Effects of plant feeding on the development,survival and reproduction of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae)

Diets consisting of leaves of cotton and/or water were insufficient to promote the complete development and survival of Podisus nigrispinus (Dallas) to the adult stage. However, nymphs fed leaves lived longer than those provided with only water. Addition of Alabama argillacea (Huebner) larvae to the diet of P. nigrispinus added a substantial increment to the survival during the nymphal stage. The addition of cotton leaves to the diet of P. nigrispinus nymphs promoted an increase in the weight of newly eclosed adults, independent of predator sex. In addition, diets supplemented with cotton leaves promoted an increase in the duration of the oviposition period, the number of egg clutches per female, and the number of eggs per female. No effects were noted on either the duration of the pre-oviposition period, the number of eggs of the first clutch, the number of eggs per clutch, the interval between egg clutches, or sex ratio. Feeding on plant material by P. nigrispinus is a potentially positive attribute in biological control against cotton leafworm.     

Biology and predation rate of the sarcophagid fly,Agria mamillata a predator of European small ermine moths

Abstract

The biology of the univoltine, predatory sarcophagid fly Agria mamillata (Pandellé) was studied in a population of Yponomeuta evonymellus(L.) (Yponomeutidae) attacking Prunuspadus L. in the Valais, Switzerland. Clarification of the literature records suggests that A. mamillata is oligophagus, attacking five Yponomeuta species in the Palaearctic. The adult flies emerged in May. The presence of host odour was advantageous to elicit mating. After a preoviposition period of 19 days, the ovolarviparous females deposited eggs/first instar larvae on the cuticle of late fifth instar prey larvae, or on cocoons of prey pupae. The potential fecundity averaged 40 eggs per female. Reid data indicated that females of the predator laid more eggs in tents with higher prey density. Larval development lasted 11 days. Rain stimulates mature predator larvae to leave the tents of Y. evonymellus to pupate in the soil. Pupation was observed between early July and mid August. Predation rates ( = number of prey eaten per predator) were estimated from laboratory food consumption tests and from the number of predator larvae and predated cocoons in prey tents in the field. It was shown that a single predator consumed an average of five Y. evonymellus individuals. Field data indicated that predation rates cannot increase with higher numbers of prey available. It was shown that the number of prey eaten per predator decrease with higher predator densities per tent in the field.     

Rhyzobius lophanthae prey consumption and fecundity

The daily and total prey consumption and the fecundity of the predatorRhyzobius lophanthae Blaisdell (Coleoptera: Coccinellidae) fed on the scaleAspidiotus nerii Bouché (Homoptera: Diaspididae) were studied under controlled laboratory conditions. The prey consumption ofR. lophanthae was studied on larvae and on virgin adults, and the fecundity on mated females. For the development of the 1 st instar larvae ofR. lophanthae at 25° C, 1.2 adult femaleA. nerii were consumed; for the development of the 2nd, 3rd and 4th instar larvae, prey consumption was 2.7, 7.5 and 24.6 adult females, respectively. The duration of the larval development of the 1st, 2nd, 3rd and 4th instars was 3, 2.2, 2.7 and 6.2 days, respectively,R. lophanthae male and female adults consumed in their lifetime 390.6 and 672.3 adult femaleA. nerii, respectively. Thus, the male’s daily prey consumption came to 7 and the female’s to 12 adult femaleA. nerii. The average fecundity ofR. lophanthae was calculated to be 633.7 eggs per female and the daily fecundity to be 18–25 eggs. The average longevity was 63.4 days for mated adult females and 119.4 days for unmated.     

Reproductive strategy ofPodisus nigrispinus females under different feeding intervals

An attempt was made to quantify the influence of prey scarcity on longevity and on the reproductive variables of females of the predatorPodisus nigrispinus (Dallas) (Heteroptera: Pentatomidae). The predators received prey (Alabama argillacea) of different sizes,viz., 50 mg (small prey) or 220 mg (large prey), for a period of 24 h, daily or every 2, 4, 8 or 16 days. In an additional trial, the predators were provided only with water or kept without food, in which latter condition they lived a significantly shorter time. Individuals that received large prey in excess (every day) and at 16-day intervals lived significantly less, while the longevity of those that fed on small prey did not differ significantly between feeding intervals. Predators that fed less frequently laid fewer eggs, with increased intervals between clutches. The results were more marked in females fed on small prey; however, evidence of trade-off between reproduction and survival was detected only in predators that received large prey. The results suggest a type of trade-off, where longevity is maintained at the expense of reproduction. This strategy can contribute to the establishment and survival ofP. nigrispinus in an environment of fluctuating food supply. http://www.phytoparasitica.org posting Dec. 11, 2007.     

