Energetic costs of resistance in the Agonoscena pistaciae Burckhardt & Lauterer, 1989 (Hemiptera: Aphalaridae), against spirotetramat, acetamiprid and hexaflumuron

The common pistachio psylla, Agonoscena pistaciae Burckhardt & Lauterer, 1989 (Hemiptera: Aphalaridae), is a key pest found in pistachio orchards in Iran. This pest has a high potential for developing resistance to insecticides due to its short life cycle and high reproductive potential. Intensive application of insecticides leads to excessive selection pressure followed by resistance to synthetic insecticides in some psylla populations. In this research, effects of four concentrations of three extensively used insecticides (spirotetramat, acetamiprid, and hexaflumuron) on energy resources (like sugar, lipid, glycogen, and protein contents), energy consumption, and cellular energy allocation were investigated in resistant and susceptible populations of the common pistachio psylla in the Kerman province of Iran. Energy resource contents in the susceptible population (133 331.2 mj/insect) were significantly more than in the resistant population (96 253.5 mj/insect), whereas energy consumption in the resistant population (38 630.4 mj energy/h/insect) was higher than in the susceptible population (31 276.8 mj energy/h/insect). Additionally, cellular energy allocation in the resistant population (2 400.9 mj energy/h/insect) was higher than in the susceptible population (2 126.13 mj energy/h/insect). Therefore, stress (especially toxicants) causes variations in metabolism, which influences the growth and reproduction of the pest.

Siirt İlinde Antepfıstığı Psillidi [Agonoscena pistaciae Burck. and Laut.) (Hemiptera: Aphalaridae)]'nın Yayılışı ve Populasyon Dinamiğinin Belirlenmesi

Bu çalışma 2015-2017 yıllarında Siirt İlinde Antepfıstığında zararlı Antepfıstığı psillidi [Agonoscena pistaciae Burck. and Laut.) (Hemiptera: Aphalaridae)]’nın yayılışı ve populasyon seyrini belirlemek amacıyla yürütülmüştür. Yayılış alanını belirlemek için Siirt İlinin Merkez, Aydınlar, Eruh, Kurtalan, Pervari, ve Şirvan ilçelerinde 24 köyde toplam 66 fıstık bahçesinde gözlem ve inceleme yapılmıştır. Zararlının popülasyon seyrini belirlemek için ise 2016-2017 yıllarında Siirt Merkez ilçede 4 bahçede çalışmalar yürütülmüştür. Yayılış alanını belirlemek için darbe yöntemi ve göz ile inceleme yöntemi, mimf ve yumurta yoğunluğunu belirlemek için ise göz ile inceleme yöntemi kullanılmıştır. Örneklemeler 1-2 haftalık aralıklarla yapılmıştır. Çalışma sonucunda A pistaciae tüm ilçelerde yayılış gösterdiği ve kontrol edilen tüm bahçelerin bulaşık olduğu belirlenmiştir. Kışlanmış erginler nisan ayının ortasında, ilk yumurtalar nisan ayının son haftasında ve birinci dönem nimflere ise nisan sonu mayıs başında belirlenmiştir. Kış geçirecek ergin formları eylül ayı ortasından itibaren görülmüştür. A pistaciae’nın ergin, nimf ve yumurta yoğunluğunun mayıs sonu ve haziran başında biraz arttığı, ancak ağustos sonlarından kasım ortalarına kadar ergin, nimf ve yumurta yoğunluğunun yüksek olduğu tespit edilmiştir. Birçok bahçede ekonomik zarar eşiğini aştığı görülmüştür. Mayıs sonu- haziran başı ve temmuz sonu-ağustos ortasından sonra yapılacak kontrollerde eğer bileşik yaprak başına 20-30 nimf tespit edilirse bir yada iki kimyasal uygulama yeterli olacaktır.

Lethal and sublethal effects of spirotetramat and abamectin on predatory beetles (Menochilus sexmaculatus) via prey (Agonoscena pistaciae) exposure, important for integrated pest management in pistachio orchards

Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae) is an important biological control agent in pistachio orchards, especially against Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psyllidae), which is the most damaging pest of pistachio. In this project we exposed M. sexmaculatus adults to two important commonly-used insecticides through feeding on treated prey (A. pistaciae) to evaluate the side-effects on this predator. We tested spirotetramat, which belongs to the keto-enol group inhibiting lipid biosynthesis in insects, at 2/1, 1/1 and 1/2 of the maximum field recommended concentration (MFRC), and abamectin, which is a mixture of avermectins and a natural fermentation product of the bacterium Streptomyces avermitilis, at 1/1, 1/2, 1/4, 1/8 and 1/16 of its MFRC. Spirotetramat did not affect adult survival of M. sexmaculatus at all three concentrations when ingested via treated prey, while in marked contrast abamectin caused 100% adult mortality of M. sexmaculatus when ingested via treated prey at 1/1, 1/2, 1/4 and 1/8 of the MFRC. At sublethal levels, spirotetramat reduced total and daily fecundity of M. sexmaculatus at all three concentrations tested, but did not affect egg hatching at 1/1 and 1/2 of the MFRC. Moreover, prey consumption was decreased when beetles were exposed to the prey treated with spirotetramat at 1/1 and 2/1 of the MFRC concentrations. With abamectin, even at 1/16 of the MFRC, total fecundity, daily fecundity and prey consumption of M. sexmaculatus adults were significantly affected. In conclusion, no acute toxicity was observed on M. sexmaculatus by ingestion of prey treated with spirotetramat, although reproduction parameters and prey consumption were affected at MFRC and lower concentrations. In marked contrast, abamectin was notably very harmful at its MFRC and also at lower concentrations. This research highlighted the importance of toxicity risk assessments, including lethal and sublethal effects, to obtain a more accurate estimation of the compatibility of insecticides in current integrated pest management (IPM) programs.

Molecular and morphometric identification of pistachio psyllids with niche modeling of Agonoscena pistaciae (Hemiptera: Aphalaridae)

Species of Agonoscena (Hemiptera: Aphalaridae) are key pests of pistachio in all of the most important pistachio producing countries in the Old World. The efficiency and accuracy of DNA barcoding for the identification of Agonoscena species were tested using mitochondrial cytochrome c oxidase subunit 1 (mtCO1) and cytochrome b (cytb) gene sequences. Moreover, morphometric sexual dimorphism was studied. Finally, the potential geographical distribution of Agonoscena pistaciae, the most important pistachio pest, was calculated using the MaxEnt model. Similar relationships of clustering were found in the morphometric analysis and the molecular analyses with mtCO1 and cytb genes, with A. bimaculata and A. pistaciae being closely related, and A. pegani constituting their sister group. Although the results showed that the cytb gene is a better marker for barcoding in this group, the mtCO1 gene clearly separates the three psyllid species making mtCO1 suitable for diagnostic purposes. A geometric morphometric analysis showed that the distance between landmark number 7 (bifurcation of vein M) to the fore margin of the forewing, and the distance between landmarks number 6 (apex of vein Cu1b) and 11 (wing base), are the most important geometric characters for diagnosing the studied species. Moreover, the forewing shape of males vs females is similar in A. pistaciae and A. bimaculata but differs significantly in A. pegani. In the ecological niche modeling of the distribution of A. pistaciae, the most important contribution was made by the variable ‘minimum temperature of coldest period’. The most suitable areas for A. pistaciae are restricted to Eastern, Southern and some parts of Central Iran.