Oviposition Site Preference and Its Effects on Subsequent Development of Variegated Grasshopper (Zonocerus variegatus L.) under Laboratory Conditions

Female grasshoppers can affect the fitness of their offspring through their selection of oviposition site. Knowledge of soil type on oviposition, and its effects on subsequent development can provide guidelines for habitat manipulations that reduce the harmful effects of these pests on farmers fields. The influence of soil types on the oviposition site preference of variegated grasshopper (Zonocerus variegatus L.) reared some cassava (Manihot esculenta Crantz) varieties, was investigated in a cage trial carried out at the Bio factory laboratory, School of Agriculture and Food Sciences, Njala University, Sierra Leone during 2022/2023. The treatments comprised three soil types (Sandy, Loamy and Clay), each with three replications laid out in a randomized complete block design (RCBD) in wooden cages. Data were collected on the following development parameters including, Net reproductive growth ratio (R0), Generation time (Tc), Intrinsic rate of increase (rm), Finite rate of increase (), Doubling time (Dt), and overall survivorship. Findings revealed that, Z. variegatus L. preferred sandy soil in which, on average, most eggs were deposited (338, 6.62 4.40), followed by loamy soil, 286 (5.53 3.96), and then, clayey soil, 200 (3.91 3.85);though, the differences were not significant. This study established that Z. variegatus deposited more eggs in sandy soil > loamy soil > clayey soil, respectively;and subsequent survivorship of the immature unto mature adult insect, revealed a similar order. This indicates that the sandy soil is the most preferred substrate for oviposition and subsequent development into adult insects.

Oviposition Site Selection of the Plateau Frog (Nanorana pleskei) in the Zoige Wetland, China

For oviparous species, oviposition site selection influences adult reproductive success as well as the fitness of the resulting offspring. Females usually choose potential egg-laying sites depending on abundance and quality to maximize their reproductive success. We focused on the oviposition site selection of this plateau frog in Zoige wetland and investigated how the egg-laying pattern of the females influences their offspring＇s survival. We found that shallow waters, decentralized spawning patterns, and egg attachment to appropriate distance to the water surface were the main spawning strategies of Nanorana pleskei endemic to Qinghai-Tibet Plateau. We argued that drought caused by increasing temperature and variable precipitation has probably influenced N. pleskei reproductive success, which may be a crucial reason for its population decline. Our findings have important significance for habitat preservation, increasing embryo survival and establishing practical conservation policies.

Oviposition Site Selection of Anoplophora glabripennis in Sugar Maple (Acer saccharum) and Its Gnawing Nidus Oviposition Habits

[Objective] The paper was to explore the oviposition site selection of Anoplophora glabripennis in sugar maple and its gnawing nidus oviposition habits. [Method] Through field and indoor rearing observation, the oviposition site selection of A. glabripennis in sugar maple was studied, and the gnawing nidus oviposition habits were analyzed. [Result] The height of oviposition site of A. glabripennis in sugar maple, the number observation holes （gnawing nidus oviposition points） and bark thickness in oviposition site showed linear correlation with diameter of branch at breast height. The gnawing nidus oviposition habit of A. glabripennis in sugar maple was mainly divided into 4 stages： gnawing nidus site selection, gnawing nidus, oviposition and nidus sealing, the duration from gnawing nidus to nidus sealing was（38.29±16.47）min. [Conclusion] The study provided reference for comprehensive prevention of A. glabripennis in greening tree species sugar maple, as well as further study on reproductive behavior and regulation mechanism of A. glabripennis.

Effects of mummy consumption on fitness and oviposition site selection on Harmonia axyridis

Intraguild predation(IGP)has been commonly reported between predators and parasitoids used as biological control agents as predators consuming parasitoids within their hosts.However,the effect of parasitoid-mummy consumption on the fitness of the predator and subsequent oviposition site selection have not been well studied.In our study,we conducted two laboratory experiments to examine the influence of Aphidius gifuen-sis Ashmead(Hymenoptera:Braconidae)mummies as prey on fitness and subsequently oviposition site selection of Harmonia axyridis(Pallas)(Coleoptera:Coccnellidae).Re-sults indicate that when H.aryridis was reared on A.gifiuensis mummies only,its larval development was prolonged,and body weight of the 4th instar larvae and newly emerged adults,and fecundity decreased.Moreover,H.axyridis did not exhibit oviposition pref-erence on plants infested with unparasitized aphids or aphids parasitized for shorter than 9 days.However,compared with plants with mummies(parasitized≥9 days),H.axryridis laid more eggs on plants with unparasitized aphids.In contrast,H.axryridis previously fed with A.gifuensis mummies did not show a significant oviposition preference between plants with unparasitized aphids and those with mummies(parasitized≥9 days).Overall,our results suggest that mummy consumption reduced the fitness of H.axyridis.Although H.axyridis avoided laying eggs on plants with A.gifuensis mummies,prior feeding ex-perience on A.gifuensis mummies could alter the oviposition site preference.Thus,in biological control practice,prior feeding experience of H.axyridis should be carflly considered for reduction of IGP and increase of fitness of H.axyridis on A.gifuensis.

