RT info:eu-repo/semantics/doctoralThesis
T1 Daños causados por Leptoglossus occidentalis Heidemann en Pinus pinea L., prospección de parasitoides de huevos y evaluación de Ooencyrtus obscurus (Mercet) como agente de control biológico
A1 Ponce Herrero, Laura
A2 Universidad de Valladolid. Escuela de Doctorado
K1 Plagas
K1 Western Conifer Seed Bug (WCSB
K1 Chinche de las piñas
K1 Stone pine
K1 Pino piñonero
K1 Dry cone syndrome
K1 Síndrome de la piña seca
K1 Natural enemy
K1 Enemigo natural
K1 31 Ciencias Agrarias
AB Leptoglossus occidentalis Heidemann, is a pest native to North America where it is associated with cone damage in seed orchards. In this area, Hadronotus pennsylvanicus Ashmead is the main natural enemy of L. occidentalis. The introduction of this pest in the Mediterranean area coincides with a reduction in the yield of pine nut crops in the Mediterranean region, a forest product of high economic value, known as "dry cone syndrome". The objectives of this study are to correlate the damage caused by L. occidentalis on Pinus pinea L. with this syndrome, to identify native parasitoids of L. occidentalis eggs, and estimate their synchrony with L. occidentalis, and to evaluate the suitability of the parasitoid with the greatest impact on the pest population as a biological control agent. Seasonal damage to cones and kernels was defined by three insect bagging trials at different times of cone development, while population damage was estimated by protecting and exposing cones throughout their development in a clonal bank. Four surveys of native egg parasitoids were conducted, three in the clone bank and one in a P. pinea reforested pine forest. Four parasitism indices were used to estimate the impact of the native egg parasitoids on the L. occidentalis population, and their synchronization was defined by two years of visual monitoring of the pest in the clone bank. The suitability of O. obscurus as a biological control agent was evaluated under standard laboratory conditions (21 ± 2°C; RH 40% ± 10%) and white light (16:8; L:D) by comparing its biological and demographic parameters with those of H. pennsylvanicus. The results suggest that L. occidentalis is one cause of the "dry cone syndrome", although the influence of other factors cannot be excluded. The severity of the damage varies with the development of the cones and kernels on which this species feeds, decreasing as development progresses. Mortality of first (10.0% - 100.0%) and third (0.0% - 90.0%) year cones decreased with bract hardening, while mortality of second year cones fluctuated and remained high throughout their development (10.0% - 100.0%). In third year cones, cone yield (2.1% - 3.6%) increases progressively with cone maturity from June, while the severity of kernel damage decreases in the following order: aborted kernels, type IIf, type IIu, type It and type Ip. Two native parasitoids were identified, Ooencyrtus pityocampae (Mercet) and Ooencyrtus obscurus (Mercet), which do not overlap with L. occidentalis until July. Ooencyrtus obscurus involves a new parasitoid-host relationship and has a greater impact on the pest population (9.9% - 26.7%) than O. pityocampae (1.3% - 15.8%). The demographic parameters of O. obscurus indicate that its population dynamics tend to increase, with a net reproductive rate (R0) of 3.55 female/female/generation in a generation time (T) of 23.93 days and a population doubling time of 14.34 days. Ooencyrtus obscurus is a synovigenic species. The mean oviposition time is 2.3 days, and the mean fecundity is 7.7 parasitoids/female. This species is gregarious with an emergence rate of 1.7 parasitoids/egg. Its sex ratio (% females) is 41.2%, although it can reproduce asexually by pseudo-arrhenotokous parthenogenesis. Field and laboratory results suggest that O. obscurus is less suitable as a biological control agent for L. occidentalis than its main natural enemy in North America. However, its advantages as a native species should not be underestimated.
YR 2024
FD 2024
LK https://uvadoc.uva.es/handle/10324/66296
UL https://uvadoc.uva.es/handle/10324/66296
LA spa
NO Escuela de Doctorado
DS UVaDOC
RD 13-may-2024