Behavior of Trichogramma atopovirilia Oatman & Platner and T. pretiosum Riley (Hymenoptera: Trichogrammatidae) on Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) egg masses.

In this study we analyzed the impact of physical barriers of Spodoptera frugiperda (J. E. Smith) egg-masses on the behavior of Trichogramma atopovirilia Oatman & Platner and Trichogramma pretiosum Riley. The duration of drumming, drilling, oviposition, period spent over the egg-mass, and interval between parasitized eggs were timed, and the number of parasitized eggs were recorded. The presence of scales on the egg-masses caused a significant increase in the time spent by both parasitoids on each process and a decrease in the residence time over the egg-mass and in the number of parasitized eggs, with an increase in the number of egg layers. There was a significant decrease in the number of parasitized eggs in relation to egg-masses with one layer and no scales. We observed that the physical barriers in fall armyworm egg-masses changed the behavior of T. atopovirilia and T. pretiosum, affecting their parasitization capacity.     

Biology and thermal requirements of Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) parasitizing eggs of Diaphania hyalinata L. (Lepidoptera: Pyralidae)

The development and parasitism of Diaphania hyalinata L. eggs by Trichogramma atopovirilia Oatman & Platner and its thermal requirements were studied at the temperatures of 18, 21, 24, 27, 30 and 33 degrees C. Thirty eggs of D. hyalinata were exposed to three females of T. atopovirilia for 5h at 25 degrees C and incubated at the different temperatures. The developmental time from egg exposure to adult, parasitism viability, number of adults per parasitized host egg and progeny sex ratio were monitored. The developmental time from egg to adult emergence of the parasitoid exhibited inverse relationship to the temperature, lasting 24.12 days at 18 degrees C and 7.36 days at 33 degrees C. Parasitism viability at 24, 27 and 30 degrees C was higher than 90%. The ratio of T. atapovirilia adult produced per egg and its sex ratio were not affected when using D. hialynata as host. The lowest threshold temperature (Tb) and estimated degree-days over Tb required by T. atopovirilia to develop on eggs of D. hyalinata was 11.99 degrees C and 130.42 masculine C, respectively. Considering the temperature regimes of two areas where cucurbitaces are cultivated in Bahia State (Rio Real and Inhambupe County) it was estimated that T. atopovirilia can achieve more than 32 generation per year. The results suggest that T. atopovirilia has potential to control D. hyalinata eggs with better chance of success under temperature regimes ranging from 24 to 27 degrees C that meets the suitable field conditions for cropping cucurbitaces.     

东北地区四种本地赤眼蜂对草地贪夜蛾寄生能力及适应性研究

草地贪夜蛾Spodoptera frugiperda(Smith)是新入侵我国的重大危险性入侵害虫,赤眼蜂是我国生物防治的优势卵寄生蜂,可用于防治多种农林作物上的鳞翅目害虫。为检测东北地区本地赤眼蜂对草地贪夜蛾卵的生防潜能,筛选防治草地贪夜蛾的有效蜂种,本研究比较研究了松毛虫赤眼蜂、玉米螟赤眼蜂、黏虫赤眼蜂和稻螟赤眼蜂对草地贪夜蛾卵的寄生能力和发育适合度。结果表明,4种赤眼蜂均能寄生草地贪夜蛾卵,并完成发育,但其寄生能力和发育适合度存在显著差异。松毛虫赤眼蜂、玉米螟赤眼蜂和黏虫赤眼蜂对草地贪夜蛾卵块寄生率均高于80%,但仅松毛虫赤眼蜂对草地贪夜蛾卵表现出较高的卵粒寄生量。松毛虫赤眼蜂、玉米螟赤眼蜂和黏虫赤眼蜂子代羽化率和雌性比无显著差异,但松毛虫赤眼蜂比其它3种赤眼蜂的发育历期更短,而稻螟赤眼蜂对草地贪夜蛾卵的寄生能力和适合度均最差。研究结果将为应用本地赤眼蜂生物防治潜在入侵东北地区的草地贪夜蛾提供技术支撑。     

Comparative Analysis of the Reproductive Attributes of Three Commercially-Produced Trichogramma Species (Hymenoptera: Trichogrammatidae)

