Interference competition occurs when access to an available resource is negatively affected by interactions with other individuals, where mutual interference involves individuals of the same species. The interactive phenomena among individuals may be size‐dependent, since body size is a major factor that may alter prey consumption rates and ultimately the dynamics and structure of food webs. A study was initiated in order to evaluate the effect of mutual interference in the prey‐specific attack rates and handling times of same size class predators, incorporating variation in consumer size. For this purpose, laboratory functional response experiments were conducted using same age predators, that is, newly hatched (first instar) or mature (fifth instar) nymphs of the polyphagous mirid predator Macrolophus pygmaeus preying on Ephestia kuehniella (Lepidoptera: Pyralidae) eggs. The experiments involved four predator density treatments, that is, one, two, three, or four predators of same age, that is, either first‐ or fifth‐instar nymphs, which were exposed to several prey densities. The Crowley–Martin model, which allows for interference competition between foraging predators, was used to fit the data. The results showed that mutual interference between predator's nymphs may occur that affect their foraging efficiency. The values of the attack rate coefficient were dependent on the predator density and for the first‐instar nymphs were significantly lower at the highest predator density than the lower predator densities, whereas for the fifth‐instar nymphs in all density treatments were significantly lower to that of the individual foragers' ones. These results indicate that mutual interference is more intense for larger predators and is more obvious at low prey densities where the competition level is higher. The wider use of predator‐dependent functional response models will help toward a mechanistic understanding of intraspecific interactions and its consequences on the stability and structure of food webs.
Origanum majorana is a medicinal and aromatic plant that belongs to the Lamiaceae family. It is cultivated in several parts of the world and, due to its splendid aroma and taste, is widely used for culinary purposes and in perfumes. The essential oil of the plant, to which is attributed its aroma, contains many secondary metabolites with valuable biological activity. One of them is the pesticide activity, which has attracted much interest. Given the necessity of replacing synthetic pesticides, essential oils are studied in an attempt to find naturally derived products. Thus, the aim of this review paper is to discuss the chemical profile of O. majorana essential oil and to present data regarding its insecticidal, repellent and fumigant activity. Data were collected from 1992 to 2022. Databases, including PubMed, Google Scholar, ScienceDirect and Scopus, were used for the research, and keywords, including O. majorana, sweet marjoram, essential oil, volatiles, pesticide, insecticide and repellent activity, were used. The results of this review paper indicate that O. majorana essential oil can be an alternative agent to manage pests. However, still, much research should be conducted to evaluate its toxicity against beneficial insects and to ensure its safety for human health.
Nymphal development, mortality and adult longevity of the plant bug Closterotomus trivialis were studied on two of its major crops (Olea europaea L. cv. 'Koroneiki' and Citrus sinensis L. cv. 'Washington Navel') and four non-crop host plants (Mercurialis annua L., Urtica urens L., Parietaria diffusa M. et K. and Sinapis alba L.) under laboratory conditions (15, 20, 24 and 27 °C ± 0.5%; 60 ± 5% RH; 16L:8D h photoperiod). Results demonstrated that C. trivialis can successfully complete its development on all tested host plants and temperatures, except for U. urens at 15 and 20 οC. Mortality rates were generally higher on U. urens, P. diffusa and olive than on S. alba, M. annua and sweet orange. Both temperature and host plant significantly affected the nymphal development of C. trivialis. Specifically, host plant affected the development of nymphs at lower and higher temperatures (15, 20, 27 °C) but not at the optimum (24 °C) for its development temperature. Adults of C. trivialis lived longer on sweet orange, M. annua and S. alba in most tested temperatures compared to U. urens, P. diffusa and olives. Overall, these results suggest a better suitability of M. annua, S. alba and sweet orange compared to U. urens, P. diffusa and olive which were proven to be less suitable host plants, covering partially the nutritional needs of C. trivialis. The estimated lower temperature developmental threshold based on the linear model for C. trivialis was found to be lowest on M. annua (3.30 °C) and highest on P. diffusa (10.7 °C). Τhe assessment of the nymphal development in various host plants and temperatures is particularly important for understanding the biology of C. trivialis and provides useful information to optimize its management strategy under integrated pest management system.
Macrohomotoma gladiata (Kuwayama) (Hemiptera: Homotomidae) has been recently recorded in the Medi- terranean Basin causing serious damage on the widely cultivated ornamental tree Ficus microcarpa L.f. The population structure and seasonal fluctuation of M. gladiata were studied on F. microcarpa in Athens, Greece, from February 2019 to February 2020. In the samples, the presence of its natural enemies was recorded too. Eggs were recorded in May, August and from October to early January; the first two nymphal instars were recorded throughout the year but not in August and September whereas their densities reduced in early May; the middle-aged and the late instars nymphs were recorded in March and April and then appeared again in June and July. Based on our results 1) during winter, only young nymphs of M. gladiata were present; 2) under autumn and winter conditions, young nymphs do not develop further; and 3) most likely M. gladiata has a bivoltine life cycle or may complete a partial third generation in autumn. Parasitized M. gladiata nymphs by a Psyllaephagus Ashmead species were recorded from April to August, with the parasitism rate reaching to 81%. The predator Anthocoris nemoralis (Fabricius) (Hemiptera: Anthocoridae) was present in low numbers in spring. This work revealed useful information for the phenology and rational management of this pest and the potential of its natural enemies in its control. Key Words: Macrohomotoma gladiata, Ficus microcarpa, life cycle, biological control, Anthocoris nemoralis, Psyllaephagus
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