## 1 Introduction  
For many years, chemical pesticides were the only option to employ in agriculture. However, as more and more of these substances are becoming obsolete or even withdrawn from the market due to the risks linked to them, finding eco-friendly and healthier alternatives has become a vital need. Such alternative tools are biopesticides that are derived from naturally occurring matter and are defined by their biodegradability and their low impact on other organisms and the environment. They can include fungi, bacteria, viruses, nematodes, protozoa, or metabolites of the forementioed, which are known for their insecticidal effect. Among various groups of insect pathogens that have been used for pest control, entomogenic viruses are distinct as they are known for their safety and target specificity. Apart from this, they are very widespread, well s  
.tudied, and can be easily replicated, characteristics that reinforce their selection for further research and commercial development [1]. The pathogenicity caused by these microorganisms is not the same in all insects and even differs between the insect's developmental stages. Despite the fact that entomopathogenicic viruses infect a plethora of species,they exhibit very high selectivity, as many of them infect only one host. Although they do not cause acute and immediate mortality, dramatic reductions in their host populations have often been observed because of their actions [1]. A special group of entomogenic viruses, Nucleopolyhedrovirus (NPVs), belonging to the family Baculoviridae, have been suggested as potential bioinsecticides, and already some of them have successfully been implemented as pest agents [2; 3]. This family consists of 600 viruses, including two genera, NPV and Granuloviruses (GVs) [4]. NPVs have been found to be effective against many lepidopterous insects, while different factors may influence outcomes, such as dose, temperature, nutrition, physical character, and the larval stage [5; 6; 7]. However, there are certain disadvantages, such as their narrow host range that limits their success against the diverse insect species in the field, and the slow speed of action that allows the pests to infest crops and forests for considerable periods of time [3; 4; 8; 9]. The pine processionary moth _T. pitycampa_ is a significant pest of pines in Mediterranean countries, Central Europe, the Middle East, and North Africa [10; 11]. It is distributed virtually everywhere in Greece, with the exception of certain regions in Central Greece and the Aegean Sea islands because of unfavorable climate conditions and isolation [12]. It is regarded as one of the most dangerous forest pests in Greece because it can cause severe defoliation [13]. The adult moth lays eggs on pine trees and some other conifer tree species. The hatched larvae that feed on pine needles form visible white winter nests, which provide unambiguous evidence of their presence [14]. Such infections can defoliate young trees severely; older ones may become weakened and more susceptible to other pathogenic organisms, or to environmental stress induced by drought or excessive moisture [15]. Although old trees rarely die, notable increment losses in diameter and volume can be seen [16]. Aside from damaging forest trees, larvae can also cause dermatitis and ocular lesions in humans and animals, as well as respiratory symptoms and anaphylactic reactions in rare cases [17]. The cotton bollworm _H. armigera_ is one of the most dangerous agricultural pests [18; 19]. Currently, it is estimated that this species is responsible for about 3 billion USD in annual global losses [20]. In addition to being a cosmopolitan species, it is also a polyphagous moth as its diet consists of a variety of crops, such as cotton, tomato, sorghum, and chickpea, among others [21]. Eggs are deposited on fruits and flowers and hatched larvae feed on plant tissue, causing significant damage [22; 23].