The reproductive attributes of commercially-produced Trichogramma platneri, T. minutum and T. pretiosum reared from eggs of both Ephestia kuehniella and Sitotroga cerealella were monitored at 25 C. The age-specific fecundity, longevity and progeny sex ratio and adult size were determined for individual females from all six combinations of Trichogramma and rearing host, using E. kuehniella as the experimental host. Rearing host had a significant influence on the lifetime fecundity, 3-day fecundity and longevity of all three Trichogramma species. In general, the performance of T. minutum and T. pretiosum was better when reared from S. cerealella, but that of T. platneri was superior when reared from E. kuehniella. The lifetime fecundity of the Trichogramma species was linearly related to longevity and the ranking between species was T. pretiosum > T. minutum > T. platneri. The age-specific pattern of oviposition for T. platneri was distinctly precocious, with 40% of its lifetime fecundity oviposited on the first day, in contrast to 17-24% for the other two species. Progeny sex ratio over the lifetime of the Trichogramma females was slightly male biased and differed significantly from 0.5 for T. minutum and T. platneri. Daily sex ratio for parasitoids reared from the most productive rearing host was female biased only for the first day of oviposition for T. platneri in contrast to the first 5-6 days of oviposition for the other two species. There was little evidence that any of the reproductive attributes of these Trichogramma species, reared from small host eggs, was dependent on the size of the adult females.     

Parasitism of the Coffee Berry Borer Hypothenemus hampei by Trichogramma pretiosum in the Laboratory

Parasitism of the coffee berry borer, Hypothenemus hampei (Ferrari) by Trichogramma pretiosum Riley resulted in high mortality of developing parasitoids and a low prevalence of adult emergence. A laboratory colony of T. pretiosum reproducing in H. hampei failed after three generations. Adult female T. pretiosum that developed in H. hampei were smaller and produced fewer eggs than conspecifics that developed in a standard lepidopteran host, Sitotroga cerealella (Olivier). Parasitoids that emerged from H. hampei preferentially parasitized S. cerealella over H. hampei. We conclude that T. pretiosum has little potential for biocontrol of the coffee berry borer.     

Do sympatric Trichogramma species parasitize the pest insect Helicoverpa armigera and the beneficial insect Chrysoperla carnea in different proportions?

Parasitism of two host species by five Trichogramma species (Hymenoptera, Trichogrammatidae) was studied in the laboratory. The host species were: i) the bollworm Helicoverpa armigera Hübner (Lepidoptera, Noctuidae), an important pest of many crops in the tropics and subtropics, and ii) one of its natural enemies, the lacewing Chrysoperla carnea Stephens (Neuroptera, Chrysopidae), a predator often used as a biological control agent. The proportion of H. armigera eggs parasitized from the total number of parasitized hosts differed between Trichogramma species. The average number of parasitized eggs per female in 24 h by Trichogramma pintoi and T. bourarachae was 10 of H. armigera and about 0.5 of C. carnea. For the other three Trichogramma species (T. cordubensis, T. evanescens and T. turkestanica) these averages varied from 6 to 11 H. armigera eggs and from 3 to 4 C. carnea eggs. Total adult offspring production, contacts with hosts, secondary clutch size and sex-ratio of each Trichogramma species were determined as well. The results show that sympatric Trichogramma may parasitize target and non-target species in different proportions. If this difference corresponds to the field situation, simple laboratory tests could be performed to select not only efficient biogical control agents, but also species which are the least detrimental to non-target hosts.     

