ABSTRACT During recent studies performed in the Atlantic Forest, a new species of Phyllocnistinae (Gracillariidae), Phyllocnistis hemera sp. nov., leaf miner of Daphnopsis fasciculata (Thymelaeaceae) was discovered. The adults are described and illustrated as well as the immature stages, with notes on natural history including a description of the leaf mine. Additionally, DNA barcode sequences were compared to other representatives of Phyllocnistinae to test for the specific status of P. hemera and to infer phylogenetic relationships. This is the fifth species described for the genus Phyllocnistis in the Atlantic Forest and the first record of a gracillarid mining Thymelaeaceae leaves.