The results of laboratory studies on the life history, morphology of immature stages, effects of food and water on adult longevity, host age preference for oviposition, parthenogenesis, and adult behavior of Telenomus solitus Johnson are presented. Telenomus solitus completed its development in 10.8 days (egg, 0.3 day ; I st instar, 2.7 days ; 2 *a instar, 3.7 days ; and pupa, 4.1 days). The adults lived longest when provided with both honey and water. Without food, they survived less than 24 h. Parasitization of host eggs varied significantly with their age, being highest in 42 h old eggs. Fewer than 10 % of eggs older than 60 h were parasitized successfully. The periodicity of oviposition was unimodal ; it occurred throughout the 24 h period and peaked in the late photophase. Females of T. solitus are arrhenotokous. The behavioral sequences during courtship, mating, and oviposition are described. KEY-WORDS:Telenomus, egg parasitoid, immature morphology, adult behavior.The Scelionidae is the largest family of Proctotrupoidea, with more than 70 genera distributed among 3 subfamilies and more than 20 tribes. Telenomus is a cosmopolitan, eurytopic genus, with more than 500 nominal species. Several species show some degree of specificity, primarily parasitizing only the eggs of host species from which they were reared (Anderson, 1976). Parasitization by a single species of Telenomus of insects in more than one order is uncommon (Johnson, 1984).In February, 1977, an undescribed Neotropical species of Telenomus was collected from eggs of an undetermined noctuid on potato foliage near Solola, Guatemala. This species was later described and named Telenomus solitus by Johnson (1983). We studied the biology of T. solitus Johnson before it was released for biological control. In this paper, we describe its life history and behavior. MATERIALS AND METHODS GENERAL EXPERIMENTAL PROCEDURESExcept for studies on the response of Telenomus solitus to varying temperatures, all experiments were conducted at 26.7 _+ 2 ~ 50 _+ 5 % RH, and 12L : 12D photoperiod (~) Current address : Southern Field Crap Insect Management Laboratory, P.O. Box 346, Stoneville, Mississippi 38776.
Structure, color, growth habit, and pubescence of plants, in addition to chemical characteristics, affect acceptability of plants as potential food, refuge, or oviposition sites for insects; however, the impact of physical characteristics of plants on egglaying by the tobacco budworm moth, Heliothis virescens (F.), is poorly understood. This study was undertaken to determine the physical attributes, especially trichome types and growth habit, that may influence oviposition by gravid H. virescens females on several species of plants. The types and densities of trichomes found on the leaves of eight plant species, pigeonpea [Cajanus cajan (L.) Huth], crimson clover (Trifolium incarnatum L.), Texas bluebonnet (Lupinus texensis Hooker), cotton (Gossypium hirsutum L.), velvetleaf (Abutilon theophrasti Medikus), rose‐scented geranium (Pelargonium graveolens L'Her.), tobacco (Nicotiana tabacum L.), and groundcherry (Physalis angulata L.) were investigated using light and scanning electron microscopy. Simple or branched, hairlike (nonglandular) trichomes and capitate or club‐shaped (glandular) trichomes were found. Greater densities of trichomes occur on the abaxial surfaces than adaxial surfaces of leaves of most species. Heliothis virescens laid more eggs on the under surfaces of leaves, although the difference in oviposition rate was significant only for tobacco. Trichome type did not influence oviposition. In choice tests in laboratory and field cages, moths preferred to oviposit on tobacco and velvetleaf. In field cages, plants with erect growthabit were more acceptable to females than plants with procumbent growth habit.
The effect of maternal age and host Heliothis virescens (F.) deprivation on egg production and allocation by Microplitis croceipes (Cresson) was determined in the laboratory on 0.5, 1.0, 3.0, 6.0, 9.0, and 12.0 days old parasitoids. In host-deprived parasitoids, newly-emerged (0.5-day old) females produced significantly fewer eggs than older ones ; egg production peaked 3 to 6 days after emergence and declined thereafter. However, the number of eggs found in undeprived parasitoids at various ages suggested a cyclical pattern of egg production. The rate of parasitization by host-deprived M. croceipes was higher in 1.0 to 6.0 days old than in newly-emerged or older females and was correlated strongly with egg production (r = 0.93). The first observation on premature larval hatching in M. croceipes was documented.