繁育寄主对三种赤眼蜂个体大小及抱卵量的影响

【目的】繁育寄主及成蜂日龄均会影响赤眼蜂体内的抱卵量,为了解繁育寄主及育出赤眼蜂个体大小与赤眼蜂抱卵量的关系,我们在室内研究了米蛾 Corcyra cephalonica（Stainton）卵和亚洲玉米螟 Ostrinia furnacalis （Güenée）卵作为繁育寄主对3种赤眼蜂雌蜂大小、抱卵量的影响。【方法】在光周期14L:10D、温度25±1℃的室内条件下,以米蛾卵、亚洲玉米螟卵作为繁育寄主,解剖不同日龄（羽化后12-72 h）松毛虫赤眼蜂 Trichogramma dendrolimi Matsumura、玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen以及稻螟赤眼蜂Trichogramma japonicum Ashmead,观察雌蜂抱卵量,测量成蜂的大小,分析雌蜂抱卵量与其日龄、个体大小以及繁育寄主的关系【结果】在羽化后48 h以内,3种蜂的抱卵量随雌蜂日龄的增长而增加。羽化后72 h,除米蛾卵繁育的玉米螟赤眼蜂及玉米螟卵繁育的松毛虫赤眼蜂的抱卵量比羽化后48 h时略高外,其他组合均出现下降。以亚洲玉米螟卵为繁育寄主时的玉米螟赤眼蜂的抱卵量显著高于对应日龄的以米蛾卵为繁育寄主时的抱卵量,而松毛虫赤眼蜂（除羽化后12和24 h外）和稻螟赤眼蜂则相反;以米蛾卵为繁育寄主时,相同日龄的赤眼蜂中,松毛虫赤眼蜂抱卵量最高,稻螟赤眼蜂的抱卵量最低;以亚洲玉米螟卵为繁育寄主时,玉米螟赤眼蜂抱卵量最高,稻螟赤眼蜂抱卵量最低。雌蜂抱卵量与雌蜂个体大小呈线性正相关,相关程度随雌蜂日龄增加而更加明显。【结论】后足胫节长度可以作为评价松毛虫赤眼蜂、玉米螟赤眼蜂和稻螟赤眼蜂质量的指标。赤眼蜂抱卵量受繁育寄主、赤眼蜂蜂种及雌蜂日龄的显著影响,寄主的适合性也会影响育出赤眼蜂的大小,筛选合适的繁育寄主有助于提高赤眼蜂的质量。     

Egg laying and development of Neotropical trichogrammatid species in artificial eggs

The goal of this work was to assess the suitability of two artificial diets for egg laying and development of Trichogramma atopovirilia Oatman & Platner, Trichogrammatoidea annulata De Santis, and Trichogramma bruni Nagaraja (all Hymenoptera: Trichogrammatidae). Additionally, the quality of wasps reared in vitro was compared with those reared in vivo. The ‘standard’ diet consisted of Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) pupal holotissues (65%), chicken egg yolk (18%), fetal bovine serum (8.5%), lactalbumin hydrolysate (8.5%), and anticontaminants (0.3%). The ‘modified’ diet differed from the standard one only in the D. saccharalis pupal holotissues, that were replaced with Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) ones. Females of the three trichogrammatid species laid eggs in artificial eggs containing any artificial medium, but the modified one received more eggs. Although the standard diet was accepted for oviposition by the three wasp species, no development occurred. On the modified diet, only T. atopovirilia was able to develop to adult emergence. Adult F1 were of a quality that was similar to insects reared in vivo.     

Naturally occurring Trichogramma species in olive farms in Egypt

A survey of two-year studies (2001-2003) was carried out in two olive groves sited at two representative olive growing areas, namely Paradise Park (arid area) and Burg E1-Arab farm (semi-arid area) to monitor the frequency of endemic Trichogramma species on olive moth (Prays oleae) and jasmine moth (Palpita unionalis). The suspended host bait traps were found to be a more practical and effective tool for collecting Trichogramma wasps than the attached ones. Four naturally occurring Trichogramma species were collected for the first time in Egypt from the olive groves, where releases have never been conducted. T.bourarachae was collected exclusively from Burg El-Arab farm. It seems that this wasp species adapts well to the semi-arid area. Three species, namely T. cordubensis, T. nr.pretiosum and T. cacociae were isolated from Paradise Park farm. All of these wasps were also bred from naturally parasitized host eggs during favorable and even at unfavorable temperature conditions of June-August. However, these endemic species did not occur naturally in sufficient numbers to keep the pest populations from reaching damaging levels.The excessive usage of insecticides and the oophagous predators (e.g., ants and lacewing larvae) are some factors that affect the performance of Trichogramma wasps in olive farms.The presence of warm weather wasp strains suggests the existence of well-adapted wasp species or swains which may be appropriate candidates for the control of target pests in olive groves. Additional study is required to determine the best “habitat-specific” species/strains of Trichogramma for augmentative release of naturally occurring wasps and to incorporate them into integrated pest management programs. Efforts should be made to conserve these endemic species from oophagous predators, hot weather and insecticides.The olive and jasmine moth-larvae and pupae found under tree canopies were bred and emerged parasitoids were listed.     

A laboratory comparison of four Trichogramma species (Hymenoptera: Trichogrammatidae) as potential biocontrol agents for the carob moth,Ectomyelois ceratoniae (Lepidoptera: Pyralidae)

Four Trichogramma species were recovered in the field from eggs of carob moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae). The oviposition rates of Trichogramma oleae, Trichogramma cacoeciae, Trichogramma evanescens and Trichogramma bourarachae were compared when presented either E. ceratoniae or Ephestia kuehniella (Lepidoptera: Pyralidae). T. oleae and T. bourarachae did not parasitise either species of Lepidoptera.     