Breeding ecology and oviposition site selection of blackspotted pond frogs (Rana nigromaculata) in Ningbo, China

The black-spotted pond frog(Rana nigromaculata)is one of the most widely distributed species in China.However,there have been only a few qualitative descriptions of their breeding ecology and oviposition site selection.From 2004 to 2006,we investigated the breeding ecology and oviposition site selection of R.nigromaculata in Ningbo,China,quantitatively.Analyses of breeding ecology show that:(1)mean frog density in the breeding season was 0.0903±0.0029 individuals per meter(n=11)(mean±SE);(2)R.nigromaculata was a sexually dimorphic species,with females significantly larger than males in both body weight and snout-vent length;(3)the clutch size averaged 4643.04±235.96 eggs(range 1546–7897,n550);and(4)the egg size ranged from 1.50 to 1.74 mm in diameter,with an average egg size of 1.6050±0.0046 mm(n=226).Oviposition sites differed significantly from random sites in percentages of water,bare ground and vegetation cover,water depth(cm),water temperature(uC)and water turbidity.Rana nigromaculata preferred microhabitats with higher percentages of water and vegetation cover,while it avoided microhabitats with deeper water.The results suggest that microhabitats with higher percentages of water and vegetation cover,but not deeper water,should be priorities for protection and conservation of the breeding habitats of R.nigromaculata.

Fatty acids derived from oviposition systems guide female black soldier flies(Hermetia illucens)toward egg deposition sites

The black soldier fly,Hermetia illucens,comes with big promises for industrial purposes since its larvae feed polyphagously on a broad spectrum of organic substrates.However,research focusing on adult flies is scarce,which is inconsistent with their reproductive relevance within the rearing cycle.In particular,directed oviposition is a challenge in artificial systems.Currently,decomposing organic matter is commonly used as oviposition substrate,which has extensive potential for improvement in view of the lack of standardization and the risk of microbial contamination.Here,we identified three fatty acids and one fatty acid methyl ester derived from the surface of old oviposition sites and targeted to elucidate their effect on preference behavior and oviposition site selection using Y-olfactometry and prepared oviposition sites,respectively.Exposure to tetradecanoic acid attracted gravid females and stimulated oviposition most strongly,while decanoic acid demonstrated a repulsive effect.Females kept in mixed-sex populations were attracted by tetradecanoic acid,resulting in a higher egg mass found in the compound box(3.0–11.4 fold),a≥2.3 fold reduction of nonspecifically deposited eggs,and the highest total egg mass.Conversely,decanoic and dodecanoic acid caused females to lay a greater proportion of eggs nonspecifically outside both boxes.Our data suggest that fatty acids,especially tetradecanoic acid,are important cues for oviposition site selection in black soldier flies.In order to achieve a directed oviposition behavior,the role of further short-and long-chain fatty acids as attractants should be examined.

The Breeding Ecology of a Critically Endangered Salamander,Hynobius amjiensis(Caudata：Hynobiidae),Endemic to Eastern China

Hynobius amjiensis is a critically endangered salamander species（IUCN Red List） endemic to eastern China. It currently has three known populations： one in Longwangshan, Zhejiang Province（type locality）, and two in Qingliangfeng between Anhui and Zhejiang Provinces. We examined the relatively unstudied breeding ecology of this species in the field and at laboratory from March 2007 to May 2014. Adult males and females were year-round terrestrial, except for the February–April breeding season. During this period, we captured only a total of 16 breeding adults（11 males and 5 females）. As few as 100 breeding females were estimated based on the number of egg sacs observed since 2007. This number was significantly reduced from the estimated number between 1992 and 1998. Males（mean total length = 16.21 cm, mean body mass = 18.8 g） were slightly smaller than females（16.51 cm, 19.2 g）. Size of breeding pools ranged from 0.2 m-2 to 1.2 m-2（0.1–1.2 m depths）. Each female deposits a pair of egg sacs by attaching the adhesive tips of the sacs to aquatic plants or dead twigs. Fifteen pairs of egg sacs had an average length of 28.6 cm and a diameter of 3.3 cm. On average, each egg sac contained 75 eggs with a diameter of 0.3 cm. Our field survey revealed that H. amjiensis used oviposition sites in small, cool, and weakly acidic pools at high elevations（1 300–1 600 m） where peat moss was abundant. Reduction in wetland size and disappearance of suitable breeding pools suggest that this salamander species is under threat of extinction, particularly at Longwangshan, where 5 of the 9 breeding pools have either dried up or disappeared. Combined size of the remaining 4 pools is less than 2 m-2. We urge immediate implementation of more effective conservation measures and suggest that preservation priority should be given to habitat that contains suitable breeding pools.

Group-spawning and Simultanous Polyandry of a Stream-dwelling Frog Feirana kangxianensis

Here we provide an example of simultaneous polyandry based on genetic evidence in Feirana kangxianensis. This stream-dwelling species occurs only in Kangxian County, southern Gansu Province, where it is sympatric with its sibling species E quadranus. During the breeding season the sex ratio of E kangxianensis was marginally female- biased （44~：59~） and the encounter rate in a relatively pristine habitat was significantly higher than that in heavily quarried habitats （9.6 ± 4.8 indiv./km vs. 3.2 ± 2.5 indiv./km）. Three egg masses containing an average of 698 eggs were deposited on the underside of one or two adjacent flat rocks, 6.0-10.0 cm under the water surface and 1.0-3.5 cm above the streambed. Using Bayesian sibship clustering of nine polymorphic microsatellite genotypes, two females were detected as group-spawning in one oviposition site, with three males fertilizing each female＇s eggs simultaneously. We also discuss the conservation requirements of this range-restricted species and the evolutionary implication of its unusual reproductive strategy.