Aspectos biológicos del anillador de la guayaba Carmenta theobromae (Lepidoptera: Sesiidae) en Santander, Colombia

El anillador de la guayaba es un lepidóptero recientemente identificado como Carmenta theobromae que ha causado pérdidas significativas en cultivos de guayaba de la Provincia de Vélez, Santander. El objetivo de esta investigación consistió en estudiar los estados de huevo y larva del anillador en campo y laboratorio durante el primer semestre de 2014. En campo, los sitios de oviposición se describieron en árboles barrenados y, en laboratorio, se examinaron las posturas en cortezas del tallo de guayaba. Se evaluó la supervivencia y duración del estado larval de inmaduros recolectados en campo en cuatro dietas semi-artificiales: aserrín de guayabo, dos dietas formuladas para Spodoptera frugiperda y otra para Synanthedon pictipes. Se describieron las características morfométricas del huevo y la larva con especímenes recolectados en cultivos de guayaba. Los sitios de oviposición se encontraron en la corteza principalmente del tallo donde las posturas fueron simples, espaciadas y de forma oblonga o elipsoidal. No se encontraron diferencias estadísticas en los tratamientos supervivencia y duración del estado larval. La duración promedio de la fase larval fue de 13,92 ± 1,36 días para individuos con longitud mayor a 10,63 ± 0,31 mm. El huevo midió 0,22 ± 0,012 mm de ancho y 0,37 ± 0,011 mm de longitud. Se identificaron cuatro estadios larvales a través del coeficiente de Dyar y distribución de frecuencias de medidas del ancho cefálico. La larva madura tiene ganchos (“crochets”) distribuidos uniordinalmente y un par de bandas en el pronoto como C. theobromae, barrenador de cacao en Venezuela.

Reduced Incidence of Lesser Peachtree Borer and Leucostoma Canker in Peach-Almond Hybrids

Damage by lesser Peachtree borer (LPB) (Synanthedon pictipes Grote & Robinson) and Leucostoma canker that had accumulated during 6 (Orchard A) and 8 (Orchard B) years were compared in peach (Prunus persica L.) and peach-almond [P. amygdalus (Mill.) D. A. Webb] hybrids. Afterward, the main trunk and scaffold limbs of the trees received 10 wounds 26 mm in diameter and a subset of these trees in Orchard A had wounds inoculated with Leucostoma persoonii Hohn. Before wounding, Leucostoma canker infection and LPB infestations that had accumulated for 6 to 8 years on peach-almond hybrids was ≈60% and 98% less than on peach in Orchard A and B, respectively. One month after wounding the trees, no significant differences in Leucostoma canker infection and LPB infestations were found among the peach-almond hybrids, treated or not treated with L. persoonii, or untreated peach. Yet, Leucostoma- treated and untreated peach-almond hybrids had 33% and 25% less Leucostoma canker and LPB, respectively, when compared with Leucostoma- treated peach. Ten months after wounding, peach-almond hybrids treated with L. persoonii still had significantly less Leucostoma canker (60%) and LPB (25%) when compared with Leucostoma- treated peach. Wound gumming and wound closure rates seemed to influence the degree of LPB infestation and Leucostoma canker. Based on these data, peach-almond hybrids could be valuable sources of resistance to LPB and Leucostoma canker.

Effects of Abamectin on Peachtree Borers in the Laboratory and in Peach Orchards (Lepidoptera: Sesiidae)2

Abamectin was effective in reducing egg hatch, larval survival, adult mating behavior and oviposition of the lesser peachtree borer, Synanthedon pictipes (Grote and Robinson) LPTB, and egg hatch and larval survival of the peachtree borer, Synanthedon exitisoa (Say) PTB, in the laboratory at rates of 10 and 20 ppm. Subsequently, tests in peach orchards with comparable rates of abamectin were effective in reducing PTB populations in Peach and Taylor counties, Georgia. Although abamectin was less effective than chlorpyrifos (standard recommendation) for PTB control, it warrants consideration as an alternative for control because it is a natural product derivative and probably poses little threat to the environment.