Effect of insecticides on Trichogramma exiguum (Trichogrammatidae: Hymenoptera) preimaginal development and adult survival

The effect of insecticides on Trichogramma exiguum Pinto & Platner emergence, adult survival, and fitness parameters was investigated. Insecticides tested were lambda cyhalothrin, cypermethrin, thiodicarb, profenophos, spinosad, methoxyfenozide, and tebufenozide. All insecticides, with the exception of methoxyfenozide and tebufenozide, adversely affected Trichogramma emergence from Helicoverpa zea (Boddie) host eggs when exposed at different preimaginal stages of development (larval, prepupal, or pupal). Regardless of the developmental stage treated, none of the insecticides tested had a significant effect on the sex ratio or frequency of brachyptery of emerged females. However, the mean life span of emerged T. exiguum females significantly varied among insecticide treatments, and was significantly affected by the developmental stage of parasitoid when treated. Based on LC50 values, spinosad and prophenofos were the most toxic compounds to female T. exiguum adults, followed by lambda cyhalothrin, cypermethrin, and thiodicarb. Insecticides field-weathered for four to 6 d on cotton leaves showed no activity against female T. exiguum adults.     

Oviposition Behaviour and Reproductive Performance of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) Reared in Artificial Diet

Biotypes of Trichogramma australicum were reared on artificial diet "A", Helicoverpa armigera (Hübner) (natural host) eggs and Sitotroga cerealella (Olivier) (factitious host) eggs. We evaluated the quality of these biotypes by comparing their oviposition behaviour and reproductive performance on H. armigera eggs. Female T. australicum reared in vitro accepted H. armigera eggs for oviposition and displayed similar behavioural components of oviposition to females reared on natural hosts. However, handling time during oviposition in H. armigera eggs by females from in vitro rearing was significantly longer than handling time of females reared on the natural host because the females needed a significantly longer time for host feeding. In vitro reared females produced significantly more progeny and parasitised more H. armigera eggs than the females reared on S. cerealella. Improvements to the artificial diet for T. australicum may reduce handling time of the in vitro reared females and increase the female population. These improvements may include changes in nutrient content and size of the artificial eggs.     

Cotton rats (Sigmodon hispidus) and black rats (Rattus rattus) as possible reservoirs of Leishmania spp. in Lara State,Venezuela

A total of 519 wild animals belonging to eleven species were collected during a two year study in a cutaneous leishmaniasis endemic area in Venezuela (La Matica, Lara State). The animals were captured in home-made Tomahawk-like traps baited with maize, bananas or other available local fruits, and parasites were isolated from 27 specimens. Two different species were found naturally infected with flagellates, i.e., cotton rats (Sigmodon hispidus) and black rats (Rattus rattus). Characterization of the parasites using PCR, kDNA restriction pattern and hybridization with species-specific probes revealed the presence of Leishmania (L.) mexicana in three of the black rats and Leishmania (V.) braziliensis in two others. The latter species was also identified in the single positive specimen of S. hispidus. The results suggested both species of animals as possible reservoirs of Leishmania sp.     

Influence of Diaphania hyalinata (L.) (Lepidoptera: Crambidae) egg density on the parasitization capacity of Trichogramma exiguum Pinto & Platner and Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)

The effects of the egg density of Diaphania hyalinata (L.) on several biological parameters of Trichogramma exiguum Pinto & Platner and T. pretiosum Riley were investigated. For that, 24h-old egg masses were isolated in glass tubes (15 replicates; 1 egg mass = 1 replicate), and offered to parasitization by a newly-emerged female of T. pretiosum or T. exiguum 24h at the proportion of one female to 5, 10, 15, 20, 25, 30, 35 and 40 eggs of D. hyalinata. The following parameters were evaluated: number of parasitized eggs, number of individuals per egg, viability and sex ratio. Trichogramma exiguum parasitized more eggs than T. pretiosum when more than 25 eggs were available per female. The percentage of emergence was satisfactory to T. pretiosum in densities up to 15 eggs/female and up to 20 eggs/female for T. exiguum. The number of individuals per egg was not statistically different in both species except in the density of 25 eggs/female. It can be concluded that T. exiguum performed better than T. pretiosum at larger clutch sizes, as T. exiguum parasitization capacity increased as a result of the size of the host clutch size.     

