2 research outputs found
Does the scion or rootstock of Citrus sp. affect the feeding and biology of Diaphorina citri Kuwayama (Hemiptera: Liviidae)?
The Asian citrus psyllid (ACP) Diaphorina citri
is the main vector of the bacteria associated with Huanglongbing,
and can exploit more than 50 species of the
family Rutaceae as hosts. The number of possible hosts is
even higher if plant varieties are included. This study
evaluated the influence of different combinations of scion
and rootstock citrus varieties on the development and
feeding of ACP. Survival rates for the egg stage were
highest on the Valencia and Sicilian varieties, both grafted
on Sunki mandarin, with means of 87.99 and 87.98%,
respectively; and lowest (67.63%) on Hamlin 9 Rangpur
lime. The lowest levels of both nymphal and total viability
(egg-adult) were obtained on Hamlin, regardless of the
rootstock used. The total development time (egg-adult)
ranged from 17.92 to 19.33 days for the Peˆra 9 Sunki and
Hamlin 9 Swingle combinations, respectively. Cluster
analysis separated the hosts into two groups, the first
consisting of the combinations of the Hamlin variety, and
the second group formed by the other varieties. The highest
food value (assessed by the area of honeydew produced)
was observed for the orange scion varieties, and among
these, the highest value was observed on Valencia
(0.902 cm2); the smallest honeydew area was obtained on
Ponkan (0.269 cm2). The rootstocks did not affect the
feeding behavior of D. citri. The results of this study could
aid in the development of management techniques, mainly
in providing information for the installation of new citrus
groves and assistance in crop-improvement research
Acute Toxicity of Fresh and Aged Residues of Pesticides to the Parasitoid Tamarixia radiata and to the HLB-Bacteria Vector Diaphorina citri
One method for controlling the Asian citrus psyllid (ACP) Diaphorina citri Kuwayama, the vector of the putative causal agent of Huanglongbing, uses the parasitoid Tamarixia radiata (Waterston). However, the general intensive use of insecticides has reduced the numbers of this parasitoid. This study evaluated the effect of the residual action of 24 insecticides on T. radiata and also determined the differential toxicity of insecticides to D. citri and T. radiata, using three bioassays. In the first, when adults of the parasitoid were exposed to residues of the 24 insecticides, ten were considered short-life (class 1), six slightly persistent (class 2), five moderately persistent (class 3), and three insecticides were considered persistent (class 4), under the IOBC/WPRS classification system. The second bioassay evaluated the sublethal concentrations of the persistent insecticides (formetanate, dimethoate, spinosad). Increasing the concentrations of the insecticides increased the number that were classified as persistent. In the third bioassay, evaluation of the differential toxicity of eight insecticides to the ACP and the parasitoid showed that chlorpyrifos and bifenthrin were more harmful to T. radiata. Therefore, these two insecticides are not recommended for application at the time of parasitoid release. Cypermethrin, imidacloprid, and dimethoate caused higher mortality of D. citri and are most often recommended in IPM programs. The choice of an insecticide for the control of citrus pests must be made with care, aiming to preserve the natural enemies in the ecosystem, and thereby contribute to the success of biological control