Impact of the Phoretic Phase on Reproduction and Damage Caused by Varroa destructor (Anderson and Trueman) to Its Host, the European Honey Bee (Apis mellifera L.)

Abstract

Varroa destructor is a parasitic mite of the honeybee that causes thousands of colony losses worldwide. The parasite cycle is composed of a phoretic and a reproductive phase. During the former, mites stay on adult bees, mostly on nurses, to feed on hemolymph. During the latter, the parasites enter brood cells and reproduce. We investigated if the type of bees on which Varroa stays during the phoretic phase and if the duration of this stay influenced the reproductive success of the parasite and the damage caused to bees. For that purpose, we used an in vitro rearing method developed in our laboratory to assess egg laying rate and the presence and number of fully molted daughters. The expression level of two Varroa vitellogenin genes (VdVg1 and VdVg2), known to vary throughout reproduction, was also quantified. Results showed that the status of the bees or time spent during the phoretic phase impacts neither reproduction parameters nor the Varroa vitellogenin genes levels of expression. However, we correlated these parameters to the gene expression and demonstrated that daughters expressed the vitellogenin genes at lower levels than their mother. Regarding the damage to bees, the data indicated that a longer stay on adult bees during the phoretic phase resulted in more frequent physical deformity in newborn bees. We showed that those mites carry more viral loads of the Deformed Wing Virus and hence trigger more frequently overt infections. This study provides new perspectives towards a better understanding of the Varroa-honeybee interactions.

Using an in vitro system for maintaining Varroa destructor mites on Apis mellifera pupae as hosts: studies of mite longevity and feeding behavior

“…Brood host cells are represented as clear Veg K-Caps size 00 capsule (Capsuline, Pompano Beach, FL, USA) gelatin capsules, which are inserted into a 32/8-Place Combo Tube Rack (USA Scientific, Orlando, FL, USA) designed to hold 30 gel capsules with the bottom half way inward and lid outward. Unlike other similar studies (Nazzi and Milani 1996;Trouiller and Milani 1999;Piou et al 2016), the capsules were without perforations. Together, capsules and rack represent a 'frame' of brood comb.…”

Varroa destructor rearing in laboratory conditions: importance of foundress survival in doubly infested cells and reproduction of laboratory-born females

“…The protocols actually range from the simple transfer of frames under controlled conditions (Donzé and Guerin 1994) to completely artificial feeding chambers (Tabart et al 2013), including the use of gelatine capsules to simulate brood cells (Nazzi and Milani 1994). This system developed by Nazzi and Milani (1994) and used in recent studies (Piou et al 2016;Annoscia et al 2017;Mondet et al 2018) is particularly promising. Indeed, this protocol can benefit from the control over many parameters and from the possibility to follow the parasite cycle in a daily manner without significantly impacting the physiology of mites (Piou et al 2016;Mondet et al 2018).…”

Extracción de apitoxina con un colector eléctrico en Irapuato, Guanajuato, México

“…A partir de enero de 2017, las colonias de las colmenas 1 y 2 se debilitaron, lo que provocó la disminución en la producción de veneno de ambas colmenas a partir de esa fecha. Desde hace varios años se han mencionado los efectos de V. destructor como plaga de las abejas, entre los que se pueden mencionar muerte de larvas y ninfas, deformaciones de alas, patas, abdomen y tórax en adultos, disminución de la potencia sexual de los zánganos, reducción en el tiempo de vida y el tamaño de las obreras, mayor vulnerabilidad a enfermedades, y como consecuencia, las abejas al sentirse débiles, trabajan menos y mal, o son expulsadas de la colmena, lo que provoca un impacto negativo en la colonia (Botta et al, 2004;Zemene et al, 2015;Piou et al, 2016).…”