Studies on three species of Trichogramma. I. Foraging behaviour for food or hosts

The foraging strategies for both food or hosts of three trichogrammatid species: Trichogramma evanescens, Trichogramma cacoecia and Trichogramma dendrolimi were compared using artificial patches of Sitotroga cerealella eggs. In all experiments, inexperienced and newly emerged wasps of < 1 h old were singly tested. When the females were allowed to land upon the hosts, the decision-making process for initial acceptance or rejection was species-dependent. The initial search in T. evanescens was for food, whereas T. dendrolimi or T. cacoeciae start to oviposit immediately after their emergence. When honey-deprived or undeprived females were each exposed to single patches for 20 or 60 min, variations in mean number of probing females 'drilling and ovipositing' were also species-dependent. Acceptance of host eggs by honey-deprived females and subsequent egg deposition were higher in both T. cacoeciae and T. dendrolimi than in T. evanescens . For all species, the probing of honey-undeprived females was higher than that of deprived ones. When the exposure period was prolonged to 24 or 48 h and the number of patches per female increased to three, most of the honey-deprived or undeprived T. evanescens females attacked one patch, and only a few of them attacked two patches. Foraging activity of honey-deprived females of T. cacoeciae was restricted to single patches, whereas most undeprived ones attacked more than one patch. In contrast, honey-deprived or undeprived T. dendrolimi females attacked more than one patch. The experiments showed that T. dendrolimi females have more powerful ovipositing urges than looking for food and that the opposite was the case for T. evanescens , with T. cacoeciae being intermediate.     

Trichogramma egg parasitism of Helicoverpa armigera on pigeonpea and sorghum in southern India

Trichogramma spp. (Hymenoptera: Trichogrammatidae) only rarely parasitize eggs of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on pigeonpea (Cajanus cajan (L.) Millspaugh), while on other plants including sorghum (Sorghum bicolor (L.)) high parasitism levels of this host are found. In this study two strategies designed to increase the parasitoid activity on pigeonpea were tested in the field: intercropping pigeonpea with sorghum and mass-releasing T. chilonis Ishii. Neither strategy led to an increase in parasitism. On pigeonpea, H. armigera oviposited >74.8% of its eggs on calyxes and pods. Parasitism levels in host eggs collected from different plant structures varied significantly with 3.6, 0.3, and 40.7% of eggs on calyxes, pods, and leaves parasitized. Earlier studies have shown that calyxes and pods possess long glandular and non-glandular trichomes, and are covered by sticky trichome exudates which inhibit parasitoid searching behaviour. Parasitism levels between 27.9 and 100% were recorded from host eggs on the intercropped sorghum. Trichogramma chilonis was the dominant parasitoid species. The mean clutch size was 2.03, but up to six parasitoids emerged per egg. Progeny sex ratio (% females) decreased with clutch size, from 63.1% at a clutch size of one to 46.0% at a clutch size of five. Sticky trap catches showed that while the parasitoid population in sorghum increased when H. armigera started ovipositing, the population within pigeonpea did not benefit from either a high parasitoid population in sorghum or a high host egg density on pigeonpea. During one of five seasons studied, however, high parasitism levels (up to 73%) were recorded on pigeonpea. During this season, H. armigera oviposited on pigeonpea plants in the vegetative growth stage and a high proportion of eggs were collected from leaves. Parasitism levels were positively correlated with the percentage of eggs collected from leaves. This study shows that the parasitization efficiency of Trichogramma spp. on pigeonpea depends mainly on the location of the host eggs. This explains why parasitism levels of H. armigera eggs on pigeonpea did not increase when intercropped with sorghum or after mass-releasing T. chilonis.     

Interactions between host attributes and wasp size: a laboratory evaluation of Trichogramma platneri as an augmentative biological control agent for two avocado pests

We compared egg parasitization of two sporadic pests of avocado, Persea americana Miller, by Trichogramma platneri Nagarkatti reared on Sitotroga cerealella (Oliver) (=smaller parasitoids) with those reared on Trichoplusia ni (Hübner) (= larger parasitoids) in the laboratory. Large T. platneri females invested less time than smaller parasitoids in obtaining offspring from eggs of either Amorbia cuneana Walsingham or Sabulodes aegrotata (Gueneé). Furthermore, large T. platneri invested substantially more time (ca. 3-fold) in obtaining offspring from S. aegrotata than A. cuneana eggs. These investment times positively correlated with percentage egg-load retained by a female after it had ceased exploiting a host species. This occurred even though the offspring produced by a parasitoid from either host species manifested the same size and fecundity (= quality). Host species utilization in the laboratory mirrored that observed in the avocado groves of southern California following augmentative release of commercially produced T. platneri (Oatman & Platner, 1985). Explanations for these differences in host utilization are discussed along with their implications for augmentative biological control.     