Effects of photoperiod on the development and growth of <Emphasis Type="Italic">Podisus nigrispinus</Emphasis>, a predator of cotton leafworm

The effects of photoperiod on nymphal development, growth and adult size in Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) were studied. Predators were collected in cotton fields in Patos (7°S, 37°W), Paraíba State, Brazil. A randomized block experimental design was used, with treatments consisting of photoperiods of 10L:14D, 11L:13D, 12L:12D, 13L:11D, 14L:10D, 15L:9D and 16L:8D (LD, in h), at a constant temperature of 28 ± 1°C and relative air humidity of 70 ± 10%. Treatments were distributed in four replications, with each experimental unit composed of 40 nymphs. The development period for each instar of P. nigrispinus varied according to the photoperiod exposure. Regardless of the photophase (PhP), the 5th instar nymphs exhibited the longest development period, except for the 15-h PhP, in which the development period of 2nd instar nymphs (4.13 days) was as long as that of the 5th instar nymphs (4.23 days). In the 1st, 3rd and 5th instars of P. nigrispinus, the development period was inversely proportional to the increase in light period in which the nymphs developed, for the PhP intervals of 10–14 h, 12–14 h, and 12–15 h, respectively. Predators exposed to a 14-h PhP developed a wider pronotum than those exposed to extreme PhP’s (of 10 h, 11 h and 16 h). Conditions from 14 h to 15 h of light resulted in higher daily growth rates in P. nigrispinus than those obtained with the other PhP’s tested. P. nigrispinus females exhibited faster daily growth rates than did males.     

Antibiosis of Eucalyptus plants on Podisus nigrispinus

The predator Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) has been used as a natural enemy to control herbivorous insects in eucalyptus plantations. However, because of the short co-evolutionary history of the predator with this imported plant species, the defensive compounds of eucalyptus may have a negative effect on the predator. Therefore, the survival and development of P. nigrispinus were studied on eucalyptus (Eucalyptus urophylla; exotic host plant) and guava (Psidium guajava; native host plant). P. nigrispinus performance was indeed superior on guava plants than on eucalyptus. The number of fertile eggs and nymphal survival were 52.6% and 12.0% on guava compared with 20.0% and 1.3% on eucalyptus, respectively. Longevity of P. nigrispinus was 115 days on guava and 98 days on eucalyptus. This shows that the predator is not yet fully adapted to the exotic host plant. One possible reason is that the plant toxic compounds in eucalyptus act on this predator by antibiosis.     

Prey consumption by the mealybug predator <Emphasis Type="Italic">Spalgis epius</Emphasis> on pink hibiscus mealybug (<Emphasis Type="Italic">Maconellicoccus hirsutus</Emphasis>)

The pink hibiscus mealybug Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) is a major pest of economically important crops. The apefly Spalgis epius (Westwood) (Lepidoptera: Lycaenidae) is a potential predator of various species of mealybugs. Studies of its preying potential and preference for prey stages on M. hirsutus are incomplete. An investigation was undertaken to determine the daily prey consumption and preference for prey stages by different larval instars of S. epius reared on M. hirsutus in the laboratory. During the 8-day larval development period with four larval instars of S. epius, the daily prey consumption increased from the first to the seventh day and decreased on the eighth day prior to the prepupal stage. Generally, there was a significant difference in the prey consumption on different days. The 1st to 4th instar larvae of S. epius consumed, respectively, a mean of 181.3, 679.1, 1770.4 and 4333.0 eggs or 19.1, 67.7, 153.0 and 639.0 nymphs or 2.72, 6.26, 13.8 and 32.1 adults of M. hirsutus. When an S. epius larva was fed on M. hirsutus eggs, nymphs and adults separately, it consumed a mean of 6952.6 eggs, 878.8 nymphs or 53.9 adults during its entire development. A single larva of S. epius consumed 2358.3 eggs, 151.2 nymphs and 34.3 adults of M. hirsutus during its entire development when the prey stages were offered all together. The study revealed that S. epius is a voracious predator of M. hirsutus and thus could be utilized as a potential biological control agent.     

