Deterred oviposition response of Monochamus alternatus (Coleoptera: Cerambycidae) to oviposition scars occupied by eggs

1 The oviposition behaviour and response of Monochamus alternatus females to oviposition scars were investigated in the laboratory. 2 Prior to oviposition, females gnawed at the bark surface of Pinus densiflora bolts to make a wound. Then females turned their bodies 180° to position their ovipositors over the wounds and inserted them under the bark through the wounds. After an oviposition, a jelly was deposited while the ovipositor was still inserted. The females then withdrew their ovipositors and rubbed the oviposition scars with the tips of their abdomens. 3 When searching females encountered oviposition scars, they stopped walking and drummed the surface and inside of the oviposition scars with their maxillary and labial palpi. 4 Eighty-six percent of females left oviposition scars containing single eggs after the palpation. By contrast, when females encountered oviposition scars containing no eggs, 76% of them began to gnaw at the scars and 64% deposited single eggs. The response to artificial oviposition scars was similar to that to vacant oviposition scars made by the females. 5 The results of various observations and experiments showed that the females could recognize oviposition scars and discriminate the scars occupied by single eggs from vacant ones, and suggested that the palpation of oviposition scars was the critical discrimination behaviour, indicating mediation by chemical cues.     

Plant secondary substances and insects behaviour

Allelochemicals are storing in different location in plant tissues as inactive form. Number of identified compounds may now exceed 100,000. Environmental factors have an effect on allelochemicals concentration in plants. Many allelochemicals classified as toxins or deterrents for herbivorous insects. Allelochemicals play a major role in feeding or ovipositing stimulants for some specialist insects. Consumption and assimilation of herbivorous insects had affected by the type of allelochemicals in host plants. Allelochemicals have an acute or chronic toxicity on herbivorous insects. Most specialist herbivorous insects rely heavily of ingested plant allelochemicals. Plant allelochemicals may influence an insect's susceptibility to pathogens such as bacteria, fungi and nematode. Specialists herbivorous insect can be using the allelochemicals in their host plants as protection against natural enemies. Some herbivorous insects are synthesising the aggregation, attracting, alarm or mating pheromone from the allelochemicals in their host plants.     

Oviposition behavior and reproductive success of the cerambycid Acanthocinus aedilis in the presence and absence of the bark beetle Tomicus piniperda

The influence of Tomicus piniperda (L.)(Col.:Scolytidae) attacks on Acanthocinus aedilis (L.)(Col.:Cerambycidae) (1) oviposition behavior, (2) breeding material preference and (3) reproductive success was investigated in caged pine bolts with and without egg galleries of T. piniperda. In addition, A. aedilis oviposition behavior was studied in the field. In the presence of T. piniperda attacks most A. aedilis eggs were laid through the entrance holes of the bark beetle egg galleries. In the absence of bark beetle attacks most A. aedilis eggs were laid at places where the outer bark had been damaged and the phloem was exposed. In cages, A. aedilis preferred to oviposit in bolts with bark beetle attacks. Thus, A. aedilis oviposited in all 17 of bark beetle attacked bolts but in only four of nine bolts without T. piniperda attacks. Neither the number of A. aedilis offspring nor the body size of emerging adults differed significantly between bolts attacked by bark beetles and unattacked bolts. Nor was there any significant relationship between the density of bark beetle egg galleries and the production of A. aedilis offspring.     

Evaluation of neemAzadirachta indica seed extracts and oils as oviposition deterrents to noctuid moths

Applications of three concentrations of oil-free neem seed extracts (Azadirachta indica A. Juss; Meliaceae) to cabbage plants in cages did not deter oviposition by individuals of three species of noctuid moths,Trichoplusia ni, Peridroma saucia, andSpodoptera litura. The concentrations used corresponded to 10, 50, and 100 ppm of the main active ingredient, azadirachtin. The total number of eggs laid per female, female longevity, and median day of oviposition were not affected. Sprays of the neem oil-based insecticide Margosan-O ^R , and a 1% aqueous emulsion of a refined neem seed oil similarly had no effect on any of the parameters studied. However, a 1% crude oil emulsion significantly reduced the proportion of eggs laid byS. litura on treated plants. Our results suggest that literature reports of significant neem-based oviposition deterrence toS. litura are the result of compounds that are removed by higher levels of processing and thus not likely to be found in most commercial neem seed formulations. Sprays consisting of highly processed neem seed extracts, used at concentrations that provide larval control, are unlikely to be generally effective as oviposition deterrents to noctuid pests.     

Reproductive behaviour of the South American fruit fly Anastrepha fraterculus (Diptera: Tephritidae): laboratory and field studies

Abstract. The mate choice, courtship and oviposition behaviour of laboratory-reared and field-collected Anastrepha fraterculus (Wied.) were compared. In laboratory cultures in Southampton the duration of male calling activity in small leks increased gradually from 1-2h at 5 days old to up to 7 h at 10 days. This finding correlates with previous reports on the time at which male salivary glands, which are believed to produce sex pheromone, are fully developed. Wild flies which emerged from infested fruits in Brazil began to oviposit on the day they mated, whereas in laboratory flies oviposition began 1 day following the first mating. Both types of fly usually defended their position on a particular fruit throughout the day, and re-mated with either virgin or mated males. There was no significant difference in mating duration. Females did not copulate before the mean age (±SE) of 16.8±0.9 days. For both types of flies mating initiation occurred in the first 2h of photophase, with virgin females choosing mainly mated males. The average number of matings in the laboratory was three for females and four for males, and the interval between matings in females was significantly increased after the second mating. It is suggested that the tendency of virgin females to mate with mated males will lead to increased fitness, as males are on average 48 days old at their second mating. The potential life span of around 200 days for both sexes would allow adults to bridge the gap between seasonally available fruits in warm-temperate and sub-tropical South America.     