Naturally occurring egg parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) in a pomegranate orchard in Tunisia

Four Trichogramma species were found in a pomegranate orchard in Gabès, an arid region of Tunisia, from parasitized eggs of Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae), an economically important insect pest. Identification based on assessment of male genitalia and internal transcribed spacer 2 ( ITS 2) sequences showed that they were T. bourarachae Pintureau and Babault, 1988, T. oleae Voegelé and Pointel, 1979, T. cacoeciae Marchal, 1927 and T. evanescens Westwood, 1833. Trichogramma evanescens is reported for the first time in Tunisia. Trichogramma cacoeciae was the largely dominant species in the analyzed samples, whereas T. bourarachae was present in a minor portion of 1.38%. The implications of these results for attempts at controlling E. ceratoniae are discussed.     

Trichogramma exiguum (Hymenoptera: Trichogrammatidae) releases in North Carolina cotton: evaluation of heliothine pest suppression

Field studies were conducted in 1996 and 1997 to reevaluate the use of augmentative releases of Trichogramma wasps for heliothine management in cotton. In 1996, nine releases of Trichogramma exiguum Pinto & Platner, spaced 3-4 d apart, were made into three 0.4-ha cotton plots. Six weekly releases were made in 1997, each containing two T. exiguum cohorts developmentally staggered by 45 degrees C degree-days. Field release rates, estimated from laboratory and field quality control data, averaged 108,357 T. exiguum female female per hectare per cohort per release in 1996 and 193,366 female female per hectare per cohort per release in 1997. In 1996, mean +/- SD adult emergence under laboratory conditions for released cohorts was 92 +/- 7%; 62 +/- 5% of emerged adults were females, 3 +/- 2% of females displayed brachyptery (nonfunctional wings), mean female longevity under laboratory conditions was 15 +/- 4 d, and mean +/- SD field emergence was 97 +/- 2%. Quality control measurements were similar in 1997. In 1996, mean +/- SD percent parasitism of heliothine eggs in field plots on the sampled dates ranged from 67 +/- 4 to 83 +/- 5% in T. exiguum release plots and 25 +/- 9 to 55 +/- 8% in control plots. In 1997, parasitism levels ranged from 74 +/- 4 to 89 +/- 5% in T. exiguum release plots and 18 +/- 18 to 69 +/- 11% in control plots. Despite increased parasitism levels in T. exiguum release plots, there were no significant differences in density of fifth instars, boll damage, or yield between T. exiguum release and control plots. Therefore, it is concluded that Trichogramma augmentation is not an effective heliothine management tool in North Carolina cotton.     

Efficiency of different egg parasitoids and increased floral diversity for the biological control of noctuid pests

Augmentative biological control of insects is a tool of Integrated Pest Management programs. In many agroecosystems, biological control is exercised largely by parasitoids, and it is found that the presence of food resources, as provided by flowering plants, can have a positive effect on survival, search ability and parasitism rate of parasitoid species. In Colombia, a recently established export crop, the cape gooseberry, is under continuous attack by a Lepidopteran species complex in the family Noctuidae. Our first objective was to test the longevity and parasitism rates of three species of egg parasitoids in the genus Trichogramma (Trichogramma atopovirilia Oatman & Platner, Trichogramma exiguum Pinto & Platner, and Trichogramma pretiosum Riley) for Spodoptera frugiperda Smith and Copitarsia decolora Gueené. Our results suggest that T. atopovirilia and T. pretiosum could be promising parasitoids for the control of S. frugiperda and C. decolora, with a percentage parasitism of between 30% and 60%, respectively. For our second objective, we selected T. atopovirilia as a model species to evaluate the effect of the presence of flowering plants on the longevity and parasitism rate in both, no choice and multiple choice experiments, under laboratory and field conditions. Our results consistently showed that the presence of red clover (Trifolium pratense L.) can increase the longevity and parasitism rate of T. atopovirilia, suggesting that providing food resources to parasitoids in cape gooseberry fields should be part of a habitat diversification strategy to control noctuid pests.