UV light attracts Diaphorina citri and its parasitoid

Diaphorina citri Kuwayama (Hemiptera: Psyllidae) transmits the bacteria associated with Huanglongbing, an incurable and lethal disease affecting citrus productivity and fruit quality worldwide. This vector is prominently phototactic and uses visual cues to find host plants. Yellow sticky traps are used for its monitoring, but their efficiency is limited, especially at low population densities. Diaphorina citri can be captured at night when light is provided and it is attracted to UV light. One way to increase the attraction of D. citri is therefore combining sticky traps with LEDs of specific colors at night, but more information about attractiveness of UV and colors combined with UV is needed. Moreover, information on the attraction of the main parasitoid of D. citri, Tamarixia radiata Waterson (Hymenoptera: Eulophidae) to UV and other light colors is lacking. We examined the attraction of males and females of D. citri to LED lights of different colors but comparable intensities separately or combined with ultraviolet (UV). The non-UV colors alone did not differ in attractiveness, whereas green, light blue and red light became more attractive when combined with UV. However, none of these color combinations were more attractive than UV alone. The parasitoid T. radiata was also attracted to UV LEDs. Female parasitoids were equally attracted to UV during day and night, but males were more attracted at night. These results suggest that the effectiveness of the commonly used yellow sticky traps can be increased by combining them with UV LEDs at night, and the parasitoid of D. citri may also be attracted. On the one hand, attraction of parasitoids to the traps may help monitoring their presence, but on the other hand, it may affect biological control by this natural enemy

A predatory mite as potential biological control agent of Diaphorina citri

Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a vector of the bacteria that cause Huanglongbing, the fatal disease threatening citriculture worldwide. One of the most important management methods is the control of D. citri with pesticides, but their intensive use causes development of resistance and pollution. An alternative method is therefore necessary to manage this vector-pathogen system. The generalist predatory mite Amblyseius herbicolus Chant (Acari: Phytoseiidae) can be found on citrus and orange jasmine plants, important hosts of D. citri in Brazil. Here we show that this phytoseiid can reproduce and develop on D. citri eggs. The predation rate was higher on D. citri eggs collected from plants in the field than on eggs from small plants from a laboratory rearing. Yet the predator preferred eggs from the laboratory. This may indicate that the higher predation rate of eggs from the field served to compensate for these eggs being of lower nutritional quality. This was confirmed with a series of experiments with limited numbers of eggs. We conclude that Amblyseius herbicolus is a potential biological control agent of D. citri, and its performance and control may be affected by the quality of the host plant

A predatory mite as potential biological control agent of Diaphorina citri

Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a vector of the bacteria that cause Huanglongbing, the fatal disease threatening citriculture worldwide. One of the most important management methods is the control of D. citri with pesticides, but their intensive use causes development of resistance and pollution. An alternative method is therefore necessary to manage this vector-pathogen system. The generalist predatory mite Amblyseius herbicolus Chant (Acari: Phytoseiidae) can be found on citrus and orange jasmine plants, important hosts of D. citri in Brazil. Here we show that this phytoseiid can reproduce and develop on D. citri eggs. The predation rate was higher on D. citri eggs collected from plants in the field than on eggs from small plants from a laboratory rearing. Yet the predator preferred eggs from the laboratory. This may indicate that the higher predation rate of eggs from the field served to compensate for these eggs being of lower nutritional quality. This was confirmed with a series of experiments with limited numbers of eggs. We conclude that Amblyseius herbicolus is a potential biological control agent of D. citri, and its performance and control may be affected by the quality of the host plant

Estimating intrinsic growth rates of arthropods from partial life tables using predatory mites as examples

The intrinsic rate of natural increase of a population (rm) has been in focus as a key parameter in entomology and acarology. It is considered especially important in studies of predators that are potential biological control agents of fast-growing pests such as mites, whiteflies and thrips. Life-table experiments under controlled laboratory conditions are standard procedures to estimate rm. However, such experiments are often time consuming and may critically depend on the precise assessment of the developmental time and the fecundity rate early in the reproductive phase. Using selected studies of predatory mites with suitable life-table data, we investigated whether and how measurements of growth rates can be simplified. We propose a new method for estimating rm from partial life tables, in which the researcher can choose a level of precision based on a stand-in measure of relative error. Based on this choice, the procedure helps the researcher to decide when a life-table experiment can be terminated. Depending on the chosen precision, significant amounts of experimental time can be saved without seriously compromising the reliability of the estimated growth parameter

Estimating intrinsic growth rates of arthropods from partial life tables using predatory mites as examples

The intrinsic rate of natural increase of a population (rm) has been in focus as a key parameter in entomology and acarology. It is considered especially important in studies of predators that are potential biological control agents of fast-growing pests such as mites, whiteflies and thrips. Life-table experiments under controlled laboratory conditions are standard procedures to estimate rm. However, such experiments are often time consuming and may critically depend on the precise assessment of the developmental time and the fecundity rate early in the reproductive phase. Using selected studies of predatory mites with suitable life-table data, we investigated whether and how measurements of growth rates can be simplified. We propose a new method for estimating rm from partial life tables, in which the researcher can choose a level of precision based on a stand-in measure of relative error. Based on this choice, the procedure helps the researcher to decide when a life-table experiment can be terminated. Depending on the chosen precision, significant amounts of experimental time can be saved without seriously compromising the reliability of the estimated growth parameter