The honeybee, Apis mellifera, is a widespread pollinator insect. Colony collapse disorder (CCD) has recently caused a significant decline in honeybee numbers worldwide. The beekeeping industry, agriculture, and world biodiversity are threatened by the honeybee population decline. We examined the mRNA levels of heat shock protein gene 60 (hsp60), acetylcholinesterase 1, and acetylcholinesterase 2, as biomolecular markers of the insect response to three separate forms of environmental stress, including high temperature, low temperature, and insecticide. The obtained results indicated increased levels of hsp60 and acetylcholinesterase 2 after the exposure of worker bees to temperatures of 17, 32, and 40°C for one hour, as well as exposure to a low dose of pesticide for 24 h ingestion of imidacloprid solution (2 ppm); meanwhile, acetylcholinesterase 1 showed remarkable expression decrease under heat and cold stresses but increased under pesticide treatment.  The responses of honeybees to hsp60, acetylcholinesterase 1, and acetylcholinesterase 2 are diverse and very specific to various stimuli. According to this research, the distinct expression profiles of hsp60 and acetylcholinesterase 2 can serve as useful instruments for tracking honeybees' vulnerability to varied environmental effects. Due to its insufficient responsiveness, acetylcholinesterase 1 expression is not permitted for use as a biomarker.

Guava die-back disease is a destructive disease. It causes serious yield losses and reduced guava fruits. Inspection of guava plant for die-back revealed that Beheira governorate had the highest frequencies of all isolated fungi from natural infected guava trees, followed by Alexandria, while Kafr El-Sheikh obtained the lowest frequency. Botryodiplodia theobromae gave the highest frequency of isolated fungi from natural infected guava trees during seasons 2015 and 2016, followed by Alternaria alternata, Alternaria sp., whereas Colletotrichum gloeosperiodes, Phomopsis sp., and Nigrospora sp. obtained minor frequency. The highest frequency of Botryodiplodia theobromae was observed at Beheira, followed by Alexandria governorate. Meanwhile, the lowest frequency was found at Kafr El-Sheikh. Pathogenicity test indicated that Botryodiplodia theobromae was the most pathogenic fungus. RAPD analysis of DNA by using three random primers exhibited five groups of DNA bands with first primer, six groups with second primer and five groups with the third primer and the overall similarities between isolates were arranged from 69 to 100% with P1, from 62 to 100% with P2 and from 33 to 100% with P3. The present study aimed to finding correlation between these isolates groups which resulted of RAPD, its pathogenesis and its geographical isolated locations. Ten isolates of B. theobromae represented ten locations of five governorates in Egypt were tested to evaluate the ability of pathogenesis in guava transplants cultivar Banaty at pots under experiments greenhouse conditions for artificial inoculation. The obtained results were exhibited that all tested isolates were clearly pathogenic to guava transplants and produced typical symptoms of guava die-back disease. Such isolates were differences of differed in their pathogenicity. The  ten isolates were coded according to their locations by three random primers (B.W.1, A.B.2, D.S.3, Q.K.4, A.A.5, B.N.6, K.Q.7, Q.S.8, D.B.9 and K.D.10). Isolate code No. Q.K.4 was the most virulent, followed by D.S.3 and Q.S.8, respectively which isolated of Qalyoubia and Damietta governorates. Meanwhile isolates K.D.10, A.A.5, K.Q.7 were moderately pathogenic, they were isolated from Kafr El-Sheikh and Alexandria, while A.B.2 and B.N.6 were the lowest pathogenic isolates isolated from Alexandria and Beheira governorates.

In this study, three isolates of Streptomyces isolated from Egyptian soil at Giza Governorate and belonging to red series were identified based on their cultural, morphological and physiological characters. According to the key proposed by Pridham and Tresner (1974), the experimental isolates ST55, ST71 and ST86 ap-peared to be related to S. lincolnensis, S. venezuelae and S. umbrinus, respectively. In addition, random amplified polymorphic DNA (RAPD)-polymerase chain reac-tion (PCR) was used to amplify the DNA genome of the three applied isolates and an identified strain to determine their fingerprints. This was carried out using 10-decamer oligonucleotides, i.e., OP-A02, OP-D01, OP-D02, OP-D05, OP-D06, OP-D07, OP-D08, OP-D11, OP-D18 and OP-D20. The PCR amplified products were detected by electrophoresing on 1.5% agarose gel and visualized by staining in eth-idium bromide and UV trasilluminator. Results showed that the same oligonucleo-tide flanking fragments differed from one isolate to another with different sizes. Monomorphic and polymorphic fragments were amplified confirming the molecular relationships as well as the genetic diversity between the four applied strains of Streptomyces. Based on the statistical analysis of RAPD-PCR polymorphisms a de-gree of similarities ranged from 33.9 to 59.2 % was found. Furthermore, frag-ment(s), whatever absent or present, were found to be unique molecular markers and could be used for characterization of some isolates. This result supported the idea for using the RAPD-PCR technique for classification of Streptomyces isolates.