Functional response of the coccinellid predator <Emphasis Type="Italic">Adalia fasciatopunctata revelierei</Emphasis> to walnut aphid (<Emphasis Type="Italic">Callaphis juglandis</Emphasis>)

The functional response types and parameters of 3rd and 4th instar larvae, and adult females and males of a coccinellid predator, Adalia fasciatopunctata revelierei (Mulsant) (Col.: Coccinellidae), were evaluated at five different densities of Callaphis juglandis (Goeze) (Hemiptera: Aphididae) in order to understand their role for the aphid’s biological control. Experiments were carried out in petri dishes at 25 ± 1°C, 60 ± 10% r.h. and 16L:8D photoperiod in a controlled temperature room. All tested stages exhibited a Type II response determined by a logistic regression model. The attack rate (α) and handling time (T _h ) coefficients of a Type II response were estimated by fitting a “random-predator” equation to the data. Although the estimates of α for all stages of A. fasciatopunctata revelierei tested were similar, the longest T _h was obtained for 3rd instar larva because of the lower consumption rate at densities above 40 prey/day. Results indicated that the adult female has the highest predation of C. juglandis followed by 4th instar larvae, adult males and 3rd instar larvae. However, further field-based studies are needed to draw firm conclusions.     

Exploration for anti-insect properties of lectin from seeds of soybean (Glycine max) usingBactrocera cucurbitae as a model

Lectin fromGlycine max L. was extracted and purified by affinity chromatography using asialofetuin-linked porous amino-activated silica beads. The concentration-dependent effect of lectin was studied on freshly laid eggs (0–8 h old) of the melon flyBactrocera cucurbitae (Coquillett); lectin failed to influence egg hatching. However, treating second instar larvae (64–72 h old) with increasing concentrations of lectin significantly reduced the development period, number of pupae and number of emergingB. cucurbitae, and was negatively correlated with the increase in the lectin concentration. The LC₅₀ value, 54μg ml⁻¹, was calculated on the basis of adult emergence. Treatment of the larvae (64–72 h old) with the LC₅₀ concentration resulted in a decrease in pupal weight. The activity of three hydrolase enzymes (esterases, acid and alkaline phosphatases), one oxidoreductase (catalase) and one group transfer enzyme (glutathione S-transferase) was assayed in second instar larvae at the LC₅₀ concentration of lectin after exposure for 24, 48 and 72 h. The activity of esterases increased significantly (P<0.01) at the three exposure intervals, whereas the activities of the three other hydrolyses and the transferases were significantly suppressed (P<0.01). http://www.phytoparasitica.org posting Sept. 13, 2006.     

瘦怒茧蜂的发育与生殖及对草地螟的控制作用

瘦怒茧蜂Orgilus ischnus Marshall是草地螟Loxostege sticticalis L.初龄幼虫寄生蜂。为探究它的生物学特性及其对草地螟的控害作用,本文在23 ℃、16L：8D光周期条件下,以1龄草地螟幼虫为寄主,测定了瘦怒茧蜂的发育历期和茧重、成虫生殖行为特征、能力和寿命,研究了瘦怒茧蜂对草地螟幼虫的功能反应和寄生率,探究了寄主幼虫的取食量及虫体大小与正常幼虫的差异。结果表明,瘦怒茧蜂卵和幼虫期为12.8 d,预蛹和蛹期10.5 d,世代历期23.2 d,平均茧重为4.1 mg。成蜂羽化当天即可交配产卵寄生,属卵育型,平均交配时间为49 s,雌蜂平均产卵量为100.5粒,产卵高峰期分别为交配后第4 d和第8 d,雌、雄蜂寿命分别为11和14 d。在5～40头/瓶（650 mL）8个密度条件下,瘦怒茧蜂的寄生量随草地螟幼虫密度的增加而增加,当密度≥15头/瓶时,寄生率会随幼虫密度的增加而减小,功能反应属HollingⅡ型;寄主幼虫一生取食量为106.7 mg,仅为正常幼虫的21.3%,寄主幼虫第6和12 d的体重、大小均极显著低于正常幼虫。本文研究结果明确了瘦怒茧蜂基本的生物学特性,证明该蜂对草地螟控害作用显著,为改善、提高草地螟的可持续控制技术提供技术支撑。     

茶毒蛾步甲研究初报

茶毒蛾步甲的成、幼虫是茶毒蛾的主要捕食性天敌。一年两代,世代重叠,以成虫越冬,雌成虫寿命246—540天。一头幼虫一生能捕食3—6龄的茶毒幼虫33.2头,一头成虫在茶毒蛾一个世代中可捕食959头茶毒蛾幼虫。成虫在活动期能忍受饥饿55天,幼虫有相互残食习性。     

