Abundance,interannual variation and potential pest predator role of two co‐occurring earwig species in citrus canopies

Earwigs are usually considered pest predators in orchards. Because of its worldwide distribution, most research on earwigs focuses on the European earwig Forficula auricularia Linnaeus (Insecta: Dermaptera: Forficulidae). However, very little is known of this species in Mediterranean citrus orchards. Earwigs and aphids were collected monthly during 5 years (2006–2010) from citrus canopies. Two species of earwigs were found: F. auricularia and Forficula pubescens Gené (=Guanchia pubescens), with the latter seldom cited in the literature. The goals of this study were (i) to document the abundance of these two earwig species in Mediterranean citrus canopies; (ii) to determine whether they are positively or negatively associated with each other, or randomly distributed; (iii) to measure the interannual variation of the abundance of both species during a 5‐year period and (iv) to evaluate the potential role of earwigs as pest predators in citrus canopies. As compared to colder regions, F. auricularia active period in citrus canopies in our study site lasted longer. Both species co‐occurred randomly in canopies. In 2006, both species showed approximately the same abundance, but in 2010, F. pubescens abundance in canopies was 28 times greater than that of F. auricularia. The potential role of earwigs as pest predators is higher in the Mediterranean than in other colder regions, because of the longer active period. F. auricularia is a sedentary generalist predator, already present in citrus canopies at the onset of most pest outbreaks, while F. pubescens arrived later to the canopies, but most likely was abundant enough to contribute in the control of citrus pests.     

陕西蟹蛛科蜘蛛三新种记述──(蜘蛛目)

本文记述陕西秦岭山区蟹蛛科Ｔｈｏｎｄｓｉｄａｅ蜘蛛三新种：高寒花蟹蛛,新种Ｘｙｓｔｉｃｕｓａｌｓｕｓｓｐ．ｎｏｖ,太白峭腹蛛,新种Ｔｍａｒｕｓｔａｉｂａｉｅｎｓｉｓｓｐ．ｎｏｖ．,秦岭峭腹蛛,新种Ｔｍａｒｕｓｑｉｎｌｉｎｇｅｎｓｉｓｓｐ．ｎｏｖ．．     

中国蟹蛛科（蜘蛛目）新种记述

记述我国蟹蛛科花蟹蛛属６新种和蟹蛛属２新种,共计８新种,金林花蟹蛛Ｘｙｓｔｉｃｕｓｊｉｎｌｉｎ,玛纳斯花蟹蛛Ｘ．ｍａｎａｓ,林芝花蟹蛛Ｘ．ｎｙｉｎｇｃｈｉｅｎｓｉｓ,拟斑花蟹蛛Ｘ．ｐａｒａｐｕｎｃｔａｔｕｓ,似旋花蟹蛛Ｘ．ｔｏｒｓｉｖｏｉｄｅｓ,吴氏花蟹蛛Ｘ．ｗｕａｅ,广西蟹蛛Ｔｈｏｍｉｓｕｓｇｕａｎｇｘｉｃｕｓ和胡氏蟹蛛Ｔ．ｈｕｉ。     

欧洲蛷螋雌性对其若虫摄食帮助的研究(英文)

欧洲蛷螋的雌性通过护卵活动可以有效地抑制卵表面霉菌的生长,以保证胚胎的正常发育。但是抚幼行为,特别是接触活动的生物学功能至今尚不明确。本实验表明：幼虫可通过雌虫间接地获取营养物质,从而明显地提高其发育速率和存活率;而单纯的抚幼活动对幼虫的生长和存活并无影响。     

Natural and human causes of earwig mortality during winter: temperature,parasitoids and soil tillage

Beneficial arthropods are often used for suppressing specific pest outbreaks in agricultural crop systems. The European earwig, Forficula auricularia L., (Dermaptera: Forficulidae), is an important natural enemy in fruit orchards. Recently, ecological studies were published describing earwig dispersal and survival during summer, hereby revealing clear differences between populations with a single brood (SBP) and two broods a year (DBP). In this article, we will describe three potential mortality factors of earwigs during the underground winter period, namely cold temperatures, parasitoids and soil tillage. This knowledge is essential for making efficient management strategies for increasing earwig abundance in fruit orchards. The effect of cold temperatures was checked during a 3‐year semi‐field experiment. Parasitism rates of Triarthria spp. (Fallén) and Ocytata pallipes (Fallén) (Diptera: Tachinidae) were obtained in a rearing experiment. The negative effect of soil tillage on the survival of earwigs nests was checked in a field experiment covering a 4‐year time period. A strong, negative relation between temperature [cooling day degrees (CDD)] and survival of female and male earwigs during winter was found. Male earwigs of SBP died very quickly, mimicking natural conditions. Between 60% and 90% of females do not survive winter. Survival of females in DBP was higher than in SBP. Parasitism rates vary a lot between species, generation, year and location (0–20%). During winter, we found a maximum mortality of 13%. There is a clear trend that soil tillage can reduce the number of nymphs in spring and summer by 50%. Implications for biocontrol are the following: (i) mortality owing to temperature can be predicted using CDD and if necessary preventive management actions can be undertaken to control pests; (ii) parasitism rates are negligible compared to high impact of temperature; and (iii) soil tillage can be timed more accurately using a recently developed day degree model.     