飞机草提取物对红脉穗螟的产卵忌避及杀卵活性

为探讨飞机草提取物对红脉穗螟Tirathaba rufivena Walker的防控潜力,采用室内生物测定法,研究了飞机草提取物对红脉穗螟的产卵忌避作用和杀卵活性。结果表明,飞机草乙酸乙酯提取物对红脉穗螟的忌避效果最好,选择性和非选择性忌避率分别为41.85%和46.84%;不同提取物处理红脉穗螟的卵后,均造成卵孵化率降低和初孵幼虫的死亡,其中乙酸乙酯提取物对红脉穗螟卵的影响最大,孵化率和1龄幼虫死亡率分别达到65.89%和40.37%。对飞机草乙酸乙酯提取物进行分级萃取测试各萃取物的活性发现,正己烷萃取物对红脉穗螟的产卵忌避作用和杀卵活性最强。田间试验表明,采用正己烷萃取物稀释50倍和100倍浓度进行田间喷雾,药后15 d对红脉穗螟的种群控制率可达到50%以上。     

Various effects of ethanolic extract of Mentha pulegium on the two-spotted spider mite,Tetranychus urticae (Tetranychidae)

Ethanolic extract of Mentha pulegium was evaluated against the adults of important arthropod pest species, the two-spotted spider mite, Tetranychus urticae. Potential acaricidal impact of plant was determined by contact application. Phytotoxicity was recorded after 24 h. The value of LC₅₀ was 59,149 mg L^?1. Also, LT₅₀ values were 27.42, 25.56 and 19.79 h for 35,000, 50,000 and 100,000 mg L^?1, respectively. Also, results showed that this ethanolic extract had impact on repellency of T. urticae. All of the tested concentrations were similar in the repellency test. On the other hand, the used concentrations (1000, 4000, 6000 and 8000 mg L^?1) affected on the oviposition of mite females. These extract doses significantly decreased the egg laying on the treated surface. The current study indicated that this ethanolic extract can be used as a safe acaricide on T. urticae.     

番茄抽提物对小菜蛾的忌避,拒食及抑制产卵作用

在自然变温条件下,研究了番茄抽提物对小菜蛾成虫的忌避、幼虫的拒食作用及成虫繁殖力的影响。试验表明：番茄抽提物对小菜蛾成虫具有很强的忌避作用;用番茄抽提物处理过的包菜叶饲喂小菜蛾幼虫,其拒食率达５３％;番茄提物对小菜蛾成虫产卵也有明显抑制作用,产卵量下降６０％;番茄与包菜间种能明显地抑制小菜蛾种群数量的增长。其种群可下降５０％以上。     

Oviposition by the African migratory locust, Locusta migratoria migratorioides, in a crop environment in South Africa

Oviposition by the African migratory locust, Locusta migratoria migratorioides (Orthoptera: Acrididae), was studied in maize and wheat crops on the Orange Free State Highveld. Maize was shown to be the most important oviposition habitat with peak laying taking place in autumn and early winter when highest pod densities were recorded. Laying was mainly concentrated along the middle of the crop interrows in maize and within clearings in the wheat crop. Despite the uniform layout of these crops, the distribution of egg pods was found to be aggregated. Non-reproductive behaviour, such as locust aggregation, basking and feeding, as well as environmental factors appeared to influence the distribution of egg pods in these crops. Secondary selection for optinum soil moisture and compaction on the laying site enhanced the aggregation of pods.     

Effects of egg load on finding and acceptance of host fruit in Ceratitis capitata flies

Abstract. In studies conducted on potted host trees in field cages and in the laboratory, we examined the influence of egg load on the finding and acceptance of high-ranking (kumquat) and lower-ranking (grapefruit) hosts for oviposition by wild-origin Mediterranean fruit fly females, Ceratitis capitata (Wiedemann). By prescribing the periods during which females had access to protein prior to testing, we generated four classes of females having progressively increasing egg loads but not differing in population origin, age, degree of protein hunger at testing, or amount of prior experience with host fruit (none). Egg load had no discernible effect on behaviour associated with finding either type of fruit but did have a significant effect on several behaviours associated with oviposition after alighting on fruit. Increasing egg load led to increasing propensity to engage in ovipositional-type behaviour on both kumquats and grapefruits. There was no evidence, however, to support a hypothesis that medflies would become less discriminating against grapefruits relative to kumquats as egg load increased. Relative to kumquats, grapefruits were accepted for oviposition by intermediate and high egg load females to a substantially greater degree in laboratory cages than on trees, suggesting that results of laboratory cage experiments on host discrimination by tephritid flies may poorly reflect differences in behavioural responses expressed under less constrained conditions.     

Effects of neem-based insecticides on beet armyworm （Lepidoptera： Noctuidae）

Abstract Three commercial neem [ Azadirachta indica A. Juss (Meliaceae)]-based insecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder, were evaluated for oviposition deterrence, antifeedant effect on larvae, and toxicity to eggs and larvae of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), on cotton leaves in the laboratory. Oviposition deterrence in no-choice, and two- and fivechoice assays, was observed for the neem-based insecticide treatments when compared with a non-treated control. Neem-based insecticides also deterred feeding by beet armyworm larvae. Direct contact with neem-based insecticides decreased the survival of beet armyworm eggs. Survival of beet armyworm larvae fed for 7 days on leaves treated with neembased insecticides was reduced to 27, 33, 60, and 61% for neem leaf powder, Ecozin, Agroneem, and Neemix, respectively. Possibilities for adoption of neem-based insecticides in commercial cotton for beet armyworm control are discussed.