桑椹瘿蚊生物学特性及其化学防控

为探索桑椹瘿蚊Cotarina sp.生物学特性,并进行有效地化学防控,通过调查桑椹瘿蚊的发生期,观察并记录其各部分形态特征,同时统计了乐果对桑椹瘿蚊的防治效果,并采用高效气相层析法测定了成熟桑椹中乐果的残留量。结果表明:桑椹瘿蚊为完全变态昆虫,经历卵、幼虫(休眠体)、蛹、成虫4个阶段,每年3月开始羽化为成虫,成虫不取食桑椹,可存活2~4 d,雌雄成虫傍晚交配,产卵于桑椹小果中,卵经6~7 d孵化为幼虫,幼虫从果柄中心取食桑椹,导致桑果局部畸形(干瘪)、早熟;幼虫经历3个龄期,老熟幼虫弹跳入土,形成休眠体进行越夏越冬,翌年2月化蛹。喷洒乐果乳剂1 000倍稀释液后,桑椹虫害率由83.3%降低到15.0%,被害桑椹虫口密度下降了89.3%;经高效气相色谱法分析,乐果残留量仅为0.75 mg/kg,低于国际标准,表明乐果对桑椹瘿蚊的防治效果较好。     

Sex-specific functional responses of dragonfly naiads Rhodothemis rufa on Culex quinquefasciatus larvae in laboratory bioassay

Laboratory bioassay was conducted to establish the biocontrol potentiality of naiads (aquatic nymphal stage) of Rhodothemis rufa (Rambur, 1842) against larvae of Culex quinquefasciatus, a common vector of filariasis in Tropical countries. From the study, it was noticed that in laboratory condition, the rate of predation of males of R. rufa was higher than that of females of almost same size and same species. The results of the present study revealed that both sexes displayed a density-dependent decelerating type-II functional response as the logistic regression estimated a significant negative linear parameter (P₁ value of ?0.330 and ?0.151 for males and females, respectively). Attack rate was almost similar for both sexes (0.082); however, handling time is less in males (0.62 min) than in females (0.852 min). The predator species usually coexist in the same aquatic habitat to that of mosquito larvae and can be effectively used in field condition to reduce the larval densities of mosquitoes in temporary or permanent aquatic water bodies.     

Laboratory evaluation of the insect growth regulator lufenuron againstHelicoverpa armigera on cotton

An insect growth regulator (IGR), lufenuron (Match 5EC), was tested for its toxicity toHelicoverpa armigera on cotton. Potency of the IGR against the larval stage of the pest was demonstrated with respect to larval instars; the LC₉₀ values of 1st, 2nd, 3rd, 4th and 5th instar larvae were 5.63, 7.89, 8.03, 11.39 and 14.76 mg a.i.l ⁻¹, respectively. However, different larval instars did not differ significantly with respect to LC₅₀ and LC₁₀. IGR-treated larvae had swollen heads and were significantly smaller (1.5–2.3 mm) than the untreated control (2.9 mm). Larval weight was significantly reduced from 190 mg in the control to 50–70 mg in the lufenuron treatment. IGR treatment in the larval stage significantly affected both pupal length and pupal weight. Pupal duration of the test insect was significantly extended by IGR treatment. Pupal deformities, including an inability to shed the last larval skin and formation of larval-pupal intermediates, occurred following treatment. A significant reduction in adult emergence was recorded. In addition, abnormalities in the form of development of cavities in the forewings of adult were evident. A significant decline in fecundity was noted in the studies. http://www.phytoparasitica.org posting Feb. 3, 2003.     

草间钻头蛛对苜蓿苔螨捕食作用的研究

草间钻头蛛成蛛对苜蓿苔螨雌成螨的捕食功能反应属Holling-Ⅱ型,对苜蓿苔螨各螨态的控制能力从小到大依次为:成螨>若螨>幼螨。草间钻头蛛对苜蓿苔螨的寻找效应(S)随猎物(Nt)和天敌密度的增加而降低。草间钻头蛛的饥饿程度等因素均可引起功能反应参数的变化。草间钻头蛛成蛛喜食苜蓿苔螨的成螨和若螨,对幼螨的捕食能力较弱。     

Secondary transmission of fipronil toxicity between Oriental cockroaches Blatta orientalis L in arenas