Natural history of the non-solitary sheetweaving spider Anelosimus jucundus (Araneae: Theridiidae)

Field observations were made on one Panamanian population of Anelosimus jucundus. Almost all webs were found in a relatively exposed area, on small shrubs and composites. This is in contrast to A. eximius , a colonial congeneric which in our study site built its large webs along moist, fern-covered banks. Web structure varied with different plant substrates; for example, only some of the webs incorporated a clearly defined lower sheet. Webs were built by penultimate instar females, and perhaps by adult females and males. In some cases, several adult females inhabited a web, but they remained under separate leaf canopies; during census observations co-operative efforts were not noted. Prey consisted mainly of winged insects. Juvenile sex ratio was about equal. The degree of sociality demonstrated by A. jucundus is discussed.     

Techniques for rearing tachinid parasitoids of the European Earwig Forficula auricularia

Two European species of the family Tachinidae (Diptera), Triarthria setipennis and Ocytata pallipes, whose larvae live as endoparasitoids of the European earwig (Forficula auricularia), were studied to develop experimental methods to improve laboratory production of the parasitoids. More than 84% parasitism was achieved by inoculating with larvae of T. setipennis when earwigs were immobilized. Lower rates of parasitism were obtained when earwigs were mobile and could fend off attacking parasitoid larvae before they could penetrate the host. For O. pallipes, where the microtype eggs have to be eaten by the host, incubation of starved earwigs with food items carrying 3–5 parasitoid eggs resulted in 60% parasitism.     

Presence of an adipokinetic peptide in the corpus cardiacum of Dermaptera but not in the neurohaemal aorta, and chemical and functional identification of the peptide

Corpora cardiaca of the earwigs Labidura riparia and Forficula auricularia contain a substance that causes hyperlipaemia in migratory locusts and hypertrehalosaemia in the American cockroaches. A conspecific bioassay in L. riparia revealed that this factor is lipid-mobilizing. Isolation of the neuropeptide was achieved by single-step RP-HPLC. The primary structure of the earwig adipokinetic peptide was elucidated by automated Edman degradation in combination with matrix-assisted laser desorption/ionization mass spectrometry. It is a blocked octapeptide, pGlu-Val-Asn-Phe-Ser-Thr-Gly-Trp-NH₂, previously denoted as Grb-AKH and first identified in Gryllus bimaculatus ( Gäde & Rinehart 1987 ). The synthetic peptide co-chromatographed under various conditions with the native peptide and, in biological assays, resulted in lipid-mobilization in L. riparia when injected in low concentration.     

中国蟹蛛科蜘蛛4新种记述（蜘蛛目）

记述蟹蛛科蜘蛛4新种:勐腊峭腹蛛Tmarus menglae sp.nov.、滇微蟹蛛Lysilelesdiamicus sp.nov.、昆明微蟹蛛Lysileles kunming ensis sp.nov.和湖北花蛛Misumenops hubeiensis sp.nov.     

Crab spider hunting performance is temperature insensitive

1. Laboratory and field experiments showed that the hunting performance of two flower-dwelling crab spiders, Misumenops asperatus and Misumenoides formosipes, was thermally insensitive over a broad range of temperatures normally experienced by these spiders. 2. In the laboratory, HP, a behavioural metric of spider hunting performance, was similar for spiders of a given species over an ≈ 30 °C temperature range. 3. Spiders in the field captured predominantly hymenopterans and dipterans, and field hunting performance, measured as the number of prey captured per spider per day, also proved to be unaffected by temperature. 4. These findings counter the general rule that physiological/ecological performance in terrestrial arthropods is temperature dependent. 5. Freedom from temperature constraints on the capacity of crab spiders to capture prey may be due to the use of venom and/or to muscle physiological adaptations for anaerobic metabolism. 6. Wide thermal performance breadth increases the spectrum of prey available to M. asperatus and M. formosipes by allowing spiders to hunt prey active during cooler periods of the day as well as those active during warmer periods. 7. Wide thermal performance breadth also benefits M. asperatus and M. formosipes due to adult phenology; both species experience a seasonal temperature shift during the adult phase.