The influence of plant age, water stress, and damage on the ovipositional response of Heliothis virescens (F.) to cotton, Gossypium hirsutum L., was tested in field cages. Further, the impact of presence of conspecific eggs on oviposition by H. virescens was tested in laboratory cages. Females laid more eggs on smaller, younger, and more pubescent leaves than older, larger leaves. The presence of conspecific eggs on these leaves appeared to elicit further oviposition as indicated by significant correlation between increase in egg density and the initial egg density. There was a significant negative correlation (r = −0.92) between oviposition and leaf moisture but a strong positive correlation (r = 0.98) between oviposition and pubescence among leaf classes. Nitrogen content did not vary significantly among leaf classes and did not show any correlation with egg density. Adult females were able to discriminate between damaged and undamaged plants, the latter receiving significantly higher numbers of eggs. Eight week‐old potted cotton plants appeared to be more acceptable to moths than younger and older plants. Oviposition on cotton plants subjected to suspension of water for up to 7 days did not vary significantly. Based on data presented, it appears that other factors, e.g., hairiness, may override leaf moisture content in affecting oviposition by H. virescens. Zusammenfassung Einfluß von Pflanzenalter, Wasserstreß, Larvenfraß und Anwesenheit arteigener Eier auf die Eiablage von Heliothis virescens (F.) an Baumwolle Untersuchungen in Freilandkäfigen und im Labor ergaben, daß die Heliothis‐Weibchen mehr Eier an kleineren, jüngeren und stärker behaarten Blättern ablegten als an solchen mit gegenteiligen Eigenschaften. Die Anwesenheit arteigener Eier schien auf die Weibchen als Stimulans für das Hinzulegen ihrer Eier zu wirken. Zwischen Eizahl und Blattfeuchtigkeit bestand eine negative (r = −0.92), zwischen Eizahl und Blattbehaarung dagegen eine positive Korrelation (r = 0.98). Der N‐Gehalt der Pflanze zeigte sich ohne Einfluß auf die Zahl abgelegter Eier. Die Weibchen waren in der Lage, zwischen beschädigten und unbeschädigten Pflanzen zu unterscheiden und legten auf letztere mehr Eier ab. Acht Wochen alte Baumwolltopfpflanzen erwiesen sich für die Eiablage als attraktiver als ältere. Unter Wasserstreß (bis zu 7 Tage dauernde starke Bewässerung) stehende Baumwollpflanzen unterschieden sich in der Zahl abgelegter Eier nicht signifikant von normal behandelten. Auf der Grundlage dieser Ergebnisse scheinen für die Eiablage von H. virescens an Baumwolle morphologische Faktoren (Größe, Behaarung) wichtiger zu sein als physiologische (Feuchtigkeits‐ und N‐Gehalt).
The relative attractiveness of velvet leaf (Abutilon theophrasti Medicus), cotton (Gossypium hirsutum L.) (host plants) and groundcherry (Physalis angulata L.) (nonhost plant), and cotton plants with or without nectaries and with or without glands to Microplitis croceipes Cresson (Hymenoptera: Braconidae) was determined in a wind tunnel. Female parasitoids flew significantly more to glandless than to glanded cotton; response to nectaried and nectariless cotton was similar. Velvet leaf and cotton were favored significantly over groundcherry; parasitoids being equally responsive to both host plant species. Addition of larval frass alone or in combination with host larvae significantly improved the attractivity of the nonhost plant (groundcherry) to the parasitoids. There was no difference in attractiveness of groundcherry terminals with or without host larvae. Parasitoid search time was significantly increased with addition of larval frass. In the presence of cotton, however, kairomone-treated groundcherry remained unattractive.
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