Mixed colonies of adult male and female Oriental cockroaches were conditioned to a 12:12 h photocycle in arenas (0.23 m²) with a harbourage, food and water and then exposed to deposits (30 mg or 2 × 30 mg) of 0.5 g kg⁻¹ fipronil gel bait at the beginning of a dark phase. The bait was rapidly consumed by the first sub‐group of insects to emerge from the harbourage; any residual bait was removed from the arenas 4 h into the following light phase. Third‐instar nymphs were then introduced and mortality was monitored over the subsequent 14 days with all cadavers left in situ. Death of cockroaches under these conditions was due to direct poisoning of the sub‐group of the adults that consumed the bait and to secondary transfer of toxicity to the remainder of the adult and to the nymphal populations. Mean mortality in the adult populations increased to > 96% (females) and > 53% (males) with consistently higher mortality of females than males; that in the third‐instar nymph (unexposed) populations increased to 25–50%. Some cadavers were wholly or partially eaten by other cockroaches during this period, and this was interpreted as the major mechanism of secondary transfer of toxicity. Individual adult females were fed weighed bait deposits (10 mg) and, following death (24 h), the cadavers were transferred to closed containers held at 33%, 52% or 76% relative humidity /28 °C for periods of up to 7 weeks. They were then added individually to groups of five adult females provided with water but no alternative food source. Mean mortalities (>64% at 1 week and > 96% at 7 weeks) were not significantly lower than mean mortalities produced by freshly poisoned cockroaches, showing that no loss in the insecticidal activity of the cadavers occurred under these storage conditions. The potential of necrophagy to supplement the primary action of fipronil bait treatment of Oriental cockroach infestations by inhibiting colony redevelopment is discussed. © 2000 Society of Chemical Industry     

Studies onDicrodiplosis manihoti Harris (Diptera, Cecidomyiidae), a common predator of mealybugs

Biweekly samples of 4 species of mealybugs infesting fruit and ornamentals in Salalh, Sultanate of Oman, revealed thatDicrodiplosis manihoti Harr. was found to associate with the long-tailed mealybug and citrus mealybug. The predator occurred almost all the year round and preyed on nymphs and adult females. Biological studies showed that the incubating period of the predator-egg averaged 2.8 days. The larval stage lasted 11.4 days and consumed an average of 5.6, adult females of the long-tailed mealybug. The pupal stage lasted 10.1 days. The total number of eggs deposited/female averaged 36 during her very short life span which averaged 2.3 days.     

三种寄主植物对小菜蛾实验种群特征的影响

为明确萝卜、白菜和油菜对小菜蛾实验种群特征的影响,测定了小菜蛾对3种寄主的取食量,通过构建两性生命表比较了不同寄主植物对其实验种群发育与繁殖的影响,并综合生命表与取食量参数,评价了小菜蛾对萝卜、白菜和油菜的危害。结果显示:小菜蛾幼虫在萝卜、油菜和白菜上的取食量差异显著,分别为93.3、105.0和114.7 mg/头。小菜蛾取食萝卜、白菜和油菜后,其幼虫的发育历期差异显著,依次为8.6、8.5和7.6 d;种群内禀增长率依次为0.18、0.23和0.23,周限增长率为1.19、1.26和1.26,净生殖率为18.7、46.1和30.6。取食萝卜的小菜蛾各发育阶段的存活率最低。小菜蛾对各供试寄主实际危害量占理论危害量的百分比为油菜(71.8%)白菜(70.8%)萝卜(53.0%)。表明同一时间内,小菜蛾对油菜危害程度最大,白菜次之,萝卜最小。     

Studies onDicrodiplosis manihoti Harris (Diptera, Cecidomyiidae), a common predator of mealybugs

Biweekly samples of 4 species of mealybugs infesting fruit and ornamentals in Salalh, Sultanate of Oman, revealed thatDicrodiplosis manihoti Harr. was found to associate with the long-tailed mealybug and citrus mealybug. The predator occurred almost all the year round and preyed on nymphs and adult females. Biological studies showed that the incubating period of the predator-egg averaged 2.8 days. The larval stage lasted 11.4 days and consumed an average of 5.6, adult females of the long-tailed mealybug. The pupal stage lasted 10.1 days. The total number of eggs deposited/female averaged 36 during her very short life span which averaged 2.3 days.     

Suitability of different artificial diets for development and survival of stages of the predaceous ladybird beetle <Emphasis Type="Italic">Eriopis connexa</Emphasis>

The ladybug Eriopis connexa (Germar) (Coleoptera: Coccinellidae) is an important natural enemy of various pests. The potential of rearing it on 17 different diets was evaluated. The percentage of E. connexa adults was higher when its larvae received only eggs of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) after freezing for 1 day (92.5%) or combined in artificial diets with honey and water (82.5% to 100.0%). The viability from larvae to adult was 72.5% with eggs of A. kuehniella (after 1 day’s freezing) plus an artificial diet based on pet food. No adults of E. connexa were obtained with artificial diets as a stand-alone food source. The duration of the larval period to adult of this predator was longer, but with low viability, with only A. kuehniella eggs (after 6 months’ freezing) or with eggs + artificial diets. Eggs of A. kuehniella (after 1 day’s freezing) supplied separately or along with artificial diets were more appropriate to rear E. connexa and both diets can be used for mass rearing of